The Star Formation Newsletter#315, 44-46#316, 01-07
島 和宏

2019/0544

https://arxiv.org/abs/1902.02052

A&A proofs: manuscript no. gaiaMCdisArxiv

AG1 kpc from the Sun and are still located in the Galactic plane 1 depicts the extinction AG feature of on- (green) and o↵-cloud(Magnani et al. 1996; Schlafly et al. 2014), They tend to occupy (blue) stars.
large areas on the sky, making them able to optically extinct a
In the second step, the distances are determined usinglarge number of stars. Consequently, the extinction AG imposed Bayesian inference with on-cloud stars and are subsequently
on stars behind molecular clouds is able to be investigated statis- confirmed with o↵-cloud stars by eye. We use two moleculartically.
clouds, Taurus (Pineda et al. 2010; Ward-Thompson et al. 2016)
We selected Gaia DR2 stars according to their parallaxes and and Gemini (Li et al. 2015), to illustrate the process of determinextinction AG . First, we removed those stars with parallaxes < ing distances.
0.5 mas, corresponding to an upper distance threshold of 2 kpc.
Molecular clouds at high Galactic latitudes are usually near theSun (< 1 kpc), and a 2-kpc cuto↵ suffices for our study. If the relative errors of stellar parallaxes exceed 20%, the corresponding
distances would di↵er from the reciprocal of their parallaxes by
・Gaia DR2を使用
Cloud distancea large amount (Bailer-Jones 2015), and consequently, we only
kept those stars whose relative parallax errors are less than 20%.
・AGのブレイクポイントから分子雲の距離を同定
As to the extinction AG , we require AG > 0, which rejects 13stars. In total, we have 30,259,242 Gaia stars meet the criteria.
On-cloud stars
・計52個、うち13個は今回で初めて距離がわかった
The extinction AG error of a single star, AG , is estimatedwith1
AG =84th_percentile 16th_percentile .
(1)
2
Oﬀ-cloud stars
where 84th_percentile and 16th_percentile are provided in Gaia
DR2. To derive the distance and its standard deviation, we drew
10000 samples from the Gaussian distribution N($, $), where$ and $ are the parallax and its error in Gaia DR2, and theDistancemean and standard deviation of the distance correspond to themean and standard deviation of the reciprocal of the 10000 sam- Fig. 1: The extinction AG of on- (green) and o↵-cloud (blue)stars. The vertical black line marks the distance of the molecularples, respectively.
We used Planck 857-GHz images (Planck Collaboration cloud.
et al. 2014) to trace the molecular clouds rather than IRAS 100-

45

https://arxiv.org/abs/1811.04381

・SiO, SO2, H2S, CH3OH, H2COで観測
SiO：disk, inner envelope, jetをトレース
CH3OH, H2CO：infalling-rotating envelopeをトレース
SO2, H2S：diskのouter partをトレース
・Core Accretion モデルを支持Ordered Envelope-disk Transition in G339.

Implications for Massive Star Formation
今回のTarget
・G339.88-1.26 (IRAS 16484-4603)

rCB = 530 au

low-mass protostarsと違うところ
・遠心力バリアが典型値(<200 au)より大きい
low-mass protostarsと同じところ
・highly collimated outﬂow
・transition from an infalling-rotating envelope to Keplerian disk

得られた示唆
massive star formation は low-mass のスケールアップ版だろう(core accretion シナリオ)

