天の川の赤外線バブルの観測
794

BEAUMONT & WILLIAMS

Vol. 709◎河野 樹人 (名古屋市科学館), Chibueze James O (North-West Univ./Univ. of Nigeria), Burns Ross A (理研), 面高俊宏,
794

BEAUMONT & WILLIAMS

Vol. 709

半田利弘 (鹿児島大),村瀬建(岐阜大), 永山匠, 砂田和良 (国立天文台), 仲野誠 (大分大), 山田麟, 立原研悟, 福井康雄 (名古屋大)

1992PASJ...44..203H

私たちの研究グループでは、天の川にある重たい星 (大質量星)がどのようにして作られるのかを明らかにするため、主に野辺山45m電波望遠鏡を使って得られた電波のデータを使った研究を行っています。このポスターでは、私が特に注目している「赤外線バブル」と呼ばれる天体の研究成果を紹介します。また、私は科学館所属の学芸員として、プラネタリウムを活用した最新天文観測データの可視化と一般向けのプラネタリウム番組の制作にも取り組んでいます。
1. 赤外線バブル と星形成

5. 運動温度の空間分布

Figure 3. Example channel map for bubble N29. The radial velocity at each slice is listed in km s−1 in the upper right corner. An ellipse is drawn in for reference,

markboundary
the interior.
bubbleFig. 3. Examples of three bubbles that are large in angular size. All the fields are 10to! ×10the! . approximate
The colours
areof thesameNoteas thatin theFig.
2. interior is largely devoid of emission. The few structures that do appear inside the shell (for−1③ 分子雲衝突による大質量星形成

example, at a radial velocity of 37.6 km s ) are not red- or blueshifted, as would be expected if N29 was an expanding sphere. Note also that the extended emission
toFigure
the northof the bubble
doesmap
not forextendintoN29.
the interiorof N29.
Thisatpoints
an absence
ambient
material
in frontAn
ofellipse
or behindthe bubble.
3. Example
channelbubble
The radialvelocity
each toslice
is listed ofin km
s−1 molecularin the upper
right corner.
is drawn
in for reference,
tocolormarkversion
the approximateboundaryof theininterior.
Notethat the bubble interior is largely devoid of emission. The few structures that do appear inside the shell (for(Aof this figure
is available
the onlinejournal.)−1
example, at a radial velocity of 37.6 km s ) are not red- or blueshifted, as would be expected if N29 was an expanding sphere. Note also that the extended emission
to the north of the bubble does not extend into the interior of N29. This points to an absenceof ambientmaterial
in front ofonor behindbubble.clouds’and thus
placemolecularstronger
constraints
their theparent(A color version of this figure is available in the online journal.)
thicknesses.

① 膨張シェルによる星間ガスの掃き集め② formed
シート状分子雲のリング構造
The stars
in compressed pre-existing globules should be(Ho & Townes 1983)

運動温度+: 大質量原始星

seen in the direction of the H  region. In this paper, we try to
観測されるバブル
identify only the most
massive second-generation stars, which
and thus place stronger
constraints
on their parent clouds’
3.2. Ring
Properties
are those able to ionize second-generation H  regions. thicknesses.

