A multi-wavelength study of the young star V1118 Orionis in outburst

Audard, M.; Stringfellow, Guy S.; Güdel, M.; Skinner, Stephen L.; Walter, Frederick M.; Guinan, E. F.; Hamilton, Ryan; Briggs, K. R.; Baldovin-Saavedra, C.

doi:10.1051/0004-6361/200913037

Cited by 38 publications

(55 citation statements)

References 89 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The colorless magnitude change could be caused by an extended hot-spot region shrinking as the accretion rate decreases, followed by cooling down towards the M5 spectrum. Similar color changes, including a substantial colorless magnitude decrease, have been observed in other outbursting stars such as V1118 Ori (Audard et al 2010). At the last stage of the outburst, the object experiences a rapid color change, becoming redder faster than expected from extinction alone.…”

Section: The End Of the Outburstsupporting

confidence: 69%

The 2014–2017 outburst of the young star ASASSN-13db

Sicilia‐Aguilar

Oprandi

Froebrich

et al. 2017

A&A

View full text Add to dashboard Cite

Context. Accretion outbursts are key elements in star formation. ASASSN-13db is a M5-type star with a protoplanetary disk, the lowest-mass star known to experience accretion outbursts. Since its discovery in 2013, it has experienced two outbursts, the second of which started in November 2014 and lasted until February 2017. Aims. We explore the photometric and spectroscopic behavior of ASASSN-13db during the 2014-2017 outburst. Methods. We use high-and low-resolution spectroscopy and time-resolved photometry from the ASAS-SN survey, the LCOGT and the Beacon Observatory to study the lightcurve of ASASSN-13db and the dynamical and physical properties of the accretion flow. Results. The 2014-2017 outburst lasted for nearly 800 days. A 4.15d period in the light curve likely corresponds to rotational modulation of a star with hot spot(s). The spectra show multiple emission lines with variable inverse P-Cygni profiles and a highly variable blue-shifted absorption below the continuum. Line ratios from metallic emission lines (Fe I/Fe II, Ti I/Ti II) suggest temperatures of ∼5800-6000 K in the accretion flow. Conclusions. Photometrically and spectroscopically, the 2014-2017 event displays an intermediate behavior between EXors and FUors. The accretion rate (Ṁ=1-3×10−7 M /yr), about two orders of magnitude higher than the accretion rate in quiescence, is not significantly different from the accretion rate observed in 2013. The absorption features in the spectra suggest that the system is viewed at a high angle and drives a powerful, non-axisymmetric wind, maybe related to magnetic reconnection. The properties of ASASSN-13db suggest that temperatures lower than those for solar-type stars are needed for modeling accretion in very-low-mass systems. Finally, the rotational modulation during the outburst reveals that accretion-related structures settle after the beginning of the outburst and can be relatively stable and long-lived. Our work also demonstrates the power of time-resolved photometry and spectroscopy to explore the properties of variable and outbursting stars.

show abstract

Section: The End Of the Outburstsupporting

confidence: 69%

The 2014–2017 outburst of the young star ASASSN-13db

Sicilia‐Aguilar

Oprandi

Froebrich

et al. 2017

A&A

View full text Add to dashboard Cite

show abstract

“…Follow-up observations of this object detected a moderate enhancement in the X-ray flux that was correlated with the optical/IR flux (Audard et al 2005(Audard et al , 2010Lorenzetti et al 2006).…”

Section: Introductionmentioning

confidence: 75%

A few days before the end of the 2008 extreme outburst of EX Lupi: accretion shocks and a smothered stellar corona unveiled by XMM-Newton

