HD 123 (HIP 518)
Triple. This system is composed of a 107 year visual-orbit
pair, the secondary of which was shown to be the more massive
component from absolute astrometry (Griffin, 1999Obs...119...27G),
suggesting that it itself was an unresolved binary. Brettman et al.,
1983IBVS.2389....1B reported a periodic variation in the component's
brightness over roughly a 1 day period, which Griffin
(1999Obs...119...27G) later disproved based on Hipparcos photometry
and instead showed it to be a spectroscopic binary with a 47.7 day
period, estimating component masses of 0.98, 0.95, and 0.22M_{sun}_
for the three components.
HD 1237 (HIP 1292)
Binary, one planet. In a systematic search for faint companions to
planet hosts, Chauvin et al. (2006A&A...456.1165C) discovered a CPM
companion to this star using VLT NACO adaptive optics (AO) and
demonstrated orbital motion. Chauvin et al. (2007A&A...475..723C)
characterized the companion as M4+/-1V.
HD 3651 (HIP 3093)
Binary, one planet. Luhman et al. (2007ApJ...654..570L) reported the
discovery of a T7.5+/-0.5 companion 43" away from this planet-host
star using Spitzer Infrared Array Camera (IRAC) images, and confirmed
CPM using 2MASS images. The brown dwarf's infrared colors are
consistent with the distance to the primary, confirming
companionship. They estimate the companion's mass as
0.051+/-0.014M_{sun}_ and age as 7+/-3Gyr by comparing luminosity
with evolutionary tracks. This was the first substellar object imaged
around an exoplanet host. An additional component listed in the WDS
is clearly optical (see Table 6).
HD 4391 (HIP 3583)
Triple. The WDS lists three measurements of a companion with
separations ranging 10.0"-16.6" over 98 years, and we discovered an
additional companion 49" away by blinking archival images (see
Section 3.1.1). Our VRI images, obtained in 2007 July and October at
the CTIO 0.9m telescope, clearly reveal both companions, confirming
CPM. The closer companion was saturated in all but one V-band image,
but the differential photometry extracted from this image allowed
confirmation as a companion (see Table 10). For the newly discovered
wider companion, our absolute VRI photometry along with 2MASS JHKS
magnitudes confirmed a physical association (see Table 5).
HD 4628 (HIP 3765)
Single, candidate Binary. Heintz & Borgman (1984AJ.....89.1068H)
detected a companion, 2.7" away, on 11 exposures over two nights,
but did not see the companion on 164 other plates or on multiple
visual checks with a micrometer. Their two observations about 25 days
apart show evidence of variation in the companion's brightness by
about 1 mag. Heintz (1994AJ....108.2338H) notes an acceleration in
proper motion for the primary and speculates that this might be
caused by the companion reported earlier. Roberts et al.
(2005AJ....130.2262R) did not detect a companion using AO down to
{Delta}I<~10 and note that only a white dwarf companion could have
escaped detection, while the flaring companion as seen by Heintz
should have been detected. Moreover, the Hipparcos and Tycho-2 proper
motions of HD 4628 match to within 2{sigma}, and the INT4
(http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/wds/int4)
lists several null results with speckle interferometry and AO.
B.D.M. and D.R. observed this target using the KPNO 4m telescope in
2008 June, and while the separation was too wide and the {Delta}m too
large for speckle observations, the finder TV showed a faint source
about 5" away at about 230{deg}. Could this be the companion seen by
Heintz after about 30 years of orbital motion? While a possibility,
follow-up observations by Elliott Horch 2 days later with the WIYN
3.6m telescope on KPNO failed to identify the source. Additionally,
5s exposures in VRI taken by T.J.H. at the CTIO 0.9m telescope in
2008 June also failed to identify any companion, although saturation
around the primary could hide the companion in these images. Nidever
et al. (2002ApJS..141..503N) report that the primary shows no
variations in its radial-velocity measurements. At this time, we do
not have sufficient information to confirm or refute this companion,
although, chances of a physical companion appear slim. The wider
component listed in the WDS is clearly optical (see Table 6).
HD 4676 (HIP 3810)
Binary. Boden et al. (1999ApJ...527..360B) presented a visual orbit
based on LBOI observations for this 14 day SB2 and derived component
masses of 1.223+/-0.021M_{sun}_ and 1.170+/-0.018M_{sun}_. Earlier,
Nadal et al. (1979A&AS...35..203N) had speculated on the presence of
a third companion based on temporal changes in the spectroscopic
orbital elements. While this suspected companion has been mentioned
in subsequent literature (Fekel, 1981ApJ...246..879F; Tokovinin et
al., 2006A&A...450..681T), it was refuted by Boden et al.
(1999ApJ...527..360B) based on imaging and spectroscopic evidence.
Two additional components listed in the WDS are clearly optical (see
Table 6).
HD 9826 (HIP 7513)
Binary, three planets. Lowrance et al. (2002ApJ...572L..79L)
discovered an M4.5V companion, 55" away from planet host u And and
confirmed its physical association by demonstrating CPM and showing
that its spectral type is consistent with its magnitudes at the
primary's distance. Two additional components listed in the WDS are
clearly optical (see Table 6).
HD 13445 (HIP 10138)
Binary, one planet. This planet-host star with a 4MJ planet exhibits a
long-term trend in radial velocity, consistent with a stellar
companion beyond 20AU (Queloz et al., 2000A&A...354...99Q). A
significant difference between the Hipparcos and Tycho-2 proper
motions (see Table 8) also suggests a nearby unseen companion. Later
work has resolved this companion and demonstrated orbital motion
(Lagrange et al., 2006A&A...459..955L). The companion was initially
misidentified as a T dwarf (Els et al., 2001A&A...370L...1E) and
later shown to be a white dwarf based on spectroscopy (Mugrauer &
Neuhauser, 2005MNRAS.361L..15M) and a dynamical analysis of
astrometry and radial velocities (Lagrange et al.,
2006A&A...459..955L).
HD 20010 (HIP 14879)
Binary, candidate Triple. The secondary of a 5" CPM pair with a
preliminary visual orbit is listed in the CNS (1969VeARI..22....1G)
as "RV-Var?". Eggen, 1956AJ.....61..405E, mentions that there is a
strong evidence of variability, quoting a 1928 publication by van
den Bos, but this reference could not be found. With insufficient
evidence to confirm or refute a physical association, the additional
companion is retained as a candidate.
HD 20807 (HIP 15371)
Binary. The wide CPM companion, HD 20766, lies 309" away and is
confirmed by matching proper motions and parallax. Additionally,the
WDS lists a single speckle interferometry measure of a companion in
1978, 0.046" away at 11{deg} (Bonneau et al., 1980A&AS...42..185B).
However, Bonneau et al. failed to resolve the companion in 1979 and
da Silva & Foy (1987A&A...177..204D) mention that the 1978 measure
was in fact an artifact in the diffraction pattern of the telescope
spider.
HD 21175 (HIP 15799)
Binary. While this companion only has three ground-based measurements,
they span more than 50 years and are consistent with a bound pair.
