Astrometric radial velocities for nearby stars

Abstract

Under certain conditions, stellar radial velocities can be determined from astrometry, without any use of spectroscopy. This enables us to identify phenomena, other than the Doppler effect, that are displacing spectral lines. The change of stellar proper motions over time (perspective acceleration) is used to determine radial velocities from accurate astrometric data, which are now available from the Gaia and Hipparcos missions. Positions and proper motions at the epoch of Hipparcos are compared with values propagated back from the epoch of the Gaia Early Data Release 3. This propagation depends on the radial velocity, which obtains its value from an optimal fit assuming uniform space motion relative to the solar system barycentre. For 930 nearby stars we obtain astrometric radial velocities with formal uncertainties better than 100 km/s; for 55 stars the uncertainty is below 10 km/s, and for seven it is below 1 km/s. Most stars that are not components of double or multiple systems show good agreement with available spectroscopic radial velocities. Astrometry offers geometric methods to determine stellar radial velocity, irrespective of complexities in stellar spectra. This enables us to segregate wavelength displacements caused by the radial motion of the stellar centre-of-mass from those induced by other effects, such as gravitational redshifts in white dwarfs.

arXiv comment7 pages, 2 figures, 2 tables. Compared with the original submission, systematic corrections to the Gaia data have been improved as detailed in Section 3. Resulting changes in Tables 1 and 2 are small and mostly insignificant. Accepted for publication in Astronomy & Astrophysics

References in corpus (35)

• The SIMBAD astronomical database
• Gaia Data Release 2: The astrometric solution
• Gaia Early Data Release 3: Parallax bias versus magnitude, colour, and position
• How to Constrain Your M Dwarf: measuring effective temperature, bolometric luminosity, mass, and radius
• Stellar and substellar companions of nearby stars from Gaia DR2 - Binarity from proper motion anomaly
• Pulkovo Compilation of Radial Velocities for 35495 Hipparcos Stars in a Common System
• The Hipparcos-Gaia Catalog of Accelerations: Gaia EDR3 Edition
• The Hipparcos-Gaia Catalog of Accelerations
• Know Your Neighborhood: A Detailed Model Atmosphere Analysis of Nearby White Dwarfs
• The low-level radial velocity variability in Barnard's star (=GJ 699). Secular acceleration, indications for convective redshift, and planet mass limits
• A Hipparcos study of the Hyades open cluster: Improved colour-absolute magnitude and Hertzsprung-Russell diagrams
• The fundamental definition of 'radial velocity'
• Constraining the difference in convective blueshift between the components of alpha Cen with precise radial velocities
• The M dwarf planet search programme at the ESO VLT + UVES. A search for terrestrial planets in the habitable zone of M dwarfs
• Long-term magnetic activity of a sample of M-dwarf stars from the HARPS program II. Activity and radial velocity
• Astrometric radial velocities III. Hipparcos measurements of nearby star clusters and associations
• Hubble Space Telescope Spectroscopy of the Balmer lines in Sirius B
• The radii of the nearby K5V and K7V stars 61 Cyg A & B - CHARA/FLUOR interferometry and CESAM2k modeling
• Characterizing and correcting the proper motion bias of the bright Gaia EDR3 sources
• Optical Spectroscopy of a Flare on Barnard's Star
• The CARMENES search for exoplanets around M dwarfs: Convective shift and starspot constraints from chromatic radial velocities
• The gravitational redshift of Sirius B
• Joint astrometric solution of Hipparcos and Gaia: A recipe for the Hundred Thousand Proper Motions project
• Rigorous treatment of barycentric stellar motion: Perspective and light-time effects in astrometric and radial velocity data
• Gravitational redshifts in main-sequence and giant stars
• Precision Millimeter Astrometry of the $\alpha$ Centauri AB System
• A Predicted Astrometric Microlensing Event by a Nearby White Dwarf
• Precise Doppler Monitoring of Barnard's Star
• Spectroscopic and astrometric radial velocities: Hyades as a benchmark
• The "DODO" survey I: limits on ultra-cool substellar and planetary-mass companions to van Maanen's star (vMa 2)
• Predictions of Gaia's prize microlensing events are flawed
• Expectations on the mass determination using astrometric microlensing by Gaia
• Stellar variability in radial velocity
• Intrinsic spectral blueshifts in rapidly rotating stars?
• A Measurement of Stellar Surface Gravity Hidden in Radial Velocity Differences of Co-moving Stars

Cited by in corpus (4)

• Stellar and substellar companions from Gaia EDR3 -- Proper motion anomaly and resolved common proper motion pairs
• First semi-empirical test of the white dwarf mass-radius relationship using a single white dwarf via astrometric microlensing
• The 3D Galactocentric velocities of Kepler stars: marginalizing over missing RVs
• htof: A new open-source tool for analyzing Hipparcos, Gaia, and future astrometric missions