LOGIN TO YOUR ACCOUNT

Username
Password
Remember Me
Or use your Academic/Social account:

CREATE AN ACCOUNT

Or use your Academic/Social account:

Congratulations!

You have just completed your registration at OpenAire.

Before you can login to the site, you will need to activate your account. An e-mail will be sent to you with the proper instructions.

Important!

Please note that this site is currently undergoing Beta testing.
Any new content you create is not guaranteed to be present to the final version of the site upon release.

Thank you for your patience,
OpenAire Dev Team.

Close This Message

CREATE AN ACCOUNT

Name:
Username:
Password:
Verify Password:
E-mail:
Verify E-mail:
*All Fields Are Required.
Please Verify You Are Human:
fbtwitterlinkedinvimeoflicker grey 14rssslideshare1
Jackson, RJ; Jeffries, RD (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.
  • The results below are discovered through our pilot algorithms. Let us know how we are doing!

    • Allard F., Homeier D., Freytag B., 2011, in Johns-Krull C., Browning M. K., West A. A., eds, 16th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun Vol. 448 of Astronomical Society of the Pacific Conference Series, Model Atmospheres From Very Low Mass Stars to Brown Dwarfs. p. 91 Asplund M., Grevesse N., Sauval A. J., Scott P., 2009, ARA&A, 47, 481
    • Baraffe I., Chabrier G., Allard F., Hauschildt P. H., 1998, A&A, 337, 403
    • Barnes J. R., Collier Cameron A., 2001, MNRAS, 326, 950 Basri G., Marcy G. W., Graham J. R., 1996, ApJ, 458, 600 Bildsten L., Brown E. F., Matzner C. D., Ushomirsky G., 1997, ApJ, 482, 442
    • Binks A. S., Jeffries R. D., 2014, MNRAS, 438, L11 Burke C. J., Pinsonneault M. H., Sills A., 2004, ApJ, 604, 272 Cargile P. A., James D. J., Jeffries R. D., 2010, ApJ, 725, L111 Chabrier G., Gallardo J., Baraffe I., 2007, A&A, 472, L17 D'Antona F., Mazzitelli I., 1994, ApJS, 90, 467 D'Antona F., Ventura P., Mazzitelli I., 2000, ApJ, 543, L77 Ekstro¨m S., Georgy C., Eggenberger P., Meynet G., Mowlavi N., Wyttenbach A., Granada A., Decressin T., Hirschi R., Frischknecht U., Charbonnel C., Maeder A., 2012, A&A, 537, A146
    • Feiden G. A., Chaboyer B., 2013, ApJ, 779, 183 Feiden G. A., Chaboyer B., 2014, ApJ, 789, 53 Gough D. O., Tayler R. J., 1966, MNRAS, 133, 85 Hayashi C., Nakano T., 1963, Progress of Theoretical Physics, 30, 460
    • Herbst W., Bailer-Jones C. A. L., Mundt R., Meisenheimer K., Wackermann R., 2002, A&A, 396, 513
    • Hillenbrand L. A., 2009, in Mamajek E. E., Soderblom D. R., Wyse R. F. G., eds, IAU Symposium Vol. 258 of IAU Symposium, Age-related observations of low mass pre-main and young main sequence stars. pp 81-94
    • Hillenbrand L. A., Bauermeister A., White R. J., 2008, in van Belle G., ed., 14th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun Vol. 384 of Astronomical Society of the Pacific Conference Series, An Assessment of HR Diagram Constraints on Ages and Age Spreads in Star-Forming Regions and Young Clusters. p. 200
