TY - JOUR
T1 - Gaia-4b and 5b
T2 - Radial Velocity Confirmation of Gaia Astrometric Orbital Solutions Reveal a Massive Planet and a Brown Dwarf Orbiting Low-mass Stars
AU - Stefánsson, Gudmundur
AU - Mahadevan, Suvrath
AU - Winn, Joshua N.
AU - Marcussen, Marcus L.
AU - Kanodia, Shubham
AU - Albrecht, Simon
AU - Fitzmaurice, Evan
AU - Mikulskytė, Onė
AU - Cañas, Caleb I.
AU - Espinoza-Retamal, Juan I.
AU - Zwart, Yiri
AU - Krolikowski, Daniel M.
AU - Hotnisky, Andrew
AU - Robertson, Paul
AU - Alvarado-Montes, Jaime A.
AU - Bender, Chad F.
AU - Blake, Cullen H.
AU - Callingham, J. R.
AU - Cochran, William D.
AU - Delamer, Megan
AU - Diddams, Scott A.
AU - Dong, Jiayin
AU - Fernandes, Rachel B.
AU - Giovinazzi, Mark R.
AU - Halverson, Samuel
AU - Libby-Roberts, Jessica
AU - Logsdon, Sarah E.
AU - McElwain, Michael W.
AU - Ninan, Joe P.
AU - Rajagopal, Jayadev
AU - Reji, Varghese
AU - Roy, Arpita
AU - Schwab, Christian
AU - Wright, Jason T.
N1 - Publisher Copyright:
© 2025. The Author(s). Published by the American Astronomical Society.
PY - 2025/2/3
Y1 - 2025/2/3
N2 - Gaia astrometry of nearby stars is precise enough to detect the tiny displacements induced by substellar companions, but radial velocity (RV) data are needed for definitive confirmation. Here we present RV follow-up observations of 28 M and K stars with candidate astrometric substellar companions, which led to the confirmation of two systems, Gaia-4b and Gaia-5b, identification of five systems that are single lined but require additional data to confirm as substellar companions, and the refutation of 21 systems as stellar binaries. Gaia-4b is a massive planet (M = 11.8 ± 0.7 MJ) in a P = 571.3 ± 1.4 day orbit with a projected semimajor axis a0 = 0.312 ± 0.040 mas orbiting a 0.644 ± 0.02M⊙ star. Gaia-5b is a brown dwarf (M = 20.9 ± 0.5MJ) in a P = 358.62 ± 0.20 days eccentric e = 0.6423 ± 0.0026 orbit with a projected angular semimajor axis of a0 = 0.947 ± 0.038 mas around a 0.34 ± 0.03M⊙ star. Gaia-4b is one of the first exoplanets discovered via the astrometric technique, and is one of the most massive planets known to orbit a low-mass star.
AB - Gaia astrometry of nearby stars is precise enough to detect the tiny displacements induced by substellar companions, but radial velocity (RV) data are needed for definitive confirmation. Here we present RV follow-up observations of 28 M and K stars with candidate astrometric substellar companions, which led to the confirmation of two systems, Gaia-4b and Gaia-5b, identification of five systems that are single lined but require additional data to confirm as substellar companions, and the refutation of 21 systems as stellar binaries. Gaia-4b is a massive planet (M = 11.8 ± 0.7 MJ) in a P = 571.3 ± 1.4 day orbit with a projected semimajor axis a0 = 0.312 ± 0.040 mas orbiting a 0.644 ± 0.02M⊙ star. Gaia-5b is a brown dwarf (M = 20.9 ± 0.5MJ) in a P = 358.62 ± 0.20 days eccentric e = 0.6423 ± 0.0026 orbit with a projected angular semimajor axis of a0 = 0.947 ± 0.038 mas around a 0.34 ± 0.03M⊙ star. Gaia-4b is one of the first exoplanets discovered via the astrometric technique, and is one of the most massive planets known to orbit a low-mass star.
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U2 - 10.3847/1538-3881/ada9e1
DO - 10.3847/1538-3881/ada9e1
M3 - Article
AN - SCOPUS:85219687353
SN - 0004-6256
VL - 169
JO - Astronomical Journal
JF - Astronomical Journal
IS - 2
M1 - 107
ER -