scholarly journals Observations of water maser sources at Arcetri

2002 ◽  
Vol 206 ◽  
pp. 39-42
Author(s):  
Giovanni Comoretto ◽  
Riccardo Valdettaro ◽  
Francesco Palla ◽  
Jan Brand ◽  
Riccardo Cesaroni ◽  
...  
Keyword(s):  
Time Variability ◽  
Star Forming ◽  
Star Forming Regions ◽  
Global Properties ◽  
Spectral Components ◽  
Water Masers ◽  
Variability Study ◽  
Maser Sources ◽  
Water Maser ◽  
Nominal Position

We present the current activity of the Arcetri group in the field of water masers. This is mainly represented by observations with the Medicina radiotelescope, whose main outcome has been the compilation of the Arcetri Catalog and the study of time variability of selected sources. The Arcetri Catalog update reports the results of the observations carried out from January 1993 to April 2000 on a sample of 300 sources. The global properties of the complete Arcetri Catalog (including Comoretto et al. 1990, and Brand et al. 1994) are discussed. Of the 1013 sources, 937 have an IRAS counterpart within 1 arcmin from the nominal position of the maser. We establish a classification scheme based on the IRAS flux densities which allows to distinguish between water masers associated with star forming regions and late-type stars. The time variability study shows a large variety of behaviors. Generally more luminous sources present less variable emission and spectral components over a wider velocity range.

scholarly journals 22 GHz Water Maser Survey of the Xinjiang Astronomical Observatory

2012 ◽  
Vol 8 (S287) ◽  
pp. 296-297
Author(s):  
Jian-jun Zhou ◽  
Jarken Esimbek ◽  
Gang Wu
Keyword(s):  
Galactic Plane ◽  
Astronomical Observatory ◽  
High Mass ◽  
Mass Star ◽  
Star Forming ◽  
Gas Kinematics ◽  
Star Forming Regions ◽  
Water Masers ◽  
Maser Sources ◽  
Water Maser

AbstractWater masers are good tracers of high-mass star-forming regions. Water maser VLBI observations provide a good probe for studying high-mass star formation and galactic structure. We plan to make a blind survey toward the northern Galactic plane in future years using the 25 m radio telescope of the Xinjiang Astronomical Observatory. We will select some water maser sources discovered in the survey and perform high resolution observations to study the gas kinematics close to high-mass protostars.

scholarly journals Online database of water masers in the star-forming regions: the first results

2021 ◽  
Author(s):  
D. A. Ladeyschikov ◽  
Keyword(s):  
Detection Probability ◽  
Generalized Linear Model ◽  
Physical Parameters ◽  
Online Database ◽  
Star Forming ◽  
Star Forming Regions ◽  
First Results ◽  
Water Masers ◽  
The Moment ◽  
Water Maser

The first results of developing a database of water masers in star-forming regions are presented. The database is stored online at the address http://maserdb.net. The coverage of the database at the time of publication is 84 % of all positive detections of water masers in star-forming regions from the available literature. Preliminary statistical analysis of the data and study of the association between water masers and ATLASGAL 870 μm sources was carried out. A relation was obtained from the generalized linear model to estimate water maser detection probability depending on the physical parameters of clumps from the ATLASGAL catalogue. According to estimates, only ∼25 % of the total number of water masers towards ATLASGAL sources has been detected at the moment.

scholarly journals Twenty-six-year monitoring of water masers

2007 ◽  
Vol 3 (S242) ◽  
pp. 330-331
Author(s):  
G. M. Rudnitskij ◽  
M. I. Pashchenko ◽  
V. F. Esipov ◽  
V. A. Samodurov ◽  
I. A. Subaev ◽  
...  
Keyword(s):  
Time Lag ◽  
Variable Stars ◽  
Late Type ◽  
Star Forming ◽  
Star Forming Regions ◽  
Type Variable ◽  
Water Masers ◽  
Velocity Drift ◽  
Maser Sources ◽  
Visual Light

AbstractSince 1980 variability of a sample of H2O maser sources has been monitored on the 22-metre radio telescope in Pushchino, Russia. The interval between successive observational sessions is 1–2 months. The sample includes 125 maser sources in star-forming regions (SFR) and late-type variable stars. Twenty-six-year time series of H2O line profiles have detected flares and velocity drift of spectral features. Very fast variations in the H2O maser flux (Δt ≲ 1 hour) have been detected in several SFR sources, in particular, W33B. Variations of circumstellar H2O masers in late-type stars correlate with visual light curves with a time lag of 0.3-0.4P (P is the star's period). Exceptionally strong H2O maser flares were recorded in SFR sources (Sgr B2 and others) and in the stars W Hya, R Cas and U Ori. Models for H2O maser variability are reviewed. For stellar masers shock-wave excitation of H2O line variability is discussed.

scholarly journals Millimetre wavelength methanol masers survey towards massive star forming regions

