Universität zu Köln

Saur, Joachim ORCID: 0000-0003-1413-1231, Fischer, Christian, Wennmacher, Alexandre, Feldman, Paul D., Roth, Lorenz ORCID: 0000-0003-0554-4691, Strobel, Darrell F. and Reiners, Ansgar (2018). The UV Spectrum of the Ultracool Dwarf LSR J1835+3259 Observed with the Hubble Space Telescope. Astrophys. J., 859 (1). BRISTOL: IOP PUBLISHING LTD. ISSN 1538-4357

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Abstract

An interesting question about ultracool dwarfs recently raised in the literature is whether their emission is purely internally driven or partially powered by external processes similar to planetary aurora known from the solar system. In this work, we present Hubble Space Telescope observations of the energy fluxes of the M8.5 ultracool dwarf LSR J1835+3259 throughout the ultraviolet (UV). The obtained spectra reveal that the object is generally UV-fainter compared with other earlier-type dwarfs. We detect the Mg II doublet at 2800 angstrom and constrain an average flux throughout the near-UV. In the far-UV without Ly alpha, the ultracool dwarf is extremely faint with an energy output at least a factor of 250 smaller as expected from auroral emission physically similar to that on Jupiter. We also detect the red wing of the Lya emission. Our overall finding is that the observed UV spectrum of LSR J1835 vertical bar 3259 resembles the spectrum of mid/late-type M-dwarf stars relatively well, but it is distinct from a spectrum expected from Jupiter-like auroral processes.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Saur, Joachim UNSPECIFIED orcid.org/0000-0003-1413-1231 UNSPECIFIED Fischer, Christian UNSPECIFIED UNSPECIFIED UNSPECIFIED Wennmacher, Alexandre UNSPECIFIED UNSPECIFIED UNSPECIFIED Feldman, Paul D. UNSPECIFIED UNSPECIFIED UNSPECIFIED Roth, Lorenz UNSPECIFIED orcid.org/0000-0003-0554-4691 UNSPECIFIED Strobel, Darrell F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Reiners, Ansgar UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-186320
DOI:	10.3847/1538-4357/aabb55
Journal or Publication Title:	Astrophys. J.
Volume:	859
Number:	1
Date:	2018
Publisher:	IOP PUBLISHING LTD
Place of Publication:	BRISTOL
ISSN:	1538-4357
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language VOLUME-LIMITED SAMPLE; LOW MASS STARS; BROWN DWARFS; CHROMOSPHERIC ACTIVITY; GIANT PLANETS; ACTIVE STARS; PHYSICAL-PROPERTIES; RADIO-EMISSION; MAIN-SEQUENCE; JUPITER Multiple languages Astronomy & Astrophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/18632