New class I methanol masers

Voronkov, M. A.; Caswell, J. L.; Ellingsen, S. P.; Breen, S. L.; Britton, Tui; Green, James; Sobolev, A. M.; Walsh, A. J.

doi:10.1017/s174392131200748x

Cited by 13 publications

(8 citation statements)

References 32 publications

(56 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Strong, point-like emission also appears at several other positions in these lines, but primarily in the 229 GHz line (Figure 8). We note that the 229 GHz line is part of the 36 GHz maser series, while the 218 GHz line is part of the 25 GHz maser series (Voronkov et al 2012). All positions with peak intensity greater than 0.55 Jy beam −1 (∼55 K) are listed in Table 8; this threshold was chosen because it excludes all of the emission seen toward the hot cores.…”

Section: Maser Action In Two 13 MM Ch 3 Oh Linesmentioning

confidence: 70%

Subarcsecond Imaging of the NGC 6334 I(n) Protocluster: Two Dozen Compact Sources and a Massive Disk Candidate

Hunter

Brogan

Cyganowski

et al. 2014

ApJ

View full text Add to dashboard Cite

Using the Submillimeter Array (SMA) and Karl G. Jansky Very Large Array, we have imaged the massive protocluster NGC 6334 I(N) at high angular resolution (0. 5 ∼ 650 AU) from 6 cm to 0.87 mm, detecting 18 new compact continuum sources. Three of the new sources are coincident with previously identified H 2 O masers. Together with the previously known sources, these data bring the number of likely protocluster members to 25 for a protostellar density of ∼700 pc −3 . Our preliminary measurement of the Q-parameter of the minimum spanning tree is 0.82-close to the value for a uniform volume distribution. All of the (nine) sources with detections at multiple frequencies have spectral energy distributions consistent with dust emission, and two (SMA 1b and SMA 4) also have long wavelength emission consistent with a central hypercompact H ii region. Thermal spectral line emission, including CH 3 CN, is detected in six sources: LTE model fitting of CH 3 CN (J = 12-11) yields temperatures of 72-373 K, confirming the presence of multiple hot cores. The fitted LSR velocities range from −3.3 to −7.0 km s −1 , with an unbiased mean square deviation of 2.05 km s −1 , implying a protocluster dynamical mass of 410 ± 260 M . From analysis of a wide range of hot core molecules, the kinematics of SMA 1b are consistent with a rotating, infalling Keplerian disk of diameter 800 AU and enclosed mass of 10-30 M that is perpendicular (within 1• ) to the large-scale bipolar outflow axis. A companion to SMA 1b at a projected separation of 0. 45 (590 AU; SMA 1d), which shows no evidence of spectral line emission, is also confirmed. Finally, we detect one 218.4400 GHz and several 229.7588 GHz Class-I CH 3 OH masers.

show abstract

Section: Maser Action In Two 13 MM Ch 3 Oh Linesmentioning

confidence: 70%

Subarcsecond Imaging of the NGC 6334 I(n) Protocluster: Two Dozen Compact Sources and a Massive Disk Candidate

Hunter

Brogan

Cyganowski

et al. 2014

ApJ

View full text Add to dashboard Cite

show abstract

“…In addition to the H2CO line shown in Figure 3a, our ALMA spectral coverage includes four other low-excitation lines of H2CO (two with Eupper=82 K and two with Eupper=141 K) and one of CH3OH (Eupper=64 K); these relatively low-excitation lines of outflow-tracing molecules all exhibit similar morphologies. The 9−1 − 80 CH3OH line shown in Figure 3b is expected to be a Class I maser (in the 36 GHz series; Voronkov et al 2012). With ALMA, Yanagida et al (2014) observe negative excitation temperatures (implying population inversion) towards bright CH3OH 9−1 − 80 emission peaks in G34.43+0.24 MM3.…”

Section: Line Emissionmentioning

confidence: 93%

“…presents peak maps of the ALMA H2CO 40,4−30,3 (νrest=290.62341 GHz, Eupper=35 K), CH3OH 9−1 − 80 (νrest=278.30451 GHz, Eupper=110 K), N2H + (3-2) (νrest=279.51175 GHz, Eupper=27 K), and DCN (4-3) ALMA peak maps of (a) H 2 CO 4 0,4 −3 0,3 , (b) CH 3 OH 9 −1 −8 0 (Class I maser line;Voronkov et al 2012;Yanagida et al 2014), (c) N 2 H + (3-2), and (d) DCN (4-3) in colourscale, overlaid with contours of ALMA 1.05 mm continuum emission (levels: [5,15,100]×0.35 mJy beam −1 ; note that with these levels MM19 is not contoured, see Section 2.1 and Tables 1 and 2). In each panel, the ALMA synthesised beam is shown at lower right, and the edge of the colourscale image corresponds to the 30% power point of the ALMA mosaic.…”

mentioning

confidence: 99%

Simultaneous low- and high-mass star formation in a massive protocluster: ALMA observations of G11.92−0.61★

