Small-Scale Structure of the Mon R2 Cloud Core

Henning, Th.; Chini, R.; Pfau, W.

doi:10.1017/s0252921100019734

Cited by 26 publications

(48 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The UC Hii region has a cometary shape and its continuum peaks toward the infrared source Mon R2 IRS 1. Previous millimeter and farinfrared spectroscopic and continuum studies (Henning et al 1992;Giannakopoulou et al 1997;Tafalla et al 1997;Choi et al 2000;Rizzo et al 2003Rizzo et al , 2005Pilleri et al 2012Pilleri et al , 2013 showed that the molecular emission presents an arc-like structure surrounding the Hii region, with the bulk of the emission to the SW (see Fig. 1).…”

Section: Ultracompact Hii Region In Mon R2mentioning

confidence: 89%

Deuteration around the ultracompact HII region Monoceros R2

Treviño-Morales¹,

Pilleri²,

Fuente³

et al. 2014

A&A

View full text Add to dashboard Cite

Context. The massive star-forming region Monoceros R2 (Mon R2) hosts the closest ultra-compact Hii region, where the photondominated region (PDR) between the ionized and molecular gas can be spatially resolved with current single-dish telescopes. Aims. We aim at studying the chemistry of deuterated molecules toward Mon R2 to determine the deuterium fractions around a high-UV irradiated PDR and investigate the chemistry of these species. Methods. We used the IRAM-30 m telescope to carry out an unbiased spectral survey toward two important positions (namely IF and MP2) in Mon R2 at 1, 2, and 3 mm. This spectral survey is the observational basis of our study of the deuteration in this massive starforming region. Our high spectral resolution observations (∼0.25-0.65 km s −1 ) allowed us to resolve the line profiles of the different species detected. Results. We found a rich chemistry of deuterated species at both positions of Mon R2, with detections of C 2 D, DCN, DNC, DCO + , D 2 CO, HDCO, NH 2 D, and N 2 D + and their corresponding hydrogenated species and rarer isotopologs. The high spectral resolution of our observations allowed us to resolve three velocity components: the component at 10 km s −1 is detected at both positions and seems associated with the layer most exposed to the UV radiation from IRS 1; the component at 12 km s −1 is found toward the IF position and seems related to the foreground molecular gas; finally, a component at 8.5 km s −1 is only detected toward the MP2 position, most likely related to a low-UV irradiated PDR. We derived the column density of the deuterated species (together with their hydrogenated counterparts), and determined the deuterium fractions as D frac = [XD]/ [XH]. The values of D frac are around 0.01 for all the observed species, except for HCO + and N 2 H + , which have values 10 times lower. The values found in Mon R2 are similar to those measured in the Orion Bar, and are well explained with a pseudo-time-dependent gas-phase model in which deuteration occurs mainly via ion-molecule reactions with H 2 D + , CH 2 D + and C 2 HD + . Finally, the [H 13 CN]/[HN 13 C] ratio is very high (∼11) for the 10 km s −1 component, which also agree with our model predictions for an age of ∼0.01 to a few 0.1 Myr. Conclusions. The deuterium chemistry is a good tool for studying the low-mass and high-mass star-forming regions. However, while low-mass star-forming regions seem well characterized with D frac (N 2 H + ) or D frac (HCO + ), a more complete chemical modeling is required to date massive star-forming regions. This is due to the higher gas temperature together with the rapid evolution of massive protostars.

show abstract

Section: Ultracompact Hii Region In Mon R2mentioning

confidence: 89%

Deuteration around the ultracompact HII region Monoceros R2

Treviño-Morales¹,

Pilleri²,

Fuente³

et al. 2014

A&A

View full text Add to dashboard Cite

show abstract

“…Palau et al (2011) Howard et al 1994;Carpenter et al 1997;Preibisch et al 2002). G213.70-12.6 hosts several infrared sources, the brightest of which is IRS 3 (L = 14 000 L ; Henning et al 1992). IRS 3 is a compact cluster of massive YSOs (Preibisch et al 2002) • ; Minier et al 2000).…”

Section: G17420-008mentioning

confidence: 99%

EVN observations of 6.7 GHz methanol maser polarization in massive star-forming regions

