scholarly journals First results from VLTI near-infrared interferometry on high-mass young stellar objects

2010 ◽  
Author(s):  
Stefan Kraus ◽  
Karl-Heinz Hofmann ◽  
Karl M. Menten ◽  
Dieter Schertl ◽  
Gerd Weigelt ◽  
...  
Keyword(s):  
Near Infrared ◽  
Young Stellar Objects ◽  
High Mass ◽  
Stellar Objects ◽  
First Results ◽  
Infrared Interferometry

scholarly journals Principal component analysis tomography in near-infrared integral field spectroscopy of young stellar objects – I. Revisiting the high-mass protostar W33A

2021 ◽  
Vol 503 (1) ◽  
pp. 270-291
Author(s):  
F Navarete ◽  
A Damineli ◽  
J E Steiner ◽  
R D Blum
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Rotation Axis ◽  
Principal Component ◽  
Young Stellar Objects ◽  
High Mass ◽  
Continuum Emission ◽  
Rotating Disc ◽  
Stellar Objects ◽  
K Band

ABSTRACT W33A is a well-known example of a high-mass young stellar object showing evidence of a circumstellar disc. We revisited the K-band NIFS/Gemini North observations of the W33A protostar using principal components analysis tomography and additional post-processing routines. Our results indicate the presence of a compact rotating disc based on the kinematics of the CO absorption features. The position–velocity diagram shows that the disc exhibits a rotation curve with velocities that rapidly decrease for radii larger than 0.1 arcsec (∼250 au) from the central source, suggesting a structure about four times more compact than previously reported. We derived a dynamical mass of 10.0$^{+4.1}_{-2.2}$ $\rm {M}_\odot$ for the ‘disc + protostar’ system, about ∼33 per cent smaller than previously reported, but still compatible with high-mass protostar status. A relatively compact H2 wind was identified at the base of the large-scale outflow of W33A, with a mean visual extinction of ∼63 mag. By taking advantage of supplementary near-infrared maps, we identified at least two other point-like objects driving extended structures in the vicinity of W33A, suggesting that multiple active protostars are located within the cloud. The closest object (Source B) was also identified in the NIFS field of view as a faint point-like object at a projected distance of ∼7000 au from W33A, powering extended K-band continuum emission detected in the same field. Another source (Source C) is driving a bipolar $\rm {H}_2$ jet aligned perpendicular to the rotation axis of W33A.

The innermost regions of massive protostars traced by masers, high-resolution radio continuum, and near-infrared imaging

2017 ◽  
Vol 13 (S336) ◽  
pp. 289-290
Author(s):  
Fabrizio Massi ◽  
Luca Moscadelli ◽  
Carmelo Arcidiacono ◽  
Francesca Bacciotti
Keyword(s):  
Near Infrared ◽  
Infrared Imaging ◽  
High Spatial Resolution ◽  
Radio Continuum ◽  
High Mass ◽  
Mass Star ◽  
Near Infrared Imaging ◽  
Stellar Objects ◽  
First Results ◽  
Low Mass

AbstractWhether high-mass stars (M > 7M⊙) emerge from a scaled-up version of the low-mass star formation scenario, i. e. through disk-mediated accretion, is still debated. We present the first results of an observational programme aimed to map the innermost regions of high-mass stellar objects by combining together high-spatial resolution maser and radio continuum observations, and near-infrared imaging.

Magnetic field structures in star-forming regions revealed by imaging polarimetry at multi-wavelengths

2018 ◽  
Vol 14 (A30) ◽  
pp. 102-102
Author(s):  
Jungmi Kwon
Keyword(s):  
Magnetic Fields ◽  
Near Infrared ◽  
Infrared Imaging ◽  
Young Stellar Objects ◽  
High Mass ◽  
Mass Star ◽  
Stellar Objects ◽  
Star Forming ◽  
Star Forming Regions ◽  
Imaging Polarimetry

AbstractMagnetic fields are ubiquitous in various scales of astronomical objects, and they are considered as playing significant roles from star to galaxy formations. However, the role of the magnetic fields in star forming regions is less well understood because conventional optical polarimetry is hampered by heavy extinction by dust. We have been conducting extensive near-infrared polarization survey of various star-forming regions from low- and intermediate-mass to high-mass star-forming regions, using IRSF/SIRPOL in South Africa. Not only linear but also circular polarizations have been measured for more than a dozen of regions. Both linear and circular polarimetric observations at near-infrared wavelengths are useful tools to study the magnetic fields in star forming regions, although infrared circular polarimetry has been less explored so far. In this presentation, we summarize our results of the near-infrared polarization survey of star forming regions and its comparison with recent submillimeter polarimetry results. Such multi-wavelength approaches can be extended to the polarimetry using ALMA, SPICA in future, and others. We also present our recent results of the first near-infrared imaging polarimetry of young stellar objects in the Circinus molecular cloud, which has been less studied but a very intriguing cluster containing numerous signs of active low-mass star formation.

scholarly journals Parsec-scale jets driven by high-mass young stellar objects

2018 ◽  
Vol 616 ◽  
pp. A126 ◽  
Author(s):  
R. Fedriani ◽  
A. Caratti o Garatti ◽  
D. Coffey ◽  
R. Garcia Lopez ◽  
S. Kraus ◽  
...  
Keyword(s):  
Mass Loss ◽  
Near Infrared ◽  
Dynamic Properties ◽  
Mass Loss Rate ◽  
Position Angle ◽  
Young Star ◽  
Young Stellar Objects ◽  
High Mass ◽  
Stellar Objects ◽  
Protostellar Jets

