SF newsletter 337 #15-21
M. Momose (Ibaraki Univ.)
15, 16, 18 (複数スライドで紹介)
19 (一枚のスライドで内容を紹介)
その他(アブストラクトのみ)

15.

The mass-loss rates (from 7e-8 to 3e-6 Msun/yr) are larger than what was measured for Class II jets. Similarly to Class
II sources, the mass-loss rates are 1%-50% of the mass accretion rates suggesting that the correlation between ejection andaccretion in young stars holds from 1e4 yr up to a few Myr.

The Carina Nebula and Gum 31 molecular complex III: The distribution of the 1-3 GHz
radio continuum across the whole nebulaDavid Rebolledo, Anne J. Green, Michael G. Burton, Shari L. Breen, Guido Garay We report the most detailed
1 3 GHz radio continuum emission map of the nearest region of massive star formation, the Carina Nebula. As part of alarge program with the Australia Telescope Compact Array, we have covered ⇠ 12 deg2 , achieving an angular resolution of⇠ 16 arcsec, representing the largest and most complete map of the radio continuum to date. Our continuum map shows aspectacular and complex distribution of emission across the nebula, with multiple structures such as filaments, shells, and fronts
across a wide range of size scales. The ionization fronts have advanced far into the southern and northern region of the Galactic
Plane, as fronts are clearly detected at distances ⇠ 80 pc from the stellar clusters in the center. We estimated an ionization
photon luminosity QH = (7.8 ± 0.8) ⇥ 1050 s 1 which corresponds to ⇠ 85% of the total value obtained from stellar population
studies. Thus, approximately 15% of the ionizing flux has escaped from the nebula into the diﬀuse Galactic Interstellar Medium.
Comparison between radio continuum and the hydrogen atomic and molecular gas maps oﬀers a clear view of the bipolar outflow
driven by the energy released by the massive stellar clusters that also aﬀects the fraction of molecular gas across the nebula.
Comparison between 8µm and 70µm emission maps and the radio continuum reveals how the hot gas permeates through themolecular cloud, shapes the material into features such as pillars, small shells and arc-like structures, and ultimately, escapes.

• Carina Nebulaの1-3GHz連続波をATCAを使ってかつてない広さ(12deg2)と完全さで16asecでマップ• 目を見張るイメージ取得• 様々なスケールでのフィラメント・シェル・Fronts• 電離フロントは銀画面から遠く離れたところ，星団中心から80pcにまで到達
6• 電離光子のLuminosity QH= (7.8±0.8) × 1050s-1，星団からの電離光子の85%• H原子との比較：アウトフロー構造の確認．そのほか，8umや70umとの比較も中心部分
の拡大図

HIとの
比較

COとの
比較

8um & 70umとの比較

8um: green
1-3GHz: red

70um: Cyan
1-3GHz: red14Some small-scale structures
Rebolledo et al.

16.

Chemical analysis of early-type stars with planets

C. Saﬀe, P. Miquelarena, J. Alacoria, M. Flores, M. Jaque Arancibia, D. Calvo, G. Martín Girardi, M. Grosso,
A. Collado Aims. To explore the chemical pattern of early-type stars with planets, searching for a possible signature of planet
formation. In particular, we study a likely relation between the lambda Bootis chemical pattern and the presence of giant
planets. Methods. We performed a detailed abundance determination in a sample of early-type stars with and without planets
via spectral synthesis. Results. We compared the chemical pattern of the stars in our sample (13 stars with planets and 24 stars
without detected planets) with those of lambda Bootis and other chemically peculiar stars. We have found four lambda Bootis
stars in our sample, two of which present planets and circumstellar disks (HR 8799 and HD 169142) and one without planets
detected (HD 110058). We have also identified the first lambda Bootis star orbited by a brown dwarf (zeta Del). This interestingpair lambda Bootis star + brown dwarf could help to test stellar formation scenarios. We found no unique chemical pattern for
the group of early-type stars bearing giant planets. However, our results support, in principle, a suggested scenario in which
giant planets orbiting pre-main-sequence stars possibly block the dust of the disk and result in a lambda Bootis-like pattern.
On the other hand, we do not find a lambda Bootis pattern in diﬀerent hot-Jupiter planet host stars, which do not support theidea of possible accretion from the winds of hot-Jupiters, recently proposed in the literature. Then, other mechanisms should
account for the presence of the lambda Bootis pattern between main-sequence stars. Finally, we suggest that the formation ofplanets around lambda Bootis stars such as HR 8799 and HD 169142 is also possible through the core accretion process andnot only gravitational instability [abridged]• λ Bootis(うしかい座)star：金属量が太陽に比べ1/10低い特異な化学組成を持つA型星
ALMA observations of the early stages of substellar formation in the Lupus 1 and 3
molecular
clouds• ~2%of B-F MS,
but ~33% of Herbig Ae/Be stars，起源は謎．

