A Search for Water Maser Emission from Brown Dwarfs and Low-luminosity Young Stellar Objects

We report the first detection of vibrationally excited water maser emission in the circumstellar envelope of two young stellar objects (W51M, Z CMa). The results suggest that the observed 96 GHz water maser emission traces hot gas in an accretional stage of the protostellar evolution.

Download Full-text

Long-term study of water maser emission associated with young stellar objects

Astronomy and Astrophysics ◽

10.1051/0004-6361:20011631 ◽

2002 ◽

Vol 383 (1) ◽

pp. 244-266 ◽

Cited By ~ 21

Author(s):

R. Valdettaro ◽

F. Palla ◽

J. Brand ◽

R. Cesaroni ◽

G. Comoretto ◽

...

Keyword(s):

Young Stellar Objects ◽

Term Study ◽

Stellar Objects ◽

Maser Emission ◽

Long Term Study ◽

Water Maser

Download Full-text

Erratum: “Water Maser Survey toward Low‐Mass Young Stellar Objects in the Northern Sky with the Nobeyama 45 Meter Telescope and the Very Large Array” (ApJS, 144, 71 [2003])

The Astrophysical Journal Supplement Series ◽

10.1086/516825 ◽

2007 ◽

Vol 171 (1) ◽

pp. 349-351 ◽

Cited By ~ 3

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

Download Full-text

A collimated jet and an infalling-rotating disk in G192 traced by H2O maser emission

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307013324 ◽

2007 ◽

Vol 3 (S242) ◽

pp. 340-341

Author(s):

Hiroshi Imai ◽

Toshihiro Omodaka ◽

Tomoya Hirota ◽

Tomofumi Umemoto ◽

Kazuo Sorai ◽

...

Keyword(s):

Spatial Distribution ◽

Massive Star ◽

Rotating Disk ◽

Stellar Mass ◽

Young Stellar Objects ◽

Proper Motions ◽

Stellar Objects ◽

Maser Emission ◽

Star Forming ◽

Bulk Motion

AbstractWe present H2O masers associated with the massive-star forming region G192 observed with the Japan VLBI network since the year 2005, The spatio-kinematical structure of the maser feature clusters has well persisted since previous observations, in which the masers are associated with two young stellar objects (YSOs) separated by ~1200 AU and expected to be associated with a highly-collimated bipolar jet and an infalling-rotating disk in the northern and southern YSOs, respectively. We estimated a jet speed of ~100 km s−1 and re-estimated a dynamical age of the whole jet to be 5.6×104 years. The spatial distribution of maser Doppler velocities found during the previous and present observations, relative proper motions of H2O maser features in the southern cluster found in the present observations, a relative bulk motion between the two maser clusters are well explained by a model of an infalling-rotating disk with a radius of ~1000 AU and a central stellar mass of ~8 M⊙.

Download Full-text

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

The Astrophysical Journal Supplement Series ◽

10.1086/342749 ◽

2003 ◽

Vol 144 (1) ◽

pp. 71-134 ◽

Cited By ~ 103

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

Download Full-text

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

The Astrophysical Journal ◽

10.3847/1538-4357/ac2c86 ◽

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.

Download Full-text

Giant burst of methanol maser in S255IR-NIRS3

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833443 ◽

2018 ◽

Vol 617 ◽

pp. A80 ◽

Cited By ~ 18

Author(s):

M. Szymczak ◽

M. Olech ◽

P. Wolak ◽

E. Gérard ◽

A. Bartkiewicz

Keyword(s):

