J/A+A/673/A60 Water maser super-flare G25.65+1.04 (Bayandina+, 2023)
Nature of continuum emission in the source of the water maser
super-flare G25.65+1.04.
Bayandina O.S., Burns R.A., Kurtz S.E., Moscadelli L., Sobolev A.M.,
Stecklum B., Val'tts I.E.
<Astron. Astrophys. 673, A60 (2023)>
=2023A&A...673A..60B 2023A&A...673A..60B (SIMBAD/NED BibCode)
ADC_Keywords: Star Forming Region ; Masers ; Radio sources
Keywords: stars: formation - masers - stars: individual: G25.65+1.04
Abstract:
G25.65+1.04 is one of a few known "super-flare" water masers in the
Milky Way, but in contrast to the other sources of the sample, it
remains the least studied; in fact, even the nature of the source
driving the water maser is still unclear. With this project, we aim to
clarify the composition and properties of the G25.65+1.04 region by
means of examining the parameters of the continuum sources and
establishing their association with masers of different types. Our
previous VLA observation detected four continuum peaks (VLA 1-4),
three of which (VLA 1-3) were closely spaced and presented a linear
orientation. However, that VLA B-configuration observation lacked the
spatial resolution to resolve the individual sources. A higher
resolution (A-configuration) VLA observation of continuum and spectral
lines was conducted in 2019 using L, S, C, and Ku-bands. For the first
time, the continuum source VLA 1 - associated with the flaring water
maser - is resolved into two components - VLA 1A and 1B. VLA 1A and
the water maser are found to spatially coincide and are thought to be
powered by the same source - a protostar at an early stage of
evolution, showing active ejection. We argue that VLA 2 pinpoints an
activly ejecting high-mass protostar as it is associated with a 6.7GHz
methanol maser and a magnetised jet traced by 22GHz H2O maser.
Highly polarised OH maser emission is detected in the vicinity of VLA
1-2, with the brightest OH maser found in VLA 2. The magnetic field,
identified from the OH maser emission, ranges from ~+0.4mG in VLA 1A
to ~-8mG in VLA 2. The G25.65+1.04 region is found to consist of at
least two young stellar objects: VLA 1A and VLA 2. Both sources are
found to be at an active accretion/ejection stage of evolution.
Description:
Position, integrated and peak flux density, and velocity of each of
the detected 6.7GHz methanol maser spots are listed. Note that we use
the term "maser spots" to refer to maser emissions detected in a
single velocity channel of a data cube.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 73 97 6.7GHz CH3OH maser parameters
table5.dat 75 235 1665 and 1667MHz OH maser parameters
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See also:
J/ApJ/884/140 : VLA obs. of the H2O maser source G25.65+1.05
(Bayandina+, 2019)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- Group Group name (S, NE or NW)
4- 5 I2 h RAh Right ascension (J2000)
7- 8 I2 min RAm Right ascension (J2000)
10- 16 F7.4 s RAs Right ascension (J2000)
18- 23 F6.4 s e_RAs Uncertainty in right ascension
25 A1 --- DE- Declination sign (J2000)
26- 27 I2 deg DEd Declination (J2000)
29- 30 I2 arcmin DEm Declination (J2000)
32- 37 F6.3 arcsec DEs Declination (J2000)
39- 44 F6.4 arcsec e_DEs Uncertainty in declination
45- 50 F6.2 Jy Fint Integrated flux at 6.7GHz
52- 55 F4.2 Jy e_Fint Uncertainty in Fint
57- 62 F6.2 Jy/beam Fpeak Peak flux at 6.7GHz
64- 67 F4.2 Jy/beam e_Fpeak Uncertainty in Fpeak
69- 73 F5.2 km/s Vel Velocity
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 4 I4 MHz Freq [1665/1667] OH transition frequency
6 A1 --- Pol [RL] Polarisation
8- 9 I2 h RAh Right ascension (J2000)
11- 12 I2 min RAm Right ascension (J2000)
14- 20 F7.4 s RAs Right ascension (J2000)
22- 27 F6.4 s e_RAs Uncertainty in right ascension
29 A1 --- DE- Declination sign (J2000)
30- 31 I2 deg DEd Declination (J2000)
33- 34 I2 arcmin DEm Declination (J2000)
36- 41 F6.3 arcsec DEs Declination (J2000)
43- 47 F5.3 arcsec e_DEs Uncertainty in declination
49- 53 F5.2 Jy Fint Integrated flux at Freq
55- 58 F4.2 Jy e_Fint Uncertainty in Fint
60- 64 F5.2 Jy/beam Fpeak Peak flux at Freq
66- 69 F4.2 Jy/beam e_Fpeak Uncertainty in Fpeak
71- 75 F5.2 km/s Vel Velocity
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Acknowledgements:
Olga Bayandina, olga.bayandina(at)inaf.it
(End) Olga Bayandina [INAF, Italy], Patricia Vannier [CDS] 10-Mar-2023