While the molecular rings can often be easily identified byeye in a CO data cube,3.2.
it isharder
to rigorously define whereRing
Properties
the bubble interaction zone ends and the ambient molecularWhilethemolecularrings
canoftenbe ofeasily
identified
by5.1. The ATLASGAL images
cloud begins. Here we describe our process
isolatingbubbleeye
inaCO
datacube,
itisharder
torigorously
definewherefeatures in the data.
thebubble
interaction
zoneinends
and theambientonly
molecular
Wesufirst cropped
the data
velocity
to include
those
We first used the interactive software sky atlas Aladin5 tocloudbegins.
Here we describe
ourtheprocess
isolatingInbubble
channelswith matching
features inSpitzerofimages.
mostperimpose the ATLASGAL images (and isocontours) on
thefeatures
the data.
cases,
theininnerring edge stands out in the integrated maps.
Wethe
first
croppedthe data
in velocity
include only
those
Spitzer-GLIMPSE 8.0 µm and 24 µm images. In a secondThus,
step,
inner
boundary
is definedby antointegrated
intensitychannels chosenwith matching
featuresinring.
the Spitzerimages.
In ring
most6threshold,manuallyforeachWhilesomeouter
we used the Kang IDL software to superimpose ATLASGAL
cases, the standinner out
ringagainstedge dark
standsout in the in
integrated
maps.
boundaries
backgrounds
the integrated
Thus,
the innerboundary
defined byan integrated
isocontours on GLIMPSE 8.0 µm, MIPSGAL 24 µm,
andmaps,rings
on theedges ofisextended
cloud
structures intensity
do not.
threshold,chosen manually
eachring.outer
Whileboundary
some outerring
a compromise,
we definefor
eachring’s
as theMAGPIS 20-cm data. For the GLIMPSE and MIPSGALAs
data,boundaries ofstandagainstthresholddark backgrounds
in theboundary.
integrated
intersection
theoutintensityand a manual
we used a logarithmic scaling to create the background images
inringsofonthis
maps,
theprocess
edges ofextended cloud
structures
dolinenot.
An
exampleis illustrated
in Figure5; the red
a compromise,
define eachring’sthethe figures. For the MAGPIS data, however, a logarithmiconAsscalthe
left traces theweboundary
definedby outerhand,boundary
while the as
blue
intersection
ofintensity
the intensity
thresholdand aonmanual
boundary.
linetraces
thethreshold;thefiguretherightshows
Figure 4. Schematican interstellar
ring, images
where a central
groupweof O insteadand B
ing accentuatedthe ofnoisein theandused
a of this process is illustrated in Figure 5; the red line
Anintersection
exampletheof these two regions, and serves to define whichstars clears out a cavity in a flattened molecular cloud. The top panel shows a faceontheleftassociatedtraces thewithboundary
defined by hand, while the blue
linear scaling.
Wecalculated
thestandard
deviationovereachon view of an approximately circular cavity of diameter a few parsecs. None,
pixels arethis ring.
7line
tracestheintensity
threshold;the figureon thearerightshows
very little,
CO emission
seen towardcavity,whereasthe ofmolecular
Figure4. Schematicofthe
an isinterstellar
ring,thewhere
a centralgroup
O and Bin the The
ring properties forour 43 CO
detections
listedinfields (σorcloudvalue)
using
IDL
routine
“mmm”
found
IDL
fora tensofinparsecsin themolecularplane of thesky.The
Wetop
interpret
our finding
theintersectionof
these
tworegions,andserves
todefinewhichstars extends
clears out
cavitya flattened
cloud.
panel showsa face
Table
1.
Near
kinematic
distances
arecalculated
using
theasindicatingthatcloudshaveline-of-sight
depthsofafewparsecs,
andthat
Astronomy
User’s
Library.
Thecavity
lowestcontourlevel
fig-areon viewof an approximately
circularof diametera few parsecs.
None,in our
pixelsassociatedwithring.& Blitz (1993), for R =galactic
rotationmodelof thisBrandbubblesbreakout of their
hosttoward
clouds (illustrated
the lowerIn"or veryrapidly
little, CO
emissionis seenthe cavity, inwhereas
the panel).
molecular
forour−1 43 CO detections are listed inures is the1-σlevel
thelevels
increasein multiples
thisscenario,
theregion
betweenstarandWe
cloudis smallerthan
8.8 Thekpc ring
and Vproperties=275
kms(Reid et al. 2009). Kinematic
cloud
extends
forinteraction
tensandof parsecs
in contour
the planetheof thesky.
interpret
our finding"
Table 1.uncertainties
Near kinematic
distancesbyare
calculated
using
theitaswouldbe thanthat
forclouds
a morehave
homogeneouscloud
geometry.
indicating
line-of-sight
depthsof a few parsecs, and thatdistanceare dominatedpeculiarmotions.
Basedof the 1-σlevel.
galactic
model
Brandwe& estimate
Blitz (1993),
for R" =bubbles
rapidly of
breakof their
host clouds
in the lower panel). In(Acolor version
thisout
figureis available
in the(illustrated
online journal.)onthe datarotationfrom Reidet al.of(2009),
thisuncertainty
this scenario, the interaction region between the star and cloud is smaller than
8.8 kpc and V" = 275 km s−1 (Reid et al. 2009). Kinematic
it would be than for a more homogeneous cloud geometry.
distance uncertainties are dominated by peculiar motions. Based5
http://aladin.u-strasbg.fr/(A color version of this figure is available in the online journal.)
on the data from Reid et al. (2009), we estimate this uncertainty