    • Irwin J., Hodgkin S., Aigrain S., Bouvier J., Hebb L., Irwin M., Moraux E., 2008, MNRAS, 384, 675
    • Irwin J., Hodgkin S., Aigrain S., Hebb L., Bouvier J., Clarke C., Moraux E., Bramich D. M., 2007, MNRAS, 377, 741 Jackson R. J., Jeffries R. D., 2010, MNRAS, 402, 1380 Jackson R. J., Jeffries R. D., 2013, MNRAS, 431, 1883 Jackson R. J., Jeffries R. D., 2014, MNRAS, 441, 2111 Jackson R. J., Jeffries R. D., Maxted P. F. L., 2009, MNRAS, 399, L89
    • Jeffries R. D., Jackson R. J., Briggs K. R., Evans P. A., Pye J. P., 2011, MNRAS, 411, 2099
    • Jeffries R. D., Naylor T., 2001, in Montmerle T., Andre´ P., eds, From Darkness to Light: Origin and Evolution of Young Stellar Clusters Vol. 243 of Astronomical Society of the Pacific Conference Series, The Lithium Depletion Boundary as a Clock and Thermometer. p. 633
    • Jeffries R. D., Naylor T., Mayne N. J., Bell C. P. M., Littlefair S. P., 2013, MNRAS, 434, 2438
    • Jeffries R. D., Oliveira J. M., 2005, MNRAS, 358, 13 Lo´pez-Morales M., 2007, ApJ, 660, 732 MacDonald J., Mullan D. J., 2013, ApJ, 765, 126 Maeder A., Meynet G., 1989, A&A, 210, 155 Mendes L. T. S., D'Antona F., Mazzitelli I., 1999, A&A, 341, 174 Messina S., Desidera S., Turatto M., Lanzafame A. C., Guinan E. F., 2010, A&A, 520, A15
    • Messina S., Pizzolato N., Guinan E. F., Rodono` M., 2003, A&A, 410, 671
    • Messina S., Rodono` M., Guinan E. F., 2001, A&A, 366, 215 Meynet G., Maeder A., 2000, A&A, 361, 101 Morales J. C., Ribas I., Jordi C., 2008, A&A, 478, 507 Moss D. L., 1968, MNRAS, 141, 165
    • Mullan D. J., MacDonald J., 2001, ApJ, 559, 353 O'Neal D., 2006, ApJ, 645, 659
    • O'Neal D., Neff J. E., Saar S. H., 1998, ApJ, 507, 919 Rebolo R., Martin E. L., Basri G., Marcy G. W., Zapatero-Osorio M. R., 1996, ApJ, 469, L53
    • Reiners A., Basri G., 2008, ApJ, 684, 1390 Reiners A., Basri G., 2010, ApJ, 710, 924 Soderblom D. R., 2010, ARA&A, 48, 581 Soderblom D. R., Hillenbrand L. A., Jeffries R. D., Mamajek E. E., Naylor T., 2013, ArXiv e-prints: 1311.7024 Solanki S. K., Unruh Y. C., 2004, MNRAS, 348, 307 Somers G., Pinsonneault M. H., 2014, ApJ, 790, 72 Spruit H. C., 1982, A&A, 108, 348
    • Spruit H. C., Weiss A., 1986, A&A, 166, 167 Stassun K. G., Kratter K. M., Scholz A., Dupuy T. J., 2012, ApJ, 756, 47
    • 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, AJ, 126, 833
    • Stauffer J. R., Navascue´s D. B. y., Bouvier J., Morrison H. L., Harding P., Luhman K. L., Stanke T., McCaughrean M., Terndrup D. M., Allen L., Assouad P., 1999, ApJ, 527, 219 Stauffer J. R., Schultz G., Kirkpatrick J. D., 1998, ApJ, 499, L199+
    • Stevenson D. J., 1991, ARA&A, 29, 163 Ushomirsky G., Matzner C. D., Brown E. F., Bildsten L., Hilliard V. G., Schroeder P. C., 1998, ApJ, 497, 253 Ventura P., Zeppieri A., Mazzitelli I., D'Antona F., 1998, A&A, 334, 953
  • No related research data.
  • No similar publications.

Share - Bookmark

Cite this article