Change search
ReferencesLink to record
Permanent link

Direct link
Doppler probe of accretion onto a T Tauri star
Stockholm University, Faculty of Science, Department of Astronomy.
Show others and affiliations
2014 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 568, L10- p.Article in journal (Refereed) Published
Abstract [en]

Context. The YY Ori stars are T Tauri stars with prominent time-variable redshifted absorption components that flank certain emission lines. S CrA, one of the brightest of these stars, affords the rare opportunity of directly probing the accretion processes on the line of sight to one of the components of this wide visual pair. Aims. We followed the spectral changes in S CrA to derive the physical structure of the accreting gas. Methods. A series of high-resolution spectra of the two components of S CrA was obtained during four nights with the UVES spectrograph at the Very Large Telescope. Results. We found that both stars are very similar with regard to surface temperature, radius, and mass. Variable redshifted absorption components are particularly prominent in the SE component. During one night, this star developed a spectrum unique among the T Tauri stars: extremely strong and broad redshifted absorption components appeared in many lines of neutral and ionized metals, in addition to those of hydrogen and helium. The absorption depths of cooler, low-ionization lines peak at low velocities - while more highly ionized lines have peak absorption depths at high velocities. The different line profiles indicate that the temperature and density of the accretion stream increase as material approaches the star. We derive the physical conditions of the flow at several points along the accretion funnel directly from the spectrum of the infalling gas. We estimated mass accretion rates of about 10(-7) M-circle dot/yr, which is similar to that derived from the relation based on the strength of Ha emission line. Conclusions. This is the first time the density and temperature distributions in accretion flows around a T Tauri star have been inferred from observations. Compared with predictions from standard models of accretion in T Tauri stars, which assume a dipole stellar magnetic field, we obtained higher densities and a steeper temperature rise toward the star.

Place, publisher, year, edition, pages
2014. Vol. 568, L10- p.
Keyword [en]
stars: pre-main sequence, stars: variables: T Tauri, Herbig Ae/Be, stars: activity
National Category
Astronomy, Astrophysics and Cosmology
URN: urn:nbn:se:su:diva-108388DOI: 10.1051/0004-6361/201424374ISI: 000341185900130OAI: diva2:757795


Available from: 2014-10-23 Created: 2014-10-22 Last updated: 2014-10-23Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Gahm, Gösta F.
By organisation
Department of Astronomy
In the same journal
Astronomy and Astrophysics
Astronomy, Astrophysics and Cosmology

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 11 hits
ReferencesLink to record
Permanent link

Direct link