Cyganowski

Brogan

Hunter

et al. 2017

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We present 1.05 mm ALMA observations of the deeply embedded high-mass protocluster G11.92−0.61, designed to search for low-mass cores within the accretion reservoir of the massive protostars. Our ALMA mosaic, which covers an extent of ∼0.7 pc at sub-arcsecond (∼1400 au) resolution, reveals a rich population of 16 new millimetre continuum sources surrounding the three previously-known millimetre cores. Most of the new sources are located in the outer reaches of the accretion reservoir: the median projected separation from the central, massive (proto)star MM1 is ∼0.17 pc. The derived physical properties of the new millimetre continuum sources are consistent with those of low-mass prestellar and protostellar cores in nearby star-forming regions: the median mass, radius, and density of the new sources are 1.3 M ⊙ , 1600 au, and n H2 ∼10 7 cm −3 . At least three of the low-mass cores in G11.92−0.61 drive molecular outflows, traced by high-velocity 12 CO(3-2) (observed with the SMA) and/or by H 2 CO and CH 3 OH emission (observed with ALMA). This finding, combined with the known outflow/accretion activity of MM1, indicates that high-and low-mass stars are forming (accreting) simultaneously within this protocluster. Our ALMA results are consistent with the predictions of competitive-accretion-type models in which high-mass stars form along with their surrounding clusters.

show abstract

“…Methanol masers can be divided into two classes (class I and II) according to the empirical classification on the basis of their different exciting locations (Batrla et al 1987;Menten 1991). Class I methanol masers are found usually offset (∼ 1 ′ , nearly 1 pc at a distance of 4 Kpc) from the presumed origin of excitation, and can be further categorized to widespread class I methanol masers (e.g., 44 and 95 GHz) and rare or weak class I methanol masers (e.g., 9.9 and 104 GHz) (Voronkov et al 2012). The rare or weak masers trace stronger shock regions which have higher temperatures and densities with regard to widespread masers Voronkov et al 2012).…”

Section: Introductionmentioning

confidence: 99%

“…Class I methanol masers are found usually offset (∼ 1 ′ , nearly 1 pc at a distance of 4 Kpc) from the presumed origin of excitation, and can be further categorized to widespread class I methanol masers (e.g., 44 and 95 GHz) and rare or weak class I methanol masers (e.g., 9.9 and 104 GHz) (Voronkov et al 2012). The rare or weak masers trace stronger shock regions which have higher temperatures and densities with regard to widespread masers Voronkov et al 2012). In contrast, class II methanol masers are often found to reside close to (within 1 ′′ ) high-mass young stellar objects (YSOs) (e.g., Caswell et al 2010) and are frequently associated with UC Hii regions, infrared sources and OH masers.…”

Section: Introductionmentioning

confidence: 99%

A SEARCH FOR 95 GHz CLASS I METHANOL MASERS IN MOLECULAR OUTFLOWS

Gan

Chen

Shen

et al. 2012

ApJ

View full text Add to dashboard Cite

We have observed a sample of 288 molecular outflow sources including 123 high-mass and 165 low-mass sources to search for class I methanol masers at 95 GHz transition and to investigate relationship between outflow characteristics and class I methanol maser emission with the PMO-13.7m radio telescope. Our survey detected 62 sources with 95 GHz methanol masers above 3σ detection limit, which include 47 high-mass sources and 15 low-mass sources. Therefore the detection rate is 38% for high-mass outflow sources and 9% for low-mass outflow sources, suggesting that class I methanol maser is relatively easily excited in high-mass sources. There are 37 newly detected 95 GHz methanol masers (including 27 high-mass and 10 low-mass sources), 19 of which are newly identified (i.e. first identification) class I methanol masers (including 13 high-mass and 6 low-mass sources). Statistical analysis for the distributions of maser detections with the outflow parameters reveals that the maser detection efficiency increases with outflow properties (e.g. mass, momentum, kinetic energy and mechanical luminosity of outflows etc.). Systematic investigations of relationships between the intrinsic luminosity of methanol maser and the outflow properties (including mass, momentum, kinetic energy, bolometric luminosity and mass loss rate of central stellar sources) indicate a positive correlations. This further supports that class I methanol masers are collisionally pumped and associated with shocks, where outflows interact with the surrounding ambient medium.

show abstract

New class I methanol masers

Cited by 13 publications

References 32 publications

Subarcsecond Imaging of the NGC 6334 I(n) Protocluster: Two Dozen Compact Sources and a Massive Disk Candidate

Subarcsecond Imaging of the NGC 6334 I(n) Protocluster: Two Dozen Compact Sources and a Massive Disk Candidate

Simultaneous low- and high-mass star formation in a massive protocluster: ALMA observations of G11.92−0.61★

A SEARCH FOR 95 GHz CLASS I METHANOL MASERS IN MOLECULAR OUTFLOWS

Contact Info

Product

Resources

About