scholarly journals Interferometric and single-dish observations of 44, 84 and 95 GHz Class I methanol masers

2017 ◽  
Vol 13 (S336) ◽  
pp. 239-242
Author(s):  
Carolina B. Rodríguez-Garza ◽  
Stanley E. Kurtz ◽  
Arturo I. Gómez-Ruiz ◽  
Peter Hofner ◽  
Esteban D. Araya ◽  
...  
Keyword(s):  
Massive Star ◽  
Wide Band ◽  
Hii Regions ◽  
Spectral Lines ◽  
Class I ◽  
Detection Rates ◽  
Very Large Array ◽  
Star Forming ◽  
Star Forming Regions ◽  
Methanol Masers

AbstractWe present observations of massive star-forming regions selected from the IRAS Point Source Catalog. The observations were made with the Very Large Array and the Large Millimeter Telescope to search for Class I methanol masers. We made interferometric observations of 125 massive star-forming regions in the 44 GHz methanol maser transition; 53 of the 125 fields showed emission. The data allow us to demonstrate associations, at arcsecond precision, of the Class I maser emission with outflows, HII regions and shocks traced by 4.5 μm emission. We made single-dish observations toward 38 of the 53 regions with 44 GHz masers detected to search for the methanol transitions at 84.5, 95.1, 96.7, 107.0, and 108.8 GHz. We find detection rates of 74, 55, 100, 3, and 45%, respectively. We used a wide-band receiver which revealed many other spectral lines that are common in star-forming regions.

Exploring the Nature of MMB sources: A Search for Class I Methanol Masers and their Outflows

2017 ◽  
Vol 13 (S336) ◽  
pp. 317-318
Author(s):  
Nichol Cunningham ◽  
Gary Fuller ◽  
Adam Avison ◽  
Shari Breen
Keyword(s):  
Massive Star ◽  
Class Ii ◽  
Class I ◽  
Star Forming ◽  
Methanol Maser ◽  
Star Forming Regions ◽  
Methanol Masers ◽  
Initial Results ◽  
Maser Sources

AbstractWe present the initial results from a class I 44-GHz methanol maser follow-up survey, observed with the MOPRA telescope, towards 272 sources from the Methanol Multi-beam survey (MMB). Over half (∼60%) of the 6.7 GHz class II MMB maser sources are associated with a class I 44-GHz methanol maser at a greater than 5σ detection level. We find that class II MMB masers sources with an associated class I methanol maser have stronger peak fluxes compared to regions without an associated class I maser. Furthermore, as part of the MOPRA follow-up observations we simultaneously observed SiO emission which is a known tracer of shocks and outflows in massive star forming regions. The presence of SiO emission, and potentially outflows, is found to be strongly associated with the detection of class I maser emission in these regions.

scholarly journals LINEAR POLARIZATION OF CLASS I METHANOL MASERS IN MASSIVE STAR-FORMING REGIONS

2016 ◽  
Vol 227 (2) ◽  
pp. 17 ◽  
Author(s):  
Ji-hyun Kang ◽  
Do-Young Byun ◽  
Kee-Tae Kim ◽  
Jongsoo Kim ◽  
A-Ran Lyo ◽  
...  
Keyword(s):  
Linear Polarization ◽  
Massive Star ◽  
Class I ◽  
Star Forming ◽  
Star Forming Regions ◽  
Methanol Masers

scholarly journals Millimetre wavelength methanol masers survey towards massive star forming regions

2007 ◽  
Vol 3 (S242) ◽  
pp. 234-235
Author(s):  
T. Umemoto ◽  
N. Mochizuki ◽  
K. M. Shibata ◽  
D.-G. Roh ◽  
H.-S. Chung
Keyword(s):  
Detection Rate ◽  
Massive Star ◽  
Molecular Line ◽  
Maser Emission ◽  
Star Forming ◽  
Methanol Maser ◽  
Physical Conditions ◽  
Star Forming Regions ◽  
Methanol Masers ◽  
Maser Sources

