TY - JOUR
T1 - The mass and radius of the unseen M dwarf companion in the single-lined eclipsing binary hat-tr-205-013
AU - Beatty, Thomas G.
AU - Fernández, José M.
AU - Latham, David W.
AU - Bakos, Gáspár Á
AU - Kovács, Géza
AU - Noyes, Robert W.
AU - Stefanik, Robert P.
AU - Torres, Guillermo
AU - Everett, Mark E.
AU - Hergenrother, Carl W.
PY - 2007/7/1
Y1 - 2007/7/1
N2 - We derive masses and radii for both components in the single-lined eclipsing binary HAT-TR-205-013, which consists of an F7 V primary and a late M dwarf secondary. The system's period is short, P = 2.230736 ± 0.000010 days, with an orbit indistinguishable from circular, e = 0.012 ± 0.021. We demonstrate generally that the surface gravity of the secondary star in a single-lined binary undergoing total eclipses can be derived from characteristics of the light curve and spectroscopic orbit. This constrains the secondary to a unique line in the mass-radius diagram, with M/R2 = constant. For HAT-TR-205-013, we assume the orbit has been tidally circularized and that the primary's rotation has been synchronized and aligned with the orbital axis. Our observed line broadening, Vrot sin irot = 28.9 ± 1.0 km s-1, gives a primary radius of RA = 1.28 ± 0.04 R⊙. Our light-curve analysis leads to the radius of the secondary, RB = 0.167 ± 0.006 R ⊙, and the semimajor axis of the orbit, a = 7.54 ± 0.30 M⊙ = 0.0351 ± 0.0014 AU. Our single-lined spectroscopic orbit and the semimajor axis then yield the individual masses MB = 0.124 ± 0.010 M⊙ and MA = 1.04 ± 0.13 M⊙. Our result for HAT-TR-205-013 B lies above the theoretical mass-radius models from the Lyon group, consistent with results from double-lined eclipsing binaries. The method we describe offers the opportunity to study the very low end of the stellar mass-radius relation.
AB - We derive masses and radii for both components in the single-lined eclipsing binary HAT-TR-205-013, which consists of an F7 V primary and a late M dwarf secondary. The system's period is short, P = 2.230736 ± 0.000010 days, with an orbit indistinguishable from circular, e = 0.012 ± 0.021. We demonstrate generally that the surface gravity of the secondary star in a single-lined binary undergoing total eclipses can be derived from characteristics of the light curve and spectroscopic orbit. This constrains the secondary to a unique line in the mass-radius diagram, with M/R2 = constant. For HAT-TR-205-013, we assume the orbit has been tidally circularized and that the primary's rotation has been synchronized and aligned with the orbital axis. Our observed line broadening, Vrot sin irot = 28.9 ± 1.0 km s-1, gives a primary radius of RA = 1.28 ± 0.04 R⊙. Our light-curve analysis leads to the radius of the secondary, RB = 0.167 ± 0.006 R ⊙, and the semimajor axis of the orbit, a = 7.54 ± 0.30 M⊙ = 0.0351 ± 0.0014 AU. Our single-lined spectroscopic orbit and the semimajor axis then yield the individual masses MB = 0.124 ± 0.010 M⊙ and MA = 1.04 ± 0.13 M⊙. Our result for HAT-TR-205-013 B lies above the theoretical mass-radius models from the Lyon group, consistent with results from double-lined eclipsing binaries. The method we describe offers the opportunity to study the very low end of the stellar mass-radius relation.
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U2 - 10.1086/518413
DO - 10.1086/518413
M3 - Article
AN - SCOPUS:34547222380
SN - 0004-637X
VL - 663
SP - 573
EP - 582
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1 I
ER -