Sampling Interval ◽

Young Stellar Objects ◽

High Mass ◽

Stellar Objects ◽

Maser Emission ◽

Methanol Maser ◽

Star Evolution ◽

Average Sampling ◽

Methanol Masers ◽

Observational Signature

Context. High-mass young stellar objects (HMYSOs) can undergo accretion episodes that strongly affect the star evolution, the dynamics of the disk, and its chemical evolution. Recently reported extraordinary bursts in the methanol maser emission may be the observational signature of accretion events in deeply embedded HMYSOs. Aims. We analyze the light curve of 6.7 GHz methanol masers in S255IR-NIRS3 during the 2015–2016 burst. Methods. 8.5-yr monitoring data with an average sampling interval of 5 days were obtained with the Torun 32 m radio telescope. Archival data were added, extending the time series to ~27 yr. Results. The maser emission showed moderate (25–30%) variability on timescales of months to years over ~23 yr since its discovery. The main burst was preceded by a 1 yr increase of the total flux density by a factor of 2.5, then it grew by a factor of 10 over ~0.4 yr and declined by a factor of 8 during the consecutive 2.4 yr. The peak maser luminosity was a factor of 24.5 higher than the pre-burst quiescent value. The light curves of individual features showed considerable diversity but indicated a general trend of suppression of the maser emission at blueshifted (<4.7 km s−1) velocities when the redshifted emission rapidly grew and new emission features appeared at velocities >5.8 km s−1. This new emission provided a contribution of about 80% to the maser luminosity around the peak of the burst. The duration of the burst at the extreme redshifted velocities of 7.1–8.7 km s−1 was from 0.9 to 1.9 yr, and its lower limit for the other features was ~3.9 yr. Conclusions. The onset of the maser burst exactly coincides with that of the infrared burst estimated from the motion of the light echo. This strongly supports the radiative pumping scheme of the maser transition. The growth of the maser luminosity is the result of an increasing volume of gas where the maser inversion is achieved.

Download Full-text

Distance and Maser Outflows of the Galactic Star-forming Region W51 Main/South

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312007454 ◽

2012 ◽

Vol 8 (S287) ◽

pp. 423-424 ◽

Cited By ~ 1

Author(s):

Mayumi Sato ◽

Mark J. Reid ◽

Andreas Brunthaler ◽

Karl M. Menten

Keyword(s):

Massive Star ◽

Young Stellar Objects ◽

Small Range ◽

Stellar Objects ◽

Maser Emission ◽

Star Forming ◽

Star Forming Regions ◽

Long Baseline ◽

Trigonometric Parallax ◽

Very Long Baseline Array

AbstractWe report on high-resolution astrometry of 22 GHz H2O maser emission in the Galactic massive star-forming region W51 Main/South using the Very Long Baseline Array. We measured the trigonometric parallax of W51 Main/South to be 0.185 ± 0.010 mas, corresponding to a distance of 5.41+0.31−0.28 kpc. The H2O maser emission in W51 Main/South traces four powerful bipolar outflows within a 0.4 pc size region, three of which are associated with dusty molecular hot cores and/or hyper- or ultra-compact Hii regions. The maser outflows in W51 Main/South have a relatively small range of internal 3D speeds, suggesting that multiple speed maser outflows in other Galactic massive star-forming regions may come from separate young stellar objects closely spaced on the sky.

Download Full-text

A study of radial self-similar non-relativistic MHD outflow models: parameter space exploration and application to the water fountain W43A

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3660 ◽

2020 ◽

Vol 501 (2) ◽

pp. 2071-2090

Author(s):

C Ceccobello ◽

M H M Heemskerk ◽

Y Cavecchi ◽

W H T Vlemmings ◽

D Tafoya

Keyword(s):

Young Stellar Objects ◽

Parameter Study ◽

Rotating Disc ◽

Stellar Objects ◽

Global Properties ◽

Wide Range ◽

Astrophysical Objects ◽

Self Similar ◽

Water Maser

ABSTRACT Outflows, spanning a wide range of dynamical properties and spatial extensions, have now been associated with a variety of accreting astrophysical objects, from supermassive black holes at the core of active galaxies to young stellar objects. The role of such outflows is key to the evolution of the system that generates them, for they extract a fraction of the orbiting material and angular momentum from the region close to the central object and release them in the surroundings. The details of the launching mechanism and their impact on the environment are fundamental to understand the evolution of individual sources and the similarities between different types of outflow-launching systems. We solve semi-analytically the non-relativistic, ideal, magnetohydrodynamics equations describing outflows launched from a rotating disc threaded with magnetic fields using our new numerical scheme. We present here a parameter study of a large sample of new solutions. We study the different combinations of forces that lead to a successfully launched jet and discuss their global properties. We show how these solutions can be applied to the outflow of the water fountain W43A for which we have observational constraints on magnetic field, density and velocity of the flow at the location of two symmetrical water maser emitting regions.

Download Full-text

Multi-epoch water maser survey towards low-mass YSOs

Symposium - International Astronomical Union ◽

10.1017/s0074180900222018 ◽

2002 ◽

Vol 206 ◽

pp. 35-38 ◽

Cited By ~ 1

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.

Download Full-text