Skip to main content Accessibility help
×
Home
Hostname: page-component-99c86f546-4k54s Total loading time: 0.186 Render date: 2021-11-28T06:45:25.691Z Has data issue: true Feature Flags: { "shouldUseShareProductTool": true, "shouldUseHypothesis": true, "isUnsiloEnabled": true, "metricsAbstractViews": false, "figures": true, "newCiteModal": false, "newCitedByModal": true, "newEcommerce": true, "newUsageEvents": true }

Stellar Magnetic Dynamos and Activity Cycles

Published online by Cambridge University Press:  07 August 2014

Nicholas J. Wright*
Affiliation:
Centre for Astrophysics Research, University of Hertfordshire, Hatfield, AL10 9AB
Rights & Permissions[Opens in a new window]

Abstract

HTML view is not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Using a new uniform sample of 824 solar and late-type stars with measured X-ray luminosities and rotation periods we have studied the relationship between rotation and stellar activity that is believed to be a probe of the underlying stellar dynamo. Using an unbiased subset of the sample we calculate the power law slope of the unsaturated regime of the activity – rotation relationship as LX / Lbol ∝ Roβ, where β = − 2.70 ± 0.13. This is inconsistent with the canonical β = − 2 slope to a confidence of 5σ and argues for an interface-type dynamo. We map out three regimes of coronal emission as a function of stellar mass and age, using the empirical saturation threshold and theoretical super-saturation thresholds. We find that the empirical saturation timescale is well correlated with the time at which stars transition from the rapidly rotating convective sequence to the slowly rotating interface sequence in stellar spin-down models. This may be hinting at fundamental changes in the underlying stellar dynamo or internal structure. We also present the first discovery of an X-ray unsaturated, fully convective M star, which may be hinting at an underlying rotation - activity relationship in fully convective stars hitherto not observed. Finally we present early results from a blind search for stellar X-ray cycles that can place valuable constraints on the underlying ubiquity of solar-like activity cycles.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2014 

References

Barnes, S. A. 2003, ApJ, 586, 464CrossRefGoogle Scholar
Donahue, R. A., Saar, S. H., & Baliunas, S. L. 1996, ApJ, 466, 384CrossRefGoogle Scholar
Favata, F., Micela, G., Orlando, S., et al. 2008, A&A, 490, 1121Google Scholar
Hoffman, J., Günther, H. M., & Wright, N. J. 2012, ApJ, 759, 145CrossRefGoogle Scholar
Hynes, R. I., et al., 2012, ApJ, 761, 162CrossRefGoogle Scholar
Jardine, M. & Unruh, Y. C. 1999, A&A, 346, 883Google Scholar
Micela, G., et al., 1985, ApJ, 292, 172CrossRefGoogle Scholar
Noyes, R. W., Hartmann, L. W., Baliunas, S. L., Duncan, D. K., & Vaughan, A. H. 1984, ApJ, 279, 763CrossRefGoogle Scholar
Pallavicini, R., Golub, L., Rosner, R., Vaiana, G. S., Ayres, T., & Linsky, J. L. 1981, ApJ, 248, 279CrossRefGoogle Scholar
Parker, E. N. 1955, ApJ, 122, 293CrossRefGoogle Scholar
Parker, E. N. 1993, ApJ, 408, 707CrossRefGoogle Scholar
Pizzolato, N., Maggio, A., Micela, G., Sciortino, S., & Ventura, P. 2003, A&A, 397, 147Google Scholar
Skumanich, A. 1972, ApJ, 171, 565CrossRefGoogle Scholar
Stȩpień, K., Schmitt, J. H. M. M., & Voges, W. 2001, A&A, 370, 157Google Scholar
Vaiana, G. S., et al., 1981, ApJ, 245, 163CrossRefGoogle Scholar
Wright, N. J., Drake, J. J., & Civano, F. 2010, ApJ, 725, 480CrossRefGoogle Scholar
Wright, N. J., Drake, J. J., Mamajek, E. E., & Henry, G. W., 2011, ApJ, 743, 48CrossRefGoogle Scholar
You have Access

Send article to Kindle

To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

Stellar Magnetic Dynamos and Activity Cycles
Available formats
×

Send article to Dropbox

To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

Stellar Magnetic Dynamos and Activity Cycles
Available formats
×

Send article to Google Drive

To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

Stellar Magnetic Dynamos and Activity Cycles
Available formats
×
×

Reply to: Submit a response

Please enter your response.

Your details

Please enter a valid email address.

Conflicting interests

Do you have any conflicting interests? *