AbstractWe present the results of a mm wavelength methanol maser survey towards massive star forming regions. We have carried out Class II methanol maser observations at 86.6 GHz, 86.9 GHz and 107.0 GHz, simultaneously, using the Nobeyama 45 m telescope. We selected 108 6.7 GHz methanol maser sources with declinations above −25 degrees and fluxes above 20 Jy. The detection limit of maser observations was ~3 Jy. Of the 93 sources surveyed so far, we detected methanol emission in 25 sources (27%) and “maser” emission in nine sources (10%), of which thre “maser” sources are new detections. The detection rate for maser emission is about half that of a survey of the southern sky (Caswell et al. 2000). There is a correlation between the maser flux of 107 GHz and 6.7 GHz/12 GHz emission, but no correlation with the “thermal” (non maser) emission. From results of other molecular line observations, we found that the sources with methanol emission show higher gas temperatures and twice the detection rate of SiO emission. This may suggest that dust evaporation and destruction by shock are responsible for the high abundance of methanol molecules, one of the required physical conditions for maser emission.

scholarly journals Class I and Class II methanol masers in high-mass star-forming regions

2010 ◽  
Vol 517 ◽  
pp. A56 ◽  
Author(s):  
F. Fontani ◽  
R. Cesaroni ◽  
R. S. Furuya
Keyword(s):  
Class Ii ◽  
Class I ◽  
High Mass ◽  
Mass Star ◽  
Star Forming ◽  
Star Forming Regions ◽  
Methanol Masers

Zeeman Effect Observations in Class I Methanol Masers

2018 ◽  
Vol 14 (A30) ◽  
pp. 140-140
Author(s):  
Emmanuel Momjian ◽  
Anuj P. Sarma
Keyword(s):  
Zeeman Effect ◽  
Linear Structure ◽  
Class I ◽  
Star Forming ◽  
Methanol Maser ◽  
Star Forming Regions ◽  
Splitting Factor ◽  
Maser Line ◽  
Methanol Masers ◽  
Expected Values

AbstractWe report the detection of the Zeeman effect in the 44 GHz Class I methanol maser line toward the star forming region DR21W. The 44 GHz methanol masers in this source occur in a ∼3” linear structure that runs from northwest to southeast, with the two dominant components at each end, and several weaker maser components in between. Toward a 93 Jy maser in the dominant northwestern component, we find a significant Zeeman detection of −23.4 ± 3.2 Hz. If we use the recently published result of Lankhaar et al. (2018) that the F=5-4 hyperfine transition is responsible for the 44 GHz methanol maser line, then their value of z = −0.92 Hz mG−1 yields a line-of-sight magnetic field of Blos =25.4 ± 3.5 mG. If Class I methanol masers are pumped in high density regions with n∼107–8 cm−3, then magnetic fields in these maser regions should be a few to several tens of mG. Therefore, our result in DR21W is certainly consistent with the expected values.Using the above noted splitting factor in past Zeeman effect detections in Class I methanol masers reported by Sarma & Momjian (2011) and Momjian & Sarma (2017) in the star forming regions OMC-2 and DR21(OH) result in Blos values of 20.0 ± 1.2 mG and 58.2 ± 2.9 mG, respectively. These are also consistent with the expected values.

scholarly journals Similarity and randomness in the molecular clouds associated with Spitzer GLIMPSE Extended Green Objects (EGOs)

2012 ◽  
Vol 8 (S292) ◽  
pp. 103-103
Author(s):  
J. H. He ◽  
S. Takahashi ◽  
X. Chen
Keyword(s):  
Massive Star ◽  
Dense Gas ◽  
Clear Trend ◽  
Detection Rates ◽  
Star Forming ◽  
Star Forming Regions ◽  
Data Scatter ◽  
Line Survey ◽  
Linear Correlations ◽  
Size Scales

AbstractEGOs are candidates of massive star forming regions that show signatures of outflows. A 1.1mm line survey has been performed to 89 EGOs using the AROSMT. Our high detection rates of H13CO+ 3-2 and SiO 6-5 lines support EGOs to be dense clouds harboring outflows.Ubiquitous line luminosity linear correlations are found among different kinds of tracer lines: dense gas tracer H13CO+ 3-2, outflow tracer SiO 6-5, mixed dense gas and outflow tracers SO3Σ 65 − 54 and CH3OH lines, and relatively lower density gas tracers 12CO, 13CO, C18O 1-0 (see an example in Fig. 1). This can be explained if a universal similarity of density and thermal structures and probably of shock properties among all these EGO clouds are assumed. Furthermore, the outflow shocks are also required to be produced mainly inside of the natal clouds of the YSOs.The data scatter of the luminosity (and line width) correlations show a clear trend of worsening across larger cloud substructure size scales or toward larger cloud sizes, which demonstrates the growth of randomness in cloud structures and velocity fields. See more details in our paper (He et al. 2012).

