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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 660885.0, MPI für Astronomie / Publikationen_mpia
The 2008 outburst of EX Lup—silicate crystals in motion
Authors:Juhász, A.; Dullemond, C. P.; van Boekel, R.; Bouwman, J.; Ábrahám, P.; Acosta-Pulido, J. A.; Henning, T.; Kóspál, A.; Sicilia-Aguilar, A.; Jones, A.; Moór, A.; Mosoni, L.; Regály, Z.; Szokoly, G.; Sipos, N.
Date of Publication (YYYY-MM-DD):2012
Journal Abbrev.:The Astrophysical Journal
Issue / Number:2
Start Page:id. 118
Audience:Not Specified
Abstract / Description:EX Lup is the prototype of the EXor class of eruptive young stars. These objects show optical outbursts which are thought to be related to runaway accretion onto the star. In a previous study we observed in situ crystal formation in the disk of EX Lup during its latest outburst in 2008, making the object an ideal laboratory to investigate circumstellar crystal formation and transport. This outburst was monitored by a campaign of ground-based and Spitzer Space Telescope observations. Here we modeled the spectral energy distribution (SED) of EX Lup in the outburst from optical to millimeter wavelengths with a two-dimensional radiative transfer code. Our results showed that the shape of the SED at optical wavelengths was more consistent with a single-temperature blackbody than a temperature distribution. We also found that this single-temperature component emitted 80%-100% of the total accretion luminosity. We concluded that a thermal instability, the most widely accepted model of EXor outbursts, was likely not the triggering mechanism of the 2008 outburst of EX Lup. Our mid-infrared Spitzer spectra revealed that the strength of all crystalline bands between 8 and 30 μm increased right after the end of the outburst. Six months later, however, the crystallinity in the 10 μm silicate feature complex decreased. Our modeling of the mid-infrared spectral evolution of EX Lup showed that, although vertical mixing should be stronger during the outburst than in the quiescent phase, fast radial transport of crystals (e.g., by stellar/disk wind) was required to reproduce the observed mid-infrared spectra.
Free Keywords:accretion; accretion disks; astrochemistry; circumstellar matter; infrared: stars; protoplanetary disks; stars: formation; stars: individual(EX Lup)
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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