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Title: An Ultraviolet Spectrum of the Tidal Disruption Flare ASASSN-14li
Authors: Cenko, S. B.
Cucchiara, A
Roth, N.
Veilleux, S.
Prochaska, J. X.
Yan, L.
Guillochon, J.
Maksym, W. P.
Arcavi, I.
Butler, N. R.
Filippenko, A. V.
Fruchter, A. S.
Gezari, S.
Kasen, D.
Levan, A. J.
Miller, J. M.
Pasham, D. R.
Ramirez-Ruiz, E.
Strubbe, L. E.
Tanvir, Nial
Tombesi, F.
First Published: 18-Feb-2016
Publisher: IOP Publishing, American Astronomical Society
Citation: Astrophysical Journal Letters, 2016, 818 L32
Abstract: We present a Hubble Space Telescope STIS spectrum of ASASSN-14li, the first rest-frame UV spectrum of a tidal disruption flare (TDF). The underlying continuum is well fit by a blackbody with $T_{\mathrm{UV}} = 3.5 \times 10^{4}$ K, an order of magnitude smaller than the temperature inferred from X-ray spectra (and significantly more precise than previous efforts based on optical and near-UV photometry). Super-imposed on this blue continuum, we detect three classes of features: narrow absorption from the Milky Way (probably a High-Velocity Cloud), and narrow absorption and broad (FWHM $\approx 2000$-8000 km s$^{-1}$) emission lines at/near the systemic host velocity. The absorption lines are blueshifted with respect to the emission lines by $\Delta v = -(250$-400) km s$^{-1}$. Together with the lack of common low-ionization features (Mg II, Fe II), we argue these arise from the same absorbing material responsible for the low-velocity outflow discovered at X-ray wavelengths. The broad nuclear emission lines display a remarkable abundance pattern: N III], N IV], He II are quite prominent, while the common quasar emission lines of C III] and Mg II are weak or entirely absent. Detailed modeling of this spectrum will help elucidate fundamental questions regarding the nature of the emission process(es) at work in TDFs, while future UV spectroscopy of ASASSN-14li would help to confirm (or refute) the previously proposed connection between TDFs and "N-rich" quasars.
DOI Link: 10.3847/2041-8205/818/2/L32
ISSN: 2041-8205
eISSN: 2041-8213
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © 2016. The American Astronomical Society. All rights reserved. The file associated with this record is distributed under the Creative Commons “Attribution Non-Commercial No Derivatives” licence, further details of which can be found via the following link:
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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