Surcis

Vlemmings

Langevelde

et al. 2015

A&A

View full text Add to dashboard Cite

Context. Theoretical simulations and observations at different angular resolutions have shown that magnetic fields have a central role in massive star formation. Like in low-mass star formation, the magnetic field in massive young stellar objects can either be oriented along the outflow axis or randomly. Aims. Measuring the magnetic field at milliarcsecond resolution (10-100 au) around a substantial number of massive young stellar objects permits determining with a high statistical significance whether the direction of the magnetic field is correlated with the orientation of the outflow axis or not. Methods. In late 2012, we started a large VLBI campaign with the European VLBI Network to measure the linearly and circularly polarized emission of 6.7 GHz CH 3 OH masers around a sample of massive star-forming regions. This paper focuses on the first seven observed sources, G24.78+0.08, G25.65+1.05, G29.86-0.04, G35.03+0.35, G37.43+1.51, G174.20-0.08, and G213.70-12.6. For all these sources, molecular outflows have been detected in the past. Results. We detected a total of 176 CH 3 OH masing cloudlets toward the seven massive star-forming regions, 19% of which show linearly polarized emission. The CH 3 OH masers around the massive young stellar object MM1 in G174.20-0.08 show neither linearly nor circularly polarized emission. The linear polarization vectors are well ordered in all the other massive young stellar objects. We measured significant Zeeman splitting toward both A1 and A2 in G24.78+0.08, and toward G29.86-0.04 and G213.70-12.6. Conclusions. By considering all the 19 massive young stellar objects reported in the literature for which both the orientation of the magnetic field at milliarcsecond resolution and the orientation of outflow axes are known, we find evidence that the magnetic field (on scales 10-100 au) is preferentially oriented along the outflow axes.

show abstract

“…The central, spherical UC Hii was created by the interaction of the central infrared source IRS1 (Wood & Churchwell 1989) with its host molecular cloud. The formation of the B0V star associated with IRS1 created a huge bipolar outflow (∼15 = 3.6 pc long, Massi et al 1985;Henning et al 1992;Tafalla et al 1994). Later CO 3 → 2 mapping of the region showed that this very extended outflow is now inactive.…”

Section: Introductionmentioning

confidence: 98%

Spectral line survey of the ultracompact HII region Monoceros R2

Ginard

Gonzalez-Garcia

Fuente

et al. 2012

A&A

View full text Add to dashboard Cite

Context. Ultracompact (UC) Hii regions constitute one of the earliest phases in the formation of a massive star and are characterized by extreme physical conditions (G 0 > 10 5 Habing field and n > 10 6 cm −3 ). The UC Hii Mon R2 is the closest example and an excellent target to study the chemistry in these complex regions. Aims. Our goal is to investigate the chemistry of the molecular gas around UC Hii Mon R2 and the variations caused by the different local physical conditions. Methods. We carried out 3 mm and 1 mm spectral surveys using the IRAM 30-m telescope towards three positions that represent different physical environments in Mon R2: (i) the ionization front (IF) at (0 , 0 ), and two peaks in the molecular cloud; (ii) molecular Peak 1 (hereafter MP1) at the offset (+15 , −15 ); and (iii) molecular Peak 2 (hereafter MP2) at the farther offset (0 , 40 ). In addition, we carried out extensive modeling to explain the chemical differences between the three observed regions. Results. We detected more than 30 different species (including isotopologues and deuterated compounds). In particular, we detected SO + and C 4 H confirming that ultraviolet (UV) radiation plays an important role in the molecular chemistry of this region. In agreement with this interpretation, we detected the typical photo-dissociation region (PDR) molecules CN, HCN, HCO, C 2 H, and c-C 3 H 2 . There are chemical differences between the observed positions. While the IF and the MP1 have a chemistry similar to that found in high UV field and dense PDRs such as the Orion Bar, the MP2 is similar to lower UV/density PDRs such as the Horsehead nebula. Our chemical modeling supports this interpretation. In addition to the PDR-like species, we detected complex molecules such as CH 3 CN, H 2 CO, HC 3 N, CH 3 OH, and CH 3 C 2 H that are not usually found in PDRs. The sulfur compounds CS, HCS + , C 2 S, H 2 CS, SO, and SO 2 and the deuterated species DCN and C 2 D were also identified. The origin of these complex species requires further study. In Mon R2, we have the two classes of PDRs, a high UV PDR towards the IF and the adjacent molecular bar, and a low-UV PDR, which extends towards the north-west following the border of the cloud.

show abstract

Small-Scale Structure of the Mon R2 Cloud Core

Cited by 26 publications

References 2 publications

Deuteration around the ultracompact HII region Monoceros R2

Deuteration around the ultracompact HII region Monoceros R2

EVN observations of 6.7 GHz methanol maser polarization in massive star-forming regions

Spectral line survey of the ultracompact HII region Monoceros R2

Contact Info

Product

Resources

About