A Survey and Analysis of
                    <i>Spitzer</i>
                    Infrared Spectrograph Spectra of T Tauri Stars in Taurus

Furlan, Elise; Hartmann, L.; Calvet, Nuria; D’Alessio, Paola; Franco-Hernández, R.; Forrest, W. J.; Watson, D. M.; Uchida, K. I.; Sargent, B.; Green, Joel D.; Keller, L. D.; Herter, T.

doi:10.1086/505468

Cited by 375 publications

(637 citation statements)

References 100 publications

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“…Jura et al (2006) also report on the detection of class-C PAH features in a circumstellar disc around the oxygen-rich K-giant HD 233517. Two young objects, the T Tauri star SU Aur (Furlan et al 2006) and the Herbig Ae/Be source HD 135344 (Sloan et al 2005), also show PAH spectra of class C, although in HD 135344 the PAH features seem to be somewhat more in between B and C. This source is also slightly hotter than other class C sources. A comparison of the PAH features in all these sources is given by Sloan et al (2007).…”

Section: Pah Featuresmentioning

confidence: 91%

Analysis of the infrared spectra of the peculiar post-AGB stars EP Lyrae and HD 52961

Gielen¹,

Winckel²,

Matsuura

et al. 2009

A&A

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Aims. We aim to study in detail the peculiar mineralogy and structure of the circumstellar environment of two binary post-AGB stars, EP Lyr and HD 52961. Both stars were selected from a larger sample of evolved disc sources observed with Spitzer and show unique solid-state and gas features in their infrared spectra. Moreover, they show a very small infrared excess in comparison with the other sample stars. Methods. The different dust and gas species are identified on the basis of high-resolution Spitzer-IRS spectra. We fit the full spectrum to constrain grain sizes and temperature distributions in the discs. This, combined with our broad-band spectral energy distribution and interferometric measurements, allows us to study the physical structure of the disc, using a self-consistent 2D radiative-transfer disc model. Results. We find that both stars have strong emission features due to CO 2 gas, dominated by 12 C 16 O 2 , but with clear 13 C 16 O 2 and even 16 O 12 C 18 O isotopic signatures. Crystalline silicates are apparent in both sources but proved very hard to model. EP Lyr also shows evidence of mixed chemistry, with emission features of the rare class-C PAHs. Whether these PAHs reside in the oxygen-rich disc or in a carbon-rich outflow is still unclear. With the strongly processed silicates, the mixed chemistry and the low 12 C/ 13 C ratio, EP Lyr resembles some silicate J-type stars, although the depleted photosphere makes nucleosynthetic signatures difficult to probe. We find that the disc environment of both sources is, to a first approximation, well modelled with a passive disc, but additional physics such as grain settling, radial dust distributions, and an outflow component must be included to explain the details of the observed spectral energy distributions in both stars.

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Section: Pah Featuresmentioning

confidence: 91%

Analysis of the infrared spectra of the peculiar post-AGB stars EP Lyrae and HD 52961

Gielen¹,

Winckel²,

Matsuura

et al. 2009

A&A

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“…Following Lada et al (2006), we divide the sample in six spectral type bins. We also show the median SEDs of the ∼2−3 Myr old cluster IC 348 from Lada et al (2006) with dotted curves, of the ∼1−2 Myr old distributed population in Taurus (Furlan et al 2006) with solid curves, and the ∼5 Myr old population in upper Scorpius (Dahm & Carpenter 2009) with dashed curves. For the cluster IC 348, Lada et al (2006) only presents "observed" SEDs.…”