A. Santamaría-Miranda, I. de Gregorio-Monsalvo, A. L. Plunkett, N. Huélamo, C. López, Á. Ribas, M. R.
Schreiber, K. Mužić, A. Palau, L. B. G. Knee, A. Bayo, F. Comerón, Boo
A. HalesThe dominant mechanism leading• 惑星がある星13個とない星24個で大気化学組成を詳細に探査，λ型星との関連調査
to the formation of brown dwarfs (BDs) remains uncertain. The most direct keys to formation, which are obtained fromyounger
objects (pre-BD
cores and proto-BDs), are limited by the very low number
statistics
available. We aim to identify and• 4つ(+λBoo)がλ
Boo型，うち2つが惑星・星周円盤付き（HR8799,
HD169142）
characterize a set of pre- and proto-BDs as well as Class II BDs in the Lupus 1 and 3 molecular clouds to test their formation• 他のうち1つはBD付随
mechanism. We performed(zeta
ALMADel)，他の1つは惑星なし(HDband 6 (1.3 mm) continuum observations110058)
of a selection of 64 cores previously identified from
AzTEC/ASTE data (1.1 mm), along with previously known Class II BDs in the Lupus 1 and 3 molecular clouds. Surveyed• 惑星があるとダストの流入が妨げられた結果かも．．．はっきりしたことは言えないがarchival data in the optical were used to complement these observations. We expect these ALMA observations prove eﬃcientin detecting the youngest sources in these regions, since they probe the frequency domain at which these sources emit most of• Hot theirJupiterからのウインドが中心星に降着したと言う説とは合致しない（特段の差が見られない）
radiation. We detected 19 sources from 15 ALMA fields. Considering all the pointings in our observing setup, the ALMAHARPSHARPS-NHIRES
SOPHIEELODIE
REOSC

115000115000
67000
75000
42000
13000

Detector
4k x 4k
4k x 4k
2k x 4k
4k x 2k
1k x 1k
1k x 1k

size
15 µm
15 µm
15 µm
15 µm
24 µm
24 µm

La Silla 3.6m
TNG 3.6m
Keck 10m
OHP 1.93m
OHP 1.93m
CASLEO 2.1m

Wave. Range
3800 - 6800
3800 - 6800
3750 - 9000
3900 - 6800
3850 - 6800
3800 - 6000

今回のサンプルと観測諸元

今回求められた星の基本パラメータ
Saffe et al.: Early-type stars with planets

ntal parameters derived for the stars in this work.

Star
β Pic
Fomalhaut
KELT-9HD 95086
HD 169142
HR 8799
KELT-17
KELT-20
MASCARA-1
WASP-33
HD 133803
β Cir
59 Dra
HR 4502 A
BU PscHD 29391
HD 105850
HD 110058
HD 115820
HD 120326
HD 129926
HD 146624
HD 153053
HD 156751
HD 159492
HD 188228
HD 23281
HD 50445
HD 56537
HD 88955
V435 Car
HAT-P-49
λ Boötis
Vega
WASP-167
WASP-189
ζ Del

Teff [K]8084 ± 1308745 ± 195
9329 ± 118
7593 ± 122
7296 ± 365
7301 ± 190
7471 ± 210
8652 ± 160
7687 ± 238
7373 ± 164
6998 ± 193
8552 ± 297
7053 ± 194
9569 ± 253
7185 ± 160
7259 ± 167
9052 ± 167
7839 ± 202
7610 ± 135
6925 ± 143
7101 ± 167
9489 ± 184
7916 ± 129
7432 ± 175
8076 ± 128
10262 ± 172
7761 ± 135
7922 ± 117
8231 ± 122
8733 ± 1547510 ± 1656730 ± 234
8512 ± 144
9505 ± 188
6770 ± 210
7946 ± 136
8236 ± 124

