scholarly journals The Solar Neighborhood. XVIII. Discovery of New Proper-Motion Stars with 0.40" yr-1> μ ≥ 0.18" yr-1between Declinations -90° and -47°

2007 ◽  
Vol 133 (6) ◽  
pp. 2898-2907 ◽  
Author(s):  
Charlie T. Finch ◽  
Todd J. Henry ◽  
John P. Subasavage ◽  
Wei-Chun Jao ◽  
Nigel C. Hambly
Keyword(s):  
Proper Motion ◽  
Solar Neighborhood

scholarly journals A survey of M stars in the field of view of Kepler space telescope

2010 ◽  
Vol 6 (S276) ◽  
pp. 448-449 ◽  
Author(s):  
Mahmoudreza Oshagh ◽  
Nader Haghighipour ◽  
Nuno C. Santos
Keyword(s):  
Radial Velocity ◽  
Proper Motion ◽  
Selection Process ◽  
Solar Neighborhood ◽  
Field Of View ◽  
Data Sets ◽  
M Dwarfs ◽  
Space Telescope ◽  
Transit Times ◽  
M Stars

AbstractM dwarfs constitute more than 70% of the stars in the solar neighborhood. They are cooler and smaller than Sun-like stars and have less-massive disks which suggests that planets around these stars are more likely to be Neptune-size or smaller. The transit depths and transit times of planets around M stars are large and well-matched to the Kepler temporal resolution. As a result, M stars have been of particular interest for searching for planets in both radial velocity and transit photometry surveys. We have recently started a project on searching for possible planet-hosting M stars in the publicly available data from Kepler space telescope. We have used four criteria, namely, the magnitude, proper motion, H-Ks and J-H colors, and searched for M stars in Q0 and Q1 data sets. We have been able to find 108 M stars among which 54 had not been previously identified among Kepler's targets. We discuss the details of our selection process and present the results.

scholarly journals THE SOLAR NEIGHBORHOOD. XXVII. DISCOVERY OF NEW PROPER MOTION STARS WITH μ ⩾ 0.″18 yr–1IN THE SOUTHERN SKY WITH 16.5

2011 ◽  
Vol 142 (3) ◽  
pp. 92 ◽  
Author(s):  
Mark R. Boyd ◽  
Todd J. Henry ◽  
Wei-Chun Jao ◽  
John P. Subasavage ◽  
Nigel C. Hambly
Keyword(s):  
Proper Motion ◽  
Solar Neighborhood

scholarly journals DIVISION I / COMMISSION 8 / WORKING GROUP ASTROGRAPHIC CATALOGUE AND CARTE DU CIEL PLATES

2007 ◽  
Vol 3 (T26B) ◽  
pp. 95-97
Author(s):  
Beatrice Bucciarelli ◽  
Alain Fresnau ◽  
Carlos Abad ◽  
Robert W. Argyle ◽  
James Biggs ◽  
...  
Keyword(s):  
Proper Motion ◽  
Working Group ◽  
Tangential Velocity ◽  
Solar Neighborhood ◽  
Division I ◽  
The Sun ◽  
Stellar Kinematics ◽  
Velocity Data ◽  
Definition Of ◽  
Radial Velocity Data

Various experiments have definitely demonstrated that one-micron accuracy (0.″06) on the definition of stellar images on CdC plates cannot be claimed, as it was speculated back in 1999. More realistically, a 2-3 micron accuracy is achievable, getting worse toward the survey magnitude limit, with an average magnitude error of 0.3. The level of astrometric accuracy corresponds to a 0.″2 - 0.″3 error in position at Epoch 1900, which, once used as first Epoch for proper motion determination in combination with modern epoch observations, can produce errors at the level of 2-5 mas/yr, thereby allowing to detect stellar motions larger than 0.″01/yr, which at a distance of 500 pc from the Sun correspond to ~25-60 km/s tangential velocity. Therefore, the AC/CdC heritage collection can be regarded as a highly valuable first-epoch material, e.g., for the realization of a Tycho-2 extension to fainter magnitudes (~15 photographic), especially in selected areas where radial velocity data are available, for the exploration of stellar kinematics beyond our solar neighborhood.

scholarly journals Astrometric detection and characterization of brown dwarfs

2007 ◽  
Vol 3 (S248) ◽  
pp. 30-35
Author(s):  
R.-D. Scholz ◽  
M. J. McCaughrean ◽  
S. Röser ◽  
E. Schilbach
Keyword(s):  
Proper Motion ◽  
Near Infrared ◽  
Critical Mass ◽  
Brown Dwarfs ◽  
Solar Neighborhood ◽  
Sky Survey ◽  
Nearby Stars ◽  
Rare Class ◽  
Low Mass

