Sign on

SAO/NASA ADS Astronomy Abstract Service

· Find Similar Abstracts (with default settings below)
· Full Refereed Journal Article (PDF/Postscript)
· Full Refereed Scanned Article (GIF)
· On-line Data
· References in the article
· Citations to the Article (27) (Citation History)
· Refereed Citations to the Article
· SIMBAD Objects (2)
· Also-Read Articles (Reads History)
· Translate This Page
X-ray emission on hybird stars: ROSAT observations of alpha Trianguli Australis and IOTA Aurigae
Kashyap, V.; Rosner, R.; Harnden, F. R., Jr.; Maggio, A.; Micela, G.; Sciortino, S.
AA(University of Chicago, Chicago, IL, US), AB(University of Chicago, Chicago, IL, US), AC(Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, US), AD(Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, US), AE(Osservatorio Astronomico, Palermo, Italy), AF(Osservatorio Astronomico, Palermo, Italy)
The Astrophysical Journal, Part 1, vol. 431, no. 1, p. 402-415 (ApJ Homepage)
Publication Date:
NASA/STI Keywords:
Auriga Constellation, Emission Spectra, Stellar Atmospheres, Stellar Coronas, Stellar Flares, X Ray Spectra, Companion Stars, Rosat Mission, Spectrum Analysis, Stellar Spectra
Bibliographic Code:


We report on deep ROSAT observations of two Hybrid atmosphere stars, alpha TrA and iota Aur, and our analysis of these observations. We detect high-energy transient phenomena on alpha TrA and consider the implications of this discovery to the atmospheres of Hybrid stars. We detect iota Aur in the high-energy passband of ROSAT, implying the existence of multimillion degree plasma on the star. Our major results include the following: discovery of two large flare events, detected during pointed observations of alpha TrA; the demonstration that the flare emission most likely comes from the giant itself, rather than from a previously unseen low-mass companion star; the demonstration that the plasma characteristics associated with the flares and with the 'quiescent' component are essentially indistinguishable; and that the geometric dimensions of the emitting plasma are considerably smaller than the critical dimension characterizing stable 'hot' coronal loop structures. Our results suggest that alpha TrA does not have any steady X-ray emission consistent with theoretical expectations, and support the argument that Hybrid stars constitute a transitional type of object in which large-scale magnetic dynamo activity ceases, and the dominant spatial scales characterizing coronal structure rapidly decline as such stars evolve across the X-ray 'Dividing Line' in the H-R diagram.

Printing Options

Print whole paper
Print Page(s) through

Return 600 dpi PDF to Acrobat/Browser. Different resolutions (200 or 600 dpi), formats (Postscript, PDF, etc), page sizes (US Letter, European A4, etc), and compression (gzip,compress,none) can be set through the Printing Preferences

More Article Retrieval Options

HELP for Article Retrieval

Bibtex entry for this abstract   Preferred format for this abstract (see Preferences)


Find Similar Abstracts:

Use: Authors
Keywords (in text query field)
Abstract Text
Return: Query Results Return    items starting with number
Query Form
Database: Astronomy
arXiv e-prints