The Rosette Eye: The Key Transition Phase in the Birth of a Massive Star

Li, J. Z.; Smith, Michael D.; Gredel, R.; Davis, C. J.; Rector, T. A.

doi:10.1086/589445

Cited by 6 publications

(8 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Fluorescent emission from unshocked cloud gas in star formation regions yields enhanced columns of gas in the para upper energy levels (e.g. Li et al 2008). Here, however, we find that, within the errors, there is no deviation from a thermalised orthopara ratio of 3 (Smith et al 1997), corresponding to linear fits on the diagrams (note the large errors associated with the noisy parts of the high Q-branch and high S-branch transitions).…”

Section: A Shock-model For the Emission From The Filamentsupporting

confidence: 60%

The circumstellar environment of the YSO TMR-1 and a revisit to the candidate very low-mass object TMR-1C

Petr-Gotzens

Cuby

Smith

et al. 2010

A&A

View full text Add to dashboard Cite

Context. TMR-1 (IRAS 04361+2547) is a class I proto-stellar source located in the nearby Taurus star-forming region. Its circumstellar environment is characterized by extended dust emission with complex structures and conspicuous filaments. A faint companion, called TMR-1C, located near the proto-star was detected in previous studies, but its nature as a very young substellar object remains inconclusive. Aims. We aim to improve the constraints on the nature of the faint object TMR-1C, and to investigate the process of very low-mass star formation in the TMR-1 system. Methods. Using very sensitive infrared imaging observations of the TMR-1 system and near-infrared spectroscopy, we compile the spectral energy distribution (SED) of TMR-1C over a much wider wavelength range than possible in previous work. We then compare the spectral energy distribution with models of extincted background stars, young sub-stellar objects, and very low-mass stars with circumstellar disk and envelope emission. We also search for additional low-luminosity sources in the immediate environment of the TMR-1 proto-stellar source. Furthermore, we study the surrounding near-infrared dust morphology, and analyse the emission line spectrum of a filamentary structure in the physical context of a bow-shock model. Results. We find that the observed SED of TMR-1C can be reproduced by neither an extincted background star, nor available models for a young extremely low-mass ( 12 M J ) object. Our near-infrared spectrum allows us to infer an effective temperature 3000 K. We achieve a close fit of TMR-1C's SED using radiation transfer models of young stellar objects with circumstellar disks, hence propose that TMR-1C is most likely a very low-mass star with M ≈ 0.1−0.2 M surrounded by a circumstellar disk of high inclination, i > 80 • . Interestingly, we detect an additional very faint source, which we call TMR-1D, that is remarkably symmetrical in terms of position with TMR-1C. Both TMR-1C and TMR-1D may have formed from a common star-formation event, triggered by a powerful outflow or by the collision of primordial proto-stellar disks. The impact of an outflow is traced by molecular hydrogen emission that we detect from a distinct filament pointing towards TMR-1C. A comparison with C-type bow shock models confirms that the emission is caused by shock excitation.

show abstract

Section: A Shock-model For the Emission From The Filamentsupporting

confidence: 60%

The circumstellar environment of the YSO TMR-1 and a revisit to the candidate very low-mass object TMR-1C

Petr-Gotzens

Cuby

Smith

et al. 2010

A&A

View full text Add to dashboard Cite

show abstract

“…Moreover, recent IR images show the bright object 30 arcsec west of AFGL 961 (known as AFGL 961 II – see Fig. 5) has bipolar shocked H 2 emission extending at position angle (PA) ∼ 345° (Li & Smith 2005; Li et al 2008). This may be associated with the second bipolar CO outflow.…”

Section: Resultsmentioning

confidence: 99%

A large-scale CO survey of the Rosette Molecular Cloud: assessing the effects of O stars on surrounding molecular gas

