「宇宙の間欠泉」から新たに出現した
双極高速ジェットからの同時噴出ガス塊
今井 裕, 宇野友理, 前山大地, 山口諒祐, 甘田 渓, 濱江勇希(鹿児島大学),
Ross Burns(国立天文台), Gabor Orosz (タスマニア大学),
José Francisco Gómez (スペイン高等学術研究院),
Daniel Tafoya (オンサラ天文台), Lucero Uscanga(メキシコ自治大学)

2019年度VLBI懇談会シンポジウム
＠大妻女子大学 2019年11月23日

Water fountains
Fast bipolar jets from dying stars traced by H2O masers
CO J=2→1 (70 — 110 km/s)
CO J=2→1 (-110 — -70 km/s)
H2O masers (<90 km/s)
230 GHz dust continuum

W43A
ALMA’sbeam

Jet’s dynamical age: t~50 years
Periodic eruptions in 7 year cycle?
Faster jet bullets with deceleration?

Image with ALMA+VLBA (Tafoya, Imai et al. in prep.)FLASHING
Finest Legacy Acquisitions of SiO- and H2O-maser
Ignitions by Nobeyama Generation
Using Nobeyama 45-m telescope+ Perforated frequency separation filter plate(Okada et al. 2020, PASJ) developed by HINOTORI(Hybrid Installation Project in Nobeyama, Triple-band Oriented)

Conducted as a Backup Program during
2018 December—2019 May (~260 hours)
Towards 17(+2) water fountains and candidates
3—14 observation sessions per source
Velocity resolution: 0.42 km/s (H2O) and 0.22 km/s (SiO)
Velocity coverage: 1258 km/s (H2O)
Follow-up VLBI target-of-opportunity observations soon after
new ignitions of highest velocity H2O maser components
Will be registered in M2O (maser monitoring organization)

Science goals of FLASHING
Monitoring 17 water fountains and candidates
Flux periodicity caused by stellar pulsation(1—5 years)
Permanent death, evolving to a planetarynebula (~10 years)
Recurrent outbursts caused by interactions
in a binary system with a large eccentricity(>5 years)
Line-of-sight velocity drifts caused by jetdeceleration

Very long time-baseline/domain astronomy
2019 December—2020 March (~120 hours) awarded

Before ignitions of the highest velocity
H2O maser components
Systemic velocity(~50 km/s)

IRAS 18286-0959
Imai et al. (2020, PASJ VERA Special Issue)

New ignitions of the highest velocity
H2O maser components

Systemic velocity(~50 km/s)-160-80080
LSR velocity [km/s]

160240IRAS 18286-0959
Imai et al. (2020, PASJ VERA Special Issue)

New ignitions of the highest velocity
H2O maser components-160-80080
LSR velocity [km/s]

160

Imai et al. (2020, PASJ VERA Special Issue)

240

KaVA ToO
follow-up
Epoch: 2019 March 4for 6 hours
Participating telescopes:
4 VERA and 3 KVN antennas in LHCP
1Gbps recording —> Velocity coverage 1727 km/s
4096 channels —> Velocity resolution 0.42 km/s
Synthesized beam: 2.1x1.4 mas, P.A.=-18 deg.
1-σ noise level: ~20 mJy/beam
Maser spot identification: > 7-σ noise level3b50

1aLSR velocity (km s-1)

1b100+2a003a-200-100-100-50

5aImai et al. (2020, PASJ VERA Special Issue)

0-100

R.A. offset (mas)-150

Decl. offset (mas)1002b4aMapped with KaVA(KVN and VERA Combined Array)on 2019 March 6200

5b 4b150

200

Highest velocity jet before
deceleration
Point symmetric pattern of maser
distribution in a ~3.5 year spacing

250

Localization of the highest velocity
H2O maser components

Decadal jet evolution
Clockwise precession andlobe expansion of the bipolar jet
Dynamical age ~30 years
New maser ignition after 2011
Short-lived (t<1 month) spots before 2011?
Previous maser ignition before 2006?

Jet deceleration from 300 km/s to 110
km/s so as to mix with entrainedmaterial in ~3.5 years(?)⇩Velocity drift over ~10 km/s/yr!

Imai et al. (2020, PASJ VERA Special Issue)

Acknowledgements

Very thanks toNobeyama Radio Observatory(Development Proposal 4171001)
Mizusawa VLBI Observatory
KVN/KASI
AGARC, Kagoshima University
FLASHING TeamKAKENHI grant-in-aid
16H02167 (P.I. Hiroshi Imai)NAOJ Development Program
P.I. Takeshi Manabe (FY2016, FY2017)