log g [dex]4.22 ± 0.13
4.17 ± 0.10
4.00 ± 0.14
4.02 ± 0.14
4.20 ± 0.25
4.12 ± 0.23
4.20 ± 0.14
4.11 ± 0.20
4.09 ± 0.14
4.14 ± 0.20
4.08 ± 0.23
3.94 ± 0.18
4.18 ± 0.21
4.00 ± 0.16
4.22 ± 0.14
4.12 ± 0.20
4.08 ± 0.08
4.00 ± 0.14
4.30 ± 0.15
4.37 ± 0.11
4.18 ± 0.20
4.13 ± 0.07
4.03 ± 0.14
3.92 ± 0.21
4.24 ± 0.13
4.29 ± 0.06
4.18 ± 0.15
4.03 ± 0.14
3.70 ± 0.12
3.76 ± 0.10
4.21 ± 0.14
4.02 ± 0.14
3.95 ± 0.06
3.95 ± 0.19
4.05 ± 0.14
3.85 ± 0.12
3.60 ± 0.12

vmicro [km s−1 ]3.31 ± 0.83
2.95 ± 0.74
2.27 ± 0.57
3.09 ± 0.77
2.75 ± 0.69
2.76 ± 0.69
2.50 ± 0.63
3.03 ± 0.76
3.17 ± 0.79
2.86 ± 0.71
2.29 ± 0.57
3.12 ± 0.78
2.38 ± 0.60
1.96 ± 0.49
2.59 ± 0.65
2.70 ± 0.68
2.61 ± 0.65
3.26 ± 0.81
3.11 ± 0.78
2.17 ± 0.54
2.46 ± 0.62
2.06 ± 0.52
3.29 ± 0.82
2.93 ± 0.73
3.31 ± 0.83
1.17 ± 0.29
3.22 ± 0.80
3.29 ± 0.82
3.29 ± 0.82
2.96 ± 0.74
3.01 ± 0.75
1.82 ± 0.46
3.15 ± 0.79
2.04 ± 0.51
1.90 ± 0.47
3.30 ± 0.82
3.29 ± 0.82

v sin i [km s−1 ]113.0 ± 1.3
82.0 ± 3.2
113.5 ± 4.6
30.0 ± 1.4
55.0 ± 0.8
50.5 ± 1.0
43.0 ± 0.6
111.0 ± 3.1
99.0 ± 3.9
82.5 ± 2.0
89.5 ± 1.3
61.0 ± 0.8
53.0 ± 1.1
18.5 ± 0.7
53.0 ± 2.6
70.0 ± 1.7
125.0 ± 1.5
153.5 ± 2.9
92.2 ± 1.8
66.5 ± 1.5
113.0 ± 2.1
34.0 ± 0.5
103.0 ± 1.6
100.0 ± 4.3
52.3 ± 1.2
83.0 ± 3.5
77.7 ± 2.4
96.0 ± 1.9
146.0 ± 4.3
99.0 ± 3.0
106.4 ± 1.9
14.8 ± 0.2
115.0 ± 3.1
20.5 ± 0.7
52.0 ± 2.0
95.2 ± 3.3
108.0 ± 3.6

A&A proofs: manuscri

Abundance analysis& spectra fit
Saffe et al.: Early-type stars with planets• 黒が観測，青が合成したスペクトル，赤が差• 赤が今回同定されたλBoo型．λBooは青今回見つけたλ Boo型のabundance pattern

One more but less clear star (HD156751) & λ Boo自身
A&A proofs: manuscript no. saffe- どちらも，これまで惑星の兆候は得られていない

Fig. 9. Abundances of the stars HD 156751 and λ Boötis (black), compared to the average pattern of λ Boötis stars (blue). We show two panels
for each star, corresponding to elements with z<32 and z>32.