上から見た図Beaumont & Williams 10

Deharveng+10
Fig. 4. Schematic view of a spherical expanding H  region and of its
neutral environment. Different processes of triggered star formation aredepicted: 1 – small-scale gravitational instabilities; 2 – large-scale gravitational instabilities leading to the formation of high-mass fragments;
3 – ionizing radiation acting on a turbulent medium; 4 – radiation-driven
compression of pre-existing dense clumps.

Habe & Ohta 92

異なるモデルと星形成シナリオが提唱

2. 赤外線バブル N49領域 (G28.83-0.25)

等高線(白): VLA 1.4 GHz 電波連続波
等高線(黒): NH3 (1,1) ピーク強度

Zavagno et al. (2010)6

http://www.bu.edu/iar/kang/
http://idlastro.gsfc.nasa.gov/ftp/pro/idlphot/mmm.
pro7

中央のクランプにある大質量原始星周囲で温度が高い (Tkin =27 K)

Page 6 of 35

6. 柱密度の空間分布
NH3 柱密度+: 大質量原始星• 距離: 5.07 kpc (Dirienzo+2012)• 13CO で長さ 〜20 pc, 幅 〜3pc のフィラメント状分子雲 フィラメント状分子雲に沿ってNH3 輝線でマッピング観測• バブルの縁にメタノールメーザー源と大質量原始星

3. NH3 の空間分布 (ピーク強度)+: 大質量原始星

等高線(白): VLA 1.4 GHz 電波連続波
等高線(黒): NH3 (1,1) ピーク強度• Clump Bの東側で柱密度が高い (〜9×1015 cm-2)• Clump AとCは柱密度が一様で、それぞれ〜2×1015 cm-2, 〜4×1015 cm-2

7. FUGIN 13CO J=1-0 とNH3 (1,1) 分布と速度構造の比較+: 大質量原始星
88 km/s 成分

等高線(白): VLA 1.4 GHz 電波連続波

95 km/s 成分(

背景画像: 13CO 95 km/s 成分
等高線 (オレンジ): 13CO 88 km/s 成分
等高線(白): NH3 (2,2) ピーク強度

フィラメントに沿って3つのクランプ(A,B,C)が存在
4. NH3 の速度分布(ピーク速度と線幅の分布)

NH3 (1,1) ピーク速度+: 大質量原始星

背景画像: 13CO
等高線 (黒): NH3 (2,2)• 88 km/s, 95 km/sの2つの速度成分• 2つの視線速度の異なる分子雲が重なった位置にNH3 (2,2)のピークと大質量原始星が存在• 位置速度図上で、2つの速度成分は互いに接続 (ブリッジ成分の存在)-> 分子雲同士の相互作用を示唆
Haworth et al. (2015)

ブリッジ成分等高線(白): VLA 1.4 GHz 電波連続波
等高線(黒): NH3 (1,1) ピーク強度

3つのクランプは視線速度が96 km/s, 87 km/s, 89 km/sで異なる分子雲の衝突 -> バブルの縁の大質量星形成 -> 周囲 (〜3pc)の高密度ガスを局所的に加熱

NH3 (1,1) 線幅+: 大質量原始星8. プラネタリウムにおける番組制作 (2023年)

等高線(白): VLA 1.4 GHz 電波連続波
等高線(黒): NH3 (1,1) ピーク強度

http://www.ncsm.city.nagoya.jp/visit/planetarium/themes/past/2022/221228.html• Clump Bの電離ガスに接するバブルの東側で線幅が大きい (3.0 km/s)• Clump Cは線幅が〜2.0 km/s で一様
http://www.ncsm.city.nagoya.jp/visit/planetarium/themes/past/2023/111111130_1.html

野辺山で得られたデータを含めてプラネタリウムに投影し、研究成果の紹介と教育普及を実践