Bibcode
Xu, Siyi; Hallakoun, Na’ama; Gary, Bruce; Dalba, Paul A.; Debes, John; Dufour, Patrick; Fortin-Archambault, Maude; Fukui, Akihiko; Jura, Michael A.; Klein, Beth; Kusakabe, Nobuhiko; Muirhead, Philip S.; Narita, Norio; Steele, Amy; Su, Kate Y. L.; Vanderburg, Andrew; Watanabe, Noriharu; Zhan, Zhuchang; Zuckerman, Ben
Bibliographical reference
The Astronomical Journal, Volume 157, Issue 6, article id. 255, 12 pp. (2019).
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6
2019
Citations
18
Refereed citations
17
Description
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 Space Telescope, Keck, Very Large Telescope (VLT), Spitzer, and
many other smaller telescopes from 2015 to 2018. Somewhat surprisingly
the ultraviolet (UV) transit depths are always shallower than those in
the optical. We develop a model that can quantitatively explain the
observed “bluing” and confirm the previous finding that: (1)
the transiting objects, circumstellar gas, and white dwarf are all
aligned along our line of sight; (2) 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 anticorrelation 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.