(HAe)や- 若い方がλ Boo型の割合が多いと知られていたが，HD169142-We have found four λ Boötis stars in our sample, two of
which present planets (HR 8799 and HD 169142), one withoutplanets (HD 110058), and the first λ Boötis star orbited by abrown dwarf (ζ Del). This last interesting pair composed by a λHR8799(42±5Myr)が該当したが，β PicやHD96086 (<50Myr)は違った

その他• Hot Jupiter とλ Boo現象が関係していると言う説があったが，今回得られたサンプル（７個）ではそのような兆候は見られない

Saffe et al.: Early-type stars with planetspre-BD or deeply embedded protostellar candidates. We detected a promising candidate for a Class 0/I proto-BD source andinferred the disk dust mass of a bona fide Class II BD. The pre-BD cores might be the byproduct of an ongoing process oflarge-scale collapse. The Class II BD disks follow the correlation between disk mass and the mass of the central object that isobserved at the low-mass stellar regime. We conclude that it is highly probable that the sources in the sample are formed as ascaled-down version of low-mass star formation, although disk fragmentation may be responsible for a considerable fraction of
BDs.

18.

Characterizing the line emission from molecular clouds. Stratified random sampling of
the Perseus cloud

M. Tafalla, A. Usero, A. Hacar Context. The traditional approach to characterize the structure of molecular clouds is to
map their line emission. Aims. We aim to test and apply a stratified random sampling technique that can characterize theline emission from molecular clouds more eﬃciently than mapping. M ethods. We sampled the molecular emission from the
Perseus cloud using the H2 column density as a proxy. We divided the cloud into ten logarithmically spaced column density
bins, and we randomly selected ten positions from each bin. The resulting 100 cloud positions were observed with the IRAM
30m telescope, covering the 3mm-wavelength band and parts of the 2 and 1mm bands. Results. We focus our analysis on 11
molecular species detected toward most column density bins. In all cases, the line intensity is tightly correlated with the H2column density. For the CO isotopologs, the trend is relatively flat, while for high-dipole moment species such as HCN, CS, andHCO+ the trend is approximately linear. We reproduce this behavior with a cloud model in which the gas density increases
with column density, and where most species have abundance profiles characterized by an outer photodissociation edge andan inner freeze-out drop. The intensity behavior of the high-dipole moment species arises from a combination of excitationeﬀects and molecular freeze out, with some modulation from optical depth. This quasi-linear dependence with the H2 column
density makes the gas at low column densities dominate the cloud-integrated emission. It also makes the emission from mosthigh-dipole moment species proportional to the cloud mass inside the photodissociation edge. Conclusions. Stratified random
sampling is an eﬃcient technique for characterizing the emission from whole molecular clouds. It shows that despite the complex
appearance of Perseus, its molecular emission follows a relatively simple pattern.

7ペルセウス座分子雲をターゲットに以下を実施
方法

結果と考察

• 分子雲構造を探る際，マップするのではな• Line intensityはH2柱密度と正の相関

く，階層的ランダムサンプリングで特徴づけられないかを試験• H2柱密度の10binそれぞれに10標本点(計100点)，λ=3mmバンド全体と2mm & 1mm
バンド一部をIRAM 30mでカバー• 11molecular species + isotopologues解析‣ COはわりとflat‣ μが大きいspeciesほどlinearに近づく(HCN, CS, HCO+, HNC)

• 以下の組み合わせで簡単に振る舞いを理解‣ 励起効果‣ ほぼ全てのbinで検出‣ Edge (光解離) - Center (凍結)で線形補間‣ 様々なdipole moment μ (← critical density)‣ Optical depthによる変調をちょっぴり

標本点の位置(左)と柱密度
A&A proofs: manuscript

COMPLETEとの比較：CO isotopologues
M. Tafalla et al.: Characterizing the line emission from molecular clouds.

青がCOMPLETE
赤が本研究

Fig. 3. Comparison between sampling observations and COMPLETE full maps for 12 CO(1–0) and 13 CO(1–0). Top panels: Scatter plots of theintegrated intensity as a function of N(H2 ). The blue dots represent the results from the COMPLETE maps presented by Ridge et al. (2006) andeach of them contains more than 2 ⇥ 105 spectra. The red symbols represent the 100 measurements obtained using stratified random sampling. The
dotted lines mark the 3 detection level of the COMPLETE maps. Middle panels: Ratio between the mean intensity derived using the sampling
data and the COMPLETE maps for each of the ten N(H2 ) bins in which the cloud was divided. For 13 CO(1–0), the measurement in lowest N(H2 )bin is not reliable since the sampling data show that the intensity often lies below the COMPLETE detection limit. Bottom panels: Ratio between
the rms derived using the sampling data and the COMPLETE maps. As with the mean values, the 13 CO(1–0) measurement for the lowest N(H2 )bin lies below the detection limit, so the rms estimate is not reliable. We note how both the mean and rms ratios for the two CO isotopologs
lie in the vicinity of 1, indicating that the sampling method allows estimating the main emission parameters with an accuracy of about 50-20%
depending on the parameter.

