The Green Bank Ammonia Survey: First Results of NH<sub>3</sub> Mapping of the Gould Belt

Friesen, Rachel; Pineda, Jaime E.; Rosolowsky, Erik; Alves, F. O.; Chacón-Tanarro, A.; Chen, Hope How-Huan; Chen, Michael Chun Yuan; Francesco, James Di; Keown, Jared; Kirk, Helen; Punanova, A.; Seo, Young Min; Shirley, Yancy L.; Ginsburg, Adam; Hall, Christine; Offner, Stella S. R.; Singh, Ayushi; Arce, Héctor G.; Caselli, P.; Goodman, Alyssa A.; Martín, P. G.; Matzner, Christopher D.; Myers, Philip C.; Redaelli, E.

doi:10.3847/1538-4357/aa6d58

Cited by 140 publications

(243 citation statements)

References 86 publications

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“…The Orion A molecular cloud has been measured in NH 3 (1,1) and (2,2) with the GBT telescope (beam size ∼30 ′′ ; Friesen et al 2017; this agrees well with our para-H 2 CO (3-2) data.) We compare maps of gas kinetic temperatures derived from para-H 2 CO and NH 3 (2,2)/(1,1) line ratios in Figure 5.…”

Section: Comparison Of Temperatures Derived From H 2 Co and Other Gassupporting

confidence: 78%

“…The gas kinetic temperatures are derived from para-H 2 CO and NH 3 (2,2)/(1,1) (Friesen et al 2017) line ratios. The beam sizes of para-H 2 CO and NH 3 are both ∼30 ′′ , so we only fit the data for para-H 2 CO and NH 3 , respectively, with distance R > 30 ′′ .…”

Section: Radiation Heatingmentioning

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%

“…A large number of molecular line observations have been performed, such as in CO (e.g., Bally et al 1987;Goldsmith et al 1997;Wilson et al 2005;Peng et al 2012;Buckle et al 2012;Shimajiri et al 2011Shimajiri et al , 2014Berné et al 2014), CS (e.g., Tatematsu et al 1993Tatematsu et al , 1998, N 2 H + (e.g., Tatematsu et al 2008;Melnick et al 2011;Hacar et al 2017), NH 3 (e.g., Batrla et al 1983;Bastien et al 1985;Murata et al 1990;Wiseman & Ho 1996Batrla & Wilson 2003;Friesen et al 2017), H 2 CO (e.g., Thaddeus et al 1971;Kutner et al 1976;Cohen & Few 1981;Batrla et al 1983;Bastien et al 1985;Mangum et al 1990van der Wiel et al 2009;Leurini et al 2010), HC 3 N (e.g., Martín-Pintado et al 1990;Rodríguez et al 1992;Bergin et al 1996), and HCN (e.g., Schilke et al 1992;Melnick et al 2011). These observations revealed the distribution of the dense gas within OMC-1 down to a ∼0.1 pc scale.…”

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 H 2 Co and Other Gassupporting

confidence: 78%

Section: Radiation Heatingmentioning

confidence: 99%

Section: Introductionmentioning

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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“…Millimeter and sub-mm continuum surveys of nearby clouds showed that prestellar cores have masses ∼ 0.1 − 10 M and sizes ∼ 0.01 − 1 pc (e.g., Enoch et al 2006;Johnstone & Bally 2006;Könyves et al 2010;Kirk et al 2013), while the gas dynamics at core scales have been investigated in spectral line observations using dense gas tracers like N2H + , H 13 CO + , or C 18 O (e.g., Ikeda et al 2009;Rathborne et al 2009;Pineda et al 2015;Punanova et al 2018;Chen et al 2019b). In particular, analyses of core kinematics from the recent Green Bank Ammonia Survey (GAS; Friesen et al 2017) shows that many dense cores are not bound by self-gravity, but are pressure-confined Keown et al 2017;Chen et al 2019c;Kerr et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Relative alignment between dense molecular cores and ambient magnetic field: the synergy of numerical models and observations

Chen

Behrens

Washington

et al. 2020

Monthly Notices of the Royal Astronomical Society

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The role played by magnetic field during star formation is an important topic in astrophysics. We investigate the correlation between the orientation of star-forming cores (as defined by the core major axes) and ambient magnetic field directions in 1) a 3D MHD simulation, 2) synthetic observations generated from the simulation at different viewing angles, and 3) observations of nearby molecular clouds. We find that the results on relative alignment between cores and background magnetic field in synthetic observations slightly disagree with those measured in fully 3D simulation data, which is partly because cores identified in projected 2D maps tend to coexist within filamentary structures, while 3D cores are generally more rounded. In addition, we examine the progression of magnetic field from pc-to core-scale in the simulation, which is consistent with the anisotropic core formation model that gas preferably flow along the magnetic field toward dense cores. When comparing the observed cores identified from the GBT Ammonia Survey (GAS) and Planck polarization-inferred magnetic field orientations, we find that the relative core−field alignment has a regional dependence among different clouds. More specifically, we find that dense cores in the Taurus molecular cloud tend to align perpendicular to the background magnetic field, while those in Perseus and Ophiuchus tend to have random (Perseus) or slightly parallel (Ophiuchus) orientations with respect to the field. We argue that this feature of relative core−field orientation could be used to probe the relative significance of the magnetic field within the cloud.

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Zooming in on Individual Star Formation: Low- and High-Mass Stars

et al. 2020

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The Green Bank Ammonia Survey: First Results of NH₃ Mapping of the Gould Belt

Cited by 140 publications

References 86 publications

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

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

Relative alignment between dense molecular cores and ambient magnetic field: the synergy of numerical models and observations

Zooming in on Individual Star Formation: Low- and High-Mass Stars

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The Green Bank Ammonia Survey: First Results of NH3 Mapping of the Gould Belt

Cited by 140 publications

References 86 publications

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

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

Relative alignment between dense molecular cores and ambient magnetic field: the synergy of numerical models and observations

Zooming in on Individual Star Formation: Low- and High-Mass Stars

Contact Info

Product

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About

The Green Bank Ammonia Survey: First Results of NH₃ Mapping of the Gould Belt