TY - JOUR
T1 - New light on the Gaia DR2 parallax zero-point
T2 - influence of the asteroseismic approach, in and beyond the Kepler field
AU - Khan, Saniya
AU - Miglio, Andrea
AU - Mosser, Benoît
AU - Arenou, Frédéric
AU - Belkacem, Kévin
AU - Brown, Anthony G. A.
AU - Katz, David
AU - Casagrande, Luca
AU - Chaplin, William J.
AU - Davies, Guy R.
AU - Rendle, Ben M.
AU - Rodrigues, Thaíse S.
AU - Bossini, Diego
AU - Cantat-Gaudin, Tristan
AU - Elsworth, Yvonne P.
AU - Girardi, Leo
AU - North, Thomas S. H.
AU - Vallenari, Antonella
PY - 2019/8/1
Y1 - 2019/8/1
N2 - The importance of studying the Gaia DR2 parallax zero-point by external means was underlined by Lindegren et al. (2018), and initiated by several works making use of Cepheids, eclipsing binaries, and asteroseismology. Despite a very efficient elimination of basic-angle variations, a small fluctuation remains and shows up as a small offset in the Gaia DR2 parallaxes. By combining astrometric, asteroseismic, spectroscopic, and photometric constraints, we undertake a new analysis of the Gaia parallax offset for nearly 3000 red-giant branch (RGB) and 2200 red clump (RC) stars observed by Kepler, as well as about 500 and 700 red giants (both RGB and RC) selected by the K2 Galactic Archaeology Program in campaigns 3 and 6. Engaging into a thorough comparison of the astrometric and asteroseismic parallaxes, we are able to highlight the influence of the asteroseismic method, and measure parallax offsets in the Kepler field that are compatible with independent estimates from literature and open clusters. Moreover, adding the K2 fields to our investigation allows us to retrieve a clear illustration of the positional dependence of the zero-point, in general agreement with the information provided by quasars. Lastly, we initiate a two-step methodology to make progress in the simultaneous calibration of the asteroseismic scaling relations and of the Gaia DR2 parallax offset, which will greatly benefit from the gain in precision with the third Data Release of Gaia.
AB - The importance of studying the Gaia DR2 parallax zero-point by external means was underlined by Lindegren et al. (2018), and initiated by several works making use of Cepheids, eclipsing binaries, and asteroseismology. Despite a very efficient elimination of basic-angle variations, a small fluctuation remains and shows up as a small offset in the Gaia DR2 parallaxes. By combining astrometric, asteroseismic, spectroscopic, and photometric constraints, we undertake a new analysis of the Gaia parallax offset for nearly 3000 red-giant branch (RGB) and 2200 red clump (RC) stars observed by Kepler, as well as about 500 and 700 red giants (both RGB and RC) selected by the K2 Galactic Archaeology Program in campaigns 3 and 6. Engaging into a thorough comparison of the astrometric and asteroseismic parallaxes, we are able to highlight the influence of the asteroseismic method, and measure parallax offsets in the Kepler field that are compatible with independent estimates from literature and open clusters. Moreover, adding the K2 fields to our investigation allows us to retrieve a clear illustration of the positional dependence of the zero-point, in general agreement with the information provided by quasars. Lastly, we initiate a two-step methodology to make progress in the simultaneous calibration of the asteroseismic scaling relations and of the Gaia DR2 parallax offset, which will greatly benefit from the gain in precision with the third Data Release of Gaia.
KW - asteroseismology
KW - astro-ph.SR
KW - astrometry
KW - parallaxes
KW - stars: low-mass
UR - http://www.scopus.com/inward/record.url?scp=85070239596&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/201935304
DO - 10.1051/0004-6361/201935304
M3 - Article
SN - 0004-6361
VL - 628
SP - 1
EP - 15
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
M1 - A35
ER -