The GALAH+ survey: a new library of observed stellar spectra improves radial velocities and hints at motions within M67

Zwitter, Tomaz and Kos, Janez and Buder, Sven and Cotar, Klemen and Asplund, Martin and Bland-Hawthorn, Joss and Casey, Andrew R. and De Silva, Gayandhi M. and D'Orazi, Valentina and Freeman, Ken C. and Hayden, Michael R. and Lewis, Geraint F. and Lin, Jane and Lind, Karin and Martell, Sarah L. and Schlesinger, Katharine J. and Sharma, Sanjib and Simpson, Jeffrey D. and Stello, Dennis and Zucker, Daniel B. and Beeson, Kevin L. and de Grijs, Richard and Nordlander, Thomas and Ting, Yuan-Sen and Traven, Gregor and Vogrincic, Rok and Watson, Fred and Wittenmyer, Rob (2021) The GALAH+ survey: a new library of observed stellar spectra improves radial velocities and hints at motions within M67. Monthly Notices of the Royal Astronomical Society, 508 (3). pp. 4202-4215. ISSN 0035-8711

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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.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: The Author(s) 2021. Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -)
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -)
Date Deposited: 10 Jan 2022 04:38
Last Modified: 14 Jan 2022 00:55
Uncontrolled 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
Fields of Research (2008): 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
Socio-Economic Objectives (2008): E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280120 Expanding knowledge in the physical sciences
Identification Number or DOI: https://doi.org/10.1093/mnras/stab2673
URI: http://eprints.usq.edu.au/id/eprint/45066

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