The Tycho-Gaia astrometric solution. How to get 2.5 million parallaxes with less than one year of Gaia data

By D. Michalik, L. Lindegren, D. Hobbs. 2014

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Context. The first release of astrometric data from Gaia will contain the mean stellar positions and magnitudes from the first year of observations, and proper motions from the combination of Gaia data with Hipparcos prior information (HTPM). Aims. We study the potential of using the positions from the Tycho-2 Catalogue as additional information for a joint solution with early Gaia data. We call this the Tycho-Gaia astrometric solution (TGAS). Methods. We adapt Gaia's Astrometric Global Iterative Solution (AGIS) to incorporate Tycho information, and use simulated Gaia observations to demonstrate the feasibility of TGAS and to estimate its performance. Results. Using six to twelve months of Gaia data, TGAS could deliver positions, parallaxes and annual proper motions for the 2.5 million Tycho-2 stars, with sub-milliarcsecond accuracy. TGAS overcomes some of the limitations of the HTPM project and allows its execution half a year earlier. Furthermore, if the parallaxes from Hipparcos are not incorporated in the solution, they can be used as a consistency check of the TGAS/HTPM solution.

Subfields: Astronomy and Astrophysics, Instrumentation, Oceanography

View Paper: https://www.semanticscholar.org/paper/8ef7393e3fd99ae9fe74d8ac5376efdb24619945

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Citations in the corpus

The California-Kepler Survey. II. Precise Physical Properties of 2025 Kepler Planets and Their Host Stars (2017, methodology): “…parameters and uncertainties, we performed an additional assessment of the quality of the derived CKS stellar radii using trigonometric parallaxes, ,trigp , from the Tycho-Gaia Astrometric Solution (TGAS; Michalik et al. 2015; Gaia Collaboration et al. 2016a, 2016b; Lindegren et al. 2016).”
Confirmation of the Gaia DR2 Parallax Zero-point Offset Using Asteroseismology and Spectroscopy in the Kepler Field (2018, methodology): “The first data release of Gaia, using the Tycho-Gaia astrometric solution (TGAS; Michalik et al. 2015; Gaia Collaboration et al. 2016), represented a significant advance over the earlier Hipparcos work (van Leeuwen 2007).”
The Hipparcos–Gaia Catalog of Accelerations (2018, methodology): “Of the 118,218 stars in the Hipparcos catalog (ESA 1997), just 83,034 are present in the Hipparcos-DR2 best neighbor catalog available on the Gaia archive (Marrese et al. 2018), and 93,635 are present in TGAS (Michalik et al. 2015; Lindegren et al. 2016).”
THE RADIAL VELOCITY EXPERIMENT (RAVE): FIFTH DATA RELEASE (2013, background): “…been launched and data collection is ongoing, a long enough time baseline has to have elapsed for sufficient accuracy of a global reduction of observations (e.g., five years for Gaia to yield positions, parallaxes and annual proper motions at an accuracy level of 5 – 25 µas, Michalik et al. 2015).”
Evidence for an Intermediate-mass Milky Way from Gaia DR2 Halo Globular Cluster Motions (2018, methodology): “…data release (Gaia Collaboration et al. 2016b) contained proper motions for ∼2 million stars in the Tycho-Gaia Astrometric Solution (TGAS) catalogue (Michalik et al. 2015), which used Tycho2 (Høg et al. 2000) measurements to provide a first epoch of data and Gaia data for the second, and has been…”
The vertical metallicity gradients of mono-age stellar populations in the Milky Way with the RAVE and Gaia data (2017, background): “Recently, Gaia Collaboration et al. (2016a,b) released their first Gaia data, including the Tycho-Gaia Astrometric Solution dataset (TGAS; Michalik et al. 2015), which provides accurate astrometry for more than 2 million bright stars.”
Precision Stellar Characterization of FGKM Stars using an Empirical Spectral Library (2017, methodology): “1Parallax from the Tycho-Gaia Astrometric Solution (TGAS; Gaia Collaboration et al. 2016; Lindegren et al. 2016; Michalik et al. 2015).”
The GALAH survey: observational overview and Gaia DR1 companion (2016, methodology): “We anticipate that they will improve further when we adapt our spectroscopic analysis pipeline to include the stellar distances derived by the Tycho-Gaia Astrometric Solution (Michalik et al. 2015) and future Gaia data releases.”
ECLIPSING BINARY STARS AS BENCHMARKS FOR TRIGONOMETRIC PARALLAXES IN THE GAIA ERA (2016, methodology): “In addition to accurate positions and mean magnitudes for stars over at least 90% of the sky, and additional information for sources at the ecliptic poles, DR1 will contain parallaxes for up to 2.5 million stars based on the Tycho-Gaia Astrometric Solution (TGAS; Michalik et al. 2015).”
A Gaia DR2 view of the open cluster population in the Milky Way (2018, methodology): “…such as the studies of Robichon et al. (1999; 50 OCs with at least four stars, within 500 pc) and van Leeuwen (2009; 20 OCs) using Hipparcos data, or Gaia Collaboration (2017; 19 OCs within 500 pc) using the Tycho-Gaia Astrometric Solution (TGAS, Michalik et al. 2015; Gaia Collaboration 2016a).”