The Hipparcos catalog (Cat. I/239) also identifies this star as a
suspected binary because the astrometry did not adequately fit either
a single or binary solution (H59="X"). Soderhjelm
(1999A&A...341..121S) presents a visual orbit combining Hipparcos and
ground-based measures, confirming a physical association.
HD 22049 (HIP 16537)
Single, one planet. This is epsilon Eri, the well-studied exoplanet
host. The WDS lists a single speckle resolution of a potential
stellar companion, 0.048" away (Blazit et al., 1977ApJ...214L..79B),
significantly closer than the planet. However, 13 other attempts by
speckle and AO have failed to resolve the companion (e.g., McAlister,
1978PASP...90..288M; Hartkopf & McAlister, 1984PASP...96..105H;
Oppenheimer et al., 2001AJ....121.2189O). Presumably, the Blazit
measure is spurious. The WDS lists 10 additional components, all of
which were confirmed as optical by blinking archival images (see
Table 6).
HD 23484 (HIP 17439)
Single, candidate Binary. The CNS (1969VeARI..22....1G) lists this as
"RV-Var," but no radial-velocity data could be found in modern
surveys. Catalogs - Abt & Biggs, 1972bsrv.book.....A; Duflot et al.,
1995A&AS..114..269D; Gontcharov, 2006AstL...32..759G - list
velocities with rms scatter of about 3km/s, but this could be due to
measurement errors or zero-point variances. This candidate companion
is retained as a candidate.
HD 24496 (HIP 18267)
Binary. The two measurements with {rho}=2.6-2.7" and
{theta}=254-256{deg} listed in the WDS are by Wulff Heintz, nine
years apart and consistent with a bound pair. The first measure is
based on observations over three nights and the second on
observations over two additional nights. Given the quality of the
observations ({Delta}m=4-5 measured) and the reasonably high proper
motion of the primary, this is likely a physical companion, but one
that could use new measurements.
HD 25680 (HIP 19076)
Binary. A companion 0.2" away was discovered by McAlister et al.,
1993AJ....106.1639M, with speckle interferometry and confirmed by the
same technique by Hartkopf et al., 2008AJ....135.1334H. These
measures show evidence of orbital motion, and given the 0.2"/yr
proper motion of the primary and an elapsed time of 15 years between
them, this companion can be confirmed as physical. Due to the
constant radial velocity of the primary (D. W. Latham et al.,
2010, in preparation), this might be close to a face-on orbit. The
WDS (Cat. B/wds) lists another potential companion 177" away, which
we also identified by blinking archival images. This candidate
(HIP 19075) was however refuted based on its significantly different
proper motion in Hipparcos (Cat. I/239) from the corresponding value
of the primary (see Table 4). The two additional WDS entries are
clearly optical (see Table 6).
HD 26491 (HIP 19233)
Binary. A comparison of Hipparcos and Tycho-2 proper motions shows a
significant difference suggesting a companion (see Section 3.2.2),
which is confirmed by radial-velocity variations (Jones et al.,
2002MNRAS.337.1170J). A preliminary spectroscopic orbit exists (H.
Jones, 2008, private communication).
HD 32923 (HIP 23835)
Single. The WDS lists 19 measurements at roughly 0.1" separation over
76 years, and Eggen (1956AJ.....61..405E) even derived two
preliminary visual orbits from these measures. However, Heintz &
Borgman (1984AJ.....89.1068H) suggest that this is likely spurious
and show that the observations are not consistent with orbital motion
of any period. Three additional speckle observations exist since the
Heintz & Borgman publication, from 1984 to 1987 (Tokovinin,
1985A&AS...61..483T; Tokovinin & Ismailov, 1988A&AS...72..563T;
McAlister et al., 1993AJ....106.1639M), but there are 17 null
detections listed in the INT4
(http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/wds/int4)
by speckle interferometry as well as by AO. This star has a stable
radial velocity in Nidever et al. (2002ApJS..141..503N) and D. W.
Latham et al. (2010, in preparation). It appears that these multiple,
but sporadic, measures are spurious.
HD 35296 (HIP 25278)
Binary. DM91 (1991A&A...248..485D) noted the primary of a 12' CPM pair
as "SB", but one that was not confirmed by their work. Modern
measures (Nidever et al., 2002ApJS..141..503N; D. W. Latham et al.,
2010, in preparation) show this star to have a stable radial
velocity, refuting the earlier claim.
HD 36705 (HIP 25647)
Quadruple. The WDS lists two measures of this 10" pair (AB Dor AB),
separated by 69 years and consistent with a bound pair. The first
observation, by Rossiter (1955POMic..11....1R), measured a
{Delta}m~6, explaining the lack of many more observations. Close et
al. (2005Natur.433..286C) recovered this pair with AO at the VLT, and
it is also seen in VRI images obtained by T.J.H. in 2008 September at
the CTIO 0.9m telescope. While the photometric distance estimate
varies from the primary's Hipparcos distance by 7{sigma} (see
Table 10), the V magnitude from Rossiter (1955POMic..11....1R) is
likely approximate. Given the high proper motion of the primary, the
consistent measures over 79 years indicate a physical association.
The 2MASS colors indicate an M dwarf with a V magnitude estimate of
about 12.0, in good agreement with the measure of Rossiter
(1955POMic..11....1R) and consistent with the primary's Hipparcos
distance. High-contrast AO efforts have split each of these
components into binaries themselves. The primary was identified by
Hipparcos as showing accelerating proper motion, indicating an unseen
companion, and this is supported by the significant difference
between Hipparcos and Tycho-2 proper motions (see Section 3.2.2). The
suspected companion has since been revealed by very long baseline
interferometry (Guirado et al., 1997ApJ...490..835G), resolved by AO
(Close et al., 2005Natur.433..286C), and confirmed as a physical
association by photometry and spectroscopy (Close et al.,
2005Natur.433..286C, 2007ApJ...665..736C; Boccaletti et al.,
2008A&A...482..939B, and references therein). Close et al.
(2005Natur.433..286C) also split the secondary into a 0.070" pair,
which was later confirmed by Janson et al. (2007A&A...462..615J)
who measured it 66.1 mas away at 238.5{deg}.
HD 40397 (HIP 28267)
Triple. The five measures in the WDS for AB between 1902 and 1932 are
consistent with a bound pair. The measured {Delta}m~7 makes this a
difficult target for classical techniques and out of the reach of
speckle interferometry. Given that more than 70 years have passed
since the latest measure, this is a good candidate for follow-up AO
observations. This pair also has a wide CPM companion, NLTT 15867,
which was confirmed by photometric distance estimates (see Table 10),
and an additional WDS component, which is clearly optical (see Table
6).
HD 43834 (HIP 29271)
Binary. Eggenberger et al. (2007A&A...474..273E) detected a companion,
3" away, three times over three years with AO at the VLT,
demonstrating CPM and showing a hint of orbital motion. They also
mention a linear trend in CORALIE radial velocities consistent with
this companion, confirming a physical association, and estimate the
companion to be M3.5-M6.5 with a mass of 0.14+/-0.01M_{sun}_.
