2021A&A...647A..23H


Query : 2021A&A...647A..23H

2021A&A...647A..23H - Astronomy and Astrophysics, volume 647A, 23-23 (2021/3-1)

Water maser variability in a high-mass YSO outburst. VERA and ALMA observations of S255 NIRS 3.

HIROTA T., CESARONI R., MOSCADELLI L., SUGIYAMA K., BURNS R.A., KIM J., SUNADA K. and YONEKURA Y.

Abstract (from CDS):


Context. Clarifying the relationship between mass accretion and ejection history is one of the key issues in understanding high-mass star formation processes.
Aims. We aim to investigate the possible relationship between the mass accretion burst event in mid-June 2015 and the jet ejection in the high-mass protostar S255 NIRS 3.
Methods. The Very Long Baseline Interferometer (VLBI) monitoring observations of the 22GHz H2O masers were carried out using VLBI Exploration of Radio Astrometry (VERA) to reveal the 3D velocity and spatial structure of the outflow/jet traced by the H2O masers in S255 NIRS 3. In addition, we conducted follow-up observations of the submillimeter continuum and the 321GHz H2O masers with the Atacama Large Millimeter/submillimeter Array (ALMA) at Band 7.
Results. We successfully measured the proper motions of the 22GHz H2O masers associated with a bipolar outflow. The structure is almost the same as was observed in 2005 and 2010. The expansion velocity of the blueshifted bow shock traced by the 22GHz H2O masers was measured to be 28 km s–1, corresponding to a dynamical timescale of 60 yr. The direction of the maser outflow is slightly tilted compared with the radio jet, which could suggest a more recent ejection episode during the accretion burst event. The total flux density of the 22GHz H2O masers gradually increases from the beginning of the VLBI monitoring in early 2017 and becomes almost constant in subsequent single-dish monitoring in 2018. The brightening of the H2O masers is more prominent in the northeast outflow lobe. For the first time, we revealed extended H2O maser emission at 22GHz in a star-forming region, which is partly resolved out by VERA and even by the most extended Very Large Array (VLA) configurations. We find that the flux variation of such an extended component is similar to that of the unresolved maser emission. The ALMA Band 7 continuum emission did not show significant variations compared with the previous observations performed five months before. We mapped the 321GHz H2O masers in S255 NIRS 3 providing the fourth example, for this maser, of the spatial distribution in a high-mass star-forming region.
Conclusions. We conclude that the bow shock structure traced by the 22GHz H2O maser features is unlikely to originate at the interface between the radio jet powered by the recent accretion outburst and the surrounding medium. The brightening of the 22GHz H2O masers could be due to radiative excitation by photons form the (declining) infrared (IR) outburst escaping along the cavity created by the newly ejected material. The lower ratio of the 22GHz/321GHz maser luminosity in the blueshifted bow shock suggests a temperature (>1000K), higher than for the other maser features in this region.

Abstract Copyright: © ESO 2021

Journal keyword(s): stars: individual: S255 NIRS 3 - stars: massive - stars: protostars - ISM: jets and outflows - masers

Simbad objects: 15

goto Full paper

goto View the references in ADS

Number of rows : 15
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 QSO B0507+179 QSO 05 10 02.36912937 +18 00 41.5815635   20.0 19.0 19.09   ~ 432 1
2 NAME Orion-KL SFR 05 35 14.16 -05 22 21.5           ~ 2291 1
3 [RLK73] IRc 2 IR 05 35 14.51548 -05 22 30.5943           ~ 640 1
4 7C 055201.39+394824.00 Bla 05 55 30.80561419 +39 48 49.1649683     18.30 17.5   ~ 504 2
5 MMB G192.600-00.048 Y*O 06 12 54.0100 +17 59 23.200           ~ 400 0
6 IC 2162 HII 06 13 04.1 +17 58 44           ~ 358 2
7 NVSS J061336+170825 Rad 06 13 36.36008547 +17 08 24.9461742           ~ 23 1
8 4C 14.18 BLL 06 25 45.9222413976 +14 40 19.738875648           ~ 46 2
9 V* VY CMa s*r 07 22 58.3261352189 -25 46 03.194390594 12.01 10.068 8.691 7.938   M5Iae 1103 0
10 [BHC2016] MM1 cor 17 20 53.415 -35 46 57.88           ~ 93 0
11 [BHT2019] G358.93-00.03 MM1 mm 17 43 10.1014 -29 51 45.693           ~ 20 0
12 W 49a BL? 19 10 15.7 +09 06 05           ~ 306 2
13 IRAS 20126+4104 Y*O 20 14 25.8816769656 +41 13 36.879427236           B2.5-B0.5 440 0
14 LDN 1204A HII 22 21 26.68 +63 51 38.2           ~ 110 0
15 NAME Cepheus A SFR 22 56 17.9 +62 01 49           ~ 738 2

To bookmark this query, right click on this link: simbad:objects in 2021A&A...647A..23H and select 'bookmark this link' or equivalent in the popup menu