scholarly journals Multi-epoch water maser survey towards low-mass YSOs

2002 ◽  
Vol 206 ◽  
pp. 35-38 ◽  
Author(s):  
Ray S. Furuya ◽  
Yoshimi Kitamura ◽  
Alwyn Wootten ◽  
Mark J. Claussen ◽  
Ryohei Kawabe
Keyword(s):  
Large Scale ◽  
Class I ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Detection Rates ◽  
Molecular Outflows ◽  
Low Mass ◽  
Water Maser

We present the results from a series of multi-epoch 22 GHz H2O maser surveys with the Nobeyama 45 m telescope and the VLA towards low-mass young stellar objects, including all the class 0 sources in the northern sky. Our Nobeyama 45 m survey is the deepest survey - down to an isotopic H2O luminosity of ∼ 10−13L⊙ - performed so far. From this survey, we obtained the following results. (1) Class 0 sources show high H2O maser activity: our derived detection rates are ∼ 38% for class 0, but only ∼ 4% for class I sources. (2) Activity of the H2O masers is more likely related to 100 AU scale ionized jets than to large scale molecular outflows.

scholarly journals Envelope Structure on 700 AU Scales and the Molecular Outflows of Low‐Mass Young Stellar Objects

1998 ◽  
Vol 502 (1) ◽  
pp. 315-336 ◽  
Author(s):  
Michiel R. Hogerheijde ◽  
Ewine F. van Dishoeck ◽  
Geoffrey A. Blake ◽  
Huib Jan van Langevelde
Keyword(s):  
Young Stellar Objects ◽  
Stellar Objects ◽  
Molecular Outflows ◽  
Low Mass

Water Maser Survey toward Low‐Mass Young Stellar Objects in the Northern Sky with the Nobeyama 45 Meter Telescope and the Very Large Array

2003 ◽  
Vol 144 (1) ◽  
pp. 71-134 ◽  
Author(s):  
Ray S. Furuya ◽  
Yoshimi Kitamura ◽  
Alwyn Wootten ◽  
Mark J. Claussen ◽  
Ryohei Kawabe
Keyword(s):  
Young Stellar Objects ◽  
Large Array ◽  
Stellar Objects ◽  
Very Large Array ◽  
Low Mass ◽  
Water Maser

scholarly journals Molecular Outflows in B335 and B1

1994 ◽  
Vol 140 ◽  
pp. 224-225
Author(s):  
N. Hirano ◽  
O. Kameya ◽  
T. Kasuga ◽  
H. Mikami ◽  
S. Saito ◽  
...  
Keyword(s):  
Aperture Synthesis ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Molecular Outflows ◽  
Low Mass

We present the aperture synthesis observations of the CO molecular outflows associated with the low-mass young stellar objects embedded in B335 and Bl. We used the Nobeyama Millimeter Array and obtained the angular resolutions of 8.1” × 5.0” for B335 and 6.5” × 4.4” for B1.

scholarly journals Masers in GLIMPSE Extended Green Objects (EGOs)

2012 ◽  
Vol 8 (S287) ◽  
pp. 127-132
Author(s):  
Claudia J. Cyganowski ◽  
Crystal L. Brogan ◽  
Todd R. Hunter ◽  
Ed Churchwell ◽  
Jin Koda ◽  
...  
Keyword(s):  
Large Scale ◽  
Galactic Plane ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Detection Rates ◽  
Hii Region ◽  
Star Forming ◽  
Common Coding ◽  
The Common ◽  
Ultracompact Hii

AbstractLarge-scale Spitzer surveys of the Galactic plane have yielded a new diagnostic for massive young stellar objects (MYSOs) that are actively accreting and driving outflows: extended emission in the IRAC 4.5 μm band, believed to trace shocked molecular gas. Maser studies of these extended 4.5 μm sources (called EGOs, Extended Green Objects, for the common coding of 3-color IRAC images) have been and remain crucial for understanding the nature of EGOs. High detection rates in VLA CH3OH maser surveys provided the first proof that EGOs were indeed MYSOs driving outflows; our recent Nobeyama 45-m survey of northern EGOs shows that the majority are associated with H2O masers. Maser studies of EGOs also provide important constraints for the longstanding goal of a maser evolutionary sequence for MYSOs, particularly in combination with high resolution (sub)mm data. New SMA results show that Class I methanol masers can be excited by both young (hot core) and evolved (ultracompact HII region) sources within the same massive star-forming region.

scholarly journals High Angular Resolution Observations of Maser Kinematics Near Low Mass Young Stellar Objects

2001 ◽  
Vol 205 ◽  
pp. 256-257
Author(s):  
Kevin B. Marvel ◽  
Mark Claussen ◽  
H. Alwyn Wootten ◽  
Bruce Wilking
Keyword(s):  
Angular Resolution ◽  
Surrounding Medium ◽  
Young Stellar Objects ◽  
High Angular Resolution ◽  
Stellar Objects ◽  
Star Forming ◽  
Low Mass ◽  
Water Masers ◽  
Driving Source ◽  
Water Maser

