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Jackson, R. J.; Jeffries, R. D. (2014)
Publisher: Oxford University Press
Languages: English
Types: Article
Subjects: Astrophysics - Solar and Stellar Astrophysics, QB460

Classified by OpenAIRE into

arxiv: Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics
A polytropic model is used to investigate the effects of dark photospheric spots on the evolution and radii of magnetically active, low-mass (M<0.5Msun), pre-main sequence (PMS) stars. Spots slow the contraction along Hayashi tracks and inflate the radii of PMS stars by a factor of (1-beta)^{-N} compared to unspotted stars of the same luminosity, where beta is the equivalent covering fraction of dark starspots and N \simeq 0.45+/-0.05. This is a much stronger inflation than predicted by the models of Spruit & Weiss (1986) for main sequence stars with the same beta, where N \sim 0.2 to 0.3. These models have been compared to radii determined for very magnetically active K- and M-dwarfs in the young Pleiades and NGC 2516 clusters, and the radii of tidally-locked, low-mass eclipsing binary components. The binary components and ZAMS K-dwarfs have radii inflated by \sim 10 per cent compared to an empirical radius-luminosity relation that is defined by magnetically inactive field dwarfs with interferometrically measured radii; low-mass M-type PMS stars, that are still on their Hayashi tracks, are inflated by up to \sim 40 per cent. If this were attributable to starspots alone, we estimate that an effective spot coverage of 0.35 < beta < 0.51 is required. Alternatively, global inhibition of convective flux transport by dynamo-generated fields may play a role. However, we find greater consistency with the starspot models when comparing the loci of active young stars and inactive field stars in colour-magnitude diagrams, particularly for the highly inflated PMS stars, where the large, uniform temperature reduction required in globally inhibited convection models would cause the stars to be much redder than observed.
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    • Alexander D. R., Ferguson J. W., 1994, Astrophys. J. , 437, 879 Allard F., Guillot T., Ludwig H., Hauschildt P. H., Schweitzer A., Alexander D. R., Ferguson J. W., 2003, in E. Mart´ın ed., Brown Dwarfs Vol. 211 of IAU Symposium, Model Atmospheres and Spectra: The Role of Dust. pp 325-+
    • An D., Terndrup D. M., Pinsonneault M. H., 2007, ApJ, 671, 1640 Baraffe I., Chabrier G., Allard F., Hauschildt P. H., 1998, A&A, 337, 403
    • Boyajian T. S., McAlister H. A., van Belle G., 2012, Astrophys. J. , 746, 101
    • Boyajian T. S., von Braun K., van Belle G., 2012, Astrophys. J. , 757, 112
    • Carpenter J. M., 2001, AJ, 121, 2851
    • Chabrier G., Gallardo J., Baraffe I., 2007, A&A, 472, L17 Collier-Cameron A., Unruh Y. C., 1994, MNRAS, 269, 814 Cutri, R. M. et al. 2003, Technical report, Explanatory supplement to the 2MASS All Sky data release. http://www.ipac.caltech.edu/2mass/
    • Donati J.-F., Semel M., Carter B. D., Rees D. E., Collier Cameron A., 1997, MNRAS, 291, 658
    • Dotter A., 2008, ApJ, 687, L21
    • Eaton J. A., Hall D. S., 1979, Astrophys. J. , 227, 907 Feiden G. A., Chaboyer B., 2012, Astrophys. J. , 761, 30 Feiden G. A., Chaboyer B., 2013a, ArXiv e-prints 1309.7668 Feiden G. A., Chaboyer B., 2013b, Astrophys. J. , 779, 183 Hall D. S., 1972, Publ. astr. Soc. Pacif. , 84, 323 Hartman J. D., Bakos G. A´., Kova´cs G., Noyes R. W., 2010, MNRAS, 408, 475