Context. Protostellar jets in high-mass young stellar objects (HMYSOs) play a key role in the understanding of star formation and provide us with an excellent tool to study fundamental properties of HMYSOs. Aims. We aim at studying the physical and kinematic properties of the near-infrared (NIR) jet of IRAS 13481-6124 from au to parsec scales. Methods. Our study includes NIR data from the Very Large Telescope instruments SINFONI, CRIRES, and ISAAC. Information about the source and its immediate environment is retrieved with SINFONI. The technique of spectro-astrometry is performed with CRIRES to study the jet on au scales. The parsec-scale jet and its kinematic and dynamic properties are investigated using ISAAC. Results. The SINFONI spectra in H and K bands are rich in emission lines that are mainly associated with ejection and accretion processes. Spectro-astrometry is applied to the Brγ line, and for the first time, to the Brα line, revealing their jet origin with milliarcsecond-scale photocentre displacements (11−15 au). This allows us to constrain the kinematics of the au-scale jet and to derive its position angle (~216°). ISAAC spectroscopy reveals H2 emission along the parsec-scale jet, which allows us to infer kinematic and dynamic properties of the NIR parsec-scale jet. The mass-loss rate inferred for the NIR jet is Ṁejec ~ 10−4 M⊙ yr−1 and the thrust is Ṗ ~ 10−2 M⊙ yr−1 km s−1, which is roughly constant for the formation history of the young star. A tentative estimate of the ionisation fraction is derived for the massive jet by comparing the radio and NIR mass-loss rates. An ionisation fraction ≲8% is obtained, which means that the bulk of the ejecta is traced by the NIR jet and that the radio jet only delineates a small portion of it.

scholarly journals The GRAVITY young stellar object survey

2020 ◽  
Vol 635 ◽  
pp. L12 ◽  
Author(s):  
◽  
A. Caratti o Garatti ◽  
R. Fedriani ◽  
R. Garcia Lopez ◽  
M. Koutoulaki ◽  
...  
Keyword(s):  
Near Infrared ◽  
Major Axis ◽  
Position Angle ◽  
Young Stellar Objects ◽  
High Mass ◽  
Continuum Emission ◽  
Stellar Objects ◽  
Axis Position ◽  
The Continuum ◽  
Gaseous Disc

Context. The inner regions of the discs of high-mass young stellar objects (HMYSOs) are still poorly known due to the small angular scales and the high visual extinction involved. Aims. We deploy near-infrared spectro-interferometry to probe the inner gaseous disc in HMYSOs and investigate the origin and physical characteristics of the CO bandhead emission (2.3–2.4 μm). Methods. We present the first GRAVITY/VLTI observations at high spectral (ℛ = 4000) and spatial (mas) resolution of the CO overtone transitions in NGC 2024 IRS 2. Results. The continuum emission is resolved in all baselines and is slightly asymmetric, displaying small closure phases (≤8°). Our best ellipsoid model provides a disc inclination of 34° ±1°, a disc major axis position angle (PA) of 166° ± 1°, and a disc diameter of 3.99 ± 0.09 mas (or 1.69  ±  0.04 au, at a distance of 423 pc). The small closure phase signals in the continuum are modelled with a skewed rim, originating from a pure inclination effect. For the first time, our observations spatially and spectrally resolve the first four CO bandheads. Changes in visibility, as well as differential and closure phases across the bandheads are detected. Both the size and geometry of the CO-emitting region are determined by fitting a bidimensional Gaussian to the continuum-compensated CO bandhead visibilities. The CO-emitting region has a diameter of 2.74±0.070.08 mas (1.16  ±  0.03 au), and is located in the inner gaseous disc, well within the dusty rim, with inclination and PA matching the dusty disc geometry, which indicates that both dusty and gaseous discs are coplanar. Physical and dynamical gas conditions are inferred by modelling the CO spectrum. Finally, we derive a direct measurement of the stellar mass of M* ∼ 14.7−3.6+2 M⊙ by combining our interferometric and spectral modelling results.

A Near-Infrared Search for Companions around Very Low Luminosity Young Stellar Objects in Taurus

1999 ◽  
Vol 117 (3) ◽  
pp. 1471-1484 ◽  
Author(s):  
Yoichi Itoh ◽  
Motohide Tamura ◽  
Tadashi Nakajima
Keyword(s):  
Near Infrared ◽  
Young Stellar Objects ◽  
Stellar Objects

First Near-infrared Imaging Polarimetry of Young Stellar Objects in the Circinus Molecular Cloud

2018 ◽  
Vol 234 (2) ◽  
pp. 42 ◽  
Author(s):  
Jungmi Kwon ◽  
Takao Nakagawa ◽  
Motohide Tamura ◽  
James H. Hough ◽  
Minho Choi ◽  
...  
Keyword(s):  
Molecular Cloud ◽  
Near Infrared ◽  
Infrared Imaging ◽  
Young Stellar Objects ◽  
Near Infrared Imaging ◽  
Stellar Objects ◽  
Imaging Polarimetry
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