Sign on

SAO/NASA ADS Astronomy Abstract Service

· Find Similar Abstracts (with default settings below)
· Electronic Refereed Journal Article (HTML)
· Full Refereed Journal Article (PDF/Postscript)
· Full Refereed Scanned Article (GIF)
· arXiv e-print (arXiv:astro-ph/0311276)
· References in the article
· Citations to the Article (15) (Citation History)
· Refereed Citations to the Article
· Also-Read Articles (Reads History)
· HEP/Spires Information
·
· Translate This Page
Title:
On the origin of ionizing photons emitted by T Tauri stars
Authors:
Alexander, R. D.; Clarke, C. J.; Pringle, J. E.
Affiliation:
AA(Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA;), AB(Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA;), AC(Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA;)
Publication:
Monthly Notices of the Royal Astronomical Society, Volume 348, Issue 3, pp. 879-884. (MNRAS Homepage)
Publication Date:
03/2004
Origin:
MNRAS
MNRAS Keywords:
accretion, accretion discs, circumstellar matter, planetary systems: protoplanetary discs, stars: pre-main-sequence
DOI:
10.1111/j.1365-2966.2004.07401.x
Bibliographic Code:
2004MNRAS.348..879A

Abstract

We address the issue of the production of Lyman continuum photons by T Tauri stars, in an attempt to provide constraints on theoretical models of disc photoionization. By treating the accretion shock as a hotspot on the stellar surface, we show that Lyman continuum photons are produced at a rate approximately three orders of magnitude lower than that produced by a corresponding blackbody, and that a strong Lyman continuum is only emitted for high mass accretion rates. When our models are extended to include a column of material accreting on to the hotspot, we find that the accretion column is extremely optically thick to Lyman continuum photons. Further, we find that radiative recombination of hydrogen atoms within the column is not an efficient means of producing photons with energies greater than 13.6 eV, and find that an accretion column of any conceivable height suppresses the emission of Lyman continuum photons to a level below or comparable to that expected from the stellar photosphere. The photospheric Lyman continuum is itself much too weak to affect disc evolution significantly, and we find that the Lyman continuum emitted by an accretion shock is similarly unable to influence disc evolution significantly. This result has important consequences for models which use photoionization as a mechanism to drive the dispersal of circumstellar discs, essentially proving that an additional source of Lyman continuum photons must exist if disc photoionization is to be significant.

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