AbstractAs a result of failed star formation, brown dwarfs (BDs) do not reach the critical mass to ignite the fusion of hydrogen in their cores. Different from their low-mass stellar brothers, the red dwarfs, BDs cool down with their lifetime to very faint magnitudes. Therefore, it was only about 10 to 20 years ago that such ultracool objects began to be detected. Accurate astrometry can be used to detect them indirectly as companions to stars by the signature of the so-called astrometric wobble. Resolved faint BD companions of nearby stars can be identified by their common proper motion (CPM). A direct astrometric detection of the hidden isolated BDs in the Solar neighborhood is possible with deep high proper motion (HPM) surveys. This technique led to the discovery of the first free-floating BD, Kelu 1, and of the nearest BD, ε Indi B. Both were meanwhile found to be binary BDs. The astrometric orbital monitoring of ε Indi Ba+Bb, for which we know an accurate distance from the Hipparcos measurement of its primary, ε Indi A, will allow the determination of individual masses of two low-mass BDs. Hundreds of BDs have been identified for the last decade. Deep optical sky survey (SDSS) and near-infrared sky surveys (DENIS, 2MASS), played a major role in the search mainly based on colours, since BDs emit most of their light at longer wavelengths. However, alternative deep optical HPM surveys based on archival photographic data are not only sensitive enough to detect some of the nearest representatives, they do also uncover many of the rare class of ultracool halo objects crossing the Solar neighborhood at large velocities. SSSPM 1444, with the extremely large proper motion of 3.5 arcsec/yr, is one of the nearest among these subdwarfs with masses at the substellar boundary. We present preliminary parallax results for this and two other ultracool subdwarfs (USDs) from the Calar Alto Omega 2000 parallax program.

scholarly journals THE SOLAR NEIGHBORHOOD. XXV. DISCOVERY OF NEW PROPER MOTION STARS WITH 0.″40 yr–1> μ ⩾ 0.″18 yr–1BETWEEN DECLINATIONS –47° AND 00°

2011 ◽  
Vol 142 (1) ◽  
pp. 10 ◽  
Author(s):  
Mark R. Boyd ◽  
Jennifer G. Winters ◽  
Todd J. Henry ◽  
Wei-Chun Jao ◽  
Charlie T. Finch ◽  
...  
Keyword(s):  
Proper Motion ◽  
Solar Neighborhood

scholarly journals Determining Motions and Birthplaces of Pulsars through VLBI Astrometry

1998 ◽  
Vol 164 ◽  
pp. 391-392
Author(s):  
T. J. Galama ◽  
J. Van Paradijs ◽  
E. P. J. van den Heuvel ◽  
A. G. de Bruyn ◽  
R. M. Campbell ◽  
...  
Keyword(s):  
Flux Density ◽  
Proper Motion ◽  
Mass Range ◽  
Solar Neighborhood ◽  
Proper Motions ◽  
First Results ◽  
Motion Measurements

AbstractWe present first results of global VLBI astrometric pulsar parallax and proper motion measurements (phase-reference). The aim is to obtain information on pulsar motions and pulsar birthplaces. Proper motions could provide answers to questions like: How large are pulsar velocities at birth? How are these velocities produced and what is the final galactic pulsar distribution? Identification of birthplaces (with, e.g., an OB-association) provides information on the pulsar progenitor population (the fraction of pulsars born in binaries; the mass range of the progenitors etc.). We have a first epoch on three pulsars, selected on the basis of age (young < 3 Myr), flux density (relatively strong) and presence in the solar neighborhood (d < 3 kpc). Gating increases the SNR by typically a factor of 5.

The Solar Neighborhood. XII. Discovery of New High Proper Motion Stars with μ ≥ 0."4 yr-1between Declinations -90° and -47°

2005 ◽  
Vol 129 (1) ◽  
pp. 413-432 ◽  
Author(s):  
John P. Subasavage ◽  
Todd J. Henry ◽  
Nigel C. Hambly ◽  
Misty A. Brown ◽  
Wei-Chun Jao
Keyword(s):  
Proper Motion ◽  
Solar Neighborhood

How could Precise Stellar Radial Velocities Help to Understand Field and Cluster Member Flare Stars?

