63 research outputs found
Comet data collections
Various collections of comet observational material are discussed in terms of developing a data base. Emphasis is placed on observational material buried in the archives of the older observatories
Stars in the USNO-B1 Catalog with Proper Motions Between 1.0 and 5.0 arcseconds per year
This paper examines a subset of objects from the USNO-B1 catalogue with
listed proper motions between 1.0 and 5.0 arcseconds per year. We look at the
degree of contamination within this range of proper motions, and point out the
major sources of spurious high proper motion objects. Roughly 0.1% of the
objects in the USNO-B1 catalogue with listed motions between 1.0 and 5.0
arcseconds per year are real. Comparison with the revised version of Luyten's
Half Second catalogue indicates that USNO-B1 is only about 47% complete for
stars in this range. Preliminary studies indicate that there may be a dip in
completeness in USNO-B1 for objects with motions near 0.1 arcseconds per year.
We also present two new stars with motions between 1.0 and 5.0 arcseconds per
year, 36 new stars with confirmed motions between 0.1 and 1.0 arcseconds per
year, several new common proper motion pairs, and the recovery of LHS237a
(VBs3).Comment: 42 pages, 16 figures, uses AASTeX v5.2, accepted by A
Cool Companions to White Dwarfs from the 2MASS Second Incremental Data Release
We present near-infrared magnitudes for all white dwarfs (selected from the
catalog of McCook & Sion) contained in the 2 Micron All Sky Survey Second
Incremental Data Release(2MASS 2IDR). We show that the near-IR color-color
diagram is an effective means of identifying candidate binary stars containing
a WD and a low mass main sequence star. The loci of single WDs and WD + red
dwarf binaries occupy distinct regions of the near-IR color-color diagram. We
recovered all known unresolved WD + red dwarf binaries located in the 2IDR sky
coverage, and also identified as many new candidate binaries (47 new candidates
out of 95 total). Using observational near-IR data for WDs and M-L dwarfs, we
have compared a sample of simulated WD + red dwarf binaries with our 2MASS
data. The colors of the simulated binaries are dominated by the low mass
companion through the late-M to early-L spectral types. As the spectral type of
the companion becomes progressively later, however, the colors of unresolved
binaries become progressively bluer. Binaries containing the lowest mass
companions will be difficult to distinguish from single WDs solely on the basis
of their near-IR colors.Comment: 18 pages, including 2 figures, accepted for publication in Ap
Classifying Luyten Stars Using An Optical-Infrared Reduced Proper Motion Diagram
We present a V-J reduced proper motion (RPM) diagram for stars in the New
Luyten Two-Tenths (NLTT) catalog. In sharp contrast to the RPM diagram based on
the original NLTT data, this optical-infrared RPM diagram shows distinct tracks
for white dwarfs, subdwarfs, and main-sequence stars. It thereby permits the
identification of white-dwarf and subdwarf candidates that have a high
probability of being genuine.Comment: Accepted ApJL version. 3 figures (2 in color). Table of candidate new
WDs closer than 20 pc is now include
New distant companions to known nearby stars: I. GJ 4047B, GJ 718B, GJ 747.2C, GJ 4100B, and GJ 4153B
In an ongoing survey for high proper motion stars at low galactic latitudes,
we have identified 5 previously uncatalogued common proper motion companions to
stars listed in the Preliminary Version of the Third Catalogue of Nearby Stars
(GJ stars). For each system, the relative proper motion between the components
is less than 5% of the common proper motion of the pair. Spectra of the pairs
have been obtained at the Lick 3-m Shane Telescope, confirming that the systems
are indeed wide separation binaries. The systems are classified as follows: GJ
4047AB = K5 V + M5 V, GJ 718AB = K5 V + M4.5 V, GJ 747.2ABC = (K7 V + K7 V) +
M4 Ve, GJ 4100AB = M1 V + M4.5 Ve, and GJ 4153AB = M0.5 V + M3.5 V. The total
area surveyed contains 346 Gliese stars, which suggests that approximately 1.5%
of the stars listed in the Preliminary Version of the Third Catalogue of Nearby
Stars have unrecognized proper motion companions. We predict that 15-50 more
new distant companions to GJ stars will be discovered in the Digitized Sky
Survey.Comment: 15 page, 5 figures, 2 tables, to appear in The Astronomical Journa
The Metallicity of Stars with Close Companions
We examine the relationship between the frequency of close companions
(stellar and planetary companions with orbital periods < 5 years) and the
metallicity of their Sun-like (~ FGK) hosts. We confirm and quantify a ~4 sigma
positive correlation between host metallicity and planetary companions. We find
little or no dependence on spectral type or distance in this correlation. In
contrast to the metallicity dependence of planetary companions, stellar
companions tend to be more abundant around low metallicity hosts. At the ~2
sigma level we find an anti-correlation between host metallicity and the
presence of a stellar companion. Upon dividing our sample into FG and K
sub-samples, we find a negligible anti-correlation in the FG sub-sample and a 3
sigma anti-correlation in the K sub-sample. A kinematic analysis suggests that
