A general catalogue of molecular hydrogen emission-line objects (MHOs) in outflows from young stars

Davis, C. J.; Gell, R.; Khanzadyan, T.; Smith, Michael D.; Jenness, Tim

doi:10.1051/0004-6361/200913561

Cited by 93 publications

(113 citation statements)

References 152 publications

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“…Our proper motion measurements supply more robust evidence for the driving source The MHOs, which are driven by the driving sources. MHO names are from Davis et al (2010). (c) "Y" or "N" indicates whether or not a 850 μm dust core is associated with the driving source.…”

Section: The Driving Sources Of Mhos In Ophiuchusmentioning

confidence: 99%

“…Using mid-infrared Spitzer/IRAC observations, Zhang & Wang (2009) detected 44 extended green object (EGO) outflow features. Based on near-infrared data, Davis et al (2010) list ∼47 MHOs consisting of ∼119 H 2 2.12 μm emission features in the ρ Ophiuchi molecular cloud. While observations with small angular coverage detected some individual MHOs (Grosso et al 2001;Ybarra et al 2006), the majority of MHOs in Ophiuchus have been detected by two unbiased surveys (Gómez et al 2003;Khanzadyan et al 2004).…”

Section: Introductionmentioning

confidence: 99%

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Proper motions of molecular hydrogen outflows in theρOphiuchi molecular cloud

Zhang

Brandner

Wang

et al. 2013

A&A

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Context. Proper motion measurements provide unique and powerful means to identify the driving sources of mass outflows, which are of particular importance in regions with complex star formation activity and deeply embedded protostars. They also provide the necessary kinematic information to study the dynamics of mass outflows, the interaction between outflows and the ambient medium, and the evolution of outflows with the age of the driving sources. Aims. We aim to take a census of molecular hydrogen emission line objects (MHOs) in the ρ Ophiuchi molecular cloud and to make the first systematic proper motion measurements of these objects in this region. The driving sources are identified based on the measured proper motions, and the outflow properties are characterized. The relationship between outflow properties and the evolutionary stages of the driving sources are also investigated. Methods. Deep H 2 near-infrared imaging is performed to search for molecular hydrogen emission line objects. Multi-epoch data are used to derive the proper motions of the features of these objects, and the lengths and opening angles of the molecular hydrogen outflows. Results. Our imaging covers an area of ∼0.11 deg 2 toward the L1688 core in the ρ Ophiuchi molecular cloud. In total, six new MHOs are discovered, 32 previously known MHOs are detected, and the proper motions for 86 features of the MHOs are measured. The proper motions lie in the range of 14 to 247 mas/yr, corresponding to transversal velocities of 8 to 140 km s −1 with a median velocity of about 35 km s −1 . Based on morphology and proper motion measurements, 27 MHOs are ascribed to 21 driving sources. The molecular hydrogen outflows have a median length of ∼0.04 pc and random orientations. We find no obvious correlation between H 2 jet length, jet opening angle, and the evolutionary stage of the driving sources as defined by their spectral indices. We find that the fraction of protostars (23%) that drive molecular hydrogen outflows is similar to the one for Class II sources (15%). For most molecular hydrogen outflows, no obvious velocity variation along the outflow has been found. Conclusions. In Ophiuchus the frequency of occurrence of molecular hydrogen outflows has no strong dependency on the evolutionary stage of the driving source during the evolution from the protostellar stage to the classical T Tauri stage.

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Section: The Driving Sources Of Mhos In Ophiuchusmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Proper motions of molecular hydrogen outflows in theρOphiuchi molecular cloud

Zhang

Brandner

Wang

et al. 2013

A&A

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“…We have selected seven embedded sources (listed in Table 1) based on their association with HH objects and/or Molecular Hydrogen emission-line Objects (MHOs, see the recent online catalogue described in Davis et al 2010 2 ). From spectroscopic studies, SVS 13 (the HH 7-11 source), HH 300-IRS (IRAS 04239+2436), HH 34-IRS and HH 72-IRS are also known to be associated with MHEL and/or FEL regions (e.g.…”

Section: Target Selectionmentioning

confidence: 99%

“…To better understand this accretion/ejection dynamic, and ultimately to constrain and distinguish between models of diskwinds, where the jet is launched from a large spread of disk radii (R ∼ 0.1-10 AU, Pudritz & Norman 1986;Garcia et al 2001;Safier 1993;Ferreira 1997) and X-winds, where the ejection occurs from a single annulus at the inner edge of the disk (R < 0.1 AU, Shu et al 1991;Shang et al 2002), spectroscopic techniques have been employed to probe the kinematics and A&A 528, A3 (2011) (Davis et al 2010), and the distance to the target adopted in this paper. (b) Total integration time spent on source.…”

Section: Introductionmentioning

confidence: 99%

VLT integral field spectroscopy of embedded protostars: using near-infrared emission lines as tracers of accretion and outflow

