Absolute positions of 6.7-GHz methanol masers

Xu, Ye; Voronkov, Maxim; Pandian, J. D.; Li, J. J.; Соболев, А. М.; Brunthaler, A.; Ritter, B.; Menten, K. M.

doi:10.1051/0004-6361/200912135

Cited by 54 publications

(68 citation statements)

References 67 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The most massive one named MCS B coincides with the MM1 clump (M ≈ 50 M ) detected at 1.2-mm by Minier et al (2005). The massive YSO NIRS 1 (V C 18 O lsr = +3.9 km s −1 , Saito et al 2007;Tamura et al 1991) is associated with MCS B and is also the 6.7-GHz CH 3 OH maser site (Minier et al 2000;Xu et al 2009). The CH 3 OH masers show a linear distribution of 120 mas with a roughly linear velocity gradient along it, although a few masers following a different velocity distribution (Minier et al 2000).…”

Section: Iras 06058+2138-nirsmentioning

confidence: 88%

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

Surcis

Vlemmings

Langevelde

et al. 2013

A&A

View full text Add to dashboard Cite

Context. Magnetic fields have only recently been included in theoretical simulations of high-mass star formation. The simulations show that magnetic fields play an important role in the formation and dynamics of molecular outflows. Masers, in particular 6.7-GHz CH 3 OH masers, are the best probes of the magnetic field morphologies around massive young stellar objects on the smallest scales of 10-100 AU. Aims. Providing new observational measurements of the morphology of magnetic fields around massive young stellar objects by using 6.7-GHz CH 3 OH maser emission is very important for setting constraints on the numerical simulations of massive star formation. Methods. This paper focuses on 4 massive young stellar objects, IRAS 06058+2138-NIRS 1, IRAS 22272+6358A, S255-IR, and S231, which complement our previous 2012 sample (the first EVN group). From all these sources, molecular outflows have been detected in the past. Seven of the European VLBI Network antennas were used to measure the linear polarization and Zeeman-splitting of the 6.7-GHz CH 3 OH masers in the star-forming regions in this second EVN group. Results. We detected a total of 128 CH 3 OH masing cloudlets. Fractional linear polarization (0.8%-11.3%) was detected towards 18% of the CH 3 OH masers in our sample. The linear polarization vectors are well ordered in all the massive young stellar objects. We measured significant Zeeman-splitting in IRAS 06058+2138-NIRS 1 (ΔV Z = 3.8 ± 0.6 m s −1 ) and S255-IR (ΔV Z = 3.2 ± 0.7 m s −1 ). Conclusions. By considering the 20 massive young stellar objects towards which the morphology of magnetic fields was determined by observing 6.7-GHz CH 3 OH masers in both hemispheres, we find no evident correlation between the linear distributions of CH 3 OH masers and the outflows or the linear polarization vectors. On the other hand, we present first statistical evidence that the magnetic field (on scales 10-100 AU) is primarily oriented along the large-scale outflow direction. Moreover, we empirically find that the linear polarization fraction of unsaturated CH 3 OH masers is P l < 4.5%.

show abstract

Section: Iras 06058+2138-nirsmentioning

confidence: 88%

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

Surcis

Vlemmings

Langevelde

et al. 2013

A&A

View full text Add to dashboard Cite

show abstract

“…A third methanol maser is observed in the direction of W43-MM4 (situated at the waist of the bipolar nebula) for which we measured a peak signal of 4.4 Jy/beam (N(H 2 ) = 2.3 × 10 23 cm −2 ). A fourth maser is given by Xu et al (2009) toward the PDR, but in a direction of very low 870 μm emission (see Table A.2).…”

Section: N52mentioning

confidence: 98%

“…the W3(OH) source, Menten et al 1992). Other methanol masers originate in the direction of (sub)-millimeter condensations containing luminous very red mid-or far-IR sources (Spitzer-GLIMPSE sources: Ellingsen 2006; 24 μm sources: Xu et al 2009;, and references therein). Breen et al (2010) present an evolutionary sequence for masers in high-mass star formation regions: 6.7 GHz masers have a lifetime in the range 2.5 × 10 4 yr to 4.5 × 10 4 yr; they are coeval with H 2 O masers, and appear before the formation of a detectable UC H ii region.…”