With the advent of new correlators and dedicated arrays, spectral line VLBI is entering its ascendancy as a probe of a variety of interesting astrophysical environments. One of the most interesting environments where spectroscopic VLBI techniques are valuable are the regions directly coincident with forming stars. In these sources, water maser emission is observed when the outflowing jets of material interact with the surrounding medium. Observations of these water masers dramatically reveal the innermost regions of the star formation process at or below the 1-AU scale.We have found that the water masers clearly trace the jets at these scales. The masers show space motions on the order of 60 to 100 kms−1 and form within a few AU of the exciting protostar. By observing the distributions and motions of the water masers associated with these objects, we may be able to address in greater detail the collimation mechanism of the jets seen in these protostars.In this brief poster proceeding, we provide a summary image of the water masers associated with SVS13, the driving source for the HH 7-11 objects. We have also mapped the masers associated with IRAS 16293-2422, IRAS 05413-0104, IRAS 4A and IRAS 4B, both in the NGC 1333 star forming region. For further information on these sources, please contact any of the authors directly.

Water Maser Survey toward Low-Mass Young Stellar Objects in the Northern Sky: Observational Constraints on Maser Excitation Conditions

2001 ◽  
Vol 559 (2) ◽  
pp. L143-L147 ◽  
Author(s):  
Ray S. Furuya ◽  
Yoshimi Kitamura ◽  
H. Alwyn Wootten ◽  
Mark J. Claussen ◽  
Ryohei Kawabe
Keyword(s):  
Young Stellar Objects ◽  
Observational Constraints ◽  
Stellar Objects ◽  
Low Mass ◽  
Excitation Conditions ◽  
Water Maser

scholarly journals Investigating episodic accretion in a very low-mass young stellar object

2020 ◽  
Vol 643 ◽  
pp. A181
Author(s):  
C. Stock ◽  
A. Caratti o Garatti ◽  
P. McGinnis ◽  
R. Garcia Lopez ◽  
S. Antoniucci ◽  
...  
Keyword(s):  
Near Infrared ◽  
Accretion Rate ◽  
Photometric Data ◽  
Class I ◽  
Young Stellar Objects ◽  
Line Of Sight ◽  
Stellar Objects ◽  
Steep Decrease ◽  
Order Of Magnitude ◽  
Low Mass

Context. Very low-mass Class I protostars have been investigated very little thus far. Variability of these young stellar objects (YSOs) and whether or not they are capable of strong episodic accretion is also left relatively unstudied. Aims. We investigate accretion variability in IRS 54 (YLW52), a Class I very low-mass protostar with a mass of M⋆ ∼ 0.1 − 0.2 M⊙. Methods. We obtained spectroscopic and photometric data with VLT/ISAAC and VLT/SINFONI in the near-infrared (J, H, and K bands) across four epochs (2005, 2010, 2013, and 2014). We used accretion-tracing lines (Paβ and Brγ) and outflow-tracing lines (H2 and [Fe II]) to examine physical properties and kinematics of the object. Results. A large increase in luminosity was found between the 2005 and 2013 epochs of more than 1 magnitude in the K band, followed in 2014 by a steep decrease. Consistently, the mass accretion rate (Ṁacc) rose by an order of magnitude from ∼10−8 M⊙ yr−1 to ∼10−7 M⊙ yr−1 between the two early epochs. The visual extinction (AV) has also increased from ∼15 mag in 2005 to ∼24 mag in 2013. This rise in AV in tandem with the increase in Ṁacc is explained by the lifting up of a large amount of dust from the disc of IRS 54, following the augmented accretion and ejection activity in the YSO, which intersects our line of sight due to the almost edge-on geometry of the disc. Because of the strength and timescales involved in this dramatic increase, this event is believed to have been an accretion burst possibly similar to bursts of EXor-type objects. IRS 54 is the lowest mass Class I source observed to have an accretion burst of this type, and therefore potentially one of the lowest mass EXor-type objects known so far.

scholarly journals 44-GHz class I methanol maser survey towards 6.7-GHz class II methanol masers

2012 ◽  
Vol 8 (S287) ◽  
pp. 284-285 ◽  
Author(s):  
Do-Young Byun ◽  
Kee-Tae Kim ◽  
Jae-Han Bae
Keyword(s):  
Class Ii ◽  
Class I ◽  
Young Stellar Objects ◽  
High Mass ◽  
Radio Telescopes ◽  
Stellar Objects ◽  
Methanol Maser ◽  
Peak Flux ◽  
Methanol Masers ◽  
Water Maser

AbstractThe Class II 6.7-GHz methanol maser is a tracer of high mass young stellar objects. We present results of a 44-GHz class I methanol maser and 22-GHz water maser survey using the KVN (Korean VLBI Network) 21-m single dish radio telescopes towards 284 6.7-GHz maser sites. Class I methanol maser and water maser emission is detected towards 116 (41%) and 136 (48%) sources, respectively. About 50 sources have a peak flux density higher than 10 Jy at 44-GHz. They are candidates for VLBI studies using the KVN.

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