HD 45270 (HIP 30314)
Single, candidate Binary. The WDS lists three measurements spanning 43
years of a {Delta}m~4 companion separated by about 16", which are
consistent with a bound pair. Curiously, no additional measurements
exist. This companion was listed in the Hipparcos input catalog, but
not resolved by Hipparcos. 2MASS lists a source near this candidate
companion, but it is clearly not the same star because its infrared
colors are more than 3 mag fainter than the visual magnitude of 10.6
from the Hipparcos input catalog. No additional information was found
on this companion and hence it is retained as a candidate.
HD 48189 (HIP 31711)
Binary. The WDS lists 19 measurements over 105 years that are
consistent with a bound pair. During this time, the separation has
closed in from about 3" to about 0.3" and the position angle has
changed by about 15{deg}. Given the small projected separation of
6-60AU, one might expect a greater change in position angle as
evidence of orbital motion. The change of only 15{deg} indicates that
the semimajor axis is larger than the observed separations, perhaps
due to a high inclination. While a more robust confirmation is not
available, the primary has moved about 9" during the measures, and
the companion seems to be moving along with it, indicating a physical
association.
HD 0 (HIP 36357)
Triple, candidate Quadruple. The primary of this system, HD 58946,
lies about 13' away, and its physical association is confirmed by
matching parallax and proper motion. The primary has a closer
companion, about 3" away, confirmed by greater than 11{sigma}
difference between Hipparcos and Tycho-2 proper motions (see Table 8)
and five measurements in the WDS over 25 years which demonstrate CPM
and orbital motion. Additionally, proper-motion variations suggest an
unseen companion to HIP 36357 as well, but one we could not confirm
(see Table 8). Two wider WDS components are clearly optical (see
Table 6).
HD 64606 (HIP 38625)
Binary. For the primary of an SB1 pair, the WDS lists two measures of
a {Delta}m~4 component separated by 4.9", one each from Hipparcos and
Tycho. The Hipparcos solution is flagged as "poor" quality, and there
is no independent confirmation of this companion. T.J.H. observed
this star using the CTIO 0.9m telescope in 2008 September and
obtained 1s exposure images in VRI. No source was found at the
expected position in those images, whereas a companion of {Delta}m~4
should easily have been seen above the background. While the SB1
pair is real, this astrometric detection is refuted.
HD 65907 (HIP 38908)
Triple. LHS 1960 is a companion to this star, separated by about 60",
and confirmed by photometric distance estimates (see Table 5). The
WDS (Cat. B/wds) lists four measures of an additional companion to
LHS 1960, observed 1930-1983, indicating that this component itself
is a 3" CPM binary. No further evidence of companionship could be
found, but given the high proper motion of the primary and the four
consistent measurements by four different telescopes over 53 years,
this system can be confirmed as a triple.
HD 68257 (HIP 40167)
Quintuple, candidate Sextuple. The three brightest roughly solar-type
components ({zeta} Cancri A, B, and C) are supported by over 1000
visual measurements each, corresponding to two visual orbits.
Component C has been noted to have an irregular motion for most of
its history and was identified as an SB1 with an orbit of 6302+/-59
days (Griffin, 2000Obs...120....1G), consistent with earlier
astrometric orbits. However, earlier efforts (Heintz,
1996AJ....111..408H) had noted a mass ratio for the C component
binary of about 1, and with C being a G0 star, the non-detection was
puzzling and attributed to the companion being a white dwarf or
itself a binary. Hutchings et al., (2000PASP..112..833H) finally
observed this pair (Ca, Cb) via AO observations at infrared
wavelengths, designated Cb as an M2 dwarf based on its infrared
colors, and argued on the basis of prior mass-ratio estimates that
it itself is an unresolved binary (Cb1, Cb2). Richichi
(2000A&A...364..225R) confirmed the presence of Cb via lunar
occultation measures. While he could not confirm its binary nature,
his K-band photometry supported the binary M-dwarf hypothesis, for
which he determined an upper limit for projected separation of
20-30mas. Further, Richichi reported the potential discovery of a
sixth component in this system (Cb3). While seen just above his
detection limit and hence retained as a candidate for this work, he
nonetheless confirmed its presence by three independent data analysis
methods and excluded it from being the unresolved companion Cb2 noted
above due to its larger separation of at least 1.6AU from the lunar
occultations. He tentatively identified Cb3 as an M2-M4 dwarf. In
addition to all these, we identified a potential wide companion, 372"
away at 107{deg}, which was later refuted (see Table 4), as were six
additional WDS components, which are clearly optical (see Table 6).
HD 72760 (HIP 42074)
Binary. This companion was suggested by a significant difference in
Hipparcos and Tycho-2 proper motions. Recently, Metchev &
Hillenbrand (2009ApJS..181...62M) resolved the companion in a
Palomar/Keck AO survey, confirmed companionship based on color and
magnitude measurements, and estimated the companion's mass as
0.13M_{sun}_.
HD 73350 (HIP 42333)
Single. The WDS lists a B component 60" away and a C component about
10" from B. While the DSS images were taken over just a two-year
interval, the SSS image provides a longer time baseline and helps
confirm component B (HD 73351) as a field star (see Table 6).
Component C is a CPM companion of B based on three consistent
measures separated by over 100 years, and hence also physically
unassociated with our sample star.
HD 73752 (HIP 42430)
Binary. The CNS (1969VeARI..22....1G) lists the primary of the 1.3"
visual binary as "SB" and notes that there are suspected
perturbations in its proper motion. The reference detailing the
perturbations (Hirst, 1943MNSSA...2..100H) presents a 35 year inner
orbit, which is noted as very preliminary with several different
orbits equally permissible. The author also states that systematic
effects alone may explain the residuals. His 214 year outer orbit was
later revised to 145 years by Heintz (1968AJ.....73..512H), who also
points out that the observed range of radial velocities could be
ascribed to scatter. Adopting a parallax of 0.058", he derived a mass
sum of 1.1M_{sun}_, and noted that at least one component must be
overluminous. If we adopt the HIP parallax of 50.2mas, we get a mass
sum of 1.9M_{sun}_, so the components are likely not overluminous.
Radial-velocity catalogs (Abt & Biggs, 1972bsrv.book.....A;
Gontcharov, 2006AstL...32..759G) list velocities in the range
40-48km/s, but the differences could be due to zero-point offsets
between observers. The early claim of a possible companion is not
supported by subsequent observations, which in fact question it.
While the visual binary is real, the third component is refuted. An
additional wide component listed in the WDS is clearly optical (see
Table 6).
HD 75767 (HIP 43557)
Quadruple. Tokovinin et al. (2006A&A...450..681T) reported the
discovery of a wide {Delta}m=4.3 companion to a 10.3 day SB1 binary
with NACO AO and confirmed CPM using a partial resolution in 2MASS
images. This companion was independently discovered by Fuhrmann et
al. (2005MNRAS.361..803F), who obtained two observations four years
apart, demonstrating CPM, and confirmed companionship by showing
consistent radial velocity with the primary. Their spectra also
enabled them to identify the companion itself as a double-lined
binary, as evidenced by its H{alpha} emission and near-infrared
absorption lines appearing as pairs with an offset of about 21km/s.