結果(1)：COA&A proofs: manuscript no. 38727ms

結果(2)：large μ species
M. Tafalla et al.: Characterizing the line emission from molecular clouds.

M. Tafalla et al.: Characterizing the line emission from molecular clouds.

柱密度 vs.
ライン積分強度

COは基本的に外側で稼ぐ
Large μは比較的全体で稼ぐものが多い
Fig. 7. Normalized ratio between integrated intensity and H2 column density as a function of H2 column density. The data points represent binaveraged values and the error bars represent the rms dispersion. The horizontal gray band encloses the region were deviations from unity are withina factor of 2.
Table 1. Linear square fits to the log-Int vs. log-N(H2 ) plots.

モデルの構築とCOとの比較
M. Tafalla et al.: Characterizing the line emission from molecular clouds.

• COのJ=2-1と1-0の比からT=11Kで一様‣ 外側のUV photonの加熱はCO解離に使

M. Tafalla et al.: Characterizing the line emission from molecular clouds.

われ大して効かない• 密度：柱密度の関数で与える．HCNや
0.75
CSの複数遷移間の比からN(H)
2Fig. 10. Comparison between observations and model results for the family of CO isotopologs. The red symbols represent the observed intensitiesof the J=1–0 line, previously presented in Fig. 4, and the dashed blue lines represent the model results. The sharp drop at low column densities iscaused by the photodissociation edge in the abundance profile.

0.15
速度分散：C18O(2-1)からN(H)
2•abundance profile. We aimed to describe these profiles using a for an outer abundance increase in the small hydrocarbons driven
parameterization that is both simple and consistent with our current knowledge of the chemical processes occurring in a molecular cloud like Perseus. After some exploring, we found that reasonable fits can be obtained by using a parameterization containing three terms:

by gas-phase reactions involving C+ .
The final factor in our abundance parameterization is fin ,which describes possible variationsin the cloud interior (i.e., atouthigh N(H2 ) values). For all species except N2 H+ , the data requirea systematic abundance decrease with N(H2 ), likely caused byfreeze out. This is consistent with previous findings toward star-2
less dense cores in di↵erent environments (Caselli et al. 1999;
Bergin et al. 2002; Tafalla et al. 2002), and for this reason, wein used2by Tafalla et al. (2002)
parameterized fin with an expression
to describe such systems. This expression has as only free parameter the volume density characteristic of freeze out, which2
has been adjusted for each molecular species.
As with the photodissociation edge, a narrow range of choices (1-2 ⇥ 105 cm 3 )• 化学組成は以下の式でパラメータ化
X(N(H2 )) = X0 ⇥ fout (N(H2 )) ⇥ fin (N(H2 )),(1)

where X0 represents a constant scaling factor, and fout and fin are
two normalized factors that represent abundance changes withrespect to X0 in the outer and inner parts of the cloud (i.e., at low
and high H2 column densities).

f : UV解離の影響をPDRモデルで評価,
ただし，C HやCNはenhancef : N H以外はdense regionで減少(凍結),N Hは増加（CO凍結との関係で）

モデルとCO以外の分子種の比較
A&A proofs: manuscript no. 38727ms

19.

Behavior of Hydroxyl Radicals on Water Ice at Low Temperatures

Masashi Tsuge, Naoki Watanabe Because chemical reactions on/in cosmic ice dust grains covered by amorphous solid
water (ASW) play important roles in generating a variety of molecules, many experimental and theoretical studies have focusedon the chemical processes occurring on the ASW surface. In laboratory experiments, conventional spectroscopic and massspectrometric detection of stable products is generally employed to deduce reaction channels and mechanisms. However, despite
their importance, the details of chemical reactions involving reactive species (i.e., free radicals) have not been clarified because of
the absence of experimental methods for in situ detection of radicals. Because OH radicals can be easily produced in interstellar
conditions by not only the photolysis and/or ion bombardments of H2O but also the reaction of H and O atoms, they arethought to be one of the most abundant radicals on ice dust. In this context, the development of a close monitoring method ofOH radicals on the ASW surface may help to elucidate the chemical reactions occurring on the ASW surface.

