Hoversten, EA;
Gronwall, C;
Berk, DEV;
Basu-Zych, AR;
Breeveld, AA;
Brown, PJ;
Kuin, NPM;
... Siegel, MH; + view all
(2011)
Swift UV/Optical Telescope Imaging of Star Forming Regions in M81 and Holmberg IX.
The Astronomical Journal
, 141
(6)
, Article 205. 10.1088/0004-6256/141/6/205.
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Abstract
We present Swift UV/Optical Telescope (UVOT) imaging of the galaxies M81 and Holmberg IX. We combine UVOT imaging in three near-ultraviolet (NUV) filters (uvw2: 1928 Å; uvm2: 2246 Å; uvw1: 2600 Å) with ground-based optical imaging from the Sloan Digital Sky Survey to constrain the stellar populations of both galaxies. Our analysis consists of three different methods. First, we use the NUV imaging to identify UV star-forming knots and then perform spectral energy distribution (SED) modeling on the UV/optical photometry of these sources. Second, we measure surface brightness profiles of the disk of M81 in the NUV and optical. Lastly, we use SED fitting of individual pixels to map the properties of the two galaxies. In agreement with earlier studies, we find evidence for a burst in star formation in both galaxies starting ~200 Myr ago coincident with the suggested time of an M81-M82 interaction. In line with theories of its origin as a tidal dwarf, we find that the luminosity-weighted age of Holmberg IX is a few hundred million years. Both galaxies are best fit by a Milky Way dust extinction law with a prominent 2175 Å bump. In addition, we describe a stacked median filter technique for modeling the diffuse background light within a galaxy and a Markov chain method for cleaning segment maps generated by SExtractor.
| Type: | Article |
|---|---|
| Title: | Swift UV/Optical Telescope Imaging of Star Forming Regions in M81 and Holmberg IX |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1088/0004-6256/141/6/205 |
| Publisher version: | http://dx.doi.org/10.1088/0004-6256/141/6/205 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Science & Technology, Physical Sciences, Astronomy & Astrophysics, galaxies: individual (M81, Holmberg IX), galaxies: star formation, H II regions, INITIAL MASS FUNCTION, DIGITAL SKY SURVEY, H-II REGIONS, DWARF IRREGULAR GALAXIES, MILKY-WAY, INFRARED-EMISSION, SPIRAL GALAXIES, GALACTIC NUCLEI, EXTINCTION LAW, DUST |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1330216 |
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