The mass and radius of the unseen M dwarf companion in the single-lined eclipsing binary hat-tr-205-013

Thomas G. Beatty, José M. Fernández, David W. Latham, Gáspár Á Bakos, Géza Kovács, Robert W. Noyes, Robert P. Stefanik, Guillermo Torres, Mark E. Everett, Carl W. Hergenrother

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Abstract

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.

Original languageEnglish (US)
Pages (from-to)573-582
Number of pages10
JournalAstrophysical Journal
Volume663
Issue number1 I
DOIs
StatePublished - Jul 1 2007

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radii
orbits
light curve
eclipses
stellar mass
diagram
gravity
diagrams
gravitation
stars
orbitals

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Beatty, T. G., Fernández, J. M., Latham, D. W., Bakos, G. Á., Kovács, G., Noyes, R. W., ... Hergenrother, C. W. (2007). The mass and radius of the unseen M dwarf companion in the single-lined eclipsing binary hat-tr-205-013. Astrophysical Journal, 663(1 I), 573-582. https://doi.org/10.1086/518413
Beatty, Thomas G. ; Fernández, José M. ; Latham, David W. ; Bakos, Gáspár Á ; Kovács, Géza ; Noyes, Robert W. ; Stefanik, Robert P. ; Torres, Guillermo ; Everett, Mark E. ; Hergenrother, Carl W. / The mass and radius of the unseen M dwarf companion in the single-lined eclipsing binary hat-tr-205-013. In: Astrophysical Journal. 2007 ; Vol. 663, No. 1 I. pp. 573-582.
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title = "The mass and radius of the unseen M dwarf companion in the single-lined eclipsing binary hat-tr-205-013",
abstract = "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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Beatty, TG, Fernández, JM, Latham, DW, Bakos, GÁ, Kovács, G, Noyes, RW, Stefanik, RP, Torres, G, Everett, ME & Hergenrother, CW 2007, 'The mass and radius of the unseen M dwarf companion in the single-lined eclipsing binary hat-tr-205-013', Astrophysical Journal, vol. 663, no. 1 I, pp. 573-582. https://doi.org/10.1086/518413

The mass and radius of the unseen M dwarf companion in the single-lined eclipsing binary hat-tr-205-013. / Beatty, Thomas G.; Fernández, José M.; Latham, David W.; Bakos, Gáspár Á; Kovács, Géza; Noyes, Robert W.; Stefanik, Robert P.; Torres, Guillermo; Everett, Mark E.; Hergenrother, Carl W.

In: Astrophysical Journal, Vol. 663, No. 1 I, 01.07.2007, p. 573-582.

Research output: Contribution to journalArticle

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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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Beatty TG, Fernández JM, Latham DW, Bakos GÁ, Kovács G, Noyes RW et al. The mass and radius of the unseen M dwarf companion in the single-lined eclipsing binary hat-tr-205-013. Astrophysical Journal. 2007 Jul 1;663(1 I):573-582. https://doi.org/10.1086/518413