Evolution of Dust and Ice Features around FU Orionis Objects

Quanz, Sascha P.; Henning, Th.; Bouwman, J.; Boekel, R. van; Juhász, A.; Linz, H.; Pontoppidan, K. M.; Lahuis, F.

doi:10.1086/521219

Cited by 72 publications

(143 citation statements)

References 76 publications

(141 reference statements)

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“…The emission spectrum of FU Ori resembles that of BBW 76 in Paper I, while the FUORs V346 Nor, V883 Ori and Z CMa of Paper I show silicate absorption features. This could be an effect of the disk orientation (pole-on vs. faceon) or represent the two FUOR categories defined by Quanz et al (2007). 3.…”

Section: Discussionmentioning

confidence: 99%

“…However, given the large number of FUORs with silicate absorption features, this difference cannot be explained by disk orientation alone. Therefore, Quanz et al (2007) defined two categories of FUORs: (1) objects for which the silicate feature is in absorption probably remain embedded in a circumstellar envelope; and (2) objects where the silicate band is in emission, which are understood to have largely shed their envelope, and the feature arises in the surface layer of their accretion disks.…”

Section: Appendix A: Comments On Individual Sourcesmentioning

confidence: 99%

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Mid-IR observations of circumstellar disks

Schuetz¹,

Meeus

Sterzik³

et al. 2009

A&A

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We present new mid-infrared spectra of 15 targets (1 FU Orionis object, 4 Herbig Ae stars, 5 T Tauri stars, and 5 Vega-type stars), obtained with the TIMMI2 camera at La Silla Observatory (ESO). Three targets are members of the β Pic moving group (HD 155 555, HD 181 296, and HD 319 139). PAH bands are observed towards the T Tauri star HD 34 700 and the Herbig Ae star PDS 144 N. For HD 34 700, the band profiles indicate processed PAHs. The spectrum of the Vega-type object η Corvi (HD 109 085), for which a resolved disk at sub-mm wavelengths is known, appears stellar between 8-13 μm, but a small excess emission was reported by Spitzer observations. Similarly, no indication of circumstellar matter at mid-infrared wavelengths is found towards the Vega-like stars HD 3003, HD 80 951, HD 181 296, and, surprisingly, the T Tauri system HD 155 555. The silicate emission features of the remaining eight sources are modelled with a mixture of silicates of different grain sizes and composition. Unprocessed dust dominates FU Ori, HD 143 006, and CD-43 344. Large amorphous grains are the main dust component around HD 190 073, HD 319 139, KK Oph, and PDS 144 S. Both small grains and crystalline dust is found for the Vega-type HD 123 356, with a dominance of small amorphous grains. We show that the infrared emission of the binary HD 123 356 is dominated by its late-type secondary, but optical spectroscopy is still required to confirm the age of the system and the spectral class of the companion. For most targets, this is their first mid-infrared spectroscopic observation. We investigate trends between stellar, disk, and silicate properties and confirm correlations identified in previous studies. Several objects present an exciting potential for follow-up high-resolution disk studies.

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Section: Discussionmentioning

confidence: 99%

Section: Appendix A: Comments On Individual Sourcesmentioning

confidence: 99%

Mid-IR observations of circumstellar disks

Schuetz¹,

Meeus

Sterzik³

et al. 2009

A&A

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“…V1057 Cyg, V1647 Ori, PV Cep, OO Ser) exhibit flat or increasing SEDs in the 20−100 μm wavelength range (Ábrahám et al 2004;Kóspál et al 2007), which is clearly different from the shape of EX Lupi's spectral energy distribution. Green et al (2006) and Quanz et al (2007) suggest that the diversity in the shape of the SEDs is related to the evolution of the system. Younger objects, still embedded in a large envelope exhibit flat SEDs, while more evolved objects, emitting T Tauri-like SEDs have already lost their envelopes and only have circumstellar disks.…”

