Stellar diameters and temperatures. II. Main-sequence K- and M-stars

Tabetha S. Boyajian, Kaspar Von Braun, Gerard Van Belle, Harold A. McAlister, Theo A. Ten Brummelaar, Stephen R. Kane, Philip S. Muirhead, Jeremy Jones, Russel White, Gail Schaefer, David Ciardi, Todd Henry, Mercedes López-Morales, Stephen Ridgway, Douglas Gies, Wei Chun Jao, Bárbara Rojas-Ayala, J. Robert Parks, Laszlo Sturmann, Judit SturmannNils H. Turner, Chris Farrington, P. J. Goldfinger, David H. Berger

Resultado de la investigación: Article

300 Citas (Scopus)

Resumen

We present interferometric angular diameter measurements of 21 low-mass, K- and M-dwarfs made with the CHARA Array. This sample is enhanced by adding a collection of radius measurements published in the literature to form a total data set of 33K-M-dwarfs with diameters measured to better than 5%. We use these data in combination with the Hipparcos parallax and new measurements of the star's bolometric flux to compute absolute luminosities, linear radii, and effective temperatures for the stars. We develop empirical relations for K0 to M4 main-sequence stars that link the stellar temperature, radius, and luminosity to the observed (B - V), (V - R), (V - I), (V - J), (V - H), and (V - K) broadband color index and stellar metallicity [Fe/H]. These relations are valid for metallicities ranging from [Fe/H] = -0.5 to +0.1 dex and are accurate to 2%, 5%, and 4% for temperature, radius, and luminosity, respectively. Our results show that it is necessary to use metallicity-dependent transformations in order to properly convert colors into stellar temperatures, radii, and luminosities. Alternatively, we find no sensitivity to metallicity on relations we construct to the global properties of a star omitting color information, e.g., temperature-radius and temperature-luminosity. Thus, we are able to empirically quantify to what order the star's observed color index is impacted by the stellar iron abundance. In addition to the empirical relations, we also provide a representative look-up table via stellar spectral classifications using this collection of data. Robust examinations of single star temperatures and radii compared to evolutionary model predictions on the luminosity-temperature and luminosity-radius planes reveal that models overestimate the temperatures of stars with surface temperatures <5000K by 3%, and underestimate the radii of stars with radii <0.7 R by 5%. These conclusions additionally suggest that the models over account for the effects that the stellar metallicity may have on the astrophysical properties of an object. By comparing the interferometrically measured radii for the single star population to those of eclipsing binaries, we find that for a given mass, single and binary star radii are indistinguishable. However, we also find that for a given radius, the literature temperatures for binary stars are systematically lower compared to our interferometrically derived temperatures of single stars by 200 to 300K. The nature of this offset is dependent on the validation of binary star temperatures, where bringing all measurements to a uniform and correctly calibrated temperature scale is needed to identify any influence stellar activity may have on the physical properties of a star. Lastly, we present an empirically determined H-R diagram using fundamental properties presented here in combination with those in Boyajian et al. for a total of 74 nearby, main-sequence, A- to M-type stars, and define regions of habitability for the potential existence of sub-stellar mass companions in each system.

Idioma originalEnglish
Número de artículo112
PublicaciónAstrophysical Journal
Volumen757
N.º2
DOI
EstadoPublished - 1 oct 2012

Huella dactilar

K stars
M stars
main sequence stars
stars
radii
luminosity
temperature
metallicity
binary stars
stellar temperature
color
habitability
stellar activity
temperature scales
parallax
stellar mass
surface temperature