scholarly journals The variability of cosmic methanol masers in massive star-forming regions

2012 ◽  
Vol 8 (S287) ◽  
pp. 108-109
Author(s):  
Jabulani P. Maswanganye ◽  
Michael J. Gaylard
Keyword(s):  
Massive Star ◽  
Flare Event ◽  
Star Forming ◽  
Star Forming Regions ◽  
Methanol Masers ◽  
Large Flare

AbstractThe methanol masers associated with G35.20-1.74 were monitored at 12178 MHz for four years and 6668 MHz for five years using the 26m Hartebeesthoek telescope. This source showed irregular variability and a single large flare event during the monitoring window.

scholarly journals Class I methanol masers in low-mass star formation regions

2017 ◽  
Vol 13 (S336) ◽  
pp. 33-36
Author(s):  
S. Kalenskii ◽  
S. Kurtz ◽  
P. Hofner ◽  
P. Bergman ◽  
C.M. Walmsley ◽  
...  
Keyword(s):  
Star Formation ◽  
Class I ◽  
Mass Star ◽  
Star Forming ◽  
Star Forming Regions ◽  
Brightness Temperatures ◽  
Push Forward ◽  
Low Mass ◽  
Methanol Masers ◽  
Star Formation Regions

AbstractWe present a review of the properties of Class I methanol masers detected in low-mass star forming regions (LMSFRs). These masers, henceforth called LMMIs, are associated with postshock gas in the lobes of chemically active outflows in LMSFRs NGC1333, NGC2023, HH25, and L1157. LMMIs share the main properties with powerful masers in regions of massive star formation and are a low-luminosity edge of the total Class I maser population. However, the exploration of just these objects may push forward the exploration of Class I masers, since many LMSFRs are located only 200–300 pc from the Sun, making it possible to study associated objects in detail. EVLA observations with a 0.2″ spatial resolution show that the maser images consist of unresolved or barely resolved spots with brightness temperatures up to 5 × 105 K. The results are “marginally” consistent with the turbulent model of maser emission.

scholarly journals 44 GHz Methanol Maser Surveys

2012 ◽  
Vol 8 (S287) ◽  
pp. 133-140
Author(s):  
S. E. Kurtz
Keyword(s):  
Star Formation ◽  
Formation Process ◽  
Class Ii ◽  
Class I ◽  
High Mass ◽  
Mass Star ◽  
Star Forming ◽  
Methanol Maser ◽  
Star Forming Regions ◽  
Methanol Masers

AbstractClass I 44 GHz methanol masers are not as well-known, as common, or as bright as their more famous Class II cousins at 6.7 and 12.2 GHz. Nevertheless, the 44 GHz masers are commonly found in high-mass star forming regions. At times they appear to trace dynamically important phenomena; at other times they show no obvious link to the star formation process. Here, we summarize the major observational efforts to date, including both dedicated surveys and collateral observations. The principal results are presented, some that were expected, and others that were unexpected.

scholarly journals Japanese VLBI network observations of 6.7-GHz methanol masers I. Array

2007 ◽  
Vol 3 (S242) ◽  
pp. 148-149
Author(s):  
Akihiro Doi ◽  
Kenta Fujisawa ◽  
Mareki Honma ◽  
Koichiro Sugiyama ◽  
Yasuhiro Murata ◽  
...  
Keyword(s):  
Massive Star ◽  
Star Forming ◽  
Methanol Maser ◽  
Star Forming Regions ◽  
Methanol Masers ◽  
Japanese Islands

AbstractThe Japanese VLBI network (JVN) has begun observations of 6.7-GHz methanol masers associated with massive star-forming regions. The JVN is a newly-established VLBI array with baselines ranging from 50 to 2560 km spread across the Japanese islands. Three observing bands of 6.7, 8.4, and 22 GHz are now available. The array consists of ten antennas: VERA Mizusawa 20 m, VERA Ishigaki 20 m, VERA Iriki 20 m, Usuda 64 m, Yamaguchi 32 m, Tomakomai 11 m, Tsukuba 32 m, Kashima 34 m, VERA Ogasawara 20 m, and Gifu 11 m, the first five of which have 6.7-GHz receiving systems. In summer 2005, we obtained the first fringes at 6.7 GHz, and VLBI images of 12 methanol maser sites including seven that had not previously been imaged with VLBI at this band. In 2006 summer, we obtained phase-reference observations toward several methanol maser sites.

Sign in / Sign up

Export Citation Format

Share Document