Folsom, C. P. and Bagnulo, S. and Wade, G. A. and Alecian, E. and Landstreet, J. D. and Marsden, S. C. and Waite, I. A. (2012) Chemical abundances of magnetic and non-magnetic Herbig Ae/Be stars. Monthly Notices of the Royal Astronomical Society, 422 (3). pp. 2072-2101. ISSN 0035-8711
Abstract
The photospheres of about 10–20 per cent of main-sequence A-and B-type stars exhibit a wide range of chemical peculiarities, often associated with the presence of a magnetic field. It is not exactly known at which stage of stellar evolution these chemical peculiarities develop. To investigate this issue, in this paper we study the photospheric compositions of a sample of Herbig Ae and Be stars, which are considered to be the pre-main-sequence progenitors of A and B stars. We have performed a detailed abundance analysis of 20 Herbig stars (three of which have confirmed magnetic fields), and one dusty young star. We have found that half the stars in our sample show λ Bootis (λ Boo) chemical peculiarities to varying degrees, only
one star shows weak Ap/Bp peculiarities and all the remaining stars are chemically normal. The incidence of λ Boo chemical peculiarities we find in Herbig stars is much higher than what is seen on the main sequence. We argue that a selective accretion model for λ Boo star formation is a natural explanation for the remarkably large number of λ Boo stars in our sample. We also find that the magnetic Herbig stars do not exhibit a range of chemical compositions remarkably different from the normal stars: one magnetic star displays λ Boo chemical peculiarities (HD101412), one displays weak Ap/Bp peculiarities (V380 Ori A) and one (HD 190073) is chemically normal. This is completely different from what is seen on the main sequence, where all magnetic A and cool B stars show Ap/Bp chemical peculiarities, and this is consistent with the idea that the magnetic field precedes the formation of the chemical peculiarities typical of Ap and Bp stars.
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| Item Type: | Article (Commonwealth Reporting Category C) |
|---|---|
| Refereed: | Yes |
| Item Status: | Live Archive |
| Additional Information: | © 2012 The Authors. Permanent restricted access to published version due to the copyright policy of the publisher. |
| Depositing User: | epEditor USQ |
| Faculty / Department / School: | Historic - Faculty of Sciences - Department of Biological and Physical Sciences |
| Date Deposited: | 07 Sep 2012 07:19 |
| Last Modified: | 16 Oct 2014 01:19 |
| Uncontrolled Keywords: | stars; abundances; chemically peculiar; magnetic field; pre-main-sequence |
| Fields of Research : | 04 Earth Sciences > 0401 Atmospheric Sciences > 040199 Atmospheric Sciences not elsewhere classified 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems 01 Mathematical Sciences > 0105 Mathematical Physics > 010599 Mathematical Physics not elsewhere classified |
| Socio-Economic Objective: | E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences |
| Identification Number or DOI: | 10.1111/j.1365-2966.2012.20718.x |
| URI: | http://eprints.usq.edu.au/id/eprint/21524 |
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