2007 ◽  
Vol 3 (S242) ◽  
pp. 234-235
Author(s):  
T. Umemoto ◽  
N. Mochizuki ◽  
K. M. Shibata ◽  
D.-G. Roh ◽  
H.-S. Chung
Keyword(s):  
Detection Rate ◽  
Massive Star ◽  
Molecular Line ◽  
Maser Emission ◽  
Star Forming ◽  
Methanol Maser ◽  
Physical Conditions ◽  
Star Forming Regions ◽  
Methanol Masers ◽  
Maser Sources

AbstractWe present the results of a mm wavelength methanol maser survey towards massive star forming regions. We have carried out Class II methanol maser observations at 86.6 GHz, 86.9 GHz and 107.0 GHz, simultaneously, using the Nobeyama 45 m telescope. We selected 108 6.7 GHz methanol maser sources with declinations above −25 degrees and fluxes above 20 Jy. The detection limit of maser observations was ~3 Jy. Of the 93 sources surveyed so far, we detected methanol emission in 25 sources (27%) and “maser” emission in nine sources (10%), of which thre “maser” sources are new detections. The detection rate for maser emission is about half that of a survey of the southern sky (Caswell et al. 2000). There is a correlation between the maser flux of 107 GHz and 6.7 GHz/12 GHz emission, but no correlation with the “thermal” (non maser) emission. From results of other molecular line observations, we found that the sources with methanol emission show higher gas temperatures and twice the detection rate of SiO emission. This may suggest that dust evaporation and destruction by shock are responsible for the high abundance of methanol molecules, one of the required physical conditions for maser emission.

scholarly journals Monitoring Water Masers in Star-Forming Regions

2005 ◽  
pp. 133-141
Author(s):  
J. Brand ◽  
R. Cesaroni ◽  
G. Comoretto ◽  
M. Felli ◽  
F. Palagi ◽  
...  
Keyword(s):  
Star Forming ◽  
Star Forming Regions ◽  
Water Masers

VLBI Water Maser Proper Motion Measurements in Star-Forming Regions

2005 ◽  
pp. 53-63
Author(s):  
J.M. Torrelles ◽  
N. Patel ◽  
J.F. Gómez ◽  
G. Anglada ◽  
L. Uscanga
Keyword(s):  
Proper Motion ◽  
Star Forming ◽  
Star Forming Regions ◽  
Motion Measurements ◽  
Water Maser

scholarly journals Masers as probes of proto-planetary discs

2004 ◽  
Vol 202 ◽  
pp. 362-364
Author(s):  
A.M.S. Richards ◽  
R. J. Cohen ◽  
M. Crocker ◽  
E. E. Lekht ◽  
V. Samodourov ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Radio Telescope ◽  
Keplerian Orbit ◽  
Proper Motions ◽  
Central Mass ◽  
Maser Emission ◽  
Star Forming ◽  
Star Forming Regions ◽  
Velocity Variations ◽  
Water Maser

Water maser emission from star forming regions has been monitored for several decades using the Puschino radio telescope, showing radial velocity variations consistent with material in Keplerian orbit around protostars. MERLIN and the EVN are now being used to image the 22 GHz emission on au scales and measure proper motions. This will distinguish discs from outflows, and provide an estimate of the central mass and possibly orbiting condensations.

scholarly journals STATISTICAL ANALYSIS OF WATER MASERS IN STAR-FORMING REGIONS: CEPHEUS A AND W75 N

2010 ◽  
Vol 715 (1) ◽  
pp. 132-142 ◽  
Author(s):  
L. Uscanga ◽  
J. Cantó ◽  
J. F. Gómez ◽  
G. Anglada ◽  
J. M. Torrelles ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Star Forming ◽  
Star Forming Regions ◽  
Water Masers ◽  
Cepheus A

scholarly journals Monitoring Water Masers in Star-Forming Regions

2005 ◽  
Vol 295 (1-2) ◽  
pp. 133-141 ◽  
Author(s):  
J. Brand ◽  
R. Cesaroni ◽  
G. Comoretto ◽  
M. Felli ◽  
F. Palagi ◽  
...  
Keyword(s):  
Star Forming ◽  
Star Forming Regions ◽  
Water Masers

scholarly journals Observations of variability of H2O Maser sources associated with star formation regions

1991 ◽  
Vol 147 ◽  
pp. 482-484
Author(s):  
M. I. Pashchenko ◽  
E. E. Lekht ◽  
I. I. Berulis ◽  
R. L. Sorochenko
Keyword(s):  
Star Formation ◽  
Flux Density ◽  
Time Variability ◽  
Line Profiles ◽  
Maser Emission ◽  
Outstanding Feature ◽  
Star Formation Regions ◽  
Maser Sources ◽  
Water Maser

An outstanding feature of the water maser emission from star formation regions is the strong time variability, which was recognised soon after the discovery of interstellar H2O masers. It is likely that the observed considerable variations of the H2O line profiles as well as of the flux density reflect the disturbancies in the protostellar nebule probably associated with the outflow from the newly formed stars.

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