TOI 694b and TIC 220568520b: Two Low-mass Companions near the Hydrogen-burning Mass Limit Orbiting Sun-like Stars
Mireles
I
author
Shporer
A
author
Grieves
N
author
Zhou
G
author
Gunther
M
N
author
Brahm
R
author
Ziegler
C
author
Stassun
K
G
author
Huang
C
X
author
Nielsen
L
author
dos Santos
L
A
author
Udry
S
author
Bouchy
F
author
Ireland
M
author
Wallace
A
author
Sarkis
P
author
Henning
T
author
Jordan
A
author
Law
N
author
Mann
A
W
author
Paredes
L
A
author
James
H
S
author
Jao
W
C
author
Henry
T
J
author
Butler
R
P
author
Rodriguez
J
E
author
Yu
L
author
Flowers
E
author
Ricker
G
R
author
Latham
D
W
author
Vanderspek
R
author
Seager
S
author
Winn
J
N
author
Jenkins
J
M
author
Furesz
G
author
Hesse
K
author
Quintana
E
V
author
Rose
M
E
author
Smith
J
C
author
Tenenbaum
P
author
Vezie
M
author
Yahalomi
D
A
author
Zhan
Z
C
author
2020
English
We report the discovery of TOI 694 b and TIC 220568520 b, two low-mass stellar companions in eccentric orbits around metal-rich Sun-like stars, first detected by the Transiting Exoplanet Survey Satellite (TESS). TOI 694 b has an orbital period of 48.05131 +/- 0.00019 days and eccentricity of 0.51946 +/- 0.00081, and we derive a mass of 89.0 +/- 5.3 M-Jup (0.0849 +/- 0.0051 M-circle dot) and radius of 1.111 +/- 0.017 R-Jup (0.1142 +/- 0.0017 R-circle dot). TIC 220568520 b has an orbital period of 18.55769 +/- 0.00039 days and eccentricity of 0.0964 +/- 0.0032, and we derive a mass of 107.2 +/- 5.2 M-Jup (0.1023 +/- 0.0050 M-circle dot) and radius of 1.248 +/- 0.018 R-Jup (0.1282 +/- 0.0019 R-circle dot). Both binary companions lie close to and above the hydrogen-burning mass threshold that separates brown dwarfs and the lowest-mass stars, with TOI 694 b being 2s above the canonical mass threshold of 0.075 M-circle dot. The relatively long periods of the systems mean that the magnetic fields of the low-mass companions are not expected to inhibit convection and inflate the radius, which according to one leading theory is common in similar objects residing in short-period tidally synchronized binary systems. Indeed we do not find radius inflation for these two objects when compared to theoretical isochrones. These two new objects add to the short but growing list of low-mass stars with well-measured masses and radii, and highlight the potential of the TESS mission for detecting such rare objects orbiting bright stars.
Low mass stars
M dwarf stars
Eclipsing binary stars
WOS:000565724400001
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text
10.3847/1538-3881/aba526
Mireles_etal2020
Astronomical Journal
Astron. J.
2020
Iop Publishing Ltd
continuing
periodical
academic journal
160
3
13 pp
0004-6256