Using composite-spectrum analysis, they derived spectral types of M3
and M4. Blinking archival images revealed a possible fifth companion
385" away, and its photometric distance estimate matches the
primary's Hipparcos value within 2{sigma}. However, the Lepine &
Shara (2005AJ....129.1483L) proper motions of the two stars are
significantly different, indicating that this might be a comoving
star perhaps born out of the same cloud as HD 75767, but one that is
not gravitationally bound to it.
HD 79096 (HIP 45170)
Quadruple. Wilson et al. (2001AJ....122.1989W) discovered an L8V
companion (Gl 337C) 43" from the SB2VB pair from 2MASS images. The
two images, separated by 2.5 years, demonstrated CPM. They also
showed that the magnitudes are consistent with the primary's
distance to within 1{sigma}, confirming companionship. Burgasser et
al. (2005AJ....129.2849B) later resolved Gl 337C as a nearly
equal-magnitude binary separated by 0.53+/-0.03" at 291+/-8{deg}
using Lick natural guide star AO. Companionship was confirmed based
on proximity and CPM, which was demonstrated by the absence of a
source in 2MASS images at the expected position of a background star.
Three other components listed in the WDS are clearly optical (see
Table 6).
HD 86728 (HIP 49081)
Binary, candidate Triple. Gizis et al. (2000MNRAS.311..385G)
identified a wide CPM companion from 2MASS and confirmed it with a
spectral-type classification of M6.5. However, based on it being
overluminous (MK=8.19 using 2MASS magnitudes and Hipparcos parallax
versus 9.60 for its spectral type) and having high activity (emission
observed twice), they argued that it is an unresolved equal-mass
binary, or even possibly a triple. We could not find any follow-up
work confirming or refuting this claim, so while this system is
confirmed as a binary, we retain the third component as a candidate.
Additionally, the Dwarf Archives lists a brown dwarf about 25' away
from the primary, but its photometric distance estimate suggests a
distant field object.
HD 90839 (HIP 51459)
Binary, candidate Triple. The CNS (1969VeARI..22....1G) lists the
primary of a wide CPM pair as "SB?" and the secondary (HD 237903,
GJ 394) as "RV-Var". The primary is a constant velocity star (see
Table 12), refuting the CNS claim, but the modern surveys did not
observe the secondary. DM91 (Duquennoy & Mayor, 1991A&A...248..485D)
listed this companion with a constant velocity of 8.24-8.62km/s over
700 days. Heintz (1981ApJS...46..247H) listed velocities of
7.7-8.4km/s over 4 days but noted that the coverage was too weak to
definitively show velocity variations. He also noted that the
spectrum had emission features. Wilson (1967AJ.....72..905W) listed a
velocity of 7.8km/s over three plates with a range of 7.7km/s and
standard deviation of 3.1km/s. Radial-velocity catalogs (Abt &
Biggs, 1972bsrv.book.....A; Duflot et al., 1995A&AS..114..269D) list
values that range over many km/s, but this could be due to zero-point
differences between observers, and these catalogs do not note any
variation. While the wide binary is confirmed based on matching
parallax and proper motion and the primary's SB claim is refuted, the
possible radial-velocity variation of the secondary is inconclusive
and hence retained as a candidate. An additional WDS component is
clearly optical (see Table 6).
HD 97334 (HIP 54745)
Triple. Kirkpatrick et al. (2001AJ....121.3235K) discovered an L4.5V
CPM companion (Gl 417B) 90" away at 245{deg} from the primary using
2MASS images and confirmed a physical association by demonstrating
CPM and consistent parallaxes. Bouy et al. (2003AJ....126.1526B)
later resolved this brown dwarf into a binary (0.070+/-0.0028" at
79.6+/-1.2{deg}) using HST WFPC2. While companionship of this pair
has not been established conclusively, proximity argues for a
physical association. Three additional WDS components are clearly
optical (see Table 6).
HD 98230 (HIP 55203)
Quadruple. {xi} UMa is a quadruple system composed of a 60 year
visual binary, the primary of which is an SB1VB and the secondary is
an SB1. Mason et al. (1995AJ....109..332M) reported a possible fifth
companion detected via speckle interferometry near the secondary.
While the single detection reported is quite convincing, this
companion has never again been seen, despite multiple attempts. Our
efforts with CHARA, while limited to {Delta}K<~2.5, also failed to
resolve any additional components. Given only one measure and about a
dozen null results with the same technique, this new companion is
likely a chance alignment of an unrelated star. An additional wide
component listed in the WDS is clearly optical (see Table 6).
HD 100180 (HIP 56242)
Binary, candidate Triple. The primary of the 15" CPM binary (see
Table 5) has two speckle interferometry measurements of a close
companion in the WDS (Cat. B/wds), observed 0.035" away at 6.8{deg}
in 2001 and 0.122" at 355.8{deg} in 2004. One of the two attempts by
B.D.M. and D.R. at the KPNO 4m telescope in 2008 June resulted in an
"uncertain" measure of 0.218" at 14.6{deg}. Given the 0.378"/yr
proper motion of the primary, these measures are consistent with a
bound pair, but further observations are warranted to obtain a
definitive confirmation, especially given the constant radial
velocity reported by Nidever et al. (2002ApJS..141..503N).
HD 100623 (HIP 56452)
Binary. The WDS lists only a single measure of this large {Delta}m
companion discovered by Luyten in 1960. While the proximity and large
magnitude difference make follow-up observations difficult, Henry et
al. (2002AJ....123.2002H) obtained spectra of this 15th magnitude
companion and showed that it is a DC or DQ white dwarf, not an
M-dwarf as reported in the CNS (1969VeARI..22....1G). The second
observation confirms CPM, and the spectral type and photometry are
consistent with a physical association.
HD 102365 (HIP 57443)
Binary. The companion, discovered by Luyten in 1960, is LHS 313 and
has a proper motion that matches the primary's 1.6"/yr. Hawley et
al. (1996AJ....112.2799H) identified the companion as M4V, which was
recovered by 2MASS at a similar position angle and separation as
Luyten's observation. Its infrared colors are consistent with an M4
dwarf at the primary's distance.
HD 103095 (HIP 57939)
Single. The CNS (1969VeARI..22....1G) and DM91 (Duquennoy & Mayor,
1991A&A...248..485D)listed a companion with separation 2" at
175{deg}. DM91 noted that the companion was flaring with magnitudes
of 8.5-12 and also mentioned that it was normally not seen. The INT4
(http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/wds/int4)
lists four null measurements with speckle interferometry and there
are no radial-velocity variations. Three attempts by B.D.M. and D.R.
in 2008 June at the KPNO 4m telescope failed to identify a companion.
Recently, Schaefer et al. (2000ApJ...529.1026S) have shown that the
brightness enhancements observed are likely due to superflares on the
stellar surface rather than due to a companion.
