KaVA Large Program for
High-Mass Star-Formation

NAOJ

Tomoya Hirota (NAOJ) and Kee-Tae Kim (KASI)
On behalf of SFRs WG

Organization• Co-PI– T. Hirota (NAOJ) and K. T. Kim (KASI)• Core members ~ 17, including 3 students– D. Y. Byun, J. O. Chibueze, K. Hachisuka, B. Hu, E. Hwang,
J. Hwang, J. H. Kang, J. Kim, J. S. Kim, M. K. Kim, T. Liu,
N. Matsumoto, K. Motogi, C. S. Oh, K. Sugiyama, K. Sunada,Y. W. Wu (~17, including 3 students)• Other members ~ 40
• Regular skype meeting since 2011; 100th on Sep. 23• New members and collaborator are always welcome!

KaVA SFRs LP• Understanding high-mass star formation through
KaVA observations of water and methanol masers– Statistical VLBI monitoring/survey to reveal
3D velocity and spatial structures of
22GHz H2O/44GHz CH3OH masers
associated with high-mass young stellar
objects (HM-YSOs)

22 GHz H2O masers; high-velocity
outflow and jet (Goddi+2017)44 GHz Class I CH3OH masers; lowvelocity outflow (Cyganowski+2009)

6.7 GHz Class II CH3OH masers; disk,
toroid or outflow (Bartkiewicz+2016)

Why star-formation studies?
• Direct link to planet formation– Origin of Solar system, Earth, and life

• In case of low-mass stars– Well established based on
observational studies– Theoretically interpreted

ALMA partnership 2015

What about high-mass stars?
• How high mass (HM)?
– Early B (B3 and earlier) and O stars– More massive than 8MSun– More luminous than 103 LSun

• Significant impacts on
astronomy, astrophysics, andastrochemistry– Influences on surroundings bystrong UV, wind, explosion, ...

ALMA (ESO/NAOJ/NRAO).
Visible light image: the NASA/ESA
Hubble Space Telescope

10000 auWhy HM-YSOs still necessary?
• Less understood in comparison with low-mass YSOs
– Still challenging due to rarer population, short lifetime, further
distances, and complicated structures in embedded clusters– There are unresolved issues such as initial condition, accretion
process, feedback process, initial mass function, first star in
the Universe, etc.

Evolutionary sequence of highmass young star (Beltran 2011)

Recent progress in observations• Evidence of disk/outflow system with 10-104 AU– At a few 10 mas resolution with the long baseline with ALMA
– But 3D velocity structure is unavailable (except full ALMA)– Still insufficient number of targets at high resolution– VLBI will play unique roles to resolve dynamical structures

Face-on disk in G353.273+0.641 (Motogi et al. 2019)

Keplerian disk in G17.64+0.14 traced byvibrationally excited H2O line (Maud et al. 2019)

Science goals• 3D dynamical structures ofdisks/outflows system traced bymultiple masers– Achievable only by using VLBI throughproper motion measurements
Matsuhita et al. (2017, 2018)

ALMA band 8 observations of SiO and H2O lines (Hirota+2017)

Science goals• Evolutionary scenario of high-mass star-forming
regions and their dynamical structures– Need statistical samples– Similar studies are in progress (Moscadelli et al. 2016, Sannaet al. 2018), but they are complementary with each other

Evolution of outflow (Beuther & Shepherd 2005)

Temporal variation of outflow in W75N (Kim. J. S. et al. 2013)

Science goals• Evolutionary scenario of high-mass star-forming regions
and their dynamical structures– Need statistical samples– Similar studies are in progress (Moscadelli et al. 2016, Sannaet al. 2018), but they are complementary with each other

Maser chronology by Reid 2007 vs Ellingsen 2007

Our tracers• Centimeter/millimeter maser lines– 22 GHz H2O; high-velocity jet/outflow– 6.7 GHz CH3OH; low-velocity outflow/disk– 44 GHz CH3OH; low-velocity outflow– Complementary with each other;

G353.273+0.641 (Motogi et al. 2016);
H2O masers tracing high velocity(~100 km/s) jet

G6.79-0.25(Sugiyama et al. 2015);
6.7 GHz Class II CH3OH masers
Associated with rotating disk

G18.34+1,78SW (Matsumoto+2014);
44 GHz Class I CH3OH masers
distributed in low-velocity outflow

Follow-up observations•

All are complementary to KaVA results––––––VERA astrometry (Mikyoung Kim and Jugha Kim)
ALMA cycle 3 (PI: Mikyoung Kim, and others)
ALMA cycle 6 (PI: Jungha Kim)
VLA 2020A (PI: Kee-Tae Kim)
JCMT (EAO site;
JVN (PI: Sugiyama)
William Montgomerie)
JCMT and ASTE SD (PI: Tie Liu)
Clem & Adri Bacri-Normier(wingsforscience.com)/ESO

6.7GHz methanol masers (JVN)
Annual parallax (VERA)

Thermal continuum/lines

VLA (NAOJ)

Radio continuum/methanol masers

ASTE (NAOJ)ASTE (NAOJ)

Large-scale structureTimeline•

First year (2016-2017)–––•

Second year (2018-2019)–––•

Snap-shot survey of 25 H2O masers at 22 GHz
Snap-shot survey of 19 CH3OH masers at 44 GHz
Selected from SD/archive data, KVN SD/fringe-check
Monitoring of selected 16 H2O masers at 22 GHz
Monitoring of selected 3 CH3OH masers at 44 GHz
Selected from 1st year and VERA archive data

Third year and beyond (2020-)–

Further sources, intensive monitoring, other sciences (TBD)?