this anti-correlation is produced by a combination of low-metallicity,
high-binarity thick disk stars and higher-metallicity, lower-binarity thin disk
stars.Comment: Conforms to version accepted by ApJ. 15 pages formatted with
emulateapj.cl
Nearby stars from the LSPM-north Proper Motion Catalog. I. Main Sequence Dwarfs and Giants Within 33 Parsecs of the Sun
A list of 4,131 dwarfs, subgiants, and giants located, or suspected to be
located, within 33 parsecs of the Sun is presented. All the stars are drawn
from the new LSPM-north catalog of 61,976 stars with annual proper motions
larger than 0.15''/yr$. Trigonometric parallax measurements are found in the
literature for 1,676 of the stars in the sample; photometric and spectroscopic
distance moduli are found for another 783 objects. The remaining 1,672 objects
are reported here as nearby star candidates for the first time. Photometric
distance moduli are calculated for the new stars based on the (M_V,V-J)
relationship, calibrated with the subsample of stars which have trigonometric
parallaxes. The list of new candidates includes 539 stars which are suspected
to be within 25 parsecs of the Sun, including 63 stars estimated to be within
only 15 parsecs. The current completeness of the census of nearby stars in the
northern sky is discussed in light of the new candidates presented here. It is
estimated that 32% (18%) of nuclear burning stars within 33 parsecs (25
parsecs) of the Sun remain to be located. The missing systems are expected to
have proper motions below the 0.15''/yr limit of the LSPM catalog.Comment: 13 pages, accepted for publication in the Astronomical Journa
The Chromospheric Activity and Ages of M Dwarf Stars in Wide Binary Systems
We investigate the relationship between age and chromospheric activity for
139 M dwarf stars in wide binary systems with white dwarf companions. The age
of each system is determined from the cooling age of its white dwarf component.
The current limit for activity-age relations found for M dwarfs in open
clusters is 4 Gyr. Our unique approach to finding ages for M stars allows for
the exploration of this relationship at ages older than 4 Gyr. The general
trend of stars remaining active for a longer time at later spectral type is
confirmed. However, our larger sample and greater age range reveals additional
complexity in assigning age based on activity alone. We find that M dwarfs in
wide binaries older than 4 Gyr depart from the log-linear relation for clusters
and are found to have activity at magnitudes, colors and masses which are
brighter, bluer and more massive than predicted by the cluster relation. In
addition to our activity-age results, we present the measured radial velocities
and complete space motions for 161 white dwarf stars in wide binaries.Comment: 22 pages including 9 figures and 5 tables. Accepted for publication
in The Astronomical Journa
A Survey for Faint Stars of Large Proper Motion Using Extra Poss II Plates
We have conducted a search for new stars of high proper motion (0.4
arcsec yr) using POSS II fields for which an extra IIIaF (red) plate of
good quality exists, along with useable IIIaJ (blue) and IV-N (infrared) plates
taken at epochs differing by a minimum of 1.5 years. Thirty-five fields at
Galactic latitudes 20 were measured, covering some 1378 deg,
or 3.3% of the sky. Searches with three plate combinations as well as all four
plates were also made. Seven new stars were found with 0.5 arcsec
yr, which were therefore missed in the Luyten Half Second (LHS) Catalog.
One of these is a common proper motion binary consisting of two subdwarf M
stars; another is a cool white dwarf with probable halo kinematics. As a test
of our completeness -- and of our ability to test that of Luyten -- 216 of 230
catalogued high proper motion stars were recovered by the software, or 94%.
Reasons for incompleteness of the LHS are discussed, such as the simple fact
that POSS II plates have deeper limiting magnitudes and greater overlap than
did POSS I. Nonetheless, our results suggest that the LHS is closer to 90%
complete than recent estimates in the literature (e.g 60%), and we propose a
reason to account for one such lower estimate. The conclusion that the LHS
Catalog is more complete has implications for the nature of the halo dark
matter. In particular it strengthens the constraint on the local density of
halo stars, especially white dwarfs at M17-18.Comment: Astronomical Journal, in press, 16 pages, 3 figure
Speckle Interferometry of Metal-Poor Stars in the Solar Neighborhood. I
We report the results of speckle-interferometric observations of 109 high
proper-motion metal-poor stars made with the 6-m telescope of the Special
Astrophysical Observatory of the Russian Academy of Sciences. We resolve eight
objects -- G102-20, G191-55, BD+19~1185A, G89-14, G87-45, G87-47,
G111-38, and G114-25 -- into individual components and we are the first to
astrometrically resolve seven of these stars. New resolved systems included two
triple (G111-38, G87-47) and one quadruple (G89-14) star. The ratio of
single-to-binary-to-triple-to-quadruple systems among the stars of our sample
is equal to 71:28:6:1.Comment: 8 pages, 4 figures, accepted to Astrophysical Bulleti
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