scholarly journals Stellar ages and masses in the solar neighbourhood: Bayesian analysis using spectroscopy and Gaia DR1 parallaxes

2018 ◽  
Vol 477 (3) ◽  
pp. 2966-2975 ◽  
Author(s):  
Jane Lin ◽  
Aaron Dotter ◽  
Yuan-Sen Ting ◽  
Martin Asplund
Keyword(s):  
Bayesian Analysis ◽  
Solar Neighbourhood ◽  
Gaia Dr1 ◽  
Stellar Ages

scholarly journals G-Band Period-Luminosity Relation For Galactic Cepheids Based on Gaia DR1 Measurements

2017 ◽  
Vol 12 (S330) ◽  
pp. 337-338
Author(s):  
Chow-Choong Ngeow ◽  
Anupam Bhardwaj ◽  
Shashi M. Kanbur
Keyword(s):  
Bayesian Analysis ◽  
Gaia Dr1 ◽  
Classical Cepheids ◽  
Standard Candle ◽  
Data Release ◽  
Future Data

AbstractClassical Cepheids (hereafter Cepheids) are important standard candle as they obey the famous period-luminosity (PL) relation. Parallax measurements from Gaia offer a unique opportunity to derive or calibrate the PL relations for Galactic Cepheids, as traditionally their distances were measured via different methods. In this work, we attempted to derive the Gaia G-band PL relation based on the Gaia Data Release 1 (DR1) measurements. We adopted the inferred distances provided by Astraatmadja & Bailer-Jones (2016), calculated using two priors in a Bayesian analysis, and cross-matched to known Galactic Cepheids. The resulting G-band PL relation, however, exhibits a much larger scatter than expected. Hence the inferred distances based on the Gaia DR1 parallaxes are not suitable for calibrating the Galactic PL relation, and future Data Releases with improved parallax measurements are desirable.

scholarly journals Physics and Structure of the Galactic disc(s)

2009 ◽  
Vol 5 (H15) ◽  
pp. 791-791
Author(s):  
Ralph A. Schönrich
Keyword(s):  
Chemical Evolution ◽  
Observational Studies ◽  
Alternative Methods ◽  
Solar Neighbourhood ◽  
Detailed Structure ◽  
Galactic Disc ◽  
Stellar Ages ◽  
Classical Models ◽  
Combining Information

AbstractThe combination of classical models of chemical evolution with radial mixing and dynamics of the Galactic disc has opened alternative methods of understanding the detailed structure of the solar neighbourhood. I will show how radial mixing alters the views on chemical evolution as demonstrated by Schönrich & Binney (2009). I will explain how the model gives rise to a very natural division of the Galactic disc into a thick and a thin component, which can be examined in the light of detailed observational studies combining information on kinematics, chemistry and stellar ages.

scholarly journals Kinematic structures found with Gaia DR1/TGAS and RAVE data in the Solar neighbourhood

2017 ◽  
Vol 13 (S334) ◽  
pp. 323-324
Author(s):  
I. Kushniruk ◽  
T. Schirmer ◽  
T. Bensby
Keyword(s):  
Wavelet Analysis ◽  
Velocity Distribution ◽  
Confidence Level ◽  
Solar Neighbourhood ◽  
Kinematic Structure ◽  
Proper Motions ◽  
Gaia Dr1

AbstractWith the much enlarged stellar sample of 55 831 stars and much increased precision in distances, proper motions, provided by Gaia DR1 TGAS we have shown with the help of the wavelet analysis that the velocity distribution of stars in the Solar neighbourhood contains more kinematic structures than previously known. We detect 19 kinematic structures between scales 3-16 km s−1 at the 3σ confidence level. Among them we identified well-known groups (such as Hercules, Sirius, Coma Berenices, Pleiades, and Wolf 630). We confirmed recently detected groups (such as Antoja12 and Bobylev16). In addition we report here about a new kinematic structure at (U, V) ≈ (37, 8) km s−1. Another three new groups are tentatively detected, but require confirmation.

Observing the galactic magnetic field

1967 ◽  
Vol 31 ◽  
pp. 375-380
Author(s):  
H. C. van de Hulst
Keyword(s):  
Magnetic Field ◽  
Fair Agreement ◽  
Solar Neighbourhood ◽  
Galactic Magnetic Field ◽  
The Magnetic Field

Various methods of observing the galactic magnetic field are reviewed, and their results summarized. There is fair agreement about the direction of the magnetic field in the solar neighbourhood:l= 50° to 80°; the strength of the field in the disk is of the order of 10-5gauss.

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