Near-infrared and optical observations of IRAS sources in and near dense cores

Myers, P. C.; Fuller, G. A.; Mathieu, Robert D.; Beichman, Charles; Benson, P. J.; Schild, Rudolph E.; Emerson, J. P.

doi:10.1086/165458

Cited by 267 publications

(161 citation statements)

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“…bol (e.g., Myers et al 1987;Chen et al 1995;Motte & André 2001;Andrews & Williams 2005). Furthermore, all of our targets have been observed with the Spitzer IRS spectrograph, and most have silicate and/or CO 2 ice absorption in their spectra, commonly associated with embedded sources (e.g., Alexander et al 2003;Boogert et al 2004;Watson et al 2004;Pontoppidan et al 2008).…”

Section: Sample Selectionmentioning

confidence: 99%

“…Young stars have historically been classified by their nearinfrared spectral index (Lada 1987;Myers et al 1987;Andre et al 1993) and bolometric temperature (e.g., Myers & Ladd 1993;Chen et al 1995). Class 0 protostars are characterized by a lack of optical and near-/mid-infrared emission and low bolometric temperatures, suggesting that the central source is highly extincted.…”

Section: Introductionmentioning

confidence: 99%

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Disk Masses for Embedded Class I Protostars in the Taurus Molecular Cloud

Sheehan

Eisner

2017

ApJ

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Class I protostars are thought to represent an early stage in the lifetime of protoplanetary disks, when they are still embedded in their natal envelope. Here we measure the disk masses of 10 Class I protostars in the Taurus Molecular Cloud to constrain the initial mass budget for forming planets in disks. We use radiative transfer modeling to produce synthetic protostar observations and fit the models to a multi-wavelength data set using a Markov Chain Monte Carlo fitting procedure. We fit these models simultaneously to our new Combined Array for Research in Millimeter-wave Astronomy 1.3 mm observations that are sensitive to the wide range of spatial scales that are expected from protostellar disks and envelopes so as to be able to distinguish each component, as well as broadband spectral energy distributions compiled from the literature. We find a median disk mass of  M 0.018 on average, more massive than the Taurus Class II disks, which have median disk mass of~ M 0.0025 . This decrease in disk mass can be explained if dust grains have grown by a factor of 75 in grain size, indicating that by the Class II stage, at a few Myr, a significant amount of dust grain processing has occurred. However, there is evidence that significant dust processing has occurred even during the Class I stage, so it is likely that the initial mass budget is higher than the value quoted here.

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Section: Sample Selectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Disk Masses for Embedded Class I Protostars in the Taurus Molecular Cloud

Sheehan

Eisner

2017

ApJ

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“…(a) In the RCrA cloud core. (b) Upper limit, according to Myers et al (1987) with V band at 0.55 μm. (c) As deduced according to Greene et al (1994).…”

Section: Irradiation Of H 2 O Ice On Carbon Grainsmentioning

confidence: 99%

Solid CO₂in low-mass young stellar objects

Ioppolo

Sangiorgio

Baratta

et al. 2013

A&A

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Context. Solid interstellar CO 2 is an abundant component of ice dust mantles. Its ubiquity towards quiescent molecular clouds, as well as protostellar envelopes, has recently been confirmed by the IRS (InfraRed Spectrograph) aboard the Spitzer Space Telescope. Although it has been shown that CO 2 cannot be efficiently formed in the gas phase, the CO 2 surface formation pathway is still unclear. To date several CO 2 surface formation mechanisms induced by energetic (e.g., UV photolysis and cosmic ray irradiation) and nonenergetic (e.g., cold atom addition) input have been proposed. Aims. Our aim is to investigate the contribution of cosmic ray irradiation to the formation of CO 2 in different regions of the interstellar medium (ISM). To achieve this goal we compared quantitatively laboratory data with the CO 2 bending mode band profile observed towards several young stellar objects (YSOs) and a field star by the Spitzer Space Telescope. Methods. All the experiments presented here were performed at the Laboratory for Experimental Astrophysics in Catania (Italy). The interstellar relevant samples were all irradiated with fast ions (30−200 keV) and subsequently annealed in a stainless steel high vacuum chamber (P < 10 −7 mbar). Chemical and structural modifications of the ice samples were monitored by means of infrared spectroscopy. Laboratory spectra were then used to fit some thirty observational spectra.Results. A qualitative analysis shows that a good fit can be obtained with a minimum of two components. The choice of the laboratory components is based on the chemical-physical condition of each source. A quantitative analysis of the sources with known visual extinction (A V ) and methanol abundances highlights that the solid carbon dioxide can be efficiently and abundantly formed after ion irradiation of interstellar ices in all the selected YSOs in a time compatible with cloud lifetimes (3 × 10 7 years). Only in the case of field stars can the expected CO 2 column density formed upon energetic input not explain the observed abundances. This result, to be confirmed along the line of sight to different quiescent clouds, gives an indirect indication that CO 2 can also be formed in an early cloud stage through surface reactions induced by non-energetic mechanisms. In a later stage, when ices are exposed to higher UV and cosmic ray doses, the CO 2 total abundance is strongly affected by energetic formation mechanisms. Conclusions. Our results indicate that energetic processing of icy grain mantles significantly contribute to the formation of solid phase interstellar CO 2 .

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“…Among some three hundred pre-main-sequence objects in the Taurus-Auriga star-formation regions that were observed at infrared wavelengths by IRAS (Beichman et al 1986(Beichman et al , 1992Myers et al 1987;Kenyon et al 1994), about a tenth are Class I protostars. This type of young stellar object ( YSO) is defined by an extremely red energy spectrum at near-and mid-infrared wavelengths (kF k k n ; n !…”

Section: Introductionmentioning

confidence: 99%

Mid‐infrared Spectra of Class I Protostars in Taurus

Watson

Kemper

Calvet

et al. 2004

ASTROPHYS J SUPPL S

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We present Spitzer Space Telescope Infrared Spectrograph observations in the 5.3-20 m range of five young stellar objects in Taurus that have Class I continuum spectral energy distributions (kF k k n ; n ! 0), often taken to represent the youngest stellar objects in this star formation region. The spectra include a rich collection of broad absorption features that we identify with amorphous silicates and various ices, notably those of carbon dioxide and water. We show that the absorption features are produced mainly in the envelopes of these systems. The apparent depths of silicate and 15.2 m CO 2 ice features vary among the objects in a manner that is consistent with a variation of inclination with respect to the line of sight, contribution to the silicate features from material throughout the envelopes, and an origin for the CO 2 ice feature in the outer parts of the envelope. Thus, these features provide new and useful constraints on models of the physical structure of Class I protostars.

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Near-infrared and optical observations of IRAS sources in and near dense cores

Cited by 267 publications

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Disk Masses for Embedded Class I Protostars in the Taurus Molecular Cloud

Disk Masses for Embedded Class I Protostars in the Taurus Molecular Cloud

Solid CO₂in low-mass young stellar objects

Mid‐infrared Spectra of Class I Protostars in Taurus

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Near-infrared and optical observations of IRAS sources in and near dense cores

Cited by 267 publications

References 0 publications

Disk Masses for Embedded Class I Protostars in the Taurus Molecular Cloud

Disk Masses for Embedded Class I Protostars in the Taurus Molecular Cloud

Solid CO2in low-mass young stellar objects

Mid‐infrared Spectra of Class I Protostars in Taurus

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Resources

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Solid CO₂in low-mass young stellar objects