A precessing Be disc as a possible model for occultation events in GX 304-1

Journal article

Publication Details

Author(s): Kühnel M, Rothschild RE, Okazaki AT, Müller S, Pottschmidt K, Ballhausen R, Choi J, Kreykenbohm I, Fuerst F, Marcu-Cheatham DM, Hemphill P, Sagredo M, Kretschmar P, Martinez-Nunez S, Torrejon JM, Staubert R, Wilms J
Journal: Monthly Notices of the Royal Astronomical Society
Publication year: 2017
Volume: 471
Journal issue: 2
Pages range: 1553-1564
ISSN: 0035-8711
eISSN: 1365-2966


We report on the RXTE detection of a sudden increase in the absorption column density, N-H, during the 2011 May outburst of GX 304-1. The NH increased up to similar to 16 x 10(22) atoms cm(-2), which is a factor of 3-4 larger than what is usually measured during the outbursts of GX 304-1 as covered by RXTE. Additionally, an increase in the variability of the hardness ratio as calculated from the energy resolved RXTE-Proportional Counter Array light curves is measured during this time range. We interpret these facts as an occultation event of the neutron star by material in the line of sight. Using a simple 3D model of an inclined and precessing Be disc around the Be-type companion, we are able to qualitatively explain the NH evolution over time. We are able to constrain the Be disc density to be of the order of 10(-11) g cm(-3). Our model strengthens the idea of inclined Be discs as origin of double-peaked outbursts as the derived geometry allows accretion twice per orbit under certain conditions.

FAU Authors / FAU Editors

Ballhausen, Ralf
Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut
Kreykenbohm, Ingo Dr.
Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut
Müller, Sebastian
Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut
Sagredo, Macarena
Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut
Wilms, Jörn Prof. Dr.
Professur für Astronomie und Astrophysik

External institutions with authors

Eberhard Karls Universität Tübingen
European Space Astronomy Centre (ESAC)
Harvard University
Hokkaido University (Hokudai) / 北海道大学
Instituto de Física de Cantabria (IFCA)
Massachusetts Institute of Technology (MIT)
Universitat d'Alacant (UA) / University of Alicante
University of California, San Diego
University of Maryland, Baltimore County

How to cite

Kühnel, M., Rothschild, R.E., Okazaki, A.T., Müller, S., Pottschmidt, K., Ballhausen, R.,... Wilms, J. (2017). A precessing Be disc as a possible model for occultation events in GX 304-1. Monthly Notices of the Royal Astronomical Society, 471(2), 1553-1564. https://dx.doi.org/10.1093/mnras/stx1663

Kühnel, Matthias, et al. "A precessing Be disc as a possible model for occultation events in GX 304-1." Monthly Notices of the Royal Astronomical Society 471.2 (2017): 1553-1564.


Last updated on 2019-26-07 at 09:33