Davis

Cervantes

Nisini

et al. 2011

A&A

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Aims. We present near-infrared spectroscopy of the forbidden emission line (FEL) and molecular hydrogen emission line (MHEL) regions at the bases of Herbig-Haro (HH) jets from seven embedded protostars: SVS 13 (the HH 7-11 progenitor), HH 26-IRS, HH 34-IRS, HH 72-IRS, HH 83-IRS, HH 300-IRS (IRAS 04239+2436) and HH 999-IRS (IRAS 06047-1117) Methods. The integral field spectrograph, SINFONI, on the European Southern Observatory's Very Large Telescope (VLT) was used to characterise jet parameters in these formative regions, where the jets are collimated and accelerated. Results. We find considerable differences in the spectra of HH 83-IRS when compared to the other six sources; CO bandhead and atomic permitted lines from Ca i, Na i, Mg i and Al i are observed in emission in all but HH 83-IRS, where they are detected in absorption. It is likely that this source is more evolved than the others (or at the very least considerably less active). Strong CO bandhead emission is also detected in emission in the other six sources, while extended H 2 ro-vibrational and [Fe ii] forbidden emission lines trace the outflows (only the HH jet from HH 83-IRS is undetected). CO bandhead and Brγ emission peaks are in most cases coincident with the jet source continuum position, consistent with excitation in an accretion disk or accretion flow. However, in the closest source, HH 300-IRS, we do find evidence for excitation in the outflow: here the emission peak is offset by 3.6(±0.7) AU along the flow axis. We also note a correlation between CO and Mg i, Na i and Ca i intensities, which supports the idea that these atomic permitted lines are associated with accretion disks. From H 2 and [Fe ii] images we measure jet widths and derive upper limits to flow component opening angles. Although we do not find that the ionised [Fe ii] component is consistently narrower than the H 2 flow component, we do find that narrower H 2 and/or [Fe ii] flow components are associated with higher radial velocities (as reported in the literature). Flow opening angles, over the first few hundred AU in each source, are measured to be in the range 21 • -42 • in both H 2 and [Fe ii]. Finally, from our 3-D data we are also able to map the extinction and electron density at the base of the outflows from some of our targets: within a few hundred AU, both decrease sharply with distance from the source. Conclusions. It seems clear that collimated atomic and molecular jets, which may initially exhibit a wide opening angle, are a feature of outflows from Class I protostars, Class II T Tauri stars, and possibly even Class 0 sources, and that these jets can be traced to within a few hundred AU of the driving source. A common jet collimation and acceleration mechanism seems inescapable for all stages of low mass star formation.

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“…Though this object is likely to be a HH-object it cannot be confirmed in the optical. Therefore it will be designated as a molecular hydrogen emission-line object MHO 1411, (Davis et al 2010). …”

Section: Spectroscopy and Narrow-band Imagingmentioning

confidence: 99%

Star formation in Cometary Globule 1: the second generation

Haikala

Mäkelä

Vaïsänen

2010

A&A

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Context. Cometary Globule 1 (CG 1) is the archetype Cometary Globule in the Gum nebula. Aims. We attempt to discover stars possibly embedded in the globule head of the Gum nebula and to map distribution of its ISM. Methods. We analyse C 18 O spectral line observations, NIR spectrosopy, narrow and broad band NIR imaging, and stellar photometry to determine the structure of the CG 1 head and the extinction of stars in its direction. Results. A young stellar object (YSO) associated with a bright NIR nebulosity and a molecular hydrogen object (MHO 1411, a probable obscured HH-object) were discovered in the globule. Molecular hydrogen and Brγ line emission is seen in the direction of the YSO. The observed maximum optical extinction in the globule head is 9. m 2. The peak N(H 2 ) column density and the total mass derived from the extinction are 9.0 × 10 21 cm −2 and 16.7 M (d/300 pc) 2 . The C 18 O emission in the globule head is detected in a 1. 5 by 4 area with a sharp maximum SW of the YSO. Three regions can be discerned in C 18 O line velocity and excitation temperature. Because of variations in the C 18 O excitation temperature the integrated C 18 O line emission does not follow the optical extinction. It is argued that the changes in the C 18 O excitation temperatures are caused by radiative heating by NX Pup and interaction of the YSO with the parent cloud. No indication of a strong molecular outflow from the YSO is evident in the molecular line data. The IRAS point source 07178-4429 located in the CG 1 head resolves into two sources in the HIRES enhanced IRAS images. The 12 and 25 μm emission originates mainly in the star NX Puppis and the 60 and 100 μm emission in the YSO.

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A general catalogue of molecular hydrogen emission-line objects (MHOs) in outflows from young stars

Cited by 93 publications

References 152 publications

Proper motions of molecular hydrogen outflows in theρOphiuchi molecular cloud

Proper motions of molecular hydrogen outflows in theρOphiuchi molecular cloud

VLT integral field spectroscopy of embedded protostars: using near-infrared emission lines as tracers of accretion and outflow

Star formation in Cometary Globule 1: the second generation

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