HD 109358 (HIP 61317)
Single. The WDS (Cat. B/wds) lists a single speckle measure of a
companion 0.1" away (Bonneau & Foy, 1980A&A....86..295B), but the
INT4 has over 20 null speckle detections. B.D.M. and D.R. failed to
resolve the suspected companion in 2008 June at the KPNO 4m
telescope. Given the mention of telescope artifacts as being
responsible for some detections by this observer (da Silva & Foy,
1987A&A...177..204D), we side with the many null detections,
including one by the same observer. Additionally, the CNS (Gliese,
1969VeARI..22....1G)listed this star as "SB" and Abt & Levy
(1976ApJS...30..273A) presented a preliminary orbital solution.
However, those claims were subsequently refuted (Morbey & Griffin,
1987ApJ...317..343M). The wide AB pair in the WDS is clearly optical,
as seen on blinking the archival images (see Table 6).
HD 111312 (HIP 62505)
Binary, candidate Triple. This is a 2.7 year SB2. The WDS lists a
single speckle measure with a separation of 0.089" at 90.6{deg} in
2001 and the pair was seen again in 2006 with a separation of 0.050"
at 44.6{deg} by B.D.M. These measurements are consistent with the
spectroscopic binary and more observations are needed to develop a
visual orbit. The WDS (Cat. B/wds) lists an additional companion,
2.7" away with {Delta}m~4 based on Hipparcos and Tycho measures. The
Hipparcos solution is flagged as "poor" quality, and there is no
independent confirmation of this companion. Its orbital period, if
real, would be too long to affect the velocities obtained over some
seven years. With no conclusive evidence to confirm or refute this
companion, it is retained as a candidate requiring further
observations.
HD 112758 (HIP 63366)
Triple. This is a triple system with an inner SB1 pair and a wider
visual component which was first resolved by van den Bos in 1945 and
then again in 1960 with {Delta}m~5. McAlister et al.
(1987AJ.....93..688M) recovered this visual companion in 1983, and
the three observations show evidence of orbital motion. The McAlister
et al. measurement with speckle interferometry implies {Delta}m<~3,
suggesting that the companion may be variable. B.D.M. and D.R.
attempted to resolve this companion at the KPNO 4m telescope in 2008
June, but could not see it, perhaps because of the large magnitude
difference.
HD 113449 (HIP 63742)
Binary. Hipparcos presents a photocentric orbit for this star with a
period of about 231 days. Moore & Paddock (1950ApJ...112...48M) noted
this star as a radial-velocity variable, Gaidos et al.
(2000AJ....120.1006G) mentioned that the velocity changed by 20km/s
over 10 months, and variations are also seen in the measurements
reported in D. W. Latham et al. (2010, in preparation). However, no
definitive orbit exists. The companion was resolved at the Palomar
200 inch telescope with aperture masking in 2007 January,
35.65+/-0.6mas away at 225.2+/-0.5{deg} with {Delta}H~1.6, and
confirmed at the Keck telescope more than a year later (M. Ireland,
2008, private communication). With consistent astrometric and
spectroscopic evidence, this is a bound pair.
HD 120136 (HIP 67275)
Binary, one planet. {tau} Boo hosts a 4.13MJ minimum-mass planet in a
3 day orbit. Additionally, 56 observations over 170 years in the WDS
confirm a stellar companion based on CPM and orbital motion, which
has a preliminary orbital solution (see Table 11). Wright et al.
(2007ApJ...657..533W) and references therein mention a long-term
drift in radial velocity consistent with this visual companion.
HD 120780 (HIP 67742)
Triple. The WDS lists two measures of a 6" pair 51 years apart and
consistent with a bound system, but follow-up observations have been
difficult due to a magnitude difference of ~5.5. We obtained I-band
images in 2006 July and 2007 June at the CTIO 0.9m telescope. The
companion was seen at both epochs about 5.6" away at 89{deg} with
{Delta}I~3.3. These three observations demonstrate CPM with a
fast-moving primary (0.6"/yr), and, in fact, hint at orbital motion,
confirming companionship. Additionally, Hipparcos identifies this
star as an accelerating proper-motion binary, and the Tycho-2 proper
motion differs from the Hipparcos value by a 19{sigma} significance
(see Table 8). While the Tycho-2 proper motion, averaged over about
100 years, is no doubt affected by the wide pair mentioned above,
whose orbital period could be about 1000 years, the Hipparcos
observations are over some three years and indicate a closer
companion.
HD 124850 (HIP 69701)
Single, candidate Binary. The ORB6 catalog
(http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/wds/orb6)
lists a photocentric orbit for this star with a period of 55 years
and an inclination of 60{deg}. The corresponding preliminary orbit
was recently presented by Gontcharov & Kiyaeva (2010NewA...15..324G)
by combining Hipparcos data with astrometric ground-based
observational catalogs, but we do not find the motion convincing
enough to confirm the companion. This star was not included in the
Nidever et al. (2002ApJS..141..503N) or D. W. Latham et al. (2010,
in preparation) survey, and radial-velocity catalogs (Abt & Biggs,
1972bsrv.book.....A; Duflot et al., 1995A&AS..114..269D; de Medeiros
& Mayor, 1999A&AS..139..433D; Gontcharov, 2006AstL...32..759G) do not
indicate variations. B.D.M. and D.R. could not resolve any companion
via speckle interferometry on the KPNO 4m telescope in 2008 June.
With inconclusive evidence to confirm or refute this companion, it is
retained as a candidate.
HD 125276 (HIP 69965)
Single, candidate Binary. The Hipparcos and Tycho-2 proper motions
differ by greater than a 3{sigma} significance, suggesting an unseen
companion (see Table 8). These proper-motion variations could be due
to a WDS and CNS companion, separated by 3"-8" over four measures
between 1891 and 1936. Some of these measures indicate a {Delta}m~8,
which might explain the several non-detections also included in the
WDS. An attempt by B.D.M. and D.R. at the KPNO 4m telescope in 2008
June could not detect this companion. While the pair is too wide and
too high in contrast for detection via speckle, the finder TV,
sensitive to faint companions, did not reveal any source at the
expected position. Without conclusive evidence to confirm or refute
this companion, it is retained as a candidate. An additional WDS
companion is clearly a background star as seen by blinking archival
images (see Table 6).
HD 125455 (HIP 70016)
Binary. This companion was discovered by Kuiper in 1937 and has
measurements in 1960 and 1987 that are consistent with a bound
system. The companion is LHS 2895 with a proper motion that matches
the primary's, and its 2MASS colors indicate a late M-dwarf at
approximately the primary's distance.
HD 128620 (HIP 71683)
Triple. This is the closest known star system, {alpha} Centauri, which
is composed of an SB2VB pair and a wide companion, Proxima Centauri,
about 2{deg} away. While the angular separation to Proxima is extreme
for bound systems, it translates to a linear projected separation of
10000AU, which is well within the limits of gravitationally bound
pairs. Wertheimer & Laughlin (2006AJ....132.1995W) used kinematic and
radial-velocity data to show that Proxima Centauri is bound to
{alpha} Centauri. A possible new substellar companion to Proxima
Centauri was reported by Schultz et al. (1998AJ....115..345S) 0.34"
away using the HST FOS as a coronagraphic camera. In a follow-up
effort, Golimowski & Schroeder (1998AJ....116..440G) used HST WFPC2
to show that the Faint Object Spectrograph (FOS) feature seen was
likely an instrumental effect and exclude any stellar or substellar
companion within 0.09"-0.85" of Proxima Centauri.
