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

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. 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 Ongoing astrometric microlensing events of two nearby stars

2018 ◽  
Vol 615 ◽  
pp. L11 ◽  
Author(s):  
J. Klüter ◽  
U. Bastian ◽  
M. Demleitner ◽  
J. Wambsganss
Keyword(s):  
Prior Knowledge ◽  
Gravitational Lensing ◽  
Proper Motion ◽  
Absolute Magnitude ◽  
Stellar Objects ◽  
Lens Position ◽  
Data Release ◽  
Nearby Stars ◽  
Excellent Tool ◽  
Background Star

Context. Astrometric microlensing is an excellent tool to determine the mass of stellar objects. By measuring the astrometric shift of a background source star in combination with precise predictions of its unlensed position and of the lens position, gravitational lensing allows to one determine the mass of the lensing star with a precision of 1%, independently of any prior knowledge. Aims. Making use of the recently published Gaia Data Release 2 (Gaia DR2) we predict astrometric microlensing events by fore-ground stars of high proper motion passing by a background star in the coming years. Methods. We compile a list of approximately 148 000 high-proper-motion stars within Gaia DR2 with µtot > 150 mas yr−1. We then search for background stars close to their paths and calculate the dates and separations of the closest approaches. Using color and absolute magnitude, we determine approximate masses of the lenses. Finally, we calculate the expected astrometric shifts and magnifications of the predicted events. Results. We detect two ongoing microlensing events by the high-proper-motion stars Luyten 143-23 and Ross 322 and predict closest separations of (108.5 ± 1.4) mas in July 2018 and (125.3 ± 3.4) mas in August 2018, respectively. The respective expected astrometric shifts are (1.74 ± 0.12) mas and (0.76 ± 0.06) mas. Furthermore, Luyten 143-23 will pass by another star in March 2021 with a closest separation of (280.1 ± 1.1) mas, which results in an expected shift of (0.69 ± 0.05) mas.

scholarly journals A preliminary color-magnitude diagram for late-type stars in the solar neighborhood

1959 ◽  
Vol 10 ◽  
pp. 39-40
Author(s):  
O. C. Wilson
Keyword(s):  
Main Sequence ◽  
Star Clusters ◽  
Solar Neighborhood ◽  
Late Type ◽  
Main Sequence Stars ◽  
Individual Values ◽  
Magnitude Diagram ◽  
Trigonometric Parallaxes ◽  
Nearby Stars ◽  
The Mean

Modern photoelectric techniques yield magnitudes and colors of stars with accuracies of the order of a few thousandths and a few hundredths of a magnitude respectively. Hence for star clusters it is possible to derive highly accurate color-magnitude arrays since all of the members of a cluster may be considered to be at the same distance from the observer. It is much more difficult to do this for the nearby stars where all of the objects concerned are at different, and often poorly determined, distances. If one depends upon trigonometric parallaxes, the bulk of the reliable individual values will refer to main sequence stars, and while the mean luminosities of brighter stars are given reasonably well by this method, the scatter introduced into a color-magnitude array by using individual trigonometrically determined luminosities could obscure important features. Somewhat similar objections could be raised against the use of the usual spectroscopic parallaxes which also should be quite good for the main sequence but undoubtedly exhibit appreciable scatter for some, at least, of the brighter stars.

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

The structure of proper-motion diagrams for nearby stars

2003 ◽  
Vol 47 (9) ◽  
pp. 789-796
Author(s):  
S. V. Vereshchagin ◽  
V. G. Reva ◽  
N. V. Chupina
Keyword(s):  
Proper Motion ◽  
Nearby Stars

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.

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