Dent

Hovey

Dewdney

et al. 2009

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We present a new large-scale survey of the J = 3-2 12 CO emission covering 4.8 deg 2 around the Rosette Nebula. The results reveal the complex dynamics of the molecular gas in this region. We identify about 2000 compact gas clumps having a mass distribution given by dN/dM ∼ M −1.8 , with no dependence of the power-law index on distance from the central O stars. A detailed study of a number of the clumps in the inner region shows that most exhibit velocity gradients in the range 1-3 km s −1 pc −1 , generally directed away from the exciting nebula. The magnitude of the velocity gradient decreases with distance from the central O stars, and we compare the apparent clump acceleration with a photoionized gas acceleration model. For most clumps outside the central nebula, the model predicts lifetimes of a few 10 5 yr. In one of the most extended of these clumps, however, a near-constant velocity gradient can be measured over 1.7 pc, which is difficult to explain with radiatively driven models of clump acceleration.As well as the individual accelerated clumps, an unresolved limb-brightened rim lies at the interface between the central nebular cavity and the Rosette Molecular Cloud. Extending over 4 pc along the edge of the nebula, this region is thought to be at an earlier phase of disruption than the accelerating compact globules.Blueshifted gas clumps around the nebula are in all cases associated with dark absorbing optical globules, indicating that this material lies in front of the nebula and has been accelerated towards us. Redshifted gas shows little evidence of associated line-of-sight dark clouds, indicating that the dominant bulk molecular gas motion throughout the region is expansion away from the O stars. In addition, we find evidence that many of the clumps lie in a molecular ring, having an expansion velocity of 30 km s −1 and radius 11 pc. The dynamical time-scale derived for this structure (∼10 6 yr) is similar to the age of the nebula as a whole (2 × 10 6 yr).The J = 3-2/1-0 12 CO line ratio in the clumps decreases with radial distance from the exciting O stars, from 1.6 at ∼8 pc distance to 0.8 at 20 pc. This can be explained by a gradient in the surface temperature of the clumps with distance, and we compare the results with a simple model of surface heating by the central luminous stars.We identify seven high-velocity molecular flows in the region, with a close correspondence between these flows and embedded young clusters or known young luminous stars. These

show abstract

“…AFGL961C is slightly elongated in the N-band image and the emission at Q-band is very extended. Aspin (1998) found H 2 bow shock features on either side of the star and Li et al (2008) present a detailed study of these features. The position angle of the elongated stucture in the Q-band image lines up with these and the extended mid-infrared emission is likely to be from hot dust filling a cavity that the star has blown out around itself.…”

Section: Morphologymentioning

confidence: 87%

Diverse Protostellar Evolutionary States in the Young Cluster Afgl961

Williams

Mann

Beaumont

et al. 2009

ApJ

View full text Add to dashboard Cite

We present arcsecond resolution mid-infrared and millimeter observations of the center of the young stellar cluster AFGL961 in the Rosette molecular cloud. Within 0.2 pc of each other, we find an early B star embedded in a dense core, a neighboring star of similar luminosity with no millimeter counterpart, a protostar that has cleared out a cavity in the circumcluster envelope, and two massive, dense cores with no infrared counterparts. An outflow emanates from one of these cores, indicating a deeply embedded protostar, but the other is starless, bound, and appears to be collapsing. The diversity of states implies either that protostellar evolution is faster in clusters than in isolation or that clusters form via quasi-static rather than dynamic collapse. The existence of a pre-stellar core at the cluster center shows that that some star formation continues after and in close proximity to massive, ionizing stars.

show abstract

The Rosette Eye: The Key Transition Phase in the Birth of a Massive Star

Cited by 6 publications

References 26 publications

The circumstellar environment of the YSO TMR-1 and a revisit to the candidate very low-mass object TMR-1C

The circumstellar environment of the YSO TMR-1 and a revisit to the candidate very low-mass object TMR-1C

A large-scale CO survey of the Rosette Molecular Cloud: assessing the effects of O stars on surrounding molecular gas

Diverse Protostellar Evolutionary States in the Young Cluster Afgl961

Contact Info

Product

Resources

About