The Gravitational Redshift of Solar-type Stars from Gaia DR3 Wide Binaries
- Creators
-
El-Badry, Kareem
Abstract
Light escaping from a gravitational potential suffers a redshift with magnitude proportional to the depth of the potential. This "gravitational redshift" is easily measurable in dense stars such as white dwarfs, but is much weaker and has evaded unambiguous detection in main-sequence stars. I show that the effect is directly measurable in the Gaia DR3 radial velocities (RVs) of the components of wide binary stars. In a sample of ∼500 wide binaries containing a solar-type main-sequence star and a red giant or red clump companion, the apparent RV of the giant is on average 0.49 ± 0.02 km s⁻¹ lower than that of the main-sequence star. This owes primarily to the giants' weaker gravitational fields and is in reasonably good agreement with the value expected from general relativity.
Additional Information
© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. I thank George Seabroke and David W. Hogg for discussions that prompted this note. This work was done at the Gaia Hike meeting at the University of British Columbia in 2022 June. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC,https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.Additional details
- Eprint ID
- 118726
- Resolver ID
- CaltechAUTHORS:20230105-895897000.50
- Gaia Multilateral Agreement
- Created
-
2023-01-06Created from EPrint's datestamp field
- Updated
-
2023-01-06Created from EPrint's last_modified field