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Citar esto

Boyajian, T. S., Von Braun, K., Van Belle, G., McAlister, H. A., Ten Brummelaar, T. A., Kane, S. R., ... Berger, D. H. (2012). Stellar diameters and temperatures. II. Main-sequence K- and M-stars. Astrophysical Journal, 757(2), [112]. https://doi.org/10.1088/0004-637X/757/2/112
Boyajian, Tabetha S. ; Von Braun, Kaspar ; Van Belle, Gerard ; McAlister, Harold A. ; Ten Brummelaar, Theo A. ; Kane, Stephen R. ; Muirhead, Philip S. ; Jones, Jeremy ; White, Russel ; Schaefer, Gail ; Ciardi, David ; Henry, Todd ; López-Morales, Mercedes ; Ridgway, Stephen ; Gies, Douglas ; Jao, Wei Chun ; Rojas-Ayala, Bárbara ; Parks, J. Robert ; Sturmann, Laszlo ; Sturmann, Judit ; Turner, Nils H. ; Farrington, Chris ; Goldfinger, P. J. ; Berger, David H. / Stellar diameters and temperatures. II. Main-sequence K- and M-stars. En: Astrophysical Journal. 2012 ; Vol. 757, N.º 2.
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abstract = "We present interferometric angular diameter measurements of 21 low-mass, K- and M-dwarfs made with the CHARA Array. This sample is enhanced by adding a collection of radius measurements published in the literature to form a total data set of 33K-M-dwarfs with diameters measured to better than 5{\%}. We use these data in combination with the Hipparcos parallax and new measurements of the star's bolometric flux to compute absolute luminosities, linear radii, and effective temperatures for the stars. We develop empirical relations for K0 to M4 main-sequence stars that link the stellar temperature, radius, and luminosity to the observed (B - V), (V - R), (V - I), (V - J), (V - H), and (V - K) broadband color index and stellar metallicity [Fe/H]. These relations are valid for metallicities ranging from [Fe/H] = -0.5 to +0.1 dex and are accurate to 2{\%}, 5{\%}, and 4{\%} for temperature, radius, and luminosity, respectively. Our results show that it is necessary to use metallicity-dependent transformations in order to properly convert colors into stellar temperatures, radii, and luminosities. Alternatively, we find no sensitivity to metallicity on relations we construct to the global properties of a star omitting color information, e.g., temperature-radius and temperature-luminosity. Thus, we are able to empirically quantify to what order the star's observed color index is impacted by the stellar iron abundance. In addition to the empirical relations, we also provide a representative look-up table via stellar spectral classifications using this collection of data. Robust examinations of single star temperatures and radii compared to evolutionary model predictions on the luminosity-temperature and luminosity-radius planes reveal that models overestimate the temperatures of stars with surface temperatures <5000K by 3{\%}, and underestimate the radii of stars with radii <0.7 R ⊙ by 5{\%}. These conclusions additionally suggest that the models over account for the effects that the stellar metallicity may have on the astrophysical properties of an object. By comparing the interferometrically measured radii for the single star population to those of eclipsing binaries, we find that for a given mass, single and binary star radii are indistinguishable. However, we also find that for a given radius, the literature temperatures for binary stars are systematically lower compared to our interferometrically derived temperatures of single stars by 200 to 300K. The nature of this offset is dependent on the validation of binary star temperatures, where bringing all measurements to a uniform and correctly calibrated temperature scale is needed to identify any influence stellar activity may have on the physical properties of a star. Lastly, we present an empirically determined H-R diagram using fundamental properties presented here in combination with those in Boyajian et al. for a total of 74 nearby, main-sequence, A- to M-type stars, and define regions of habitability for the potential existence of sub-stellar mass companions in each system.",
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Boyajian, TS, Von Braun, K, Van Belle, G, McAlister, HA, Ten Brummelaar, TA, Kane, SR, Muirhead, PS, Jones, J, White, R, Schaefer, G, Ciardi, D, Henry, T, López-Morales, M, Ridgway, S, Gies, D, Jao, WC, Rojas-Ayala, B, Parks, JR, Sturmann, L, Sturmann, J, Turner, NH, Farrington, C, Goldfinger, PJ & Berger, DH 2012, 'Stellar diameters and temperatures. II. Main-sequence K- and M-stars', Astrophysical Journal, vol. 757, n.º 2, 112. https://doi.org/10.1088/0004-637X/757/2/112

