TY  - JOUR
A1  - Bomans, Dominik J.
A1  - Becker, Andrew C.
A1  - Kleemann, B.
A1  - Weis, K.
A1  - Pasquali, A.
T1  - Luminous Wolf-Rayet stars at low metallicity
JF  - Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.–5. June 2015
N2  - The evolution of massive stars in very low metallicity galaxies is less well observationally
constrained than in environments more similar to the Milky Way, M33, or the LMC. We discuss
in this contribution the current state of our program to search for and characterize Wolf-Rayet stars (and other massive emission line stars) in low metallicity galaxies in the Local Volume.
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-87635
SP  - 51
EP  - 54
ER  - 
TY  - JOUR
A1  - Richter, Philipp
A1  - Fox, Andrew J.
A1  - Ben Bekhti, Nadya
A1  - Murphy, M. T.
A1  - Bomans, Dominik J.
A1  - Frank, S.
T1  - High-resolution absorption spectroscopy of the circumgalactic medium of the Milky Way
JF  - Astronomische Nachrichten = Astronomical notes
KW  - Galaxy: halo
KW  - Galaxy: structure
KW  - quasars: absorption lines
KW  - techniques: spectroscopic
Y1  - 2014
U6  - https://doi.org/10.1002/asna.201312013
SN  - 0004-6337
SN  - 1521-3994
VL  - 335
IS  - 1
SP  - 92
EP  - 98
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Becker, Andrew C.
A1  - Bomans, Dominik J.
A1  - Weis, K.
T1  - Finding new Wolf-Rayet stars in the Magellanic Clouds
JF  - Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.–5. June 2015
N2  - Obtaining a complete census of massive, evolved stars in a galaxy would be a key ingredient for testing stellar evolution models. However, as the evolution of stars is also strongly dependent on their metallicity, it is inevitable to have this kind of data for a variety of galaxies with different metallicities. Between 2009 and 2011, we conducted the Magellanic Clouds Massive Stars and Feedback Survey (MSCF); a spatially complete, multi-epoch, broad- and narrow-band optical imaging survey of the Large and Small Magellanic Clouds. With the inclusion of shallow images, we are able to give a complete photometric catalog of stars between B ≈ 18 and B ≈ 19 mag.
These observations were augmented with additional photometric data of similar spatial res-
olution from UV to IR (e.g. from GALEX, 2MASS and Spitzer) in order to sample a large portion of the spectral energy distribution of the brightest stars (B < 16 mag) in the Magel- lanic Clouds. Using these data, were are able to train a machine learning algorithm that gives us a good estimate of the spectral type of tens of thousands of stars.
This method can be applied to the search for Wolf-Rayet-Stars to obtain a sample of candi- dates for follow-up observations. As this approach can, in principle, be adopted for any resolved galaxy as long as sufficient photometric data is available, it can form an effective alternative method to the classical strategies (e.g. He II filter imaging).
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-87618
SP  - 47
EP  - 50
ER  - 
TY  - JOUR
A1  - Gvaramadze, Vasily V.
A1  - Fabrika, Sergei Nikolaevich
A1  - Hamann, Wolf-Rainer
A1  - Sholukhova, Olga N.
A1  - Valeev, Azamat F.
A1  - Goranskij, Vitaly P.
A1  - Cherepashchuk, Anatol M.
A1  - Bomans, Dominik J.
A1  - Oskinova, Lida
T1  - Discovery of a new Wolf-Rayet star and its ring nebula in Cygnus
N2  - We report the serendipitous discovery of a ring nebula around a candidate Wolf-Rayet (WR) star, HBHA 4202-22, in Cygnus using the Spitzer Space Telescope archival data. Our spectroscopic follow-up observations confirmed the WR nature of this star (we named it WR 138a) and showed that it belongs to the WN8-9h subtype. We thereby add a new example to the known sample of late WN stars with circumstellar nebulae. We analysed the spectrum of WR 138a by using the Potsdam Wolf-Rayet (PoWR) model atmospheres, obtaining a stellar temperature of 40 kK. The stellar wind composition is dominated by helium with 20 per cent of hydrogen. The stellar spectrum is highly reddened and absorbed (EB- V = 2.4 mag, A(V) = 7.4 mag). Adopting a stellar luminosity of log L/L-circle dot = 5.3, the star has a mass-loss rate of 10-4.7 M- circle dot yr-1, and resides in a distance of 4.2 kpc. We measured the proper motion for WR 138a and found that it is a runaway star with a peculiar velocity of similar or equal to 50 km s-1. Implications of the runaway nature of WR 138a for constraining the mass of its progenitor star and understanding the origin of its ring nebula are discussed.
Y1  - 2009
UR  - http://www3.interscience.wiley.com/cgi-bin/issn?DESCRIPTOR=PRINTISSN&VALUE=0035-8711
U6  - https://doi.org/10.1111/j.1365-2966.2009.15492.x
SN  - 0035-8711
ER  -