Detection of Irregular, Submillimeter Opaque Structures in the Orion Molecular Clouds: Protostars within 10,000 yr of Formation?

Karnath, Nicole; Megeath, S. Thomas; Tobin, John J.; Stutz, Amelia M.; Li, Z.-Y.; Sheehan, Patrick; Reynolds, Nickalas; Sadavoy, Sarah; Stephens, Ian; Osorio, M. R. Zapatero; Anglada, Guillem; Díaz-Rodríguez, A. K.; Cox, Erin G.

doi:10.3847/1538-4357/ab659e

Cited by 24 publications

(43 citation statements)

References 58 publications

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“…This is highly suggestive that the emission at 0.87mm is optically thick. It is not likely that these are all disks viewed nearly face-on, given that the outflows (when detected and resolved) are extended in the plane of the sky (Takahashi & Ho 2012;Tobin et al 2016b;Karnath et al 2020). Thus, for at least some of these most massive, non-disklike sources, we may be detecting very dense, compact inner envelope emission.…”

Section: How Much Envelope Contamination Is Present?mentioning

confidence: 97%

The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Orion Protostars. II. A Statistical Characterization of Class 0 and Class I Protostellar Disks

Tobin

Sheehan

Megeath

et al. 2020

ApJ

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255

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We have conducted a survey of 328 protostars in the Orion molecular clouds with the Atacama Large Millimeter/ submillimeter Array at 0.87 mm at a resolution of ∼0 1 (40 au), including observations with the Very Large Array at 9mm toward 148 protostars at a resolution of ∼0 08 (32 au). This is the largest multiwavelength survey of protostars at this resolution by an order of magnitude. We use the dust continuum emission at 0.87 and 9mm to measure the dust disk radii and masses toward the Class 0, Class I, and flat-spectrum protostars, characterizing the evolution of these disk properties in the protostellar phase. The mean dust disk radii for the Class 0, Class I, and flat-spectrum protostars are -+ 44.9 3.4 5.8 , -+ 37.0 3.0 4.9 , and -+ 28.5 2.3 3.7 au, respectively, and the mean protostellar dust disk masses are 25.9 -+ 4.0 7.7 , -+ 14.9 2.2 3.8 , -+11.6 1.93.5 Å M , respectively. The decrease in dust disk masses is expected from disk evolution and accretion, but the decrease in disk radii may point to the initial conditions of star formation not leading to the systematic growth of disk radii or that radial drift is keeping the dust disk sizes small. At least 146 protostellar disks (35% of 379 detected 0.87 mm continuum sources plus 42 nondetections) have disk radii greater than 50 au in our sample. These properties are not found to vary significantly between different regions within Orion. The protostellar dust disk mass distributions are systematically larger than those of Class II disks by a factor of >4, providing evidence that the cores of giant planets may need to at least begin their formation during the protostellar phase.

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Section: How Much Envelope Contamination Is Present?mentioning

confidence: 97%

The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Orion Protostars. II. A Statistical Characterization of Class 0 and Class I Protostellar Disks

Tobin

Sheehan

Megeath

et al. 2020

ApJ

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255

310

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“…-Orion A. The Orion star-forming region is the most massive and most active star-forming complex in the local neighborhood (e.g., Maddalena et al 1986;Brown et al 1995;Bally 2008;Lombardi et al 2011;Kainulainen et al 2017;Friesen et al 2017;Monsch et al 2018;Getman et al 2019;Karnath et al 2020;Tobin et al 2020;Hacar et al 2020). It contains the nearest massive star-forming cluster to Earth, the Trapezium cluster (e.g., Hillenbrand 1997;Lada et al 2000;Muench et al 2002;Da Rio et al 2012;Robberto et al 2013;Zari et al 2019), at a distance of 388 pc (Kounkel et al 2017).…”

Section: Sample Selectionmentioning

confidence: 99%

Gas phase Elemental abundances in Molecular cloudS (GEMS)

