Spectroscopic evidence for infall around an extraordinary IRAS source in Ophiuchus

Walker, Christopher K.; Lada, Charles J.; Young, Erick T.; Maloney, Philip R.; Wilking, B. A.

doi:10.1086/184758

Cited by 135 publications

(102 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Evidence for large-scale infall toward this protostellar system has been found using single-dish observations (Walker et al 1986;Narayanan et al 1998). Chandler et al (2005) suggested that there is evidence for infall toward I16293B from the tentative absorption feature seen in SO when imaged using only baselines longer than 55 kλ.…”

Section: Introductionmentioning

confidence: 94%

The first ALMA view of IRAS 16293-2422

Pineda

Maury

Fuller

et al. 2012

A&A

120

164

View full text Add to dashboard Cite

Aims. We focus on the kinematical properties of a proto-binary to study the infall and rotation of gas toward its two protostellar components. Methods. We present ALMA Science Verification observations with high-spectral resolution of IRAS 16293-2422 at 220.2 GHz. The wealth of molecular lines in this source and the very high spectral resolution offered by ALMA allow us to study the gas kinematics with unprecedented detail. Results. We present the first detection of an inverse P-Cygni profile toward source B in the three brightest lines. The line profiles are fitted with a simple two-layer model to derive an infall rate of 4.5 × 10 −5 M yr −1 . This infall detection would rule-out the previously suggested possibility that source B is a T Tauri star. A position velocity diagram for source A shows evidence of rotation with an axis close to the line-of-sight.

show abstract

Section: Introductionmentioning

confidence: 94%

The first ALMA view of IRAS 16293-2422

Pineda

Maury

Fuller

et al. 2012

A&A

120

164

View full text Add to dashboard Cite

show abstract

“…The first one is an asymmetric profile of an optically thick line that is skewed to the blue and sometimes features a self-absorption dip (due to absorption from the outer low-excitation material). In order to exclude the possibility that the observed spectral profile is due to two separate, overlapping velocity components, an optically thin, symmetric (and single-peaked) line is required to peak at a velocity in between the red and blue portions of the optically thick line (Leung & Brown 1977;Walker et al 1986;Zhou 1992;Myers et al , 1996. Strictly speaking, the infall signature may in some cases trace early or large-scale contraction motions in layers that are not (yet) gravitationally collapsing.…”

Section: Contraction Motionsmentioning

confidence: 99%

Star formation in Chamaeleon I and III: a molecular line study of the starless core population

Tsitali

Беллоче

Garrod

et al. 2015

A&A

View full text Add to dashboard Cite

Context. The Chamaeleon dark molecular clouds are excellent nearby targets for low-mass star formation studies. Even though they belong to the same cloud complex, Cha I and II are actively forming stars while Cha III shows no sign of ongoing star formation. Aims. We aim to determine the driving factors that have led to the very different levels of star formation activity in Cha I and III and examine the dynamical state and possible evolution of the starless cores within them. Methods. Observations were performed in various molecular transitions with the APEX and Mopra telescopes. We examine the kinematics of the starless cores in the clouds through a virial analysis, a search for contraction motions, and velocity gradients. The chemical differences in the two clouds are explored through their fractional molecular abundances, derived from a non-LTE analysis, and comparison to predictions of chemical models.Results. Five cores are gravitationally bound in Cha I and one in Cha III. The so-called infall signature indicating contraction motions is seen toward 8-17 cores in Cha I and 2-5 cores in Cha III, which leads to a range of 13-28% of the cores in Cha I and 10-25% of the cores in Cha III that are contracting and may become prestellar. There is no significant difference in the turbulence level in the two clouds. Future dynamical interactions between the cores will not be dynamically significant in either Cha I or III, but the subregion Cha I North may experience collisions between cores within ∼0.7 Myr. Turbulence dissipation in the cores of both clouds is seen in the high-density tracers N 2 H + 1-0 and HC 3 N 10-9 which have lower non-thermal velocity dispersions compared to C 17 O 2-1, C 18 O 2-1, and C 34 S 2-1. Evidence of depletion in the Cha I core interiors is seen in the abundance distributions of the latter three molecules. The median fractional abundance of C 18 O is lower in Cha III than Cha I by a factor of ∼2. The median abundances of most molecules (except methanol) in the Cha III cores lie at the lower end of the values found in the Cha I cores. A difference in chemistry is thus seen. Chemical models suitable for the Cha I and III cores are used to constrain the effectiveness of the HC 3 N to N 2 H + abundance ratio as an evolutionary indicator. Both contraction and static chemical models indicate that this ratio is a good evolutionary indicator in the prestellar phase for both gravitationally bound and unbound cores. In the framework of these models, we find that the cores in Cha III and the southern part of Cha I are in a similar evolutionary stage and are less chemically evolved than the central region of Cha I. Conclusions. The measured HC 3 N/N 2 H + abundance ratio and the evidence for contraction motions seen towards the Cha III starless cores suggest that Cha III is younger than Cha I Centre and that some of its cores may form stars in the future if contraction does not cease. The cores in Cha I South may on the other hand be transient structures.

show abstract

“…IRAS 16293−2422 (hereafter I16293) is a well-studied solartype protostar, originally singled out as having one of the most prominent outflows of all the IRAS sources associated with the ρ Ophiuchus cloud, and showing indications of infall (Walker et al 1986(Walker et al , 1988. Sub-millimetre and radio observations reveal that the source breaks up into two sources, A and B, located at a projected distance of 5 (Mundy et al 1986;Wootten 1989).…”

Section: Introductionmentioning

confidence: 99%

ALMA COJ= 6–5 observations of IRAS 16293–2422

Kristensen

Klaassen

Mottram

et al. 2012

A&A

View full text Add to dashboard Cite

Observations of higher-excited transitions of abundant molecules such as CO are important for determining where energy in the form of shocks is fed back into the parental envelope of forming stars. The nearby prototypical and protobinary low-mass hot core, IRAS 16293-2422 (I16293) is ideal for such a study. The source was targeted with ALMA for science verification purposes in band 9, which includes CO J = 6−5 (E up /k B ∼ 116 K), at an unprecedented spatial resolution (∼0. 2, 25 AU). I16293 itself is composed of two sources, A and B, with a projected distance of 5 . CO J = 6−5 emission is detected throughout the region, particularly in small, arcsecond-sized hotspots, where the outflow interacts with the envelope. The observations only recover a fraction of the emission in the line wings when compared to data from single-dish telescopes, with a higher fraction of emission recovered at higher velocities. The very high angular resolution of these new data reveal that a bow shock from source A coincides, in the plane of the sky, with the position of source B. Source B, on the other hand, does not show current outflow activity. In this region, outflow entrainment takes place over large spatial scales, 100 AU, and in small discrete knots. This unique dataset shows that the combination of a high-temperature tracer (e.g., CO J = 6−5) and very high angular resolution observations is crucial for interpreting the structure of the warm inner environment of low-mass protostars.

show abstract

Spectroscopic evidence for infall around an extraordinary IRAS source in Ophiuchus

Cited by 135 publications

References 0 publications

The first ALMA view of IRAS 16293-2422

The first ALMA view of IRAS 16293-2422

Star formation in Chamaeleon I and III: a molecular line study of the starless core population

ALMA COJ= 6–5 observations of IRAS 16293–2422

Contact Info

Product

Resources

About