Star formation in massive protoclusters in the Monoceros OB1 dark cloud

Wolf-Chase, G.; Moriarty‐Schieven, G. H.; Fich, M.; Barsony, M.

doi:10.1046/j.1365-8711.2003.06863.x

Cited by 40 publications

(76 citation statements)

References 48 publications

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“…The gray scale image shows the 850 μm dust emission in the vicinity of AR 6, mapped using the SCUBA bolometer array (Holland et al 1999) in UT 1999 August and November, and 2000 October. These data were first published by Wolf-Chase et al (2003). Data reduction and analysis are described in that paper.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

“…Wolf-Chase et al (2003), using data from 12 μm through 850 μm, derived a dust temperature of 23 K for source S1 (Figure 3), which Teixeira et al (2007) identified as a dense cluster of Class 0 protostars. Ward-Thompson et al (2000) used 1300 through 350 μm data to derive dust temperatures of ∼15 K for nearby sub-mm sources.…”

Section: The Local Environment Around Armentioning

confidence: 99%

“…We therefore used the James Clerk Maxwell Telescope (JCMT) to map the region surrounding AR 6 in 12 CO J = 3-2 emission, to look for outflow activity, and in HCN J = 3-2 emission, to search for dense gas from a circumstellar core/envelope. In addition, we utilize a JCMT archival Submillimeter Common-User Bolometric Array (SCUBA) 850 μm map of the region, first published by Wolf-Chase et al (2003) to trace dust emission structure near AR 6.…”

Section: Introductionmentioning

confidence: 99%

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The Local Environment of the Fu-Orionis-Like Objects Ar 6a and 6b

Moriarty‐Schieven

Aspin

Davis

2008

The Astronomical Journal

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We present new 12 CO J = 3-2 and HCN J = 3-2 molecular line maps of the region surrounding the young star AR 6 using the 15 m James Clerk Maxwell Telescope (JCMT). AR 6 was previously found to be a double source with both components exhibiting several characteristics of FU Orionis (FUor) eruptive variable stars. The aims of this investigation were to determine if the AR 6 sources are associated with molecular outflows and if a significant reservoir of natal molecular gas and dust exists around the stars. These observations form a part of a large-scale study of the outflow and circumstellar environment characteristics of FUors and FUor-like objects to place constrains on the age and evolutionary state of sources exhibiting FUor-like tendencies. Our data indicate that AR 6, like FUor itself, does not possess a CO outflow and likewise, does not show evidence for large amounts of molecular gas in its circumstellar environment. In fact, AR 6 seems to lie in a local minimum of HCN emission. This is also found in 850 μm dust emission seen in JCMT archival data. We conclude that from the near-infrared to the sub-millimeter, AR 6 is similar to FUor in several respects. We interpret the lack of significant dust and molecular gas in the circumstellar environment of AR 6, together with the large near-infrared (NIR) thermal excess, as evidence that the sources have exhausted their natal envelopes, that they have at least small hot circumstellar disks, and that they are more evolved than Class I protostars. This, in itself, suggests that, since FUor eruptions have also been observed in stars with large dust mass envelopes (e.g., V346 Nor) and with CO outflows (e.g., L1551 IRS5), FUor events probably occur at many different stages in the early, formative phase of a star's life, and lends support to the idea that FUor outbursts are repetitive like their shorter-lived relatives occurring in EXor eruptive variables. Finally, we study the stellar environment around AR 6 using Two Micron All Sky Survey, Spitzer Infrared Array Camera, and Chandra ACIS images and show that, being part of the "Spokes" young stellar cluster, AR 6 is unlike many FUors which are typically located in more sparsely populated regions.

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Section: Observations and Data Reductionmentioning

confidence: 99%

Section: The Local Environment Around Armentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Local Environment of the Fu-Orionis-Like Objects Ar 6a and 6b

Moriarty‐Schieven

Aspin

Davis

2008

The Astronomical Journal

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“…There are numerous works investigating star formation using a wide variety of probes that encompass the examination of a single or multiple protostar(s), the embedded cluster, the gas and dust distribution, the dynamics in various stages of evolution, as well as the probable star formation history. However, studies probing clusters of protostars are relatively few, for example Cyganowski et al (2007), Wang et al (2012), Wolf-Chase et al (2003). These mostly investigate the massive and rarer end of the initial mass function as other intermediate to low mass cluster members are usually difficult to isolate.…”

