The Arcetri Catalog of H<sub>2O</sub> maser sources: Update 2000

Valdettaro, R.; Palla, F.; Brand, J.; Cesaroni, R.; Comoretto, G.; Franco, S.; Felli, M.; Natale, E.; Palagi, F.; Panella, D.; Tofani, G.

doi:10.1051/0004-6361:20000526

Cited by 114 publications

(139 citation statements)

References 20 publications

Supporting

Mentioning

127

Contrasting

Order By: Relevance

“…Walsh et al (1998) reported methanol maser emission located approximately 45 ′′ toward the southwest of the radio source and probably not directly related to it. Water maser activity has also been detected toward this source (Valdettaro et al 2001). …”

Section: G009mentioning

confidence: 82%

Search for Ionized Jets Toward High-Mass Young Stellar Objects

Guzmán

Garay

Brooks

et al. 2012

ApJ

View full text Add to dashboard Cite

We are carrying out multi-frequency radio continuum observations, using the Australia Telescope Compact Array, to systematically search for collimated ionized jets towards high-mass young stellar objects (HMYSOs). Here we report observations at 1.4, 2.4, 4.8 and 8.6 GHz, made with angular resolutions of about 7 ′′ , 4 ′′ , 2 ′′ , and 1 ′′ , respectively, towards six objects of a sample of 33 southern HMYSOs thought to be in very early stages of evolution. The objects in the sample were selected from radio and infrared catalogs by having positive radio spectral indices and being luminous (L bol > 2 × 10 4 L ⊙ ), but underluminous in radio emission compared to that expected from its bolometric luminosity. This criteria makes the radio sources good candidates for being ionized jets. As part of this systematic search, two ionized jets have been discovered: one previously published and the other reported here. The rest of the observed candidates correspond to three hypercompact H II regions and two ultracompact H II regions. The two jets discovered are associated with two of the most luminous (7 × 10 4 and 1.0 × 10 5 L ⊙ ) HMYSOs known to harbor this type of objects, showing that the phenomena of collimated ionized winds appears in the formation process of stars at least up to masses of ∼ 20 M ⊙ and provides strong evidence for a disk-mediated accretion scenario for the formation of high-mass stars. From the incidence of jets in our sample, we estimate that the jet phase in high-mass protostars lasts for ∼ 4 × 10 4 yr.

show abstract

Section: G009mentioning

confidence: 82%

Search for Ionized Jets Toward High-Mass Young Stellar Objects

Guzmán

Garay

Brooks

et al. 2012

ApJ

View full text Add to dashboard Cite

show abstract

“…Furthermore, several 1.2 mm continuum sources coincide with OH, H 2 O, and/or CH 3 OH maser sources (e.g. Braz & Epchtein 1983;Valdettaro et al 2001;Pestalozzi et al 2005). Most of these dense cores are associated with centimeter continuum and/or mid-infrared emission, but one (CygX-N53) is neither a centimeter nor a MSX source.…”

Section: Coincidence With Radio Free-free and Maser Emissionmentioning

confidence: 95%

The earliest phases of high-mass star formation: a 3 square degree millimeter continuum mapping of Cygnus X

Motte

Bontemps

Schilke

et al. 2007

A&A

327

722

View full text Add to dashboard Cite

Aims. Our current knowledge of high-mass star formation is mainly based on follow-up studies of bright sources found by IRAS, and is thus biased against its earliest phases, inconspicuous at infrared wavelengths. We therefore started searching, in an unbiased way and in the closest high-mass star-forming complexes, for the high-mass analogs of low-mass pre-stellar cores and class 0 protostars. Methods. We have made an extensive 1.2 mm continuum mosaicing study of the Cygnus X molecular cloud complex using the MAMBO cameras at the IRAM 30 m telescope. The ∼ 3 • 2 imaged areas cover all the high-column density (A V ≥ 15 mag) clouds of this nearby (∼ 1.7 kpc) cloud complex actively forming OB stars. We then compared our millimeter maps with mid-infrared images, and have made SiO(2-1) follow-up observations of the best candidate progenitors of high-mass stars. Results. Our complete study of Cygnus X with ∼ 0.09 pc resolution provides, for the first time, an unbiased census of massive young stellar objects. We discover 129 massive dense cores (FWHM size ∼ 0.1 pc, M 1.2 mm = 4 − 950 M ⊙ , volume-averaged density ∼ 10 5 cm −3 ), among which ∼ 42 are probable precursors of high-mass stars. A large fraction of the Cygnus X dense cores (2/3 of the sample) remain undetected by the MSX satellite, regardless of the mass range considered. Among the most massive (> 40 M ⊙ ) cores, infrared-quiet objects are driving powerful outflows traced by SiO emission. Our study qualifies 17 cores as good candidates for hosting massive infrared-quiet protostars, while up to 25 cores potentially host high-luminosity infrared protostars. We fail to discover in the high-mass analogs of pre-stellar dense cores (∼ 0.1 pc, > 10 4 cm −3 ) in Cygnus X, but find several massive starless clumps (∼ 0.8 pc, 7 × 10 3 cm −3 ) that might be gravitationally bound. Conclusions. Since our sample is derived from a single molecular complex and covers every embedded phase of high-mass star formation, it gives the first statistical estimates of their lifetime. In contrast to what is found for low-mass class 0 and class I phases, the infrared-quiet protostellar phase of high-mass stars may last as long as their better-known high-luminosity infrared phase. The statistical lifetimes of high-mass protostars and pre-stellar cores (∼ 3 × 10 4 yr and < 10 3 yr) in Cygnus X are one and two order(s) of magnitude smaller, respectively, than what is found in nearby, low-mass star-forming regions. We therefore propose that high-mass pre-stellar and protostellar cores are in a highly dynamic state, as expected in a molecular cloud where turbulent processes dominate.

