A long-lasting quiescence phase of the eruptive variable V1118 ORI

Journal Article · Fri Mar 20 04:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/802/1/24· OSTI ID:22882601

Lorenzetti, D.; Antoniucci, S.; Giannini, T.; Paola, A. Di; Causi, G. Li; Nisini, B.; Speziali, R.; Vitali, F. ^[1]; Harutyunyan, A. ^[2]; Arkharov, A. A.; Larionov, V. M. ^[3]

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1. INAF—Osservatorio Astronomico di Roma, via Frascati 33, I-00040 Monte Porzio (Italy)
2. Fundación Galileo Galilei INAF, Telescopio Nazionale Galileo, E-38700 Santa Cruz de la Palma, Tenerife (Spain)
3. Central Astronomical Observatory of Pulkovo, Pulkovskoe shosse 65, 196140 St. Petersburg (Russian Federation)

V1118 Ori is an eruptive variable belonging to the EXor class of pre-main-sequence stars whose episodic outbursts are attributed to disk accretion events. Since 2006, V1118 Ori has been in the longest quiescence stage ever observed between two subsequent outbursts in its recent history. We present near-infrared photometry of V1118 Ori carried out over the last eight years, along with complete spectroscopic coverage from 0.35 to 2.5 μm. Long term sampling of V1118 Ori in quiescence has never been performed, and hence we can benefit from the current circumstance by determining the lowest values (i.e., the zeroes) of the parameters to be used as reference for evaluating the physical changes typical of more active phases. A quiescence mass accretion rate of 1–3 × 10{sup −9} M yr{sup −1} can be derived and the difference from previous determinations is discussed. Based on line emission and IR color analysis, a visual extinction of 1–2 mag is consistently derived, confirming that V1118 Ori (at least in quiescence) is a low-extinction T Tauri star with a bolometric luminosity of about 2.1 L. An anti-correlation exists between the equivalent width of the emission lines and the underlying continuum. We searched the literature to evaluate whether or not such behavior is a common feature for the whole class. The anti-correlation is clearly recognizable for all of the available EXors in the optical range (Hβ and Hα lines); however, this is not as evident in the infrared (Paβ and Brγ lines). The observed anti-correlation supports the accretion-driven mechanism as the most likely to account for continuum variations.

• OSTI ID: 22882601
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 802; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCRETION DISKS
BOLOMETERS
CORRELATIONS
EMISSION
LUMINOSITY
MAIN SEQUENCE STARS
MASS
PHOTOMETRY
T TAURI STARS