（このアブストラクトは3つの段落のうち一段落目しかない）
Distinguishing between diﬀerent mechanisms of FU-Orionis-type luminosity outbursts

EduardI.
Vorobyov,VardanG.
Elbakyan,
Hauyu
BaobabLiu,
Michihiro
Takami
Aims.
Accretion
andluminosity• 低温下でのHydroxyl radicalsのアモルファス氷(ASW)表面での振る舞bursts triggered by three distinct mechanisms: the magnetorotational instability in the inner disk regions, clump infall ingravitationally fragmented disks and close encounters with an intruder star, were studied to determine the disk kinematic
いに関連し．筆者自身が開発した，ASW表面のOHラジカル検出法を
characteristics that can help to distinguish between these burst mechanisms. Methods. Numerical hydrodynamics simulations
用いて，λ=532nmの光子一つでOHがdesorotionすることを確認．
in the thin-disk limit were employed to model the bursts in disk environments that are expected for each burst mechanism.
Results. We found that the circumstellar
disks featuring accretion bursts can bear kinematic features that are distinct for–• 氷表面のOHは容易に電子を引き寄せ，OHになる．今回はさらに，
diﬀ

OH–の形成がnegative currentを誘起することを突き止め，protontransferのmirror imageとして100年前に予言されていたproton-holetransfer (Grotthuss mechanism)で実効的に氷内で素早く輸送されることを明かした．
• 低温下の氷マントルでは起こらないと思われていた関連反応が重要になる可能性がある．

17.

planets around lambda Bootis stars such as HR 8799 and HD 169142 is also possible through the core accretion process andnot only gravitational instability [abridged]

ALMA observations of the early stages of substellar formation in the Lupus 1 and 3
molecular clouds

A. Santamaría-Miranda, I. de Gregorio-Monsalvo, A. L. Plunkett, N. Huélamo, C. López, Á. Ribas, M. R.
Schreiber, K. Mužić, A. Palau, L. B. G. Knee, A. Bayo, F. Comerón, A. Hales The dominant mechanism leading
to the formation of brown dwarfs (BDs) remains uncertain. The most direct keys to formation, which are obtained fromyounger objects (pre-BD cores and proto-BDs), are limited by the very low number statistics available. We aim to identify and• Lupus1,3の分子雲に対しAzTEC/ASTE data (1.1mm)で同定されたコア64個をALMAでサーベイ• 19個をALMAで検出．クラス分け• Class II BDに関しては，中心星質量と円盤質量の相関を確認．BD形成はlow mass starformation のスケールダウンバージョンらしい20.

the absence of experimental methods for in situ detection of radicals. Because OH radicals can be easily produced in interstellar
conditions by not only the photolysis and/or ion bombardments of H2O but also the reaction of H and O atoms, they arethought to be one of the most abundant radicals on ice dust. In this context, the development of a close monitoring method ofOH radicals on the ASW surface may help to elucidate the chemical reactions occurring on the ASW surface.

Distinguishing between diﬀerent mechanisms of FU-Orionis-type luminosity outbursts

Eduard I. Vorobyov, Vardan G. Elbakyan, Hauyu Baobab Liu, Michihiro Takami Aims. Accretion and luminosity
bursts triggered by three distinct mechanisms: the magnetorotational instability in the inner disk regions, clump infall ingravitationally fragmented disks and close encounters with an intruder star, were studied to determine the disk kinematiccharacteristics that can help to distinguish between these burst mechanisms. Methods. Numerical hydrodynamics simulationsin the thin-disk limit were employed to model the bursts in disk environments that are expected for each burst mechanism.
Results. We found that the circumstellar disks featuring accretion bursts can bear kinematic features that are distinct for
diﬀerent burst mechanisms, which can be useful when identifying the burst origin. The disks in the stellar encounter andclump-infall models are characterized by tens of percent deviations from the Keplerian rotation, whie the disks in the MRI
models are characterized only a few percent deviation, which is mostly caused by the gravitational instability that fuels the
MRI bursts. Velocity channel maps also show distinct kinks and wiggles, which are caused by gas disk flows that are peculiar
to each considered burst mechanism. The deviations of velocity channels in the burst-hosting disks from a symmetric patterntypical of Keplerian disks are strongest for the clump-infall and collision models, and carry individual features that may be
useful for the identification of the corresponding burst mechanism. The considered burst mechanisms produce a variety of light
curves with the burst amplitudes varying in the
m=2.5-3.7 limits, except for the clump-infall model wherem can reach
5.4, although the derived numbers may be aﬀected by a small sample and boundary conditions. Conclusions. Burst triggering
mechanisms are associated with distinct kinematic features in the burst-hosting disks that may be used for their identification.
Abridged.

