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 Early results from a diagnostic 1.3 cm survey of massive young protostars

2012 ◽  
Vol 8 (S287) ◽  
pp. 497-501
Author(s):  
Crystal L. Brogan ◽  
Todd R. Hunter ◽  
Claudia J. Cyganowski ◽  
Remy Indebetouw ◽  
Rachel Friesen ◽  
...  
Keyword(s):  
Massive Star ◽  
Thermal Emission ◽  
Young Stellar Objects ◽  
Large Array ◽  
Stellar Objects ◽  
Very Large Array ◽  
Early Results ◽  
Wide Range ◽  
First Time ◽  
24 Ghz

AbstractWe have used the recently-upgraded Karl G. Jansky Very Large Array (JVLA) to conduct a K-band (~24 GHz) study of 22 massive young stellar objects in 1.3 cm continuum and a comprehensive set of diagnostic lines. This survey is unique in that it samples a wide range of massive star formation signposts simultaneously for the first time. In this proceeding we present preliminary results for the 11 sources in the 2-4 kpc distance bin. We detect compact NH3 cores in all of the fields, with many showing emission up through the (6,6) transition. Maser emission in the 25 GHz CH3OH ladder is present in 7 of 11 sources. We also detect non-thermal emission in the NH3 (3,3) transition in 7 of 11 sources.

scholarly journals VLA Observations of Nine Extended Green Objects in the Milky Way: Ubiquitous Weak, Compact Continuum Emission, and Multi-epoch Emission from Methanol, Water, and Ammonia Masers

2021 ◽  
Vol 923 (2) ◽  
pp. 263
Author(s):  
A. P. M. Towner ◽  
C. L. Brogan ◽  
T. R. Hunter ◽  
C. J. Cyganowski
Keyword(s):  
Milky Way ◽  
Thermal Emission ◽  
Young Stellar Objects ◽  
Continuum Emission ◽  
Large Array ◽  
Spectral Indices ◽  
Physical Processes ◽  
Stellar Objects ◽  
Maser Emission ◽  
Very Large Array

Abstract We have observed a sample of nine Extended Green Objects (EGOs) at 1.3 and 5 cm with the Very Large Array (VLA) with subarcsecond resolution and ∼7–14 μJy beam−1-sensitivities in order to characterize centimeter continuum emission as it first appears in these massive protoclusters. We find an EGO-associated continu um emission—within 1″ of the extended 4.5 μm emission—in every field, which is typically faint (order 101–102 μJy) and compact (unresolved at 0″.3–0″.5). The derived spectral indices of our 36 total detections are consistent with a wide array of physical processes, including both non-thermal (19% of detections) and thermal free–free processes (e.g., ionized jets and compact H ii regions, 78% of sample) and warm dust (1 source). We also find an EGO-associated 6.7 GHz CH3OH and 22 GHz H2O maser emission in 100% of the sample and a NH3 (3,3) masers in ∼45%; we do not detect any NH3 (6,6) masers at ∼5.6 mJy beam−1 sensitivity. We find statistically-significant correlations between L radio and L bol at two physical scales and three frequencies, consistent with thermal emission from ionized jets, but no correlation between L H 2 O and L radio for our sample. From these data, we conclude that EGOs likely host multiple different centimeter continuum-producing processes simultaneously. Additionally, at our ∼1000 au resolution, we find that all EGOs except G18.89−0.47 contain 1 ∼ 2 massive sources based on the presence of CH3OH maser groups, which is consistent with our previous work suggesting that these are typical massive protoclusters, in which only one to a few of the young stellar objects are massive.

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 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 The Observational Evidence for Accretion

1997 ◽  
Vol 182 ◽  
pp. 391-405 ◽  
Author(s):  
Lee Hartmann
Keyword(s):  
Large Range ◽  
Observational Evidence ◽  
Young Stars ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
T Tauri ◽  
Accretion Rates ◽  
Low Mass ◽  
Stellar Magnetospheres ◽  
Mass Ejection

Outflows from low-mass young stellar objects are thought to draw upon the energy released by accretion onto T Tauri stars. I briefly summarize the evidence for this accretion and outline present estimates of mass accretion rates. Young stars show a very large range of accretion rates, and this has important implications for both mass ejection and for the structure of stellar magnetospheres which may truncate T Tauri disks.

Submillimeter CO Spectroscopy of Low Mass Young Stellar Objects

1995 ◽  
pp. 117-120
Author(s):  
K. F. Schuster ◽  
A. P. G. Russell ◽  
A. I. Harris
Keyword(s):  
Young Stellar Objects ◽  
Stellar Objects ◽  
Low Mass

scholarly journals Orbital Motions in Binary Protostellar Systems

2004 ◽  
Vol 191 ◽  
pp. 92-99
Author(s):  
L.F. Rodríguez
Keyword(s):  
Nuclear Reactions ◽  
Molecular Complexes ◽  
Close Approach ◽  
Young Star ◽  
Double Star ◽  
Large Array ◽  
Very Large Array ◽  
Low Mass ◽  
Third Law ◽  
The Masses

AbstractUsing high-resolution (~ 01), multi-epoch Very Large Array observations, we have detected orbital motions in several low-luminosity protobinary systems in the Taurus and ρ Ophiuchus molecular complexes. The masses obtained from Kepler’s third law are of the order of 0.5 to 2 M⊙, as expected for such low-mass protostars. The relatively large bolometric luminosities of these young systems corroborates the notion that protostars obtain most of their luminosity from accretion and not from nuclear reactions. In addition, in one of the sources studied (a multiple system in Taurus), a low-mass young star has shown a drastic change in its orbit after a close approach with another component of the system, presumed to be a double star. The large proper motion achieved by this low mass protostar (20 km s−1), suggests an ejection from the system.

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