Shallow Ultraviolet Transits of WD 1145+017
| Autor: | Paul A. Dalba, Akihiko Fukui, Nobuhiko Kusakabe, John H. Debes, Philip S. Muirhead, Siyi Xu, Beth Klein, Andrew Vanderburg, Maude Fortin-Archambault, Bruce L. Gary, Zhuchang Zhan, Barry Zuckerman, Amy Steele, Kate Y. L. Su, Norio Narita, Noriharu Watanabe, Na'ama Hallakoun, Patrick Dufour, Michael Jura |
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| Rok vydání: | 2019 |
| Předmět: |
Earth and Planetary Astrophysics (astro-ph.EP)
Physics 010504 meteorology & atmospheric sciences FOS: Physical sciences Astronomy Astronomy and Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics 01 natural sciences Astrophysics - Solar and Stellar Astrophysics 13. Climate action Space and Planetary Science 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics Astrophysics::Earth and Planetary Astrophysics 010303 astronomy & astrophysics Ultraviolet radiation Astrophysics::Galaxy Astrophysics Solar and Stellar Astrophysics (astro-ph.SR) Astrophysics - Earth and Planetary Astrophysics 0105 earth and related environmental sciences |
| Zdroj: | The Astronomical Journal. 157:255 |
| ISSN: | 1538-3881 |
| Popis: | WD 1145+017 is a unique white dwarf system that has a heavily polluted atmosphere, an infrared excess from a dust disk, numerous broad absorption lines from circumstellar gas, and changing transit features, likely from fragments of an actively disintegrating asteroid. Here, we present results from a large photometric and spectroscopic campaign with Hubble, Keck , VLT, Spitzer, and many other smaller telescopes from 2015 to 2018. Somewhat surprisingly, but consistent with previous observations in the u' band, the UV transit depths are always shallower than those in the optical. We develop a model that can quantitatively explain the observed "bluing" and the main findings are: I. the transiting objects, circumstellar gas, and white dwarf are all aligned along our line of sight; II. the transiting object is blocking a larger fraction of the circumstellar gas than of the white dwarf itself. Because most circumstellar lines are concentrated in the UV, the UV flux appears to be less blocked compared to the optical during a transit, leading to a shallower UV transit. This scenario is further supported by the strong anti-correlation between optical transit depth and circumstellar line strength. We have yet to detect any wavelength-dependent transits caused by the transiting material around WD 1145+017. Comment: 16 pages, 11 figures, 6 tables, ApJ, in press |
| Databáze: | OpenAIRE |
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