HD 130948 (HIP 72567)
Triple. Potter et al. (2002ApJ...567L.133P) discovered a pair of brown
dwarf companions using AO on the Gemini North 8m telescope. They
demonstrated CPM with observations over 7 months and confirmed
companionship based on their infrared colors, spectral-type of
dL2+/-2, and a consistent age with the primary of less than 0.8Gyr
derived by comparing their position on an H-R diagram with
theoretical models. They also noted that the relative youth is
consistent with the high X-ray activity, Li abundance, and fast
rotation. The Dwarf Archives lists an additional brown dwarf 523"
away from the primary, but its photometric distance estimate
suggests a distant field object. An additional CNS (Gliese W.,
1969VeARI..22....1G) claim of an SB companion was refuted by modern
surveys (see Table 12).
HD 135204 (HIP 74537)
Binary. A companion, 0.1" away, is listed in the WDS and CNS (Gliese
W., 1969VeARI..22....1G) and confirmed by the 17 measurements in the
WDS (Cat. B/wds) over 82 years which not only demonstrate CPM, but
also orbital motion.
HD 137107 (HIP 75312)
Triple. Kirkpatrick et al. (2001AJ....121.3235K) discovered a wide L8V
companion (Gl 584C) to the SB2VB binary using 2MASS images and
confirmed the physical association with additional measures and
spectroscopy. Two additional WDS components are clearly optical (see
Table 6).
HD 137763 (HIP 75718)
Quadruple. The primary of a 52" CPM binary is itself SB2, and also has
a wide companion about 20' away that was first mentioned by CNS
(Gliese W., 1969VeARI..22....1G) and confirmed by a spectral-type
identification of M4.5 and a distance estimate of 21.6+/-1.9pc
(Reid et al., 1995AJ....110.1838R). Another wide WDS (Cat. B/wds)
component is clearly optical (see Table 6).
HD 140901 (HIP 77358)
Binary. The WDS lists seven measures for this companion from 1897 to
1960 which are consistent with a bound system. We obtained VRI images
at the CTIO 0.9m telescope in 2006 July and 2007 July, which reveal
the companion at the expected position, confirming CPM. The magnitude
difference of over six makes photometry difficult, but given the
large matching proper motion and proximity, this companion can be
confirmed as physical. An additional WDS component is clearly
optical, as seen when blinking the archival images (see Table 6).
HD 141272 (HIP 77408)
Binary. The WDS lists four micrometer observations of this pair over
56 years that are consistent with a bound system. Eisenbeiss et al.
(2007AN....328..521E) confirm companionship using photometry and
spectroscopy, and derive an estimated mass for the dM3+/-0.5
companion of 0.26^+0.07^_-0.06_M_{sun}_.
HD 143761 (HIP 78459)
Single planet-host or binary with no known planets. {rho} CrB
definitely has a companion, but it is not clear whether it is
planetary or stellar in nature. Hipparcos identified a photocentric
orbit with a period of 78 days, exactly twice that of the planetary
companion reported by Noyes et al. (1997ApJ...487L.195N). Gatewood et
al. (2001ApJ...548L..61G) used Hipparcos and ground-based
observations to conclude that the photocentric orbit is of the same
period as the planet, and in fact the "planet" is an M-dwarf
companion with a mass estimate of 0.14M_{sun}_ in a nearly face-on
orbit. Bender et al. (2005AJ....129..402B) failed to identify such a
companion using high-resolution infrared spectroscopy, and placed an
upper limit on the companion's mass of 0.11-0.15M_{sun}_. Baines et
al. (2008ApJ...682..577B) attempted to resolve this question with
LBOI observations at the CHARA Array, and could not settle the issue
once again. While interferometric visibilities did not perfectly fit
a single-star solution, additional data are required for a definitive
conclusion. This system has a stellar or planetary companion, but not
both. Further observations are warranted. A WDS component is clearly
optical (see Table 6).
HD 144284 (HIP 78527)
Binary. Mazeh et al. (2002ApJ...564.1007M) presented a 3 day SB2 orbit
for this star using infrared spectroscopy to measure the faint
companion, deriving a mass ratio of 0.380+/-0.013. Mayor & Mazeh
(1987A&A...171..157M) had identified this system as a possible triple
based on a 1.7km/s variation in the velocity semiamplitude between
their solution and that of Luyten (1936ApJ....84...85L). While the
velocity semiamplitude does seem to vary for the different orbital
solutions presented for this pair (Luyten, 1936ApJ....84...85L; Mazeh
et al. 2002ApJ...564.1007M; DM91 (Duquennoy & Mayor,
1991A&A...248..485D)) and the D. W. Latham et al. (2010, in
preparation) SB1 orbital solution has residuals of up to 2km/s on
each side, there is no obvious periodic pattern or long-term drift
over the 4.8 years of velocity coverage. The most recent velocity
measure of this star in D. W. Latham et al. (2010, in preparation) is
from 1990, so additional observations are warranted.
HD 144579 (HIP 78775)
Binary. The proper motion of the primary is 0.574"/yr and of the CPM
candidate is 0.550"/yr from the LSPM. The companion's distance
estimate has a large uncertainty and differs from the primary's
Hipparcos value by 1.5{sigma} (see Table 5). Given the proximity of
these two stars in the sky, the very large and similar proper
motions, and similar distances, this appears to be a physical
companion, as it has been previously recognized (DM91,
1991A&A...248..485D; CNS, Gliese W., 1969VeARI..22....1G). The
differences in the proper motions might indicate that the companion
or the primary has a close unresolved companion and warrants further
observations.
HD 145958 (HIP 79492)
Binary, candidate Triple. The primary of a 4" visual binary has two
additional possible companions, one of which was refuted by this
effort and the other remains a candidate. The WDS lists a nearby
companion, 0.2" away, detected by H.A.M. in 1983. The INT4 catalog
(http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/wds/int4)
lists this as a weak detection and possibly spurious, and includes a
null detection using the same technique. B.D.M. and D.R. failed to
resolve a companion at the KPNO 4m telescope in 2008 June. Nidever et
al. (2002ApJS..141..503N) identify this as a constant velocity star.
Evidence seems to be mounting against this candidate companion, which
is considered refuted for this work. Separately, the Dwarf Archives
includes a T6 object about 27' away from this star. Looper et al.
(2007AJ....134.1162L) discovered this T dwarf in the 2MASS survey,
obtained spectra, typing it as T6, and estimated its proper motion
and distance, but did not suggest an association with HD 145958.
Their proper motion and distance estimates are similar to the
primary's corresponding values from van Leeuwen, 2007A&A...474..653V.
While the projected linear separation is very large at about 40000AU,
this could be a loosely bound companion to HD 145958, and is
retained as a candidate. An additional wide component listed in the
WDS (Cat. B/wds) is clearly optical (see Table 6).
HD 146361 (HIP 79607)
Quintuple. See Raghavan et al. (2009ApJ...690..394R) for a
comprehensive treatment of all components of this system.
