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STAR FORMATION: MY PAST, CURRENT AND FUTURE WORK

STAR FORMATION: MY PAST, CURRENT AND FUTURE WORK. Ana López Sepulcre November 2007. PAST WORK. October 2006 - June 2007 Universitat de Barcelona Departament d’Astronomia i Meteorologia. October 2006 - June 2007: Collaboration grant for last year undergraduate students. Supervisors:

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STAR FORMATION: MY PAST, CURRENT AND FUTURE WORK

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  1. STAR FORMATION: MY PAST, CURRENT AND FUTURE WORK Ana López Sepulcre November 2007

  2. PAST WORK October 2006 - June 2007 Universitat de Barcelona Departament d’Astronomia i Meteorologia

  3. October 2006 - June 2007: Collaboration grant for last year undergraduate students • Supervisors: • José María Torrelles (IEEC; UB) • João Lin Yun (Universidade Lisboa) Study of young embedded clusters in the 3rd Galactic quadrant  Cloud properties and star formation activity as a function of Galactocentric distance in the outer Galaxy PARTICULAR CASE: IRAS 06361-0142

  4. CO(1-0) line observations: 15m Swedish-ESO Submillimetre Telescope (SEST), September 1999 Line centred at a LSR velocity of ~53 km/s Kinematic distance: 7 kpc Galactocentric distance: 15 kpc Resolution: 0.22 km/s

  5. J H K Near IR observations (J, H, Ks bands): ESO Antu Telescope + ISAAC instrument, 10th November 2000

  6. Plot of colour index (H-Ks) against R.A. Cluster region: 36” on each side (R.A. and dec)  1.2 x 1.2 pc2 at 7 kpc. Cluster members: located within the “cluster region” and with (H-Ks)>0.65

  7. Colour-colour diagram: > 50% of the cluster members have cleared their inner circumstellar disks responsible for (H-Ks) excess Age > 3 Myr (see Haisch et al., 2001) Isochrone fitting (Siess, Dufour & Forestini, 2000): - 4 Myr with variable extinction between AV = 6 and AV = 13 within the cloud - Cluster composed of low- and intermediate-mass stars (up to ~7 Msun)

  8. Radio continuum observations at 6 cm: VLA Data Archive (Observed on 2005 May 8 in VLA’s B configuration) No emission detected at this wavelength Very Large Array (NRAO) Upper luminosity limit: L~5500Lsun for the individual members of the cluster (~12 Msun)

  9. SUMMARY New distant young stellar cluster embedded in a molecular cloud, seen towards IRAS 06361-0142. Distance: 7 kpc. Galactocentric distance: 15 kpc (far outer Galaxy). Composed of several tens of low and intermediate-mass young reddened stars, surrounded by a spherical nebulosity. Approximate size of the region: 1.2 x 1.2 pc2. Possible fit to the age of the cluster: 4 Myr, with variable extinction within the cloud between AV = 6 and AV = 13. The outer Galactic disk is active in the formation of new stellar clusters; the star formation process is unaffected by the properties that distinguish the outer Galaxy from the inner Galaxy. Yun, J.L., Lopez-Sepulcre, A, Torrelles, J.M. A new young stellar cluster embedded in a molecular cloud in the far outer Galaxy A&A 471, 573-578 (2007)

  10. CURRENT AND FUTURE WORK October 2007 - October 2010 (?) Osservatorio Astrofisico di Arcetri

  11. CONSTELLATION: The origin of stellar masses www.constellation-rtn.eu European Commission FP6 Marie Curie Research Training Network involving a large number of European astronomy institutions who will be training young scientists through research into the origin ofstellar masses. Work Packages: 1. From clouds to cores to protostars 2. The birth and influence of massive stars 3. The physics of the low-mass end of the IMF

  12. WP1 WP2 WP3 Exeter ER ESR Prague ER Potsdam ESR Saclay ER ESR Cardiff ER Lyon ESR Lisbon ER Tenerife ESR ER INAF-Arcetri ESR INAF-Palermo ER Grenoble ESR, ER Cambridge ESR St Andrews ER CONSTELLATION: The origin of stellar masses ESR = Early Stage Researcher ER = Experienced Researcher Supervisors: M. Walmsley, R. Cesaroni, C. Codella, D. Galli.

  13. High-mass star formation: Problems • Observational problems • - Rare; located at high distances • - Fast evolution towards ZAMS • Formation in clustered mode Theoretical problem Stars with M ≥ 8Msun reach the ZAMS while still accreting  radiation pressure should halt the accretion process Stars with M ≥ 8Msun cannot form (?!)

  14. High-mass star formation. Possible scenarios 1. Non-spherical accretion with larger accretion rates than those for low-mass stars Well-defined disk/outflow system 2. Merging of stars with masses below 8 solar masses Disks/outflows associated with the low-mass stars should be destroyed during merging So far, evidence seems to support scenario number 1 (e.g. G24.78+0.08)

  15. Study of the kinematics of clumps hosting OB (proto)stars Properties of clumps Size: ~1 pc Density: 105 -106 cm-3 Temperature: 30 - 50 K Mass: 103 -104 Msun Clumps are the sites of star formation and may contain: -Hot Molecular Cores: smaller, hotter and denser cores with embedded stars -Stars already in the Main Sequence -(Compact) HII regions powered by high-mass stars (OB) Fontani et al (2002): Mgas/Mvir > 1 for a sample of 12 clumps  massive clumps are unstable; indirect evidence for infall Difficult to detect infall directly, since the contribution of Vff to line broadening is hidden by the contribution due to turbulence within the clump and outflow motions

  16. Study of clump kinematics requires multi-line observations Molecular tracers: 12CO, 13CO: bipolar outflows  location and luminosity of embedded stars C18O, C17O: ambient gas  velocity field and column density distribution CH3C2H: temperature map NH3