show abstract

“…The observed sources are listed in Palla et al (1991), Valdettaro et al (2001), Wouterloot et al (1993), Henning et al (1992), and Medicina archival data.…”

Section: Observed Sources and Detection Summarymentioning

confidence: 99%

“…These are: 06291+0421, 17582-2234 and 19045+0813, among the sources detected in the H 2 O maser, and 17571-2328 and 19186+1440 (see Tables B.2 and B.3) among those detected in the CH 3 OH masers. V sys for the H 2 O maser detections was taken from ammonia measurements (Molinari et al 1996;Valdettaro et al 2001). For spectra with multiple lines we adopted as V maser that of the peak.…”

Section: Velocity Ranges In Class I and Class Ii Masersmentioning

confidence: 99%

Class I and Class II methanol masers in high-mass star-forming regions

Fontani¹,

Cesaroni

Furuya

2010

A&A

Self Cite

103

View full text Add to dashboard Cite

Context. Among the tracers of the earliest phases in the massive star formation process, methanol masers have gained increasing importance. The phenomenological distinction between Class I and II methanol masers is based on their spatial association with objects such as jets, cores, and ultracompact Hii regions, but is also believed to correspond to different pumping mechanisms: radiation for Class II masers, collisions for Class I masers. Aims. We surveyed a large sample of massive star-forming regions in Class I and II methanol masers. The sample consists of 296 sources, divided into two groups named high and low according to their and [60-12] IRAS colours. Previous studies indicate that the two groups may contain similar sources in different evolutionary stages, with the high sources representing the more evolved stages. Therefore, the sample can be used to assess a sequence for the occurrence of Class I and II methanol masers during the evolution of a massive star-forming region. Methods. We observed the 6 GHz (Class II) CH 3 OH maser with the Effelsberg 100-m telescope, and the 44 GHz and 95 GHz (Class I) CH 3 OH masers with the Nobeyama 45-m telescope. Results. We detected 55 sources in the Class II line (39 high and 16 low, 12 new detections); 27 sources in the 44 GHz Class I line (19 high and 8 low, 17 new detections); 11 sources in the 95 GHz Class I line (eight high and three low, all except one are new detections). The detection rate of Class II masers decreases with the distance of the source (as expected), whereas that of Class I masers peaks at ∼5 kpc. This could be due to the Class I maser spots being spread over a region < ∼ 1 pc, comparable to the telescope beam diameter at a distance of ∼5 kpc. We also find that the two Class I lines have similar spectral shapes at 44 GHz and 95 GHz, which confirms that they have the same origin.Conclusions. Our statistical analysis shows that the ratio between the detection rates of Class II and Class I methanol masers is basically the same in high and low sources. Therefore, both maser types seem to be equally associated with each evolutionary phase. In contrast, all maser species (including H 2 O) have about three times higher detection rates in high than in low sources. This could indicate that the phenomena from which all masers originate become progressively more active with time during the earliest evolutionary phases of a high-mass star-forming region.

show abstract

The Arcetri Catalog of H_2O maser sources: Update 2000

Cited by 114 publications

References 20 publications

Search for Ionized Jets Toward High-Mass Young Stellar Objects

Search for Ionized Jets Toward High-Mass Young Stellar Objects

The earliest phases of high-mass star formation: a 3 square degree millimeter continuum mapping of Cygnus X

Class I and Class II methanol masers in high-mass star-forming regions

Contact Info

Product

Resources

About

The Arcetri Catalog of H2O maser sources: Update 2000

Cited by 114 publications

References 20 publications

Search for Ionized Jets Toward High-Mass Young Stellar Objects

Search for Ionized Jets Toward High-Mass Young Stellar Objects

The earliest phases of high-mass star formation: a 3 square degree millimeter continuum mapping of Cygnus X

Class I and Class II methanol masers in high-mass star-forming regions

Contact Info

Product

Resources

About

The Arcetri Catalog of H_2O maser sources: Update 2000