HD 147776 (HIP 80366)
Binary, candidate Triple. The WDS (Cat. B/wds) lists three candidate
companions, but the details actually correspond to four stars. The
{Delta}m~4 component 103" away at 281{deg} is clearly a field star,
as seen by blinking the archival images (see Table 6). Three
additional companions were reported by Sinachopoulos
(1988A&AS...76..189S) - 6.4" separation at 173{deg} with {Delta}m~3,
9.7" separation at 14{deg}, and 71.9" separation at 28{deg}. The
latter two components do not have differential-magnitude
measurements. Sinachopoulos measured these pairs using a 1.5m
telescope by combining 4-16 exposures of a few seconds each. The wide
companion 72" away should have been seen in the DSS images, but no
stellar source was seen at the expected position. The closest star to
this position in the 1995 DSS image is 83" away at 15{deg} and is
clearly a field star. The other two sources seen by them would be
buried in the saturation around the primary in the DSS images, so we
obtained VRI frames in 2008 May and August at the CTIO 0.9m
telescope. The images clearly show a faint companion about 9" away at
19{deg}. This is likely the 9.7" companion seen by Sinachopoulos
(1988A&AS...76..189S), exhibiting CPM, and given the proximity, is
likely physical. The closest source seen by Sinachopoulos is not
detected in the CTIO images and remains a candidate. Additionally,
the CNS (Gliese W., 1969VeARI..22....1G) lists a companion for this
star 3" away at 281{deg} in 1909. This is likely the same as the
component measured by Burnham as listed in the WDS, which was seen
103" away at 281{deg} in 1909 and as discussed above, is clearly
optical.
HD 148704 (HIP 80925)
Binary. This is a 32 day SB2 binary for which Hipparcos and Tycho
identified another companion 4.1" away at 221{deg}. Our CTIO 0.9m
images obtained in 2008 October do not reveal any companion at the
expected position, while a {Delta}m~3 companion as indicated by
Hipparcos should have been seen above the tail of the primary's
point-spread function (PSF). However, given the proper motion of the
primary, a field star would have moved closer and possibly could be
buried within the primary's PSF. Gray et al. (2006AJ....132..161G)
list the spectral type of the companion as G9V and its coordinates
imply a separation of 2.4" at 55{deg}, the exact position where a
field star would be 15 years since the Hipparcos measure. The Gray et
al. spectral type, along with the Tycho-2 V=10.5, implies a
significantly larger distance to this star compared to the primary,
enabling us to refute this candidate.
HD 149806 (HIP 81375)
Binary. This companion was first reported by Rossiter
(1955POMic..11....1R) 5.9" away at 22{deg} and has two additional
measurements in the WDS (Cat. B/wds) over the next 54 years, which
are consistent with a bound system. While the photometric distance
estimate is not a good match (see Table 10), the R magnitude listed
is likely approximate. Given the moderate proper motion of the
primary, the consistent measures over 54 years indicate a physical
association. The 2MASS colors indicate an M-dwarf with a V magnitude
estimate of about 12, in fair agreement with the measure of Rossiter
(1955POMic..11....1R). B.D.M. and D.R. attempted to observe this
companion at the KPNO 4m telescope in 2008 June. While the separation
and {Delta}m are too large to be resolved using speckle, the finder
image at the telescope showed a source at the expected position with
a {Delta}m similar to those of prior observations.
HD 153557 (HIP 83020)
Triple. The WDS (Cat. B/wds) lists 17 measurements over 95 years with
separations of 1.9"-4.9", which are consistent with a bound system,
and given the 0.3"/yr proper motion of the primary, imply a physical
association. This pair also has a wider companion, HD 153525, about
2' away, which is confirmed by matching proper motion and parallax.
HD 165341 (HIP 88601)
Binary. CNS (Gliese W., 1969VeARI..22....1G) lists component A of an
88 year SB2VB as a possible binary with a period of about 17 years,
but this is inconsistent with modern measurements (D. W. Latham et
al. 2010, in preparation). Heintz (1988JRASC..82..140H) presented a
revised orbit of the SB2 and excluded the possibility of any
additional companions with periods below 55 years, stating that the
once suspected velocity variation of A is disallowed by the more
precise recent measurements. The WDS lists 15 more components for
this star, all of which are clearly optical (see Table 6).
HD 165908 (HIP 88745)
Binary, candidate Triple. This is a 56 year visual binary orbit.
Additionally, the WDS (Cat. B/wds) lists one speckle measure with a
separation of 0.228" at 50.2{deg} from Scardia et al.
(2008AN....329...54S), who list this new discovery as "faint". They
also resolved the known VB companion about 1" away, and noted it as
"very faint." In the absence of additional measures that can help
confirm CPM, this close companion is retained as a candidate. Five
other components listed in the WDS are clearly optical (see Table 6).
HD 178428 (HIP 93966)
Binary. The primary of a 22 day SB1 has a single 1987 measure listed
in the WDS (Cat. B/wds) with a separation of 0.2". However, the INT4
(http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/wds/int4)
lists six null results and attempts by B.D.M. and D.R. at the KPNO 4m
telescope in 2008 June once again failed to reveal any visual
companion. A wider component listed in the WDS is clearly optical
(see Table 6).
HD 186408 (HIP 96895)
Triple, one planet. This close companion to 16 Cyg A was first
resolved 3" away by Turner et al. (2001AJ....121.3254T) with AO at
the Mount Wilson Observatory and confirmed by Patience et al.
(2002ApJ...581..654P), who demonstrated CPM and measured infrared
magnitudes consistent with the primary's distance. Four velocity
measures over 25 years show a slow drift (D. W. Latham et al. 2010,
in preparation), consistent with this companion. This system also has
a wide companion, 16 Cyg B, which is a planet host. The WDS (Cat.
B/wds) lists an additional source, 16" away from 16 Cyg B, but
Patience et al. (2002ApJ...581..654P) measured the infrared
magnitudes of this candidate, demonstrating that it is a background
star. This is the only planetary system in this study with more than
two stars.
HD 190067 (HIP 98677)
Binary. This companion was discovered by Turner et al.
(2001AJ....121.3254T) with AO at the Mount Wilson Observatory, but
the single-epoch measure with no color information does not allow
confirmation of a physical association. B.D.M. and D.R. observed this
star at the KPNO 4m telescope in 2008 June. While the separation and
{Delta}m are too large for speckle observations, a stellar source was
seen at the expected position, confirming CPM, and given the
proximity to a large proper motion (0.6"/yr) primary, the physical
association of this companion is very likely.
HD 190406 (HIP 98819)
Binary. Liu et al. (2002ApJ...571..519L) discovered a faint companion
0.8" from this star with AO at the Gemini North and Keck II
telescopes and confirmed a physical association by demonstrating CPM,
consistent spectroscopy, and long-term radial-velocity trend. They
determined a spectral type for the companion of L4.5+/-1.5, estimated
its mass to be 55-78MJ and age as 1-3Gyr. This is the first
substellar object imaged so close to a solar-type star and indicates
that brown dwarfs can exist in extra solar systems at positions
comparable to the gas giants in our solar system. Eight additional
WDS (Cat. B/wds) components are clearly optical (see Table 6).
