Far Outer Galaxy H II Regions

Rudolph, Alexander; Brand, J.; Geus, E. J. de; Wouterloot, J. G. A.

doi:10.1086/176847

Cited by 48 publications

(64 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This source also displays extended infrared nebulosity of comparable size as the H ii region. No radio source was found by Rudolph et al (1996) within 3 0 of IRAS 02395+6244, the most luminous IRAS point source in our survey, implying that either the source does not contain a star earlier than B1, or any H ii region that may be present is too diffuse or too compact to detect.…”

Section: Figmentioning

confidence: 73%

“…Several of the IRAS sources have far-infrared luminosities greater than 10 4 L and are likely associated with massive star-forming sites. Further evidence for the association with massive star formation is provided by the study of Rudolph et al (1996), who obtained multiwavelength radio continuum images of four of the IRAS sources in our survey using the Very Large Array. They identified H ii regions associated with three sources.…”

Section: Far-infrared Luminositymentioning

confidence: 75%

“…Detailed studies of the stellar content associated with far outer Galaxy clouds besides that provided by the IRAS data have been more limited. Fich & Blitz (1984), Brand & Blitz (1993), and Rudolph et al (1996) identified a number of H ii regions associated with far outer Galaxy clouds, verifying the presence of recent massive star formation. Near-infrared imaging (Kobayashi & Tokunaga 2000;Santos et al 2000) has provided further evidence for recent star formation in several far outer Galaxy clouds.…”

Section: Introductionmentioning

confidence: 87%

“…2.-Continued 2.-Continued zero-age main-sequence star needed to produce the radio continuum flux as given by Rudolph et al (1996) is indicated in the last column of Table 3. In all cases the total luminosity expected from these stars (Panagia 1973) can account for most of the observed far-infrared luminosity.…”

Section: Figmentioning

confidence: 99%

“…The stellar disk of our Galaxy exhibits a sharp decline at approximately the same Galactocentric radii (Robin, Crézé, & Mohan 1992;Ruphy et al 1996), attesting to the low rate of star formation in the outer reaches of the Galactic disk. However, star formation activity is not completely absent at these larger radii, as young, Population I stars and H ii regions (Chromey 1978;Moffat, Fitzgerald, & Jackson 1979;Chini & Wink 1984;Fich & Blitz 1984;Brand & Blitz 1993;Rudolph et al 1996) and star-forming molecular clouds (Blitz, Fich, & Stark 1982;Wouterloot & Brand 1989;Mead, Kutner, & Evans 1990) have been identified. While the level of star formation activity in the far outer Galaxy is negligible compared to that in the inner disk, studies of the far outer Galaxy may provide a different perspective on how molecular clouds are assembled and on the various pathways by which massive stars form.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Molecular Clouds and Infrared Stellar Clusters in the Far Outer Galaxy

Snell

Carpenter

Heyer

2002

ApJ

View full text Add to dashboard Cite

We present a study of the molecular cloud content and star formation activity in the far outer Galaxy at Galactocentric radii greater than 13.5 kpc. The properties of star-forming regions associated with far outer Galaxy clouds are examined within a 60 deg 2 area toward the second Galactic quadrant based on the FCRAO CO Survey of the Outer Galaxy, the IRAS Point Source Catalog, and follow-up 13 CO(J ¼ 1 0) and K 0 -band near-infrared imaging. This region contains 63 far outer Galaxy molecular clouds; the most massive clouds have molecular masses of $10 4 M . The K 0 -band imaging of 10 IRAS point sources associated with the far outer Galaxy clouds resulted in the detection of 11 stellar clusters with Galactocentric distances between 13.5 and 17.3 kpc. Several of these clusters are comparable to the well-studied clusters found within 1 kpc of the Sun in terms of the number of stars. We have also examined a much larger sample of far outer Galaxy molecular clouds using the entire FCRAO CO survey. The mass spectrum of 246 far outer Galaxy clouds found within a 300 deg 2 area has a power-law slope of À1.88, similar to, although slightly steeper than that found for molecular clouds inside the solar circle. Global measures of the star formation activity, as traced by the ratio of far-infrared luminosity to molecular cloud mass, indicate that these far outer Galaxy clouds are equally active sites of massive star formation as molecular clouds associated with the W3/W4/W5 region and clouds found in the inner Galaxy. Therefore, despite the different environment expected in the far outer Galaxy, the cloud mass spectrum and star formation activity per unit mass are similar to that found throughout the Galaxy. Finally, based on Two Micron All Sky Survey data, we identify 31 additional candidate far outer Galaxy star-forming regions within the larger survey area.

