The GALAH+ survey: a new library of observed stellar spectra improves radial velocities and hints at motions within M67
Article
Article Title | The GALAH+ survey: a new library of observed stellar spectra improves radial velocities and hints at motions within M67 |
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ERA Journal ID | 1074 |
Article Category | Article |
Authors | Zwitter, Tomaz (Author), Kos, Janez (Author), Buder, Sven (Author), Cotar, Klemen (Author), Asplund, Martin (Author), Bland-Hawthorn, Joss (Author), Casey, Andrew R. (Author), De Silva, Gayandhi M. (Author), D'Orazi, Valentina (Author), Freeman, Ken C. (Author), Hayden, Michael R. (Author), Lewis, Geraint F. (Author), Lin, Jane (Author), Lind, Karin (Author), Martell, Sarah L. (Author), Schlesinger, Katharine J. (Author), Sharma, Sanjib (Author), Simpson, Jeffrey D. (Author), Stello, Dennis (Author), Zucker, Daniel B. (Author), Beeson, Kevin L. (Author), de Grijs, Richard (Author), Nordlander, Thomas (Author), Ting, Yuan-Sen (Author), Traven, Gregor (Author), Vogrincic, Rok (Author), Watson, Fred (Author) and Wittenmyer, Rob (Author) |
Journal Title | Monthly Notices of the Royal Astronomical Society |
Journal Citation | 508 (3), pp. 4202-4215 |
Number of Pages | 14 |
Year | 2021 |
Publisher | Oxford University Press |
Place of Publication | United Kingdom |
ISSN | 0035-8711 |
1365-2966 | |
Digital Object Identifier (DOI) | https://doi.org/10.1093/mnras/stab2673 |
Web Address (URL) | https://academic.oup.com/mnras/article/508/3/4202/6372926 |
Abstract | GALAH+ is a magnitude-limited survey of high-resolution stellar spectra obtained by the HERMES spectrograph at the Australian Astronomical Observatory. Its third data release provides reduced spectra with new derivations of stellar parameters and abundances of 30 chemical elements for 584 015 dwarfs and giants, 88 per cent of them in the Gaia magnitude range 11 < G < 14. Here, we use these improved values of stellar parameters to build a library of observed spectra which is useful to study variations of individual spectral lines with stellar parameters. This and other improvements are used to derive radial velocities with uncertainties which are generally within 0.1 km s(-1) or similar to 25 per cent smaller than in the previous release. Median differences in radial velocities measured here and by the Gaia DR2 or APOGEE DR16 surveys are smaller than 30 m s(-1), a larger offset is present only for Gaia measurements of giant stars. We identify 4483 stars with intrinsically variable velocities and 225 stars for which the velocity stays constant over >= 3 visits spanning more than a year. The combination of radial velocities from GALAH+ with distances and sky plane motions from Gaia enables studies of dynamics within streams and clusters. For example, we estimate that the open cluster M67 has a total mass of similar to 3300 M-circle dot and its outer parts seem to be expanding, though astrometry with a larger time-span than currently available from Gaia eDR3 is needed to judge if the latter result is real. |
Keywords | methods: data analysis; surveys; stars: fundamental parameters; stars: kinematics and dynamics; Galaxy: kinematics and dynamics; open; clusters and associations: individual: M67; Astrophysics - Solar and; Stellar Astrophysics; Astrophysics - Astrophysics of Galaxies; Astrophysics - Instrumentation and Methods for Astrophysics |
ANZSRC Field of Research 2020 | 510109. Stellar astronomy and planetary systems |
Institution of Origin | University of Southern Queensland |
Byline Affiliations | University of Ljubljana, Slovenia |
Australian National University | |
Max Planck Society, Germany | |
ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions, Australia | |
Monash University | |
Macquarie University | |
National Institute for Astrophysics, Italy | |
University of Sydney | |
Stockholm University, Sweden | |
Princeton University, United States | |
Lund Observatory, Sweden | |
Department of Industry, Science and Resources, Australia | |
Centre for Astrophysics |
https://research.usq.edu.au/item/q6x8q/the-galah-survey-a-new-library-of-observed-stellar-spectra-improves-radial-velocities-and-hints-at-motions-within-m67
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