HD 191499 (HIP 99316)
Binary. The WDS (Cat. B/wds) lists 51 measurements of this companion
between 1782 and 2003, which are consistent with a bound system.
There is little evidence of orbital motion during the roughly 200
years of observations, possibly because the companion is near
apastron in an eccentric orbit or the orbit is highly inclined.
Hipparcos and Tycho-2 proper motions differ by 5.6{sigma}, suggesting
some orbital motion (see Table 8). The photometric distance estimate
is not a very good match (see Table 10), but photometry would be
tricky for this close pair as indicated by the large uncertainties of
the 2MASS magnitudes. Given the evidence of consistent WDS measures,
proper motion differences between Hipparcos and Tycho-2, and similar
distance estimates, this pair likely has a physical association. An
additional wide WDS component is clearly optical (see Table 6).
HD 195564 (HIP 101345)
Binary. The WDS (Cat. B/wds) lists 16 measures over 110 years that are
consistent with a bound pair. While proximity to the primary and
{Delta}m~5 (from WDS) make photometry of the companion difficult, the
proximity and CPM implied by the measures argue for a physical
association. An additional wide WDS component is clearly optical (see
Table 6).
HD 200525 (HIP 104440)
Triple. The CNS (Gliese W., 1969VeARI..22....1G) and Hipparcos
(Cat. I/239) identified the closer pair as a possible binary
(stochastic solution) and Goldin & Makarov (2006ApJS..166..341G)
derived a photocentric orbit using the Hipparcos intermediate
astrometry data. Their orbital solutions using data from the two
independent Hipparcos reduction methods, Fundamental Astronomy by
Space Techniques (FAST) and the Northern Data Analysis Consortium
(NDAC), are consistent. They tested their orbit determination method
satisfactorily against 235 known binaries and derived a better than
99% confidence level based on simulations. The WDS lists four
measurements from 1898 to 1932, during which time the separation
reduced from about 1" to 0.16". The respective position angles of the
measurements are consistent with a high-inclination orbit. Given
these independent measurements leading to similar results, we
conclude that while the orbital elements may be preliminary, this
companion is physically bound. For the wider component, the WDS has
five measures over 88 years that are also consistent with a bound
pair. The companion is NLTT 50542 with a proper motion that matches
the primary's, and the notes in the catalog recognize this component
as gravitationally bound. 2MASS magnitudes have a large error, but
are consistent with a mid-K dwarf companion at approximately the
primary's distance.
HD 200560 (HIP 103859)
Binary. The WDS (Cat. B/wds) has seven measures of a companion with
separations 2.8"-3.3" over 28 years, suggesting a bound system. This
is especially significant given the primary's large proper motion of
0.4"/yr. The companion, GJ 816.1B, is recognized in the CNS (Gliese,
1969VeARI..22....1G) as bound, although no conclusive evidence is
presented. The 2MASS photometry has large errors, and hence is not
very useful. The Hipparcos and Tycho-2 proper motions are different
by about 8{sigma}, providing evidence of orbital motion and lending
credibility to a physical association. The WDS lists this pair as the
CD component of the B3V binary HD 200595 AB, but there is clearly no
physical association between HD 200560 and HD 200595 as seen by
blinking archival images. An additional wide WDS component is also
clearly optical (see Table 6).
HD 202275 (HIP 104858)
Binary. This is a 5.7 year SB2VB. Tokovinin et al.
(2006A&A...450..681T) give an additional orbit with a period of 5.7
days, which is in fact the former orbit listed with an incorrect unit
(A. Tokovinin, 2007, private communication). This system is a binary
with mass estimates of 1.2M_{sun}_ and 1.1M_{sun}_ by Pourbaix
(2000A&AS..145..215P). An additional wide WDS component is clearly
optical (see Table 6).
HD 206860 (HIP 107350)
Binary. Luhman et al. (2007ApJ...654..570L) reported the discovery of
a T2.5+/-0.5 companion using Spitzer IRAC images and confirmed CPM
using 2MASS images. The infrared colors are consistent with the
distance to the primary, confirming companionship. By comparing the
luminosity with evolutionary tracks, they estimate the companion's
mass as 0.021+/-0.009M_{sun}_ and age as 0.3+/-0.2Gyr. An additional,
potentially wide companion was identified 591'' away by blinking
archival images but refuted based on its photometric distance
estimate (see Table 5).
HD 215648 (HIP 112447)
Binary. A companion, 11" away, is listed in the WDS (Cat. B/wds) and
CNS (Gliese, 1969VeARI..22....1G) and confirmed by the 23
measurements in the WDS over 179 years which not only demonstrate
CPM, but also orbital motion. A wider WDS component is clearly
optical (see Table 6).
HD 217107 (HIP 113421)
Single star with two planets or a binary with one planet. The WDS
(Cat. B/wds) lists two measurements, 15 years apart, of a companion
0.3" away from this star, which also hosts two planets. These
speckle interferometry detections could however not be confirmed by
the same technique on at least three other occasions, indicating that
this pair might have a large or varying {Delta}m. Interestingly, the
farther planet is one of the most widely separated planets reported,
at least 5AU from the star. Vogt et al. (2005ApJ...632..638V) present
orbital solutions with periods of 7-9 years, but mention that it
could be three times larger. Wright et al. (2009ApJ...693.1084W)
present an updated orbit with P=11.5+/-0.5 years and a=5.27+/-0.36AU.
At the 20pc distance to the star, these separations are consistent
with the speckle observations. Given the inconsistent measures, if we
assume a {Delta}V near the speckle limit of about 3, the companion to
the G8 IV-V primary (Gray et al., 2003AJ....126.2048G) could be an
early M-dwarf. The mass sum of such a binary is consistent with the
Wright et al. (2009ApJ...693.1084W) orbital elements. Vogt et al.
(2005ApJ...632..638V) note that an AO image obtained with the Keck
telescope did not reveal any stars beyond 0farcs1 from the primary,
and Chauvin et al. (2006A&A...456.1165C) confirm this null result
with VLT and CFHT AO observations. The M-dwarf companion would also
imply a significantly larger velocity semi-amplitude for the
primary, but that possibility is not excluded by the orbital plot in
Wright et al. (2009ApJ...693.1084W). While it appears that this
"planetary" companion could be a star, further observations are
warranted.
HD 220140 (HIP 115147)
Triple. The WDS (Cat. B/wds) has five measurements over 100 years for
the closer visual companion at separations of about 10" that are
consistent with a bound pair. The companion is NLTT 56532 with a
proper motion matching that of the primary and 2MASS colors
consistent with an early M-dwarf at approximately the primary's
distance. The wide CPM companion, 16' away, was first identified by
Lepine & Shara (2005AJ....129.1483L) and confirmed by Makarov et al.
(2007ApJ...668L.155M) who show that the companion's trigonometric
parallax is consistent with the primary's Hipparcos value. Their BVRI
photometry along with 2MASS near-infrared magnitudes show that this
star is overluminous in the Ks band, confirming its suspected
pre-main-sequence status, and enabling an age estimate of 12-20Myr.