46

https://arxiv.org/abs/1902.03673

3

The weakening outburst of V582 Aur2016

Magnitude

・V582 Aur (オリオン座FU型星)を長時間観測
・あと80年ぐらいで明るさの変化は落ち着くだろう・accretion diskのモデル化の参考になる？

2017
ASO

N

DJF2018MAM

JJASONDJF

2019
M

A

M

JJA

S

O

N

DJFM

A

68101214

161820
7600

7800

8000

8200
JD (2,450,000 + )

8400

8600

01

IR region of the SED, which are known as Lada indices
The YSOs can be classified as Class 0, Class I, Clas
IIhttps://arxiv.org/abs/1903.01070
and Class III, based on the steepness of the indiceat various wavelength intervals (Lada 1987; Andre et al1993). The estimation and analysis of Lada indices arvery important in studying the evolution of HAeBe staras it gives an idea about the evolution of the CSM. Th
equation defining the spectral index (Lada 1987; Wilking
1989; Greene et al. 1994) is expressed as,λ F

nλ1 −λ2 =log( λ21 Fλλ2 )1log( λλ12 )(10For our analysis we consider the spectral index
n2−4.6 , which is the ratio of the flux values at 2MASS(Skrutskie et al. 2006) Ks -band (i.e., λ1 = 2.159 µm
and WISE (Cutri et al. 2013) W2-band (i.e., λ2 = 4.
µm). The age estimates are available only for 110 stars
However, the spectral index is not calculated for thHAeBe stars CPD-61 3587B and LkHA 224 due to th
unavailability of WISE magnitudes. Hence, a sample o
108 stars is used for this analysis.

・Gaia DR2を使用
・photometryと距離からHAeBeのageとmassを推定・BeとAeでディスクの構造が違いそう？

02

https://arxiv.org/abs/1903.03540

A&A proofs: manusc

・どんな惑星が中心星に落ちずに生き残れるか・分子雲のcollapseから計算
・いろんな惑星がtype-I migrationから逃れられる

c
H
att
I
cwt
pdyt
a

12B

101

100

10102

101

100-1

10 -1
10 -2

10 -2

10 0

10 2

04

・ALMAを使って2つのYMC progenitorを観測
・C3H2(7-6)で最も密度の高いガスをトレース
・初めて重力収縮していることを確認

https://arxiv.org/abs/1903.06158

05https://arxiv.org/abs/1903.06537

・MWC 758 (Herbig A5 star)のdiskで２つのclumpが観測されている
・dust-trappingシナリオをシミュレーションで再現simulation

ALMA
bandin7 theobservation
Two vortices
MWC 758 disc

Keplerrotation

vortexdusttrapping

2つの巨大惑星によるもの

Particles

AzimuthModel & Methods

00.004-4-1
10・2D gas (isothermal) + dust hydrodynamical simulation・gas self-gravity (実は重要)-2
・惑星はmigrateしない・gap -> Rossby wave
instability -> dust trapping-3
10-5100・constant120 140 alpha turbulent
4060 viscosity
80 100 ->120
140
内側でringを形成
0.002

080
Radius [au]rtensity at 1277 orbits
0.00.40.8

1234

Radius [au]Perturbed vortensity at 1277 orbits-0.8-0.4
0.0
0.4
0.8
4

3

2

10.5

1.0

0-0.5

0.0

0.5

1.0

3

gap

Azimuth [rad]21.5 Msun

80
100
Radius [au]1.5 Mj@ 35 au
120

140

10-2

0.010

0.008

10-3

1

gap

0.006

00.00410-4-1-2

0.002-304060

80 100Radius [au]1205 Mj @ 140 au

140

1234

10-5

Particles size [m]0.0

06

https://arxiv.org/abs/1903.05106

6E. R. Beasor et al.

Figure 4. Plot showing best fitting isochrones from each of the three age eisochrones represents the main sequence. The purple star symbol indicates t

・星団はSSPsでは説明できない・明るい星はmergeによるものだろう07

https://arxiv.org/abs/1903.07610

14Biazzo, Beccari, De Marc

・LH95にあるlow-mass PMSをHSTで観測
・accretion luminosityの時間変化が普通よりゆっくり-> metallicityが重要なパラメータ

Figure 8. Accretion luminosity versus stellar luminosity.
Circle and diamond symbols are as in Fig. 5. Dashed lines

pears
and hagreem
ments
shade
tion oThesecreasi
stars(see dal. 20of thi
by us
again
dates
thanGalac
kpc;
ports
accordthe lo