Section: Median Sedsmentioning

confidence: 99%

Star and protoplanetary disk properties in Orion's suburbs

Fang

Boekel²,

Wang³

et al. 2009

A&A

251

401

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Context. Knowledge of the evolution of circumstellar accretion disks is pivotal to our understanding of star and planet formation; and yet despite intensive theoretical and observational studies, the disk dissipation process is not well understood. Infrared observations of large numbers of young stars, as performed by the Spitzer Space Telescope, may advance our knowledge of this inherently complex process. While infrared data reveal the evolutionary status of the disk, they hold little information on the properties of the central star and the accretion characteristics. Aims. Existing 2MASS and Spitzer archive data of the Lynds 1630N and 1641 clouds in the Orion GMC provide disk properties of a large number of young stars. We wish to complement these data with optical data that provide the physical stellar parameters and accretion characteristics. Methods. We performed a large optical spectroscopic and photometric survey of the aforementioned clouds. Spectral types, as well as accretion and outflow characteristics, are derived from our VLT/VIMOS spectra. Optical SDSS and CAHA/LAICA imaging was combined with 2MASS, Spitzer IRAC, and MIPS imaging to obtain spectral energy distributions from 0.4 to 24 μm. Reddened model atmospheres were fitted to the optical/NIR photometric data, keeping T eff fixed at the spectroscopic value. Mass and age estimates of individual objects were made through placement in the HR diagram and comparison to several sets of pre-main sequence evolutionary tracks. Results. We provide a catalog of 132 confirmed young stars in L1630N and 267 such objects in L1641. We identify 28 transition disk systems, 20 of which were previously unknown, as well as 42 new transition disk candidates for which we have broad-band photometry but no optical spectroscopy. We give mass and age estimates for the individual stars, as well as equivalent widths of optical emission lines, the extinction, and measures of the evolutionary state of the circumstellar dusty disk. We estimate mass accretion ratesṀ acc from the equivalent widths of the Hα, Hβ, and He I 5876 Å emission lines, and find a dependence ofṀ acc ∝ M α * , with α ∼ 3.1 in the subsolar mass range that we probe. An investigation of a large literature sample of mass accretion rate estimates yields a similar slope of α ∼ 2.8 in the subsolar regime, but a shallower slope of α ∼ 2.0 if the whole mass range of 0.04 M ≤ M * ≤ 5 M is included. The fraction of stars with transition disks that show significant accretion activity is relatively low compared to stars with still optically thick disks (26 ± 11% vs. 57 ± 6%, respectively). However, those transition disks that do show significant accretion have the same median accretion rate as normal optically thick disks of 3−4 × 10 −9 M yr −1 . Analyzing the age distribution of various populations, we find that the ages of the CTTSs and the WTTSs with disks are statistically indistinguishable, the WTTSs without disks are significantly older than the CTTSs, and the ages of the transition disks and the WTTSs wi...

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“…SED spectral index between 1 and 3 mm versus indicators of grain growth from the 10-μm silicate feature. Left SED slope between 1 and 3 mm vs. the ratio between the 10-μm line flux and the continuum as derived from Spitzer/IRS observations by Furlan et al (2006) for the sample of Taurus-Auriga class II YSOs described in R10. Right SED slope between 1 and 3 mm vs. the ratio between the flux at 11.3 and 9.8 μm as derived from Spitzer/IRS observations by McClure et al (2010); the plotted points are all the class II YSOs described in this paper with a value of F 11.3 /F 9.8 reported in McClure et al In the two plots the arrows in the lower left corners show toward which direction the values of the plotted quantities are indicative of the presence of largest grains.…”

Section: Grain Growthmentioning

confidence: 99%

Dust grain growth inρ-Ophiuchi protoplanetary disks

Ricci¹,

Testi²,

Natta

et al. 2010

A&A

211

140

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We present new ATCA observations at 3.3 mm of 27 young stellar objects in the ρ-Oph young cluster. 25 of these sources have been detected. We analyze the sub-millimeter and millimeter SED for a subsample of 17 isolated class II protoplanetary disks and derive constraints on the grain growth and total dust mass in the disk outer regions. All the disks in our sample show a mm slope of the SED which is significantly shallower than the one observed for the ISM at these long wavelengths. This indicates that 1) class II disks in Ophiuchus host grains grown to mm/cm-sizes in their outer regions; 2) formation of mm/cm-sized pebbles is a fast process and 3) a mechanism halting or slowing down the inward radial drift of solid particles is required to explain the data. These findings are consistent with previous results in other star forming regions. We compare the dust properties of this sample with those of a uniformly selected sample in Taurus-Auriga and find no statistical evidence of any difference in terms of grain growth between the two regions. Finally, in our sample the mm slope of the SED is not found to correlate with indicators of grain growth to micron sizes in the surface layers of the inner disk.

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A Survey and Analysis of Spitzer Infrared Spectrograph Spectra of T Tauri Stars in Taurus

Cited by 375 publications

References 100 publications

Analysis of the infrared spectra of the peculiar post-AGB stars EP Lyrae and HD 52961

Analysis of the infrared spectra of the peculiar post-AGB stars EP Lyrae and HD 52961

Star and protoplanetary disk properties in Orion's suburbs

Dust grain growth inρ-Ophiuchi protoplanetary disks

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