THE ORION H ii REGION AND THE ORION BAR IN THE MID-INFRARED

Salgado, Francisco; Berné, O.; Adams, Joseph D.; Herter, T.; Keller, L. D.; Tielens, A. G. G. M.

doi:10.3847/0004-637x/830/2/118

Cited by 67 publications

(89 citation statements)

References 109 publications

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“…Likely, the dust emission at FIR wavelengths originates primarily from cold dust components that may not be directly associated with star formation activity (Schnee et al 2009;Bendo et al 2012;Mangum et al 2013a). The cold dust temperatures derived from the FIR measurements have a range of ∼14-60 K with a roughly constant value, ∼30 K, in the extended parts of OMC-1 (Mookerjea et al 2000;Vaillancourt 2002;Lombardi et al 2014;Goicoechea et al 2015;Salgado et al 2016), which agrees remarkably well with results obtained from NH 3 (2,2)/(1,1) and CH 3 CCH (6-5), but is lower than that derived from para-H 2 CO (3-2) line ratios. This indicates that the gas temperatures derived from NH 3 (2,2)/(1,1) and CH 3 CCH (6-5) tend to be related to the cold dust component responsible for FIR emission.…”

Section: Comparison Of Temperatures Derived From the Gas And The Dustsupporting

confidence: 80%

“…The dust temperature in the Orion A molecular cloud has been well studied from far-infrared (FIR) to mid-infrared (MIR) wavelengths (e.g., Downes et al 1981;Mookerjea et al 2000;Vaillancourt 2002;Megeath et al 2012;Lombardi et al 2014;Goicoechea et al 2015;Salgado et al 2016). The dust temperatures derived from FIR measurements rarely exceed 50 K in star formation regions of our Galaxy and external galaxies (e.g., Henkel et al 1986;Mangum et al 2013a;Guzmán et al 2015;Merello et al 2015;He et al 2016;König et al 2017;Lin et al 2016;Yu & Xu 2016;Tang et al 2017a).…”

Section: Comparison Of Temperatures Derived From the Gas And The Dustmentioning

confidence: 99%

“…Many observations have been performed to reveal the temperatures of gas and dust in the Orion region (e.g., Downes et al 1981;Churchwell & Hollis 1983;Bergin et al 1994;Wiseman & Ho 1998;Mookerjea et al 2000;Vaillancourt 2002;Batrla & Wilson 2003;Megeath et al 2012;Peng et al 2012;Lombardi et al 2014;Goicoechea et al 2015;Nishimura et al 2015;Salgado et al 2016;Friesen et al 2017). However, critical links between H 2 CO and other measurements of gas temperatures as well as dust temperatures are still unclear.…”

Section: Introductionmentioning

confidence: 99%

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Kinetic temperature of massive star-forming molecular clumps measured with formaldehyde

Tang

Henkel

Menten

et al. 2017

A&A

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We mapped the kinetic temperature structure of the Orion molecular cloud 1 (OMC-1) with para-H 2 CO (J KaKc = 3 03 -2 02 , 3 22 -2 21 , and 3 21 -2 20 ) using the APEX 12 m telescope. This is compared with the temperatures derived from the ratio of the NH 3 (2,2)/(1,1) inversion lines and the dust emission. Using the RADEX non-LTE model, we derive the gas kinetic temperature modeling the measured averaged line ratios of para-H 2 CO 3 22 -2 21 /3 03 -2 02 and 3 21 -2 20 /3 03 -2 02 . The gas kinetic temperatures derived from the para-H 2 CO line ratios are warm, ranging from 30 to >200 K with an average of 62 ± 2 K at a spatial density of 10 5 cm −3 . These temperatures are higher than those obtained from NH 3 (2,2)/(1,1) and CH 3 CCH (6-5) in the OMC-1 region. The gas kinetic temperatures derived from para-H 2 CO agree with those obtained from warm dust components measured in the mid infrared (MIR), which indicates that the para-H 2 CO (3-2) ratios trace dense and warm gas. The cold dust components measured in the far infrared (FIR) are consistent with those measured with NH 3 (2,2)/(1,1) and the CH 3 CCH (6-5) line series. With dust at MIR wavelengths and para-H 2 CO (3-2) on one side and dust at FIR wavelengths, NH 3 (2,2)/(1,1), and CH 3 CCH (6-5) on the other, dust and gas temperatures appear to be equivalent in the dense gas (n(H 2 ) 10 4 cm −3 ) of the OMC-1 region, but provide a bimodal distribution, one more directly related to star formation than the other. The non-thermal velocity dispersions of para-H 2 CO are positively correlated with the gas kinetic temperatures in regions of strong non-thermal motion (Mach number 2.5) of the OMC-1, implying that the higher temperature traced by para-H 2 CO is related to turbulence on a ∼0.06 pc scale. Combining the temperature measurements with para-H 2 CO and NH 3 (2,2)/(1,1) line ratios, we find direct evidence for the dense gas along the northern part of the OMC-1 10 km s −1 filament heated by radiation from the central Orion nebula.