Stellar diameters and temperatures. II. Main-sequence K- and M-stars. / Boyajian, Tabetha S.; Von Braun, Kaspar; Van Belle, Gerard; McAlister, Harold A.; Ten Brummelaar, Theo A.; Kane, Stephen R.; Muirhead, Philip S.; Jones, Jeremy; White, Russel; Schaefer, Gail; Ciardi, David; Henry, Todd; López-Morales, Mercedes; Ridgway, Stephen; Gies, Douglas; Jao, Wei Chun; Rojas-Ayala, Bárbara; Parks, J. Robert; Sturmann, Laszlo; Sturmann, Judit; Turner, Nils H.; Farrington, Chris; Goldfinger, P. J.; Berger, David H.

En: Astrophysical Journal, Vol. 757, N.º 2, 112, 01.10.2012.

Resultado de la investigación: Article

TY - JOUR

T1 - Stellar diameters and temperatures. II. Main-sequence K- and M-stars

AU - Boyajian, Tabetha S.

AU - Von Braun, Kaspar

AU - Van Belle, Gerard

AU - McAlister, Harold A.

AU - Ten Brummelaar, Theo A.

AU - Kane, Stephen R.

AU - Muirhead, Philip S.

AU - Jones, Jeremy

AU - White, Russel

AU - Schaefer, Gail

AU - Ciardi, David

AU - Henry, Todd

AU - López-Morales, Mercedes

AU - Ridgway, Stephen

AU - Gies, Douglas

AU - Jao, Wei Chun

AU - Rojas-Ayala, Bárbara

AU - Parks, J. Robert

AU - Sturmann, Laszlo

AU - Sturmann, Judit

AU - Turner, Nils H.

AU - Farrington, Chris

AU - Goldfinger, P. J.

AU - Berger, David H.

PY - 2012/10/1

Y1 - 2012/10/1

N2 - We present interferometric angular diameter measurements of 21 low-mass, K- and M-dwarfs made with the CHARA Array. This sample is enhanced by adding a collection of radius measurements published in the literature to form a total data set of 33K-M-dwarfs with diameters measured to better than 5%. We use these data in combination with the Hipparcos parallax and new measurements of the star's bolometric flux to compute absolute luminosities, linear radii, and effective temperatures for the stars. We develop empirical relations for K0 to M4 main-sequence stars that link the stellar temperature, radius, and luminosity to the observed (B - V), (V - R), (V - I), (V - J), (V - H), and (V - K) broadband color index and stellar metallicity [Fe/H]. These relations are valid for metallicities ranging from [Fe/H] = -0.5 to +0.1 dex and are accurate to 2%, 5%, and 4% for temperature, radius, and luminosity, respectively. Our results show that it is necessary to use metallicity-dependent transformations in order to properly convert colors into stellar temperatures, radii, and luminosities. Alternatively, we find no sensitivity to metallicity on relations we construct to the global properties of a star omitting color information, e.g., temperature-radius and temperature-luminosity. Thus, we are able to empirically quantify to what order the star's observed color index is impacted by the stellar iron abundance. In addition to the empirical relations, we also provide a representative look-up table via stellar spectral classifications using this collection of data. Robust examinations of single star temperatures and radii compared to evolutionary model predictions on the luminosity-temperature and luminosity-radius planes reveal that models overestimate the temperatures of stars with surface temperatures <5000K by 3%, and underestimate the radii of stars with radii <0.7 R ⊙ by 5%. These conclusions additionally suggest that the models over account for the effects that the stellar metallicity may have on the astrophysical properties of an object. By comparing the interferometrically measured radii for the single star population to those of eclipsing binaries, we find that for a given mass, single and binary star radii are indistinguishable. However, we also find that for a given radius, the literature temperatures for binary stars are systematically lower compared to our interferometrically derived temperatures of single stars by 200 to 300K. The nature of this offset is dependent on the validation of binary star temperatures, where bringing all measurements to a uniform and correctly calibrated temperature scale is needed to identify any influence stellar activity may have on the physical properties of a star. Lastly, we present an empirically determined H-R diagram using fundamental properties presented here in combination with those in Boyajian et al. for a total of 74 nearby, main-sequence, A- to M-type stars, and define regions of habitability for the potential existence of sub-stellar mass companions in each system.

AB - We present interferometric angular diameter measurements of 21 low-mass, K- and M-dwarfs made with the CHARA Array. This sample is enhanced by adding a collection of radius measurements published in the literature to form a total data set of 33K-M-dwarfs with diameters measured to better than 5%. We use these data in combination with the Hipparcos parallax and new measurements of the star's bolometric flux to compute absolute luminosities, linear radii, and effective temperatures for the stars. We develop empirical relations for K0 to M4 main-sequence stars that link the stellar temperature, radius, and luminosity to the observed (B - V), (V - R), (V - I), (V - J), (V - H), and (V - K) broadband color index and stellar metallicity [Fe/H]. These relations are valid for metallicities ranging from [Fe/H] = -0.5 to +0.1 dex and are accurate to 2%, 5%, and 4% for temperature, radius, and luminosity, respectively. Our results show that it is necessary to use metallicity-dependent transformations in order to properly convert colors into stellar temperatures, radii, and luminosities. Alternatively, we find no sensitivity to metallicity on relations we construct to the global properties of a star omitting color information, e.g., temperature-radius and temperature-luminosity. Thus, we are able to empirically quantify to what order the star's observed color index is impacted by the stellar iron abundance. In addition to the empirical relations, we also provide a representative look-up table via stellar spectral classifications using this collection of data. Robust examinations of single star temperatures and radii compared to evolutionary model predictions on the luminosity-temperature and luminosity-radius planes reveal that models overestimate the temperatures of stars with surface temperatures <5000K by 3%, and underestimate the radii of stars with radii <0.7 R ⊙ by 5%. These conclusions additionally suggest that the models over account for the effects that the stellar metallicity may have on the astrophysical properties of an object. By comparing the interferometrically measured radii for the single star population to those of eclipsing binaries, we find that for a given mass, single and binary star radii are indistinguishable. However, we also find that for a given radius, the literature temperatures for binary stars are systematically lower compared to our interferometrically derived temperatures of single stars by 200 to 300K. The nature of this offset is dependent on the validation of binary star temperatures, where bringing all measurements to a uniform and correctly calibrated temperature scale is needed to identify any influence stellar activity may have on the physical properties of a star. Lastly, we present an empirically determined H-R diagram using fundamental properties presented here in combination with those in Boyajian et al. for a total of 74 nearby, main-sequence, A- to M-type stars, and define regions of habitability for the potential existence of sub-stellar mass companions in each system.

KW - Hertzsprung-Russell and C-M diagrams

KW - infrared: stars

KW - planetary systems

KW - stars: atmospheres

KW - stars: fundamental parameters

KW - stars: general

KW - stars: late-type

KW - stars: low-mass

KW - techniques: high angular resolution

KW - techniques: interferometric

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U2 - 10.1088/0004-637X/757/2/112

DO - 10.1088/0004-637X/757/2/112

M3 - Article

AN - SCOPUS:84866562972

VL - 757

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2

M1 - 112

ER -

Boyajian TS, Von Braun K, Van Belle G, McAlister HA, Ten Brummelaar TA, Kane SR y otros. Stellar diameters and temperatures. II. Main-sequence K- and M-stars. Astrophysical Journal. 2012 oct 1;757(2). 112. https://doi.org/10.1088/0004-637X/757/2/112