1999 ◽  
Vol 170 ◽  
pp. 218-222
Author(s):  
G. Szécsényi-Nagy
Keyword(s):  
Radial Velocity ◽  
Proper Motion ◽  
Variable Stars ◽  
Radial Velocities ◽  
Solar Neighborhood ◽  
Final Decision ◽  
Data Set ◽  
Membership Probability ◽  
Cluster Membership ◽  
Flare Stars

AbstractUntil recently the problem of collecting high resolution spectra of flare stars has been intractable since the techniques available have not been sensitive enough to reach these extremely faint objects. Although many of the nearest stars (and practically all of the nearby variable stars) belong to this class, even the ones nearest to our sun are fainter than magnitude 8 or 10. In determining the radial velocity of nearby flare stars astronomers accepted the available accuracy of ~ 1 km/s. This may be adequate for the classification of the objects into age classes (according their kinematic properties).The other considerable group of flare stars is taken traditionally as a natural by-product of star formation processes which go on in clusters and associations. Until recently there has not been any serious attack against the widely popular hypothesis that all but a few of the flare stars discovered in the fields of stellar aggregates (their number exceeds that of the solar neighborhood flare stars) are physical members of the systems. The discovery (Szécsényi-Nagy et al. 1997, 1998) that hundreds of flare stars found in the field of M45 may not be cluster members may change the situation. Most flare stars observed there are very faint and consequently they were missing from previously published lists of Pleiades members. For one third of the objects only reliable membership probabilities have been determined, and many of them are listed as probable non-members (Haro, Chavira, & Gonzalez 1982). However, a recently published photographic proper motion survey of the Pleiades’ field (Souchay & Schilbach 1995) provided reliable membership probability values for many stars of extremely low luminosity too. Based on that about 85% of the well-documented flare stars can be – and have been – identified. Our results (Szécsényi-Nagy et al. 1997) undoubtedly prove that a substantial fraction (~ 40%) of the so called Pleiades flare stars are (more or less) definitely non-members. Since all of these new cluster membership probability calculations have been based on stellar proper motion values, in order to be able to reach a final decision, we badly need some other independent data set for the very same stars. It is to be shown that precise stellar radial velocities, an unexploited – because almost unknown – parameter for flare stars, could solve the problem by supporting or disproving these faint objects’ cluster membership. Consequently the flare stars of these two kinds (which are accidentally mixed on the photographic plates) could be classified into different age groups and their evolutionary stages and tracks could be investigated more deeply.Our intention is to persuade astronomers involved in stellar radial velocity business that developing and using a method of high precision stellar radial-velocity measurement for late dK/dM stars is not a waste of time but a really feasible job and that we can and will contribute to the success of it by identifying the best tartgets, taking part in the necessary observations and evaluating the data.

scholarly journals Multiplicity of Nearby Free-floating Late M and L Dwarfs: HST-WFPC2 Observations of Candidates and Bona Fide Binary Brown Dwarfs

2003 ◽  
Vol 211 ◽  
pp. 245-248 ◽  
Author(s):  
Hervé Bouy ◽  
Wolfgang Brandner ◽  
Eduardo L. Martín ◽  
Xavier Delfosse ◽  
France Allard ◽  
...  
Keyword(s):  
Proper Motion ◽  
Multiplicity Distribution ◽  
High Spatial Resolution ◽  
Solar Neighborhood ◽  
Brown Dwarf ◽  
Multiple Systems ◽  
Origin And Evolution ◽  
Bona Fide ◽  
Low Mass ◽  
Binary Separations

We review the results of HST/WFPC2 observations of a sample of 50 very-low-mass objects in the solar neighborhood (30 from our own program and 20 from the archive). Using high spatial resolution HST/WFPC2 images, we observed these objects in two filters (F814W and F675W) in order to identify close companions, measure their colours, and obtain first epoch data of the newly discovered binaries. In addition to 3 previously known binaries we discovered 3 new multiple systems. Second epoch data are required to confirm that they are real common proper motion pairs. Binary properties like multiplicity, distribution of binary separations and brightness ratios hold clues on the origin and evolution of free-floating brown dwarf binaries.

scholarly journals The Solar Neighborhood. VIII. Discovery of New High Proper Motion Nearby Stars Using the SuperCOSMOS Sky Survey

2004 ◽  
Vol 128 (1) ◽  
pp. 437-447 ◽  
Author(s):  
Nigel C. Hambly ◽  
Todd J. Henry ◽  
John P. Subasavage ◽  
Misty A. Brown ◽  
Wei-Chun Jao
Keyword(s):  
Proper Motion ◽  
Solar Neighborhood ◽  
Sky Survey ◽  
Nearby Stars
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