Section: Comparison With Young Stellar Objectsmentioning

confidence: 99%

EX Lupi in quiescence

Sipos

Ábrahám

Acosta–Pulido

et al. 2009

A&A

111

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Aims. EX Lupi is the prototype of EXors, a subclass of low-mass pre-main sequence stars whose episodic eruptions are attributed to temporarily increased accretion. In quiescence the optical and near-infrared properties of EX Lup cannot be distinguished from those of normal T Tau stars. Here we investigate whether it is the circumstellar disk structure that makes EX Lup an atypical Class II object. During outburst the disk might undergo structural changes. Our characterization of the quiescent disk is intended to serve as a reference for studying the physical changes related to one of EX Lupi's strongest known eruptions in 2008 Jan-Sep. Methods. We searched the literature for photometric and spectroscopic observations including ground-based, IRAS, ISO, and Spitzer data. After constructing the optical-infrared spectral energy distribution (SED), we compared it with the typical SEDs of other young stellar objects and modeled it using the Monte Carlo radiative transfer code RADMC. We determined the mineralogical composition of the 10 μm silicate emission feature and also gave a description of the optical and near-infrared spectra. Results. The SED is similar to that of a typical T Tauri star in most aspects, though EX Lup emits higher flux above 7 μm. The quiescent phase data suggest low-level variability in the optical-mid-infrared domain. By integrating the optical and infrared fluxes, we derived a bolometric luminosity of 0.7 L . The 10 μm silicate profile could be fitted by a mixture consisting of amorphous silicates, but no crystalline silicates were found. A modestly flaring disk model with a total mass of 0.025 M and an outer radius of 150 AU was able to reproduce the observed SED. The derived inner radius of 0.2 AU is larger than the sublimation radius, and this inner gap sets EX Lup apart from typical T Tauri stars.

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“…which remain embedded within their circumstellar envelopes (Quanz et al 2007). The longer duration (few tens of years or longer) ones are named FU Orionis objects after the archetype source FU Ori (see Hartmann & Kenyon 1996 for a review).…”

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confidence: 99%

A concordant scenario to explain FU Orionis from deep centimeter and millimeter interferometric observations

Liu

Vorobyov

Dong

et al. 2017

A&A

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Aims. The aim of this work is to constrain properties of the disk around the archetype FU Orionis object, FU Ori, with as good as ∼25 au resolution. Methods. We resolved FU Ori at 29-37 GHz using the Karl G. Jansky Very Largy Array (JVLA) in the A-array configuration, which provided the highest possible angular resolution to date at this frequency band (∼0 ′′ .07). We also performed complementary JVLA 8-10 GHz observations, the Submillimeter Array (SMA) 224 GHz and 272 GHz observations, and compared with archival Atacama Large Millimeter Array (ALMA) 346 GHz observations to obtain the spectral energy distributions (SEDs). Results. Our 8-10 GHz observations do not find evidence for the presence of thermal radio jets, and constrain the radio jet/wind flux to at least 90 times lower than the expected value from the previously reported bolometric luminosity-radio luminosity correlation. The emission at frequencies higher than 29 GHz may be dominated by the two spatially unresolved sources, which are located immediately around FU Ori and its companion FU Ori S, respectively. Their deconvolved radii at 33 GHz are only a few au, which is two orders of magnitude smaller in linear scale than the gaseous disk revealed by the previous Subaru-HiCIAO 1.6 µm coronagraphic polarization imaging observations. We are struck by the fact that these two spatially compact sources contribute to over 50% of the observed fluxes at 224 GHz, 272 GHz, and 346 GHz. The 8-346 GHz SEDs of FU Ori and FU Ori S cannot be fit by constant spectral indices (over frequency), although we cannot rule out that it is due to the time variability of their (sub)millimeter fluxes. Conclusions. The more sophisticated models for SEDs considering the details of the observed spectral indices in the millimeter bands suggest that the >29 GHz emission is contributed by a combination of free-free emission from ionized gas, and thermal emission from optically thick and optically thin dust components. We hypothesize that dust in the innermost parts of the disks ( 0.1 au) has been sublimated, and thus the disks are no more well shielded against the ionizing photons. The estimated overall gas and dust mass based on SED modeling, can be as high as a fraction of a solar mass, which is adequate for developing disk gravitational instability. Our present explanation for the observational data is that the massive inflow of gas and dust due to disk gravitational instability or interaction with a companion/intruder, was piled up at the few au scale due to the development of a deadzone with negligible ionization. The piled up material subsequently triggered the thermal instability and the magnetorotational instability when the ionization fraction in the inner sub-au scale region exceeded a threshold value, leading to the high protostellar accretion rate.

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Evolution of Dust and Ice Features around FU Orionis Objects

Cited by 72 publications

References 76 publications

Mid-IR observations of circumstellar disks

Mid-IR observations of circumstellar disks

EX Lupi in quiescence

A concordant scenario to explain FU Orionis from deep centimeter and millimeter interferometric observations

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