Second year; monitoring of selected sources• Finished in last May– 16 H2O masers– 3 CH3OH masers– 4 epochs monitoringwith 2 month interval– Additional observations in
2019B for 3 H2O and 3
CH3OH masers• Publication plan
– Some individual studies
including the previous data
– Summary (survey) papers

11
1
1
2
2
2
2
3
3
3
3
4
444

H2O masers
G13.87
G10.62
G45.07
G25.82
G19.61
G34.24 G34.26
IRAS18018
G30.82
G354.61
G351.24
G0.54/RCW142
IRAS18018
IRAS18056
IRAS20198
G049.49
W51D
G12.88
IRAS18556
IRAS18094
G18.34SW
CH3OH masers
G357.967
G18.34SW
G049.49

HirotaMotogiJunghaJungha, Giseon
Eodam, Giseon
Byun
JunghaMotogiJunghaEodam, Giseon
Eodam

Burns
Kee-Tae, Sugiyama
Burns

Survey results• Imaging of H2O maser sources (Hirota et al.)
– Script for maser identification, proper motion fitting, plotting
maser maps and proper motion vectors almost ready– To be compared with ALMA (waiting for allocation) and JVLA(proposal submitted) data
200 AU

8000 AU

200 AU

Some examples from preliminary results of the 22 GHz H2O maser survey

Some examples of case studies• KaVA+ALMA for G25.82-0.17 (Kim, J. et al. submitted)– Cycle 3 for CH3OH samples (Mikyoung Kim)
– Cycle 6 for H2O samples (Jungha Kim)
– Direct comparison of spatial/velocity structure by filling thegaps of sparse maser distributions

See talk by
Jungha Kim

Some examples of case studies• KaVA imaging of G19.61-0.23 (Hwang, E. et al. in prep.)– Analyzed by currently developing “Parsel-Tongue” script– Imaging of extended maser features will become easier(e.g. 100 mas FoV in 1”x1” regions for 100 channels
correspond to 10000 images!)

See talks by
Eodam Hwang

Possible future plan
• Collaboration with Maser Monitoring Organization (M2O)– Since 2017 September in IAUS 336 “Astrophysical masers”– ToO VLBI observations based on systematic SD monitoring– Follow-up observations (e.g. ALMA DDT approved yesterday)– Catching accretion burst events in high-mass YSOs

See talks by
Ross burns and Kitiyanee Asanok
and poster by
Koichiro Sugiyama

Possible future plan
• EAVN LP for C-band methanol masers (Sugiyama et al.)Figure 3. ATCA spectrum of the 6.7 GHz CH3 OH maser.
and outflow within 400 AU from a high-mass protostar
Data from all baselines were integrated. Thin curves show
the six best-fit Gaussian components. The post-fit residual
motions, wateris also plotted with an oﬀset of -0.25 Jy.

3– Complementary with H2O and 44 GHz methanol masers

Dec offset (mas)e sky. If theynclination angle (i.e., 25◦ ).
ions is much
Accretion from 100 au scale
km s−1 anddisk: 1D
reference forrs have interin G 353.273+0.641 (Motogi+motion of only17)
nternal properr of motion ofs true for theirce red masers
putative proong the l.o.s.,sGHzan estimate76%,
ted
the centerat 6features
withpeakng
proper mopanel-projected vesving
size with theottedlarger amplim of whichmasers,Figure 4. Internal distribution of the 6.7 GHz CH3 OH
indicate infall
masers. Filled triangle shows a position of each maser spot
hanol masers
with a color indicating the LOS velocity. Only the brightheforegroundmaser spots (SNR > 30 σ), which had better accuracy of ansults
k at 6.7GHz).
3internal position, were shown here. The maser map is su×10
r of methanol
perposed on the (Replaced: 7-mm replaced with: 45-GHz)ithin
f the protostar
continuum map, assuming that (Replaced: the central posionds support
ments
tion of the masers is identical with the peak position of theellar
in a symmetcontinuum replaced with: the peak position of the 6-GHz. the outflow
tocontinuum is identical to that of the 45-GHz continuum).
s ofinwater andThe contour levels are same as that in Figure 1. The synss
rrespondence
thesized beam of J-VLA is shown in lower left corner. Blackions.
entroid
dotted line marks the axis of the position-velocity diagram.
h es- of theed toa interpret Infall: 3D
desocation of the AFGL5142 MM1
4. DISCUSSION
xact
3.2).
(Goddi+ 11)
4.1. Origin of the continuum emission

Rotation + Expansion
G23.01-0.41: 3D(Sanna+ 10b)

K. Sugiyama et al.: Infall motion of the Cep A meth[-0.5:-0.3][-3.3:-1.0][-3.5:-2.4][-4.0:-3.3][-4.5:-3.7][-5.1:-4.5]

Table 3. Tanover each mVClusteIIIIVI / IIII

2 km s-1

200 auI/IIIIRotation + Infall
Cepheus A-HW2: 3D(Sugiyama+ 14)

IIIIV
V

RA offset(mas)maps collected by Sugiyama
Notes. Colu
Methanolmaser

ity in the clu

Possible future plan
• EAVN LP for C-band methanol masers

Yamaguchi 32 m
© NAOJKVNCVNTNRT40

Hitachi 32 m
©NAOJ

VERA
JVN
C-band EAVN
(by Sugiyama)

20XX semester ??

Summary and future• KaVA LPs have started since 2016
– Monitoring observations will be completed in 2019B– Data analysis are still on-going– Follow-up observations are carried out using VERA, ALMA, etc.

• Future EAVN LP will be discussed until 2020B– EAVN imaging of 6.7 GHz methanol masers will becomplementary to the current KaVA LP– Time-domain maser studies under collaboration with M2O will
be a key for understanding of accretion processes in HM-YSOs– Possible new sciences with polarimetry and astrometry• New members/collaboration for EAVN LP are welcome