Ababakr, KM, Oudmaijer, RD and Vink, JS (2017) A Statistical Spectropolarimetric Study of Herbig Ae/Be Stars. Monthly Notices of the Royal Astronomical Society, 472 (1). pp. 854-868. ISSN 0035-8711
Abstract
We present Halpha linear spectropolarimetry of a large sample of Herbig Ae/Be stars. Together with newly obtained data for 17 objects, the sample contains 56 objects, the largest such sample to date. A change in linear polarization across the Halpha line is detected in 42 (75 %) objects, which confirms the previous finding that the circumstellar environment around these stars on small spatial scales has an asymmetric structure, which is typically identified with a disk. A second outcome of this research is that we confirm that Herbig Ae stars are similar to T Tauri stars in displaying a line polarization effect, while depolarization is more common among Herbig Be stars. This finding had been suggested previously to indicate that Herbig Ae stars form in the same manner than T Tauri stars through magnetospheric accretion. It appears that the transition between these two differing polarization line effects occurs around the B7-B8 spectral type. This would in turn not only suggest that Herbig Ae stars accrete in a similar fashion as lower mass stars, but also that this accretion mechanism switches to a different type of accretion for Herbig Be stars. We report that the magnitude of the line effect caused by electron scattering close to the stars does not exceed 2%. Only a very weak correlation is found between the magnitude of the line effect and the spectral type or the strength of the Halpha line. This indicates that the detection of a line effect only relies on the geometry of the line-forming region and the geometry of the scattering electrons.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. This article has been published in Monthly Notices of the Royal Astronomical Society. Reproduced in accordance with the publisher's self-archiving policy. |
Keywords: | techniques: polarimetric, circumstellar matter, stars: formation, stars: individual: Herbig Ae/Be, stars: pre-main-sequence |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Physics and Astronomy (Leeds) > Astrophysics (Leeds) |
Funding Information: | Funder Grant number PPARC PPA/V/S/2001/00498 PPARC PP/D001420/1 PPARC PP/D001625/1 PPARC ST/F002092/1 Science & Technology Facilities Council (STFC) ST/F002092/1 Science & Technology Facilities Council (STFC) ST/I001557/1 Science & Technology Facilities Council (STFC) ST/I001557/1 Science & Technology Facilities Council (STFC) ST/P00041X/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 28 Jul 2017 09:41 |
Last Modified: | 16 Jan 2018 17:11 |
Status: | Published |
Publisher: | Oxford University Press |
Identification Number: | 10.1093/mnras/stx1891 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:119582 |