show abstract

Section: Figmentioning

confidence: 73%

Section: Far-infrared Luminositymentioning

confidence: 75%

Section: Introductionmentioning

confidence: 87%

Section: Figmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Molecular Clouds and Infrared Stellar Clusters in the Far Outer Galaxy

Snell

Carpenter

Heyer

2002

ApJ

View full text Add to dashboard Cite

show abstract

Molecular gas and a new young stellar cluster in the far outer Galaxy

Yun

Elia

Palmeirim

et al. 2009

A&A

View full text Add to dashboard Cite

Aims. We investigate the star-formation ocurring in the region towards IRAS 07527-3446 in the molecular cloud [MAB97]250. 63-3.63, in the far outer Galaxy. We report the discovery of a new young stellar cluster, and describe its properties and those of its parent molecular cloud. Methods. Near-infrared JHK S images were obtained with VLT/ISAAC, and millimetre line CO spectra were obtained with the SEST telescope. VLA archive date were also used. Results. The cloud and cluster are located at a distance of 10.3 kpc and a Galactocentric distance of 15.4 kpc, in the far outer Galaxy. Morphologically, IRAS 07527-3446 appears as a young embedded cluster of a few hundred stars seen towards the position of the IRAS source, extending for about 2-4 pc and exhibiting sub-clustering. The cluster contains low and intermediate-mass young reddened stars, a large fraction having cleared the inner regions of their circumstellar discs responsible for (H − K S ) colour excess. The observations are compatible with a ≤5 Myr cluster with variable spatial extinction of between A V = 5 and A V = 11. Decomposition of CO emission in clumps, reveals a clump clearly associated with the cluster position, of mass 3.3 × 10 3 M . Estimates of the slopes of the K S -band luminosity function and of the star-formation efficiency yield values similar to those seen in nearby star-formation sites. These findings reinforce previous results that the distant outer Galaxy continues to be active in the production of new and rich stellar clusters, with the physical conditions required for the formation of rich clusters continuing to be met in the very distant environment of the outer Galactic disc.

show abstract

VLT/MUSE discovers a jet from the evolved B[e] star MWC 137

Mehner

Wit

Groh

et al. 2015

A&A

View full text Add to dashboard Cite

Aims. Not all stars exhibiting the optical spectral characteristics of B [e] stars are in the same evolutionary stage. The Galactic B[e] star MWC 137 is a prime example of an object with uncertain classification, where previous work has suggested either a pre-or a postmain sequence classification. Our goal is to settle this debate and provide a reliable evolutionary classification. Methods. Integral field spectrograph observations with the Very Large Telescope Multi Unit Spectroscopic Explorer (VLT MUSE) of the cluster SH 2-266 are used to analyze the nature of MWC 137. Results. A collimated outflow is discovered that is geometrically centered on MWC 137. The central position of MWC 137 in the cluster SH 2-266 within the larger nebula suggests strongly that it is a member of this cluster and that it is the origin of both the nebula and the newly discovered jet. Comparison of the color-magnitude diagram of the brightest cluster stars with stellar evolutionary models results in a distance of about 5.2 ± 1.4 kpc. We estimate that the cluster is at least 3 Myr old. The jet emanates from MWC 137 at a position angle of 18-20• . The jet extends over 66 (1.7 pc) projected on the plane of the sky, shows several knots, and has electron densities of about 10 3 cm −1 and projected velocities of up to ±450 km s −1 . From the Balmer emission line decrement of the diffuse intracluster nebulosity, we determine E(B-V) = 1.4 mag for the inner 1 cluster region. The spectral energy distribution of the brightest cluster stars yields a slightly lower extinction of E(B-V) ∼ 1.2 mag for the inner region and E(B-V) ∼ 0.4-0.8 mag for the outer region. The extinction toward MWC 137 is estimated to be E(B-V) ∼ 1.8 mag (A V ∼ 5.6 mag). Conclusions. Our analysis of the optical and near-infrared color-magnitude and color-color diagrams suggests a post-main sequence stage for MWC 137. The existence of a jet in this object implies the presence of an accretion disk. Several possibilities for MWC 137's nature and the origin of its jet are discussed: e.g., the presence of a companion and a merger event.

show abstract

Far Outer Galaxy H II Regions

Cited by 48 publications

References 0 publications

Molecular Clouds and Infrared Stellar Clusters in the Far Outer Galaxy

Molecular Clouds and Infrared Stellar Clusters in the Far Outer Galaxy

Molecular gas and a new young stellar cluster in the far outer Galaxy

VLT/MUSE discovers a jet from the evolved B[e] star MWC 137

Contact Info

Product

Resources

About