The GALAH Survey: Accurate Radial Velocities and Library of Observed Stellar Template Spectra

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    Tomaž Zwitter, Janez Kos, Andrea Chiavassa, Sven Buder, Gregor Traven, Klemen Čotar, Jane Lin, Martin Asplund, Joss Bland-Hawthorn, Andrew R. Casey, Gayandhi De Silva, Ly Duong, Kenneth C. Freeman, Karin Lind, Sarah Martell, Valentina D'Orazi, Katharine J. Schlesinger, Jeffrey D. Simpson, Sanjib Sharma, Daniel B. Zucker, Borja Anguiano, Luca Casagrande,
  • Remo Collet
  • Jonathan Horner, Michael J. Ireland, Prajwal R. Kafle, Geraint Lewis, Ulisse Munari, David M. Nataf, Melissa Ness, Thomas Nordlander,
  • Dennis Stello
  • Yuan-Sen Ting, Chris G. Tinney, Fred Watson, Rob A. Wittenmyer, Maruša Žerjal
GALAH is a large-scale magnitude-limited southern stellar spectroscopic survey. Its second data release (GALAH DR2) provides values of stellar parameters and abundances of 23 elements for 342,682 stars (Buder et al.). Here we add a description of the public release of radial velocities with a typical accuracy of 0.1 km/s for 336,215 of these stars, achievable due to the large wavelength coverage, high resolving power and good signal to noise ratio of the observed spectra, but also because convective motions in stellar atmosphere and gravitational redshift from the star to the observer are taken into account. In the process we derive medians of observed spectra which are nearly noiseless, as they are obtained from between 100 and 1116 observed spectra belonging to the same bin with a width of 50 K in temperature, 0.2 dex in gravity, and 0.1 dex in metallicity. Publicly released 1181 median spectra have a resolving power of 28,000 and trace the well-populated stellar types with metallicities between -0.6 and +0.3. Note that radial velocities from GALAH are an excellent match to the accuracy of velocity components along the sky plane derived by Gaia for the same stars. The level of accuracy achieved here is adequate for studies of dynamics within stellar clusters, associations and streams in the Galaxy. So it may be relevant for studies of the distribution of dark matter.
Original languageUndefined/Unknown
JournalRoyal Astronomical Society. Monthly Notices
Issue number1
Pages (from-to)645–654
StatePublished - 17 Apr 2018

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