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Section: Comparison Of Temperatures Derived From the Gas And The Dustsupporting

confidence: 80%

Section: Comparison Of Temperatures Derived From the Gas And The Dustmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Kinetic temperature of massive star-forming molecular clumps measured with formaldehyde

Tang

Henkel

Menten

et al. 2017

A&A

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“…Further tools provided are a visualisation application, graphics with statistical overviews of the data, an online help system, and the means to upload user generated tables which can be combined with Gaia data and shared with other users of the Gaia archive. More details on the data access facilities are provided in Salgado et al (2016).…”

Section: Gaia Dr1 Access Facilitiesmentioning

confidence: 99%

GaiaData Release 1

Brown¹,

Vallenari²,

Prusti³

et al. 2016

A&A

1,739

272

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Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. Aims. A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release. Methods. The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue. Results. Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the Hipparcos and Tycho-2 catalogues -a realisation of the Tycho-Gaia Astrometric Solution (TGAS) -and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of ∼3000 Cepheid and RR Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yr −1 for the proper motions. A systematic component of ∼0.3 mas should be added to the parallax uncertainties. For the subset of ∼94 000 Hipparcos stars in the primary data set, the proper motions are much more precise at about 0.06 mas yr −1 . For the secondary astrometric data set, the typical uncertainty of the positions is ∼10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to ∼0.03 mag over the magnitude range 5 to 20.7. Conclusions. Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five-parameter astrometry for all sources. Extensive validation shows that Gaia DR1 represents a major advance in the mapping of the heavens and the availability of basic stellar data that underpin observational astrophysics. Nevertheless, the very preliminary nature of this first Gaia data release does lead to a number of important limitations to the data quality which should be carefully considered before drawing conclusions from the data.

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“…gest that dust grains are destroyed by intense UV radiation in star-forming clouds (e.g., Voit 1992;Tielens 2008;Deharveng et al 2010;Lopez et al 2014;Salgado et al 2016;Binder & Povich 2018;Chastenet et al 2019), which may lessen the UV extinction and boost escape of radiation in ionized gas. For example, Glatzle et al (2019) adopted Weingartner, & Draine (2001)'s case A size distributions and found that σ d,i can be reduced by a factor ∼ 2-3 if the two log-normal components representing PAHs and very small carbon grains (b C = 0.0) are completely absent.…”

Section: B Effects Of Dust Destruction For the Fiducial Modelmentioning

confidence: 99%

Modeling UV Radiation Feedback from Massive Stars. III. Escape of Radiation from Star-forming Giant Molecular Clouds

Kim

Ostriker

2019

ApJ

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Using a suite of radiation hydrodynamic simulations of star cluster formation in turbulent clouds, we study the escape fraction of ionizing (Lyman continuum) and non-ionizing (FUV) radiation for a wide range of cloud masses and sizes. The escape fraction increases as H II regions evolve and reaches unity within a few dynamical times. The cumulative escape fraction before the onset of the first supernova explosion is in the range 0.05-0.58; this is lower for higher initial cloud surface density, and higher for less massive and more compact clouds due to rapid destruction. Once H II regions break out of their local environment, both ionizing and non-ionizing photons escape from clouds through fully ionized, low-density sightlines. Consequently, dust becomes the dominant absorber of ionizing radiation at late times and the escape fraction of non-ionizing radiation is only slightly larger than that of ionizing radiation. The escape fraction is determined primarily by the mean τ and width σ of the optical-depth distribution in the large-scale cloud, increasing for smaller τ and/or larger σ. The escape fraction exceeds (sometimes by three orders of magnitude) the naive estimate e − τ due to non-zero σ induced by turbulence. We present two simple methods to estimate, within ∼ 20%, the escape fraction of non-ionizing radiation using the observed dust optical depth in clouds projected on the plane of sky. We discuss implications of our results for observations, including inference of star formation rates in individual molecular clouds, and accounting for diffuse ionized gas on galactic scales.

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THE ORION H ii REGION AND THE ORION BAR IN THE MID-INFRARED

Cited by 67 publications

References 109 publications

Kinetic temperature of massive star-forming molecular clumps measured with formaldehyde

Kinetic temperature of massive star-forming molecular clumps measured with formaldehyde

GaiaData Release 1

Modeling UV Radiation Feedback from Massive Stars. III. Escape of Radiation from Star-forming Giant Molecular Clouds

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