Section: Other Signposts Of Massive-star Formationmentioning

confidence: 99%

See 1 more Smart Citation

A gallery of bubbles

Deharveng

Schüller

Anderson

et al. 2010

A&A

Self Cite

364

584

View full text Add to dashboard Cite

Context. This study deals with infrared bubbles, the H ii regions they enclose, and triggered massive-star formation on their borders.Aims. We attempt to determine the nature of the bubbles observed by Spitzer in the Galactic plane, mainly to establish if possible their association with massive stars. We take advantage of the very simple morphology of these objects to search for star formation triggered by H ii regions, and to estimate the importance of this mode of star formation.Methods. We consider a sample of 102 bubbles detected by Spitzer-GLIMPSE, and catalogued by Churchwell et al. (2006; hereafter CH06). We use mid-infrared and radio-continuum public data (respectively the Spitzer-GLIMPSE and -MIPSGAL surveys and the MAGPIS and VGPS surveys) to discuss their nature. We use the ATLASGAL survey at 870 μm to search for dense neutral material collected on their borders. The 870 μm data traces the distribution of cold dust, thus of the dense neutral material where stars may form. Results. We find that 86% of the bubbles contain ionized gas detected by means of its radio-continuum emission at 20-cm. Thus, most of the bubbles observed at 8.0 μm enclose H ii regions ionized by O-B2 stars. This finding differs from the earlier CH06 results (∼25% of the bubbles enclosing H ii regions). Ninety-eight percent of the bubbles exhibit 24 μm emission in their central regions. The ionized regions at the center of the 8.0 μm bubbles seem to be devoid of PAHs but contain hot dust. PAH emission at 8.0 μm is observed in the direction of the photodissociation regions surrounding the ionized gas. Among the 65 regions for which the angular resolution of the observations is high enough to resolve the spatial distribution of cold dust at 870 μm, we find that 40% are surrounded by cold dust, and that another 28% contain interacting condensations. The former are good candidates for the collect and collapse process, as they display an accumulation of dense material at their borders. The latter are good candidates for the compression of pre-existing condensations by the ionized gas. Thirteen bubbles exhibit associated ultracompact H ii regions in the direction of dust condensations adjacent to their ionization fronts. Another five show methanol masers in similar condensations. Conclusions. Our results suggest that more than a quarter of the bubbles may have triggered the formation of massive objects.Therefore, star formation triggered by H ii regions may be an important process, especially for massive-star formation.

show abstract

“…Long-term and frequent flux monitoring was conducted toward source samples only less than 20%, which was estimated from ∼200 sources (e.g., Goedhart et al 2004;Szymczak et al 2015;Maswanganye et al 2016) in more than 1000 methanol masers samples (e.g., Pestalozzi et al 2005;Xu et al 2009;Caswell et al 2010Caswell et al , 2011Green et al 2010Green et al , 2012bOlmi et al 2014;Sun et al 2014;Breen et al 2015, and references therein). Furthermore, most of the monitored sources have been selected simply by their peak flux densities > 5 Jy in Szymczak, Wolak, and Bartkiewicz (2015).…”

Section: Introductionmentioning

confidence: 99%

The shortest periodic and flaring flux variability of a methanol maser emission at 6.7 GHz in G 014.23−00.50

Sugiyama

Nagase

Yonekura

et al. 2017

Publications of the Astronomical Society of Japan

View full text Add to dashboard Cite

We detected flaring flux variability that regularly occurred with the period of 23.9 days on a 6.7 GHz methanol maser emission at V lsr = 25.30 km s −1 in G 014.23−00.50 through highly frequent monitoring using the Hitachi 32-m radio telescope. By analyzing data from 05 January 2013 to 21 January 2016, the periodic variability has persisted in at least 47 cycles, corresponding to ∼1,100 days. The period of 23.9 days is the shortest one observed in masers at around high-mass young stellar objects so far. The flaring component normally falls below the detection limit (3σ) of ∼0.9 Jy. In the flaring periods, the component rises above the detection limit with the ratio of the peak flux density more than 180 in comparison with a quiescent phase, showing intermittent periodic variability. The time-scale of the flux rise was typically two days or shorter, and both symmetric and asymmetric profiles of flux variability were observed through intraday monitoring. These characteristics might be explained by a change in the flux of seed photons by a colliding-wind binary (CWB) system or a variation of the dust temperature by an extra heating source of a shock formed by the CWB system within a gap region in a circumbinary disk, in which the orbital semi-major axes of the binary are 0.26-0.34 au.

show abstract

Absolute positions of 6.7-GHz methanol masers

Cited by 54 publications

References 67 publications

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

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

A gallery of bubbles

The shortest periodic and flaring flux variability of a methanol maser emission at 6.7 GHz in G 014.23−00.50

Contact Info

Product

Resources

About