Grosso

Hamaguchi

Kastner

et al. 2010

A&A

View full text Add to dashboard Cite

Context. EX Lup is a pre-main sequence star that exhibits repetitive and irregular optical outbursts driven by an increase in the mass accretion rate in its circumstellar disk. In mid-January 2008, EX Lup, the prototype of the small class of eruptive variables called EXors, began an extreme outburst that lasted seven months. Aims. We attempt to characterize the X-ray and UV emission of EX Lup during this outburst. Methods. We observed EX Lup during about 21 h with XMM-Newton, simultaneously in X-rays and UV, on August 10-11, 2008 -a few days before the end of its 2008 outburst -when the optical flux of EX Lup remained about 4 times above its pre-outburst level. Results. We detected EX Lup in X-rays with an observed flux in the 0.2-10 keV energy range of 5.4 × 10 −14 erg s −1 cm −2 during a low-level period. This observed flux increased by a factor of four during a flaring period that lasted about 2 h. The observed spectrum of the low-level period is dominated below ∼1.5 keV by emission from a relatively cool plasma (∼4.7 MK) that is lightly absorbed (N H 3.6 × 10 20 cm −2 ) and above ∼1.5 keV by emission from a plasma that is ∼ten times hotter and affected by a photoelectric absorption that is 75 times larger. The intrinsic X-ray luminosity of the relatively cool plasma is ∼4 × 10 28 erg s −1 . The intrinsic X-ray luminosity of EX Lup, ∼3.4 × 10 29 erg s −1 , is hence dominated by emission from the hot plasma. During the X-ray flare, the emission measure and the intrinsic X-ray luminosity of this absorbed plasma component is five times higher than during the low-level period. We detected UV variability on timescales ranging from less than one hour up to about four hours. We show from simulated light curves that the power spectral density of the UV light curve can be modeled with a red-noise spectrum with a power-law index of 1.39 ± 0.06. None of the UV events observed on August 10-11, 2008 correlate unambiguously with simultaneous X-ray peaks. Conclusions. The soft X-ray spectral component is most likely associated with accretion shocks, as opposed to jet activity, given the absence of forbidden emission lines of low-excitation species (e.g., [O i]) in optical spectra of EX Lup obtained during outburst. The hard X-ray spectral component, meanwhile, is most likely associated with a smothered stellar corona. The UV emission is reminiscent of accretion events, such as those already observed with the Optical/UV Monitor from other accreting pre-main sequence stars, and is evidently dominated by emission from accretion hot spots. The large photoelectric absorption of the active stellar corona is most likely due to high-density gas above the corona in accretion funnel flows.

show abstract

“…The estimate of the mass accretion rate of EX Lupi during the 2008 optical outburst is very similar to the value of (4-7) × 10 −7 M yr −1 derived by Lorenzetti et al (2009) for V1118 Ori (on 2005 September 10, i.e., during the outburst) from the luminosities of emission lines Paβ and Brγ . In addition, the X-ray-emitting plasma of V1118 Ori was shown to be cooler during the outburst than during optical quiescence, suggesting that the X-ray plasma temperature change was likely due to enhanced accretion onto the star (Audard et al 2005(Audard et al , 2010. During the 2008 outburst of EX Lupi, we observed that the optical flux varied by a factor of 50-100 while the X-ray flux changed by a factor of 4-5.…”

Section: Ex Lupi Compared To Other Young Stellar Objects In Optical/nmentioning

confidence: 68%

Detection of a Cool, Accretion-Shock-Generated X-Ray Plasma in Ex Lupi During the 2008 Optical Eruption

Teets

Weintraub

Kastner

et al. 2012

ApJ

View full text Add to dashboard Cite

EX Lupi is the prototype for a class of young, pre-main-sequence stars which are observed to undergo irregular, presumably accretion-generated, optical outbursts that result in a several magnitude rise of the optical flux. EX Lupi was observed to optically erupt in 2008 January, triggering Chandra ACIS Target of Opportunity observations shortly thereafter. We find very strong evidence that most of the X-ray emission in the first few months after the optical outburst is generated by accretion of circumstellar material onto the stellar photosphere. Specifically, we find a strong correlation between the decreasing optical and X-ray fluxes following the peak of the outburst in the optical, which suggests that these observed declines in both the optical and X-ray fluxes are the result of declining accretion rate. In addition, in our models of the X-ray spectrum, we find strong evidence for a ∼0.4 keV plasma component, as expected for accretion shocks on low-mass, pre-main-sequence stars. From 2008 March through October, this cool plasma component appeared to fade as EX Lupi returned to its quiescent level in the optical, consistent with a decrease in the overall emission measure of accretion-shock-generated plasma. The overall small increase of the X-ray flux during the optical outburst of EX Lupi is similar to what was observed in previous X-ray observations of the 2005 optical outburst of the EX Lupi-type star V1118 Ori but contrasts with the large increase of the X-ray flux from the erupting young star V1647 Ori during its 2003 and 2008 optical outbursts.

show abstract

A multi-wavelength study of the young star V1118 Orionis in outburst

Cited by 38 publications

References 89 publications

The 2014–2017 outburst of the young star ASASSN-13db

The 2014–2017 outburst of the young star ASASSN-13db

A few days before the end of the 2008 extreme outburst of EX Lupi: accretion shocks and a smothered stellar corona unveiled by XMM-Newton

Detection of a Cool, Accretion-Shock-Generated X-Ray Plasma in Ex Lupi During the 2008 Optical Eruption

Contact Info

Product

Resources

About