Section: Introductionmentioning

confidence: 99%

Dust and gas environment of the young embedded cluster IRAS 18511+0146

Vig

Testi

Walmsley

et al. 2017

A&A

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Context. Since massive and intermediate mass stars form in clusters, a comparative investigation of the environments of the young embedded cluster members can reveal significant information about the conditions under which stars form and evolve. Aims. IRAS 18511+0146 is a young embedded (proto)cluster located at 3.5 kpc surrounding what appears to be an intermediate mass protostar. In this paper, we investigate the nature of cluster members (two of which are believed to be the most massive and luminous) using imaging and spectroscopy in the near and mid-infrared. In particular, we examine the three brightest mid-infrared objects and two among these are believed to be most massive ones driving the luminosity of this region. Methods. Near-infrared spectroscopy of nine objects (bright in K bands) towards IRAS 18511+0146 has been carried out. Several cluster members have also been investigated in the mid-infrared using spectroscopic and imaging with VISIR on the VLT. Far-infrared images from the Herschel Hi-GAL survey have been used to construct the column density and temperature maps of the region. Results. The brightest point-like object associated with IRAS 18511+0146 is referred to as S7 in the present work (designated UGPS J185337.88+015030.5 in the UKIRT Galactic Plane survey). S7 is likely the most luminous object in the cluster as it is bright at all wavelengths ranging from the near-infrared to millimetre. Seven of the nine objects show rising spectral energy distributions (SED) in the near-infrared, with four objects showing Br-γ emission. Three members: S7, S10 (also UGPS J185338.37+015015.3) and S11 (also UGPS J185338.72+015013.5) are bright in mid-infrared with diffuse emission being detected in the vicinity of S11 in PAH bands. Silicate absorption is detected towards these three objects, with an absorption maximum between 9.6 and 9.7 µm, large optical depths (1.8 − 3.2), and profile widths of 1.6 − 2.1 µm. The silicate profiles of S7 and S10 are similar, in contrast to S11 (which has the largest width and optical depth). The cold dust emission peaks at S7, with temperature at 26 K and column density N(H 2 )∼ 7 × 10 22 cm −2 . The bolometric luminosity of IRAS 18511 region is L∼ 1.8 × 10 4 L ⊙ . S7 is the main contributor to the bolometric luminosity, with L (S7) 10 4 L ⊙ . Conclusions. S7 is a high mass protostellar object with ionised stellar winds, evident from the correlation between radio and bolometric luminosity as well as the asymmetric Br-γ profile. The differences in silicate profiles of S7 and S11 could be due to different radiation environment as we believe the former to be more massive and in an earlier phase than the latter.

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“…It is believed that the grains get aligned by an ambient magnetic field by a mechanism originally suggested by Davis & Greenstein (1951) and subsequently modified by many authors. Recently, many photometric, polarimetric, spectrometric, and radiometric studies have been reported on star-forming clouds by various authors (Huard et al 2000;Larson et al 2000;Sen et al 2000;Wiebe & Watson 2001;Khanzadyan et al 2002;Launhardt & Sargent 2001;Matthews & Wilson 2002;Wolf-Chase et al 2003;Draine 2003;Ghosh et al 2005;Sen et al 2005;Kandori et al 2005;Massi et al 2004Massi et al , 2005Kirk et al 2006;Gouliermis et al 2006;Maheswar & Bhatt 2006;Naoi et al 2006;Vaidya et al 2007; Ward- Thompson et al 2000;Whittet 2007). It is generally expected that the increasing extinction along a line of sight corresponds to increasing polarization.…”

Section: Introductionmentioning

confidence: 99%

Photopolarimetric study of the star-forming clouds CB3, CB25, and CB39

Sen

Polcaro

Dey³

et al. 2010

A&A

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Context. The small compact isolated dark clouds also known as "Bok globules" are believed to be ideal sites for low-mass star formation. Some of these clouds are undergoing gravitational collapse, and the ambient magnetic field plays a key role in collapse dynamics. The background star polarimetry is generally accepted as a good tool to map the magnetic field, which is responsible for the alignment of dichroic grains that produce polarization. Aims. The background star polarization when studied together with extinction is expected to help us to understand various grain properties and the role of polarimetry as a tracer of magnetic field in these star-forming clouds. With this idea, polarization and colour excess E(B − V) values for a set of background stars have been studied together to understand various astrophysical process in some star-forming dark clouds. Methods. Optical photometric observations of the three clouds CB3, CB25, and CB39 were carried out at the 2 m H.C. Telescope, India, to determine the colour excess E(B − V) of the background stars by following a technique adopted by Bernabei & Polacaro (2001, A&A, 371, 123). These three clouds were selected from a set of eight clouds previously observed by us in optical polarimetry (Sen et al. 2000, A&AS, 141, 175). Further independent spectroscopic measurements of a few selected sample stars were recently carried out during February and March 2010 from 1.52 m Cassini Telescope, Loinao, Italy, to confirm the correctness of estimated E(B − V) values obtained by this photometric technique. Results. The colour excess E(B − V) values so obtained were compared with optical polarization values obtained for the same set of stars. It was found that the measured extinction values increase with the increase in percentage polarization for the cloud CB39 and to some extent for CB25. However, for cloud CB31 no such correlation was observed. It is normally expected that the grains causing extinction should also cause polarization of the light from background stars. Any possible deviation from this under different circumstances here has been discussed in the light of the ongoing physical processes in the star-forming clouds.

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Star formation in massive protoclusters in the Monoceros OB1 dark cloud

Cited by 40 publications

References 48 publications

The Local Environment of the Fu-Orionis-Like Objects Ar 6a and 6b

The Local Environment of the Fu-Orionis-Like Objects Ar 6a and 6b

Dust and gas environment of the young embedded cluster IRAS 18511+0146

Photopolarimetric study of the star-forming clouds CB3, CB25, and CB39

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