Molecular Clouds and Star Formation in the Magellanic Clouds and Milky Way

Transcription

1 Molecular Clouds and Star Formation in the Magellanic Clouds and Milky Way Outline 1. Introduction 2. Surveys of the molecular clouds in the Milky Way and the Magellanic clouds 3. Molecular cloud cores in the Magellanic clouds 4. The Galactic Center 5. NANTEN2 project Akiko Kawamura (Nagoya University)

2 Tracing the life cycle of the matter Intermediate mass stars High mass stars Distributions and physical properties of the ISM vs YSOs, -> Star formation in the molecular clouds ISM evolution due to the star formation/evolution new understanding of star formation process and the ISM evolution in galaxies from multi-wavelength studies & ALMA

3 Studies of Molecular clouds in the Milky Way Surveys of the Molecular clouds along the Galactic Plane. Detailed studies of the molecular clouds and star formation CO map by NANTEN Optical image (ESO)

4 GMC Distribution in the Solar neighborhood

5 ISM, Star formation Studies < Milky Way > nearby-> highest resolution informations data from multi-wavelength obs. contaminations along los different spatial resolution due to the different distances One of the best studied galaxies But Difficult to study through out the whole galaxy Extra galaxies Studies of the ISM and star formation activities throughout a galaxy Bridge between the Milky way and the nearby galaxies Magellanic system 1 =>0.24pc, 0.1 =>0.024pc)

6 Magellanic Clouds D~ 50 kpc (one of the nearest) Different environment from the MW. High gas-dust ratio Low metallicity Active star formation Massive star formation Young populous clusters The Large Magellanic Cloud The Small Magellanic Cloud

7 Active Star Formation in the LMC LMC 4 N 11 N Dor N 206

8 Distribution of the Molecular Clouds Contours: CO (Fukui et al. 2006) HI(Kim et al. 2003: ATCA+Parkes) HI 7x10^8Mo CO ~10 % of HI in mass

9 Mass Spectrum Slope Very similar Blitz et al. 2006

10 Mass Spectrum Mo n(>m ) M^(S+1) Slope steeper in high mass range. Blitz et al. 2006

11 Star formation indicators: Clusters and Associations in the LMC SWB0:10 Myr LMC 30 Myr

12 Star formation indicators: HII regions Ori A HII regions SNRs Unidentified Filipovic et al. (1998) High mass stars with > O8 * H alpha Davies et al. (1976) Henize (1976) radio continuum by Parkes 483oint sources (e.g., Fillipovic et al. 1995) at frequencies of 1.4, 2.45, 4.75, 4.8, 8.55GHz Identification of HII regions from Spectral index, comparisons with Hα IRAS 60µm X-rays radio continuum by ATCA+Parkes 1.4GHz (Philipovic et al. in preparation) 4.8 GHz & 8.6 GHz (Dickel et al. 2005) Select 1.4 GHz point sources Beamsize 40"

13 30 Dor south: Molecular ridge & CO arc GMCs without massive star formation

14 Star Formation Activities GMCs > 10^5Mo

15 Properties of the GMCs 10 5 Mo GMC with HII regions and clusters Number of clouds GMC with HII regions Starless GMC ΔV (km/s) log (R/pc) log (MCO/Mo)

16 Time Scale of the Molecular Clouds 7 Myr 14 Myr Life time of the molecular clouds~ 30 Myrs c.f. Milky Way, M33 6 Myr 10Myrs 4Myr

17 Survey of molecular clouds over a large-scale in a galaxy with uniform sampling Comparisons with Star formation activities Molecular clouds evolution -> Star formation Extending surveys of the molecular clouds to the nearby galaxies Recent studies and Observations with ALMA -> sessions on the 15th & 16th

18 Orion with different beam NANTEN (40 pc) SEST (10 pc) NANTEN (0.3 pc) Higher resolution observations by SEST, MOPRA, APEX, ASTE

19 SEST, MOPRA, ASTE observations Clumps, sores with ~5-10 pc resolution Size, line width, and virial mass of 12CO(3-2) clumps are 7 pc, 7 km/s and 6x10^4Mo H alpha flux is correlated well with the intensity ratio of 12 CO(3-2) and 12 CO(1-0) Minamidani et al. (2006) in prep.

20 Proto star/cluster condensation Compact (<1pc), dense (10 4 /cc) and warm (50K) Derive density, temperature and kinematics -> high resolution CO high transitions -> high density tracers HCO +, HCN -> with uniform sampling over a large scale in an entire galaxy Compliment with multi-wave length studies Envelope of molecular clouds In low metallicity, intense UV environment CO -> C ->C + (PDR) -> high resolution [CI] observation Energetic events like SNRs High transition lines

21 Large scale observations in IR Spitzer survey of the LMC SAGE: Surveying the Agency of the galaxy s evolution (Meixner et al. ) 3.6um 8.0um 24um dust, YSOs, HII regions, SNRs, AGBs,, CO: from 1.2 Kkm/s 1.2Kkm/s intervals (Fukui et al. 2006)

22 N206 in the LMC: CO & 24um image Contour:SEST 12CO(1-0) Contour: 12 CO(1-0) Image :Visible

23 Large scale observations in IR AKARI: Launched in Feb All Sky Survey & Pointing Observations AKARI: 3, 7, 11um Pointing Obs. (Onaka et al.). AKARI: 60,90,140um From All Sky Survey (JAXA) (JAXA)

24 The Galactic Center High stellar density High star formation activities Magneto-hydrodynamic Formation of Loop Structures Initial Results reported in Science, 314 (2006) by Fukui et al. See also poster #293 by Torii et al.

25 Integrated Intensity Map observed with NANTEN Central Molecular Zone (CMZ) : Broad molecular features km/s --- SNR? High temperature component ~ K Strong magnetic fields ~ 100µG-1mG

26 Loop 1 and Loop 2 Length(pc) Mass (Msun) 300 pc 220 pc loop1 loop pc 300 pc *Distance from earth:8500pc *Estimated mass: lower limit (We assume LTE to 13CO) kinetic energy about erg 100 SN energy Fukui et al. (2006) Poster # 293 Torii et al.

27 Velocity Gradients in loops Blue shift Red shift

28 Magnetic flotation of Parker instability Loop structures observed in the solar corona are produced by the buoyant rise of magnetic loops from below the photosphere. Parker (1966) proposed that magnetic loops can be created in galactic gas disks by an MHD instability driven by buoyancy. However, it was hard to observe such galactic magnetic loops. Magnetic loop in solar corona (TRACE 191Å) MHD activities of galactic disks Shibata et al.

29 Two Dimensional MHD simulations of the Parker instability Matsumoto et al β=pgas/pmag=1, isothermal ideal MHD

30 Formation of magnetic loops Magnetic loop structure : plasma β=1 height 400pc length 1kpc inclination angle 40deg, MHD Simulation by Machida, Nozawa, Matsumoto asumptions (1) an ideal MHD plasma, (2) adiabatic with specific heat ratio γ = 5/3, (3) magnetic field is frozen into the gas, (4) viscosity and resistivity are neglected, (5) the effects of the rotation are neglected

31 2D MHD simulations of Parker instability Fukui et al. (2006)

32 Poster # 106 by Onishi et al. NANTEN & Campanas, alt.4800m

33 Nagoya Univ. Y. Fukui Osaka Pref. Univ H. Ogawa Univ. of Cologne J. Stutzki Univ. of Bonn F. Bertoldi Seoul National Univ. B.C. Koo University of Chile L. Bronfman Collaborators Univ. of New South Wales M. Burton ETH Zurich A. Benz

34 San Pedro de Atacama 2400 m Site Sairecabur 5500 m Toco 5600 m Chajnanto 5600 m NANTEN 4800 m ALMA OSF 2900 m Salar de Atacama Chascón 5650 m CBI APEX ALMA 5000 m Negro 5000 m 15 km Google Earth

35 Target frequencies CO(J=1-0) 115 GHz CO(J=2-1) 230 GHz CO(J=3-2) 345 GHz CO(J=4-3) 460 GHz CO(J=7-6) 806 GHz CI ( 3 P 1-3 P 0 ) 492 GHz 2. 6 (HPBW) 1. 3 (HPBW) 0. 9 (HPBW) 39 (HPBW) 22 (HPBW) 37 (HPBW) Nagoya RX Cologne SMART CI ( 3 P 2-3 P 1 ) 809 GHz 22 (HPBW) 8 beams in 490GHz, 8 beams in 810GHz, simultaneously

36 NANTEN -> NANTEN2 Large scale survey of interstellar gas in the Galaxy, Magellanic Clouds, and nearby galaxies in CI ( 3 P 1-3 P 0 ), CI ( 3 P 2-3 P 1 ) and CO (J= 2-1, 3-2, 4-3,..) Moved NANTEN telescope to Atacama, Chile Alt. 4,800m starting from October 2003 Replaced the main-ref for higher-freq. operation Enclosed in a Dome Measurements of the surface accuracy, pointing accuracy, Beam size Test observations with test receiver systems

37 Summary Molecular clouds surveys covering an entire galaxy Milky Way, Magellanic Clouds, some nearby galaxies Star formation history throughout a galaxy High resolution observations can be done toward the galactic plane but it is hard to identify molecular clouds entirely the galaxy We started to understand the molecular gas distribution in the nearby galaxies Multi-wavelength observations started toward the nearby galaxies IR and CO observations covering the whole LMC ALMA will bring us the surveys of the molecular clouds in the nearby galaxies Active region in a galaxy the Galactic Center NANTEN-> NANTEN2 Large scale survey in submm wavelength > selection of targets for ALMA