Rodríguez-Baras

Fuente

Riviére-Marichalar

et al. 2021

A&A

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Gas phase Elemental abundances in Molecular CloudS (GEMS) is an IRAM 30 m Large Program designed to provide estimates of the S, C, N, and O depletions and gas ionization degree, X(e−), in a selected set of star-forming filaments of Taurus, Perseus, and Orion. Our immediate goal is to build up a complete and large database of molecular abundances that can serve as an observational basis for estimating X(e−) and the C, O, N, and S depletions through chemical modeling. We observed and derived the abundances of 14 species (13CO, C18O, HCO+, H13CO+, HC18O+, HCN, H13CN, HNC, HCS+, CS, SO, 34SO, H2S, and OCS) in 244 positions, covering the AV ~3 to ~100 mag, n(H2) ~ a few 103 to 106 cm−3, and Tk ~10 to ~30 K ranges in these clouds, and avoiding protostars, HII regions, and bipolar outflows. A statistical analysis is carried out in order to identify general trends between different species and with physical parameters. Relations between molecules reveal strong linear correlations which define three different families of species: (1) 13CO and C18O isotopologs; (2) H13CO+, HC18O+, H13 CN, and HNC; and (3) the S-bearing molecules. The abundances of the CO isotopologs increase with the gas kinetic temperature until TK ~ 15 K. For higher temperatures, the abundance remains constant with a scatter of a factor of ~3. The abundances of H13 CO+, HC18 O+, H13 CN, and HNC are well correlated with each other, and all of them decrease with molecular hydrogen density, following the law ∝ n(H2)−0.8 ± 0.2. The abundances of S-bearing species also decrease with molecular hydrogen density at a rate of (S-bearing/H)gas ∝ n(H2)−0.6 ± 0.1. The abundances of molecules belonging to groups 2 and 3 do not present any clear trend with gas temperature. At scales of molecular clouds, the C18O abundance is the quantity that better correlates with the cloud mass. We discuss the utility of the 13CO/C18O, HCO+/H13CO+, and H13 CO+/H13CN abundance ratios as chemical diagnostics of star formation in external galaxies.

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“…The Orion B protostars are similar to those in the ISF in the distribution of their far-IR colors. Orion B, specifically NGC 2068, contains an excess of Herschel-detected protostars that are too deeply embedded to have been detected with Spitzer (Stutz et al 2013) and have morphological evidence of youth (Karnath et al 2020). Like the ISF, Orion B is dominated by young stellar clusters, in contrast to the young stars in LDN 1641, which are primarily found in smaller groups or in relative isolation (Megeath et al 2016).…”

Section: Discussionmentioning

confidence: 99%

“…The exact fraction is determined by the time since the onset of star formation and how the SFR varies with time. Given the unusually low star formation efficiency in Orion B (Megeath et al 2016) and the high fraction of very young protostars there (Stutz & Gould 2016;Karnath et al 2020), the Orion B cloud may be undergoing a rapid rise in the SFR. The OMC 2/3 region in the ISF, which is rich in young protostars, may also be undergoing such a rise.…”

Section: Discussionmentioning

confidence: 99%

“…This paper is part of a series describing results from HOPS. These papers include evolutionary studies of protostars via modeling of their SEDs (Furlan et al 2016;Fischer et al 2017), the analysis of far-IR protostellar spectra (Manoj et al 2013(Manoj et al , 2016, the discovery and characterization of the youngest protostars (Stutz et al 2013;Tobin et al 2015Tobin et al , 2016Karnath et al 2020), a study of multiplicity in the Orion YSOs (Kounkel et al 2016), progress on understanding outburst phenomena in protostars (Fischer et al 2012(Fischer et al , 2019Safron et al 2015), and detailed studies of the active OMC 2/3 region (Furlan et al 2014;González-García et al 2016;Osorio et al 2017).…”

Section: Introductionmentioning

confidence: 99%

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The Herschel Orion Protostar Survey: Far-infrared Photometry and Colors of Protostars and Their Variations across Orion A and B*

Fischer

Megeath

Furlan

et al. 2020

ApJ

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The degree to which the properties of protostars are affected by environment remains an open question. To investigate this, we look at the Orion A and B molecular clouds, home to most of the protostars within 500 pc. At ∼400 pc, Orion is close enough to distinguish individual protostars across a range of environments in terms of both the stellar and gas projected densities. As part of the Herschel Orion Protostar Survey (HOPS), we used the Photodetector Array Camera and Spectrometer to map 108 partially overlapping square fields with edge lengths of 5′ or 8′ and measure the 70 and 160 μm flux densities of 338 protostars within them. In this paper we examine how these flux densities and their ratio depend on evolutionary state and environment within the Orion complex. We show that Class 0 protostars occupy a region of the 70 μm flux density versus 160 μm/70 μm flux density ratio diagram that is distinct from their more evolved counterparts. We then present evidence that the Integral-Shaped Filament (ISF) and Orion B contain protostars with more massive inner envelopes than those in the more sparsely populated LDN 1641 region. This can be interpreted as evidence for increasing star formation rates in the ISF and Orion B or as a tendency for more massive inner envelopes to be inherited from denser birth environments. We also provide technical details about the mapmaking and photometric procedures used in the HOPS program.

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Detection of Irregular, Submillimeter Opaque Structures in the Orion Molecular Clouds: Protostars within 10,000 yr of Formation?

Cited by 24 publications

References 58 publications

The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Orion Protostars. II. A Statistical Characterization of Class 0 and Class I Protostellar Disks

The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Orion Protostars. II. A Statistical Characterization of Class 0 and Class I Protostellar Disks

Gas phase Elemental abundances in Molecular cloudS (GEMS)

The Herschel Orion Protostar Survey: Far-infrared Photometry and Colors of Protostars and Their Variations across Orion A and B*

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