HII regions and high-mass starless clump candidates II. Fragmentation and induced star
at 0.025 pc scale: An ALMA continuum study• FUformation
Ori型星のメカニズムを区別する方法をシミュレーションをもとに考察

S. Zhang, A. Zavagno, A. López-Sepulcre, H. Liu, F. Louvet, M. Figueira, D. Russeil, Y. Wu, J. Yuan, T. G.
S. Pillai The ionization feedback from HII regions modifies the properties of high-mass starless clumps (HMSCs,
of several• アクリーションバーストの場合は，他のメカニズムでは見られないkinematicalfeaturesを示すはず
hundred to a few thousand solar masses with a size of 0.1-1 pc), such as temperature and turbulence, on the clump scale. The
question of whether the presence of HII regions modifies the core-scale fragmentation and star formation in HMSCs remains to
be explored. We aim to investigate the diﬀerence of 0.025 pc-scale fragmentation between candidate HMSCs that are strongly
impacted by HII regions and less disturbed ones. We also search for evidence of mass shaping and induced star formation in
the impacted HMSCs. Using the ALMA 1.3 mm continuum with a resolution of 1.3", we imaged eight candidate HMSCs,
including four impacted by HII regions and another four situated in the quiet environment. The less-impacted HMSCs are21.

5.4, although the derived numbers may be aﬀected by a small sample and boundary conditions. Conclusions. Burst triggering
mechanisms are associated with distinct kinematic features in the burst-hosting disks that may be used for their identification.
Abridged.

HII regions and high-mass starless clump candidates II. Fragmentation and induced starformation at 0.025 pc scale: An ALMA continuum study

S. Zhang, A. Zavagno, A. López-Sepulcre, H. Liu, F. Louvet, M. Figueira, D. Russeil, Y. Wu, J. Yuan, T. G.
S. Pillai The ionization feedback from HII regions modifies the properties of high-mass starless clumps (HMSCs, of several
hundred to a few thousand solar masses with a size of 0.1-1 pc), such as temperature and turbulence, on the clump scale. The
question of whether the presence of HII regions modifies the core-scale fragmentation and star formation in HMSCs remains to
be explored. We aim to investigate the diﬀerence of 0.025 pc-scale fragmentation between candidate HMSCs that are strongly
impacted by HII regions and less disturbed ones. We also search for evidence of mass shaping and induced star formation in
the impacted HMSCs. Using the ALMA 1.3 mm continuum with a resolution of 1.3", we imaged eight candidate HMSCs,
including four impacted by HII regions and another four situated in the quiet environment. The less-impacted HMSCs are
selected on the basis of their similar mass and distance compared to the impacted ones to avoid any possible bias linked to theseparameters. A total of 51 cores were detected in eight clumps, with three to nine cores for each clump. Within our limited
sample, we did not find a clear diﬀerence in the 0.025 pc-scale fragmentation between impacted and non-impacted HMSCs,
even though HII regions seem to aﬀect the spatial distribution of the fragmented cores. Both types of HMSCs present a thermalthfragmentation with two-level hierarchical features at the clump thermal Jeans length thand
0.3
J,clumpJ,clump . The ALMA
emission morphology of the impacted HMSCs AGAL010.214-00.306 and AGAL018.931-00.029 sheds light on the capacities of
HII regions to shape gas and dust in their surroundings and possibly to trigger star formation at 0.025 pc-scale in HMSCs.
Future ALMA surveys covering a large number of impacted HMSCs with high turbulence are needed to confirm the trend of
fragmentation indicated in this study.

•

High Mass Starless Clumps (HMSCs)がHII領域から与えられるフィードバックの影響を調査•

ALMA 1.3mm連続波イメージにより，8つのHMSCsの構造調査，4つはHII領域の影響大のもの• 内部に0.025pcのコアを計51個同定，HII領域の影響有無は見出せるほど明瞭な違いを生んでいなかった
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