星形成ゼミ 2017/4/21
SFN #291 6-10
内山 瑞穂

• L dwarfの大気構造：field L dwarf と planetary young L-type objectsで異なる• 若いほうがより弱い重力？

• 時間変化を調査：若い(2-3Myr)天体であるROXs 42B b• Keck/NIRC 3-5umのデータ取得し、先行のNIRデータと合わせてmodel fitting• Closely resembles: GSC06214 B and And b• slightly bluer Ks−Ms color: currently lacks
evidence of a circumplanetary disk

• Fitting : dust-free/dusty/cloudy• models with substantial atmosphericdust/clouds seem to be best

• ROXS 42B b: mid-IR photometric featuresthat are systematically different fromother previously observed planetary-mass
and field objects of similar temperature• First extensive spectroscopic study ofthe global population• Trumpler 16, Trumpler 14 and Collinder 232
in the Carina Nebula• Using data from the Gaia-ESO Survey,
down to solar-mass stars• ~400 good candidate members• from OB types to sub-solar masses• ~100 heavily-reddened early-type Carina members• Previously unrecognized or poorly classified• Including 2 candidate O stars andseveral candidate Herbig Ae/Be stars• Complex spatial structure• With definite clustering of low-mass members around the most massive stars• 各天体の視線方向減光も測定： Spatially-variable extinction• Trumpler 14: systematically younger than other sub-clusters• X-ray study of the North-America and Pelican star-forming region(NGC 7000/IC 5070)• この領域の若い天体とその特徴を調べる• Chandra (four pointings) and XMM-Newton (seven pointings)• Opt/NIRデータとマッチングして天体のstageなどを推定

• Less than 30% of X-ray sources: a previously known young star
• Most X-ray sources with an optical/NIR counterpart: likely candidate membersof the star-forming region• Wide range of extinction & near-IR excesses→prevent derivation of accurate stellar parameters: ages between 1-10 Myrs

• IR 超過のあるX線天体の分布：
suggestive of sequential
star formation especiallynear the “Gulf of Mexico”
region• Investigate the formation and early evolution of star clusters• Assuming they form from a turbulent starless clump of given mass bounded
inside a parent self-gravitating molecular cloud characterized by a particularmass surface density• Assuming instantaneous star cluster formation and gas expulsion• Follow the early evolution of the clusters up to 20 Myr• Investigating efects of different star formation efficiencies, primordial binary fractions
and eccentricities and primordial mass segregation levels• Clusters expand rapidly, even considering only the bound members• Clusters formed from higher Σcloud environments tend to expand more quicklyΣ = 0.1 g cm-2
cloud

Σ = 1 g cm-2
cloud

• To form a young cluster of a given age, stellar massand mass surface density, models need to assume
a parent molecular clump that is unrealistic density• Initial binary properties are only slightly modified
by interactions: very similar to those at birth• The protoplanetary system HD 169142: one of the few cases where apotential candidate protoplanet has been recently detected via direct
imaging in the near-infrared• New ALMA observations of the dust continuum at 1.3 mm, 12CO, 13CO
and C18O J = 2-1 emission• To study the interaction between the protoplanet and the disk

• Dust continuum emission reveals
a double-ring structure• size and position of the inner ring is ingood agreement with previous polarimetricobservations in the near-infrared and isconsistent with dust trapping by a massiveplanet• Channel maps of the J = 2-1 line of the three CO isotopologues reveal
the presence of gas inside the dust cavity and dust gap• Gaseous disk is also much larger than the compact dust emission• This difference and the sharp drop of the continuum emission at large radii
point to radial drift of large dust grains• Using the thermo-chemical disk code DALI, the continuum and the CO
isotopologues emission are modelled• Resulting gas surface density is reduced by a factor of 30 - 40 inward of thedust gap• Gas and dust distribution hint at the presence of multiple planets shaping thedisk structure