G25.82-0.17 Jungha Kim (D2/SOKENDAI/NAOJ) Tomoya Hirota, Kee-Tae - - PowerPoint PPT Presentation

Disk+outflow system in G25.82-0.17

Jungha Kim (D2/SOKENDAI/NAOJ) Tomoya Hirota, Kee-Tae Kim, KaVA SWG for star formation EA EAVW 2018 18 @ P Pyeo eongChang gChang

CONTENTS

➤ Introduction ➤ Observations ➤ Results

• KaVA imaging survey at 22 GHz
• Case study toward G25.82-0.17

➤ Future works

INTRODUCTION

HIGH-MASS STAR FORMATION (HMSF)

Fe Feedback ack!! !!

HIGH-MASS STAR FORMATION (HMSF)

HMSF is still far from understanding “OBSERVATIONALLY”

➤ Locations are distant ( > 1

kpc)

➤ Typically occurred in clustered

environments.

➤ Evolutional time scale is

short ( ≲105 yrs). Targets are rare and limited.

LU LUCI I JH JHKs color composit ite image of f W3 Main (B (Bik ik+2012)

D=1 D=1.95 5 kpc (Xu Xu+2 +2006) 06)

HIGH-MASS STAR FORMATION (HMSF)

Evolutionary Sequence of high-mass young stellar objects (HMYSOs) Observational studies to understand HMSF have been done.

Beltrán 2011

DISK-OUTFLOW SYSTEM IN HIGH-MASS STAR FORMATION

➤ High velocity jets/outflows can be traced by resolving 1AU scale

water maser structure to trace motion in milli arc second (mas)/month

➤ Large scale of view (disk+outflow) can be investigated by thermal

line and continuum emission Massive disks and outflow G24.78+0.08

Beltran+2006

Disk in ~103-4 AU scale The inner most part of jet/outflow

MOTIVATIONS

➤ To establish an evolutionary scenario using different maser

species enlarge samples of HMYSOs having VLBI image

➤ To investigate dynamics of jet/outflow+disk systems driven

by HMYSOs by analyzing 3D velocity field and spatial structure of water masers

➤ To reveal their launching and mass accretion processes

OBSERVATIONS

KaVA (KVN and VERA Array)

Base line range: 200 km ~ 2300 km Observable bands: 22 GHz and 44 GHz The highest angular resolution: ~1.2 mas @ 22 GHz

OBSERVATIONS

KaVA LP 87 sources

KaVA LP 1st 25 sources

KVN single dish survey based target list Sources having no VLBI image but also famous VLBI sources to verify our observations Methanol interesting sources ALMA 12 sources VERA 2 sources

KaVA LP 2nd 14 +2 sources

G25.82-0.17 14 sources including G25.82-0.17

RESULTS IMAGING SURVEY

SPECTRA OF WATER MASERS - EXAMPLES

Systemic velocities

v~3 km s-1

Blue only

G351.243+0.671 S255N Blue Red

Red only

G28.37+0.07MM1

Blue and Red

AFGL5142 G30.82-0.05

~10 km s-1 ~40 km s-1

Lar arge ge veloc

• city

ty distri ribut bution

• n

~200 km s-1

DISTRIBUTIONS OF WATER MASERS

➤ Two large trends in distributions of water masers

Compac Compact El Elongat ated ed

860 AU 1,220 AU

Each (0,0) is indicating position of the strongest water maser components

DISTRIBUTIONS OF WATER MASERS - EXAMPLES

1,660 AU 428 AU 356 AU 980 AU 1,200 AU 600 AU

RESULTS CASE STUDY

CASE STUDY - G25.82-0.17

➤ G25.82-0.17 is one of high-mass star forming region. ➤ Detailed study toward this source has not been done yet.

↑ Water maser spectrum at 22 GHz

• btained with KaVA.

↑ Spatial distribution of water

• masers. (green: systemic velocity of

91 km s-1 ; shirley+2013)

D~5.0 kpc Green & McClure-Griffiths 2011

1,000 AU

CASE STUDY - G25.82-0.17

➤ G25.82-0.17 is one of high-mass star forming region. ➤ A compact distribution (within 0.15 x 0.15 arcsec) is

shown with blue- and red shifted components. (first VLBI image)

1,000 100

G25.82-0.17 - DISTRIBUTIONS

➤ Detected molecular line emissions show a compact shell-

like structure with velocity gradient within the shell.

Channel maps of CH3OH 224-215 E

+dust continuum peak

Rotating disk

The moment 1 map of CH3OH 224-215 E (color) with the dust continuum emission (contours).

𝑁𝑒𝑣𝑡𝑢+𝑕𝑏𝑡 = 97 𝑁⨀

G25.82-0.17 - OUTFLOWS/SiO

➤ Complicated distribution of outflowing gas ➤ Similar distribution is shown in 229 GHz Class I methanol maser

map (not shown)

Integrated intensity map of SiO 5-4 overlaid onto dust continuum emission

Blue: ≤ 90.2 km s-1 Red: ≥ 98.4 km s-1 + water maser

10,000 AU

G25.82-0.17 - OUTFLOWS

Outflow axes are inconsistent each other (SiO vs water maser) Measuring proper motion by monitoring observations is

+ water maser

10,000 AU 1,000 AU

Integrated intensity map of SiO 5-4

• verlaid onto dust continuum

emission

Gray scale - dust continuum emission Contours - SiO outflow

• water masers

* - class I methanol masers at 229 GHz

HM-YSO Another YSO?

FUTURE PROSPECTIVES - KAVA LP

➤ Monitoring observations using KaVA

• In total, four epochs of observations in 2-3 months

period will be done to measure proper motions of water masers toward 16 sources including G25.82-0.17.

• Two epochs of observations were already done.

3d velocity field will be investigated to define parameters of outflows such as inclination

➤ Monitoring observations using VERA

• Positions of maser spots will be derived using phase

referencing method

SUMMARY

➤ The first year project of water maser survey at 22 GHz using KaVA has been

done.

➤ Both blue and red shifted components were apparently detected toward 16

sources among 21 detected sources. Monitoring observations toward 16 sources are in progress.

➤ Disk+outflow system is detected toward G25.82-0.17 by ALMA follow-up

• bservations. Masses derived from molecular line and dust continuum

suggest that G25.82-0.17 is potential a HM-YSO. Outflowing gas traced by SiO and Class I methanol maser presents complicated structure, suggesting multiple outflows.

➤ Analysis of monitoring observations with KaVA and VERA is in progress.