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Post Info TOPIC: V2775 Orionis
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RE: V2775 Orionis
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Title: The ALMA Early Science view of FUor/EXor objects. I. Through the looking-glass of V2775 Ori
Author: Alice Zurlo, Lucas A. Cieza, Jonathan P. Williams, Hector Canovas, Sebastian Perez, Antonio Hales, Koraljka Muzic, David A. Principe, Dary Ruíz-Rodríguez, John Tobin, Yichen Zhang, Zhaohuan Zhu, Simon Casassus, Jose L. Prieto

As part of an ALMA survey to study the origin of episodic accretion in young eruptive variables, we have observed the circumstellar environment of the star V2775 Ori. This object is a very young, pre-main sequence object which displays a large amplitude outburst characteristic of the FUor class. We present Cycle-2 band 6 observations of V2775 Ori with a continuum and CO (2-1) isotopologue resolution of 0.25\as (103 au). We report the detection of a marginally resolved circumstellar disc in the ALMA continuum with an integrated flux of 106±2 mJy, characteristic radius of ~ 30 au, inclination of 14.0^{+7.8}_{-14.5} deg, and is oriented nearly face-on with respect to the plane of the sky. The \co~emission is separated into distinct blue and red-shifted regions that appear to be rings or shells of expanding material from quasi-episodic outbursts. The system is oriented in such a way that the disc is seen through the outflow remnant of V2775 Ori, which has an axis along our line-of-sight. The 13CO emission displays similar structure to that of the \co, while the C18O line emission is very weak. We calculated the expansion velocities of the low- and medium-density material with respect to the disc to be of -2.85 km s^-1 (blue), 4.4 km s^-1 (red) and -1.35 and 1.15 km s^-1 (for blue and red) and we derived the mass, momentum and kinetic energy of the expanding gas. The outflow has an hourglass shape where the cavities are not seen. We interpret the shapes that the gas traces as cavities excavated by an ancient outflow. We report a detection of line emission from the circumstellar disc and derive a lower limit of the gas mass of 3 \MJup.

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Blobrana


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Title: Multiwavelength Observations of V2775 Ori, an Outbursting Protostar in L 1641: Exploring the Edge of the FU Orionis Regime
Authors: William J. Fischer, S. Thomas Megeath, John J. Tobin, Amelia M. Stutz, Babar Ali, Ian Remming, Marina Kounkel, Thomas Stanke, Mayra Osorio, Thomas Henning, P. Manoj, T. L. Wilson

Individual outbursting young stars are important laboratories for studying the physics of episodic accretion and the extent to which this phenomenon can explain the luminosity distribution of protostars. We present new and archival data for V2775 Ori (HOPS 223), a protostar in the L 1641 region of the Orion molecular clouds that was discovered by Caratti o Garatti et al. (2011) to have recently undergone an order-of-magnitude increase in luminosity. Our near-infrared spectra of the source have strong blueshifted He I 10830 absorption, strong H2O and CO absorption, and no H I emission, all typical of FU Orionis sources. With data from IRTF, 2MASS, HST, Spitzer, WISE, Herschel, and APEX that span from 1 to 70 microns pre-outburst and from 1 to 870 microns post-outburst, we estimate that the outburst began between 2005 April and 2007 March. We also model the pre- and post-outburst spectral energy distributions of the source, finding it to be in the late stages of accreting its envelope with a disk-to-star accretion rate that increased from about 2x10^-6 solar masses/yr to about 10^-5 solar masses/yr during the outburst. The post-outburst luminosity at the epoch of the FU Orionis-like near-IR spectra is 28 L_sun, making V2775 Ori the least luminous documented FU Orionis outburster with a protostellar envelope. The existence of low-luminosity outbursts supports the notion that a range of episiodic accretion phenomena can partially explain the observed spread in protostellar luminosities.

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