CO abundance variations in the Orion Molecular Cloud

Ripple, F.; Heyer, M. H.; Gutermuth, Robert; Snell, R. L.; Brunt, Christopher M.

doi:10.1093/mnras/stt247

Cited by 103 publications

(140 citation statements)

References 47 publications

Supporting

Mentioning

116

Contrasting

Order By: Relevance

“…In order to study the extended morphology of these structures, we first identify a ridgeline of peak gas surface density, using the dust column density map of Stutz & Kainulainen (2015) as a function of Declination δ, α ridge (δ). We obtain comparable column density maps to those reported by Polychroni et al (2013) in L1641, Ripple et al (2013) from CO measurements, and Lombardi et al (2014) using a combination of near-infrared extinction and Herschel emission. We then define (x, y) positions by…”

Section: Power-law Morphology Of the Integral-shaped Filamentsupporting

confidence: 75%

Slingshot mechanism in Orion: Kinematic evidence for ejection of protostars by filaments

Stutz

Gould

2016

A&A

132

260

View full text Add to dashboard Cite

By comparing three constituents of Orion A (gas, protostars, and pre-main-sequence stars), both morphologically and kinematically, we derive the following conclusions. The gas surface density near the integral-shaped filament (ISF) is very well represented by a power law, Σ(b) = 37 M pc −2 (b/pc) −5/8 , for the entire range to which we are sensitive, 0.05 pc < b < 8.5 pc, of projected separation from the filament ridge. Essentially all Class 0 and Class I protostars lie superposed on the ISF or on identifiable filament ridges farther south, while almost all pre-main-sequence (Class II) stars do not. Combined with the fact that protostars are moving < ∼ 1 km s −1 relative to the filaments, while stars are moving several times faster, this implies that protostellar accretion is terminated by a slingshot-like "ejection" from the filaments. The ISF is the third in a series of identifiable star bursts that are progressively moving south, with separations of several Myr in time and 2-3 pc in space. This, combined with the observed undulations in the filament (both spatial and velocity), suggest that repeated propagation of transverse waves through the filament is progressively digesting the material that formerly connected Orion A and B into stars in discrete episodes. We construct a simple, circularly symmetric gas density profile ρ(r) = 17 M pc −3 (r/pc) −13/8 consistent with the two-dimensional data. The model implies that the observed magnetic fields in this region are subcritical on spatial scales of the observed undulations, suggesting that the transverse waves propagating through the filament are magnetically induced. Because the magnetic fields are supercritical on scales of the filament as a whole (as traced by the power law), the system as a whole is relatively stable and long lived. Protostellar "ejection" (i.e., the slingshot) occurs because the gas accelerates away from the protostars, not the other way around. The model also implies that the ISF is kinematically young, which is consistent with several other lines of evidence. In contrast to the ISF, the southern filament (L1641) has a broken power law, which matches the ISF profile for 2.5 pc < b < 8.5 pc, but is shallower closer in. L1641 is kinematically older than the ISF.

show abstract

Section: Power-law Morphology Of the Integral-shaped Filamentsupporting

confidence: 75%

Slingshot mechanism in Orion: Kinematic evidence for ejection of protostars by filaments

Stutz

Gould

2016

A&A

132

260

View full text Add to dashboard Cite

show abstract

“…This is consistent with the many cold clouds interpretation above, with freeze out of CO onto dust grain mantles depleting the gas phase CO in cold, dense clouds-as observed in Milky Way cold cores (Kramer et al 1999;Tafalla et al 2002;Liu et al 2013;Ripple et al 2013). This might also explain the very strangely hot and diffuse CS model solutions from the precursor models (Table 7): CS is depleted along with CO (Tafalla et al 2002), so the only CS we observe is in the hot gas phase.…”

Section: Dense Gas and Star Formation In Ngc 6240supporting

confidence: 88%

Modeling the Molecular Gas in NGC 6240

Tunnard

Greve

García‐Burillo

et al. 2015

ApJ

View full text Add to dashboard Cite

We present the first observations of H 13 CN 1 0 ( ) -, H 13 CO + 1 0 ( ) -, and SiO 2 1 ( ) -in NGC 6240, obtained with the IRAM Plateau de Bure Interferometer. Combining a Markov Chain Monte Carlo code with Large Velocity Gradient (LVG) modeling, and with additional data from the literature, we simultaneously fit three gas phases and six molecular species to constrain the physical condition of the molecular gas, including mass−luminosity conversion factors. We find M 10 10  of dense molecular gas in cold, dense clouds (T 10 k~K , n 10 ) which we attribute to isotope fractionation in the cold, dense clouds.

show abstract

“…For 13 CO, we estimate the uncertainty of the conversion factor from integrated intensity to N ( 13 CO) by varying the assumed excitation temperature from 4 to 16 K in steps of 2 K. The fractional root mean square of values about the adopted value for 8 K is 27%. The variations of 13 CO abundance, [H 2 / 13 CO] both within clouds and from cloud-to-cloud in the solar neighborhood is ∼30% (Ripple et al 2013). These uncertainties are included in the values in Table 3, but distance errors are not (see Appendix).…”

Section: Gas Structures 331 Molecular Cloud Propertiesmentioning

confidence: 99%

Star Formation Relations in the Milky Way

Vutisalchavakul¹,

Evans²

2016

ApJ

110

141

View full text Add to dashboard Cite

The relations between star formation and properties of molecular clouds are studied based on a sample of star forming regions in the Galactic Plane. Sources were selected by having radio recombination lines to provide identification of associated molecular clouds and dense clumps. Radio continuum and mid-infrared emission were used to determine star formation rates, while 13 CO and submillimeter dust continuum emission were used to obtain masses of molecular and dense gas, respectively. We test whether total molecular gas or dense gas provides the best predictor of star formation rate. We also test two specific theoretical models, one relying on the molecular mass divided by the free-fall time, the other using the free-fall time divided by the crossing time. Neither is supported by the data. The data are also compared to those from nearby star forming regions and extragalactic data. The star formation "efficiency," defined as star formation rate divided by mass, spreads over a large range when the mass refers to molecular gas; the standard deviation of the log of the efficiency decreases by a factor of three when the mass of relatively dense molecular gas is used rather than the mass of all the molecular gas.

show abstract

CO abundance variations in the Orion Molecular Cloud

Cited by 103 publications

References 47 publications

Slingshot mechanism in Orion: Kinematic evidence for ejection of protostars by filaments

Slingshot mechanism in Orion: Kinematic evidence for ejection of protostars by filaments

Modeling the Molecular Gas in NGC 6240

Star Formation Relations in the Milky Way

Contact Info

Product

Resources

About