The 2015–2016 Outburst of the Classical EXor V1118 Ori
- INAF—Osservatorio Astronomico di Roma, via Frascati 33, I-00078, Monte Porzio Catone (Italy)
- INAF—Osservatorio Astronomico di Padova, via dell’ Osservatorio 8, I-36012, Asiago (VI) (Italy)
- Scientific Support Office, Directorate of Science, European Space Research and Technology Centre (ESA/ESTEC), Keplerlaan 1, 2201, AZ Noordwijk (Netherlands)
- Central Astronomical Observatory of Pulkovo, Pulkovskoe shosse 65, 196140, St.Petersburg (Russian Federation)
- ANS Collaboration, Astronomical Observatory, I-36012, Asiago (VI) (Italy)
- Fundación Galileo Galilei—INAF, Telescopio Nazionale Galileo, E-38700, Santa Cruz de la Palma, Tenerife (Spain)
- INAF—Osservatorio Astronomico di Brera, Via Brera 28, I-20122, Milano (Italy)
- INAF—Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127, Bologna (Italy)
After a quiescence period of about 10 years, the classical EXor source V1118 Ori has undergone an accretion outburst in 2015 September. The maximum brightness (ΔV≳4 mag) was reached in 2015 December and was maintained for several months. Since 2016 September, the source is in a declining phase. Photometry and low/high-resolution spectroscopy were obtained with MODS and LUCI2 at the Large Binocular Telescope, with the facilities at the Asiago 1.22 and 1.82 m telescopes, and with GIANO at the Telescopio Nazionale Galileo. The spectra are dominated by emission lines of H i and neutral metallic species. From line and continuum analysis we derive the mass accretion rate and its evolution during the outburst. Considering that extinction may vary between 1.5 and 2.9 mag, we obtain M-dot {sub acc} = 0.3–2.0 10{sup −8} M {sub ⊙} yr{sup −1} in quiescence and M-dot {sub acc} = 0.2–1.9 10{sup −6} M {sub ⊙} yr{sup −1} at the outburst peak. The Balmer decrement shape has been interpreted by means of line excitation models, finding that from quiescence to outburst peak, the electron density has increased from ∼2 10{sup 9} cm{sup −3} to ∼4 10{sup 11} cm{sup −3}. The profiles of the metallic lines are symmetric and narrower than 100 km s{sup −1}, while H i and He i lines show prominent wings extending up to ±500 km s{sup −1}. The metallic lines likely originate at the base of the accretion columns, where neutrals are efficiently shielded against the ionizing photons, while faster ionized gas is closer to the star. Outflowing activity is testified by the detection of a variable P Cyg-like profile of the Hα and He i 1.08 μm lines.
- OSTI ID:
- 22872770
- Journal Information:
- Astrophysical Journal, Vol. 839, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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