    • Hayashi C., Ho¯shi R., Sugimoto D., 1962, Progress of Theoretical Physics Supplement, 22, 1
    • Herbst W., Mundt R., 2005, Astrophys. J. , 633, 967 Irwin J., Bouvier J., 2009, in E. E. Mamajek, D. R. Soderblom, & R. F. G. Wyse ed., IAU Symposium Vol. 258 of IAU Symposium, The rotational evolution of low-mass stars. pp 363-374 Jackson R. J., Jeffries R. D., 2010a, MNRAS, 402, 1380 Jackson R. J., Jeffries R. D., 2010b, MNRAS, 407, 465 Jackson R. J., Jeffries R. D., 2012, MNRAS, 423, 2966 Jackson R. J., Jeffries R. D., 2013, MNRAS, 431, 1883 Jackson R. J., Jeffries R. D., Maxted P. F. L., 2009, MNRAS, 399, L89
    • Jeffries R. D., 2007, MNRAS, 376, 1109
    • Jeffries R. D., Jackson R. J., Briggs K. R., Evans P. A., Pye J. P., 2011, MNRAS, 411, 2099
    • Johns-Krull C. M., Valenti J. A., 1996, in R. Pallavicini & A. K. Dupree ed., Cool Stars, Stellar Systems, and the Sun Vol. 109 of Astronomical Society of the Pacific Conference Series, Detection of strong magnetic fields on M dwarfs. pp 609-+ Krause F., Raedler K., 1980, Mean-field magnetohydrodynamics and dynamo theory. Pergamon Press, Oxford Leggett S. K., 1992, Astrophys. J. Suppl. , 82, 351 Lo´pez-Morales M., 2007, Astrophys. J. , 660, 732 MacDonald J., Mullan D. J., 2013, Astrophys. J. , 765, 126 Marcy G. W., 1982, Publ. astr. Soc. Pacif. , 94, 989 Meynet G., Mermilliod J.-C., Maeder A., 1993, A&AS, 98, 477 Morales J. C., Ribas I., Jordi C., Torres G., Gallardo J., Guinan E. F., Charbonneau D., Wolf M., Latham D. W., Anglada-Escude´ G., Bradstreet D. H., Everett M. E., O'Donovan F. T., Mandushev G., Mathieu R. D., 2009, Astrophys. J. , 691, 1400 Mullan D. J., MacDonald J., 2001, Astrophys. J. , 559, 353 Noyes R. W., Weiss N. O., Vaughan A. H., 1984, Astrophys. J. , 287, 769
    • O'Neal D., 2006, Astrophys. J. , 645, 659
    • O'Neal D., Neff J. E., Saar S. H., 1998, Astrophys. J. , 507, 919 O'Neal D., Neff J. E., Saar S. H., Cuntz M., 2004, Astron. J. , 128, 1802
    • Pinsonneault M. H., Stauffer J., Soderblom D. R., King J. R., Hanson R. B., 1998, ApJ, 504, 170
    • Pizzolato N., Maggio A., Micela G., Sciortino S., Ventura P., 2003, A&A, 397, 147
    • Prialnik D., 2000, An Introduction to the Theory of Stellar Structure and Evolution. Cambridge University Press Reiners A., Basri G., Browning M., 2009, Astrophys. J. , 692, 538 Reinhold T., Reiners A., Basri G., 2013, A&A, 560, A4 Rieke G. H., Lebofsky M. J., 1985, ApJ, 288, 618 Rozyczka M., Pietrukowicz P., Kaluzny J., Pych W., Angeloni R., De´ka´ny I., 2013, MNRAS, 429, 1840
    • Semel M., 1989, A&A, 225, 456
    • Siess L., Dufour E., Forestini M., 2000, A&A, 358, 593 Soderblom D. R., Laskar T., Valenti J. A., Stauffer J. R., Rebull L. M., 2009, Astron. J. , 138, 1292
    • Spruit H. C., 1982, A&A, 108, 348
    • Spruit H. C., Weiss A., 1986, A&A, 166, 167 Stauffer J. R., Jones B. F., Backman D., Hartmann L. W., Barrado y Navascue´s D., Pinsonneault M. H., Terndrup D. M., Muench A. A., 2003, Astron. J. , 126, 833
    • Stauffer J. R., Schultz G., Kirkpatrick J. D., 1998, ApJ, 499, L199+
    • Strassmeier K. G., 2002, Astronomische Nachrichten, 323, 309 Terndrup D. M., Pinsonneault M., Jeffries R. D., Ford A., Stauffer J. R., Sills A., 2002, Astrophys. J. , 576, 950 Torres G., 2013, Astronomische Nachrichten, 334, 4 Torres G., Andersen J., Gime´nez A., 2010, A&ARv, 18, 67 van Leeuwen F., 2007, A&A, 474, 653
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