J/AJ/168/53 Proper motion properties of H2O maser spots in VX Sgr (Yoon+, 2024)
Investigating Asymmetry Development from SiO to H2O Maser Regions in
VX Sagittarii.
Yoon D.-H., Cho S.-H., Yun Y., Yang H., Kim J.
<Astron. J., 168, 53 (2024)>
=2024AJ....168...53Y 2024AJ....168...53Y
ADC_Keywords: Stars, supergiant; Radio sources; Radial velocities;
Proper motions
Keywords: Circumstellar masers ; Red supergiant stars ; Silicon monoxide
masers ; Water masers ; Circumstellar envelopes ; Radio
astrometry ; Single-dish antennas ; Very long baseline
interferometry ; Radio astronomy ; Stellar mass loss ;
Asymptotic giant branch stars ; Evolved stars
Abstract:
Simultaneous very-long-baseline interferometry monitoring observations
of H2O and SiO masers toward VX Sagittarii were conducted from 2014
February to 2019 January. Thirty epochs of observations revealed that
the H2O and SiO masers had asymmetric and ring-like structures,
respectively. However, from 2017 September to 2018 March, the SiO
maser transformed from a ring-like structure to a northeast-southwest
(NE-SW) extension, and the 43.1 and 86.2GHz SiO maser components had
velocities of 39.48 and 10.65km/s in the NE-SW direction, suggesting a
possible localized strong shock wave. The H2O maser had a double-sided
structure oriented in the NE-SW direction with near-stellar velocity
components, which aligned with the extended direction of the SiO
maser. The nonregular optical brightness and maser intensity
variations were speculated to be related to the morphological
evolution of the SiO maser. During the stable states attained by
regular pulsations, the SiO maser region was presumed to experience
radial acceleration, which reverted the SiO maser to a ring-like
structure. However, the H2O maser region, where the acceleration
almost terminates, retained its asymmetric morphology due to the prior
influence of external forces. The results suggest that substantial
energy transfer can alter the dynamics of the SiO maser and
surrounding atmosphere, leading to an asymmetric distribution in the
H2O maser region.
Description:
Simultaneous VLBI monitoring observations of H2O 616-523
(22.235080GHz), SiO v=1,2, J=1-0, SiO v=1, J=2-1,3-2 (43.122080,
42.820587, 86.243442, and 129.363359GHz) maser lines toward VX Sgr
were conducted using the KVN.
Objects:
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RA (2000) DE Designation(s)
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18 08 04.04 -22 13 26.6 VX Sagitarii = V* VX Sgr
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table6.dat 54 142 Proper motion properties of H2O maser spots
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See also:
B/gcvs : General Catalogue of Variable Stars (Samus+, 2007-2017)
J/A+AS/93/121 : CO emission from a sample of IRAS sources (Nyman+ 1992)
J/ApJ/640/982 : 43GHz SiO maser features around VX Sgr (Chen+, 2006)
J/A+A/546/A16 : 22-GHz water maser clouds (Richards+, 2012)
J/A+A/565/A127 : SiO masers v=1,2,3 for 4 AGB (Desmurs+, 2014)
J/A+A/561/A47 : 8.1um SiO spectra of cool evolved stars (Ohnaka, 2014)
Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- NumID [1/142] Number identifier
5- 10 F6.2 km/s RVel [-14.28/24.06] Radial velocity
12- 18 F7.2 mas RA-17 [-132/133] 2017 September 14th Right ascension
in mas
20- 26 F7.2 mas DE-17 [-120/138] 2017 September 14th declination in mas
28- 34 F7.2 mas RA-18 [-133/135] 2018 January31 right ascension in mas
36- 42 F7.2 mas DE-18 [-121/140] 2018 January 31 declination in mas
44- 48 F5.2 mas/yr pmRA [-3.48/3.57] Proper motion in right ascension
50- 54 F5.2 mas/yr pmDE [-2.46/3.16] Proper motion in declination
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 26-Aug-2024