МЕЖЗВЕЗДНАЯ ПОЛЯРИЗАЦИЯ В МЕСТНОМ ПУЗЫРЕ И ПОЯСЕ ГУЛДА ПО ДАННЫМ GAIA DR2

2018 ◽  
Keyword(s):  
Gaia Dr2

Sixteen Open Clusters Discovered with Sample-based Clustering Search of Gaia DR2

2020 ◽  
Vol 132 (1009) ◽  
pp. 034502 ◽  
Author(s):  
ChaoJie Hao ◽  
Ye Xu ◽  
ZhenYu Wu ◽  
ZhiHong He ◽  
ShuaiBo Bian
Keyword(s):  
Open Clusters ◽  
Clustering Search ◽  
Gaia Dr2

scholarly journals Gaia DR2 data and the evolutionary status of eight high-velocity hot post-AGB candidates

2020 ◽  
Vol 72 (6) ◽  
Author(s):  
Mudumba Parthasarathy ◽  
Tadafumi Matsuno ◽  
Wako Aoki
Keyword(s):  
Effective Temperature ◽  
High Velocity ◽  
Circumstellar Dust ◽  
Evolutionary Status ◽  
Agb Stars ◽  
Horizontal Branch ◽  
Dust Shells ◽  
The Past ◽  
Gaia Dr2 ◽  
Branch Star

Abstract From Gaia DR2 data of eight high-velocity hot post-AGB candidates, LS 3593, LSE 148, LS 5107, HD 172324, HD 214539, LS IV −12 111, LS III +52 24, and LS 3099, we found that six of them have accurate parallaxes which made it possible to derive their distances, absolute visual magnitudes (MV) and luminosity (log L/L⊙). All the stars except LS 5107 have an accurate effective temperature (Teff) in the literature. Some of these stars are metal poor, and some of them do not have circumstellar dust shells. In the past, the distances of some stars were estimated to be 6 kpc, which we find to be incorrect. The accurate Gaia DR2 parallaxes show that they are relatively nearby, post-AGB stars. When compared with post-AGB evolutionary tracks we find their initial masses to be in the range 1 M⊙ to 2 M⊙. We find the luminosity of LSE 148 to be significantly lower than that of post-AGB stars, suggesting that this is a post-horizontal-branch star or post-early-AGB star. LS 3593 and LS 5107 are new high-velocity hot post-AGB stars from Gaia DR2.

scholarly journals HD 76920 b pinned down: A detailed analysis of the most eccentric planetary system around an evolved star

2021 ◽  
Vol 38 ◽  
Author(s):  
C. Bergmann ◽  
M. I. Jones ◽  
J. Zhao ◽  
A. J. Mustill ◽  
R. Brahm ◽  
...  
Keyword(s):  
Spectroscopic Analysis ◽  
Planetary System ◽  
Continuous Phase ◽  
Minimum Mass ◽  
Orbital Elements ◽  
Stellar Envelope ◽  
Orbital Decay ◽  
Fundamental Stellar Parameters ◽  
Transit Probability ◽  
Gaia Dr2

Abstract We present 63 new multi-site radial velocity (RV) measurements of the K1III giant HD 76920, which was recently reported to host the most eccentric planet known to orbit an evolved star. We focused our observational efforts on the time around the predicted periastron passage and achieved near-continuous phase coverage of the corresponding RV peak. By combining our RV measurements from four different instruments with previously published ones, we confirm the highly eccentric nature of the system and find an even higher eccentricity of $e=0.8782 \pm 0.0025$ , an orbital period of $415.891^{+0.043}_{-0.039}\,\textrm{d}$ , and a minimum mass of $3.13^{+0.41}_{-0.43}\,\textrm{M}_{\textrm{J}}$ for the planet. The uncertainties in the orbital elements are greatly reduced, especially for the period and eccentricity. We also performed a detailed spectroscopic analysis to derive atmospheric stellar parameters, and thus the fundamental stellar parameters ( $M_*, R_*, L_*$ ), taking into account the parallax from Gaia DR2, and independently determined the stellar mass and radius using asteroseismology. Intriguingly, at periastron, the planet comes to within 2.4 stellar radii of its host star’s surface. However, we find that the planet is not currently experiencing any significant orbital decay and will not be engulfed by the stellar envelope for at least another 50–80 Myr. Finally, while we calculate a relatively high transit probability of 16%, we did not detect a transit in the TESS photometry.

Yarkovsky drift detectability using the Gaia DR2 asteroid astrometry  

2021 ◽  
Author(s):  
Karolina Dziadura ◽  
Dagmara Oszkiewicz ◽  
Federika Spoto ◽  
Przemysław Bartczak
Keyword(s):  
Direct Detection ◽  
Signal To Noise Ratio ◽  
Parameter Determination ◽  
Small Bodies ◽  
Radar Observations ◽  
Orbital Parameters ◽  
Yarkovsky Effect ◽  
Reliable Detection ◽  
Right Ascension ◽  
Gaia Dr2

<div>The orbital motion of small bodies is affected by the Yarkovsky effect (semiminor axes change in time (da/dt)). The first direct detection was only made in 2003 thanks to radar observations. Nowadays there are over a hundred detections for NEAs and only a few for Main-Belt objects, however, the Yarkovsky effect remains difficult to detect for a large group of asteroids.</div> <div>The ESA Gaia mission was claimed to provide extremely precise astrometry of asteroids. Gaia observations were expected to lead to new Yarkovsky detections. In this work, we present the results for the most promising Yarkovsky candidates indexed before the start of the mission.</div> <div>We converted all available data (ground-based optical astrometry, satellite astrometry measurements, radar observations and GAIA DR2 data) to ADES format and then used it for orbit determination. We included the standard error of right ascension (RA), declination (Dec) and correlation of Ra and Dec errors for Gaia astrometry. We found a reliable detection of the Yarkovsky effect with a signal-to-noise ratio (SNR) greater than 3 for 21 asteroids, including 7 confirmations and 14 new detections. In 10 cases the resulting da/dt parameter SNR increased with the usage of the DR2 catalogue data, but no reliable detection can yet be claimed. Furthermore, we present a comparison of our empirical results with expected values estimated using physical and orbital parameters of studied objects. GAIA DR2 asteroids astrometry impacts positively the Yarkovsky drift determination. GAIA DR3 will elongate the observational arc, therefore, contribute to A2 parameter determination.</div>

scholarly journals Three Hypervelocity White Dwarfs in Gaia DR2: Evidence for Dynamically Driven Double-degenerate Double-detonation Type Ia Supernovae

2018 ◽  
Vol 865 (1) ◽  
pp. 15 ◽  
Author(s):  
Ken J. Shen ◽  
Douglas Boubert ◽  
Boris T. Gänsicke ◽  
Saurabh W. Jha ◽  
Jennifer E. Andrews ◽  
...  
Keyword(s):  
White Dwarfs ◽  
Type Ia Supernovae ◽  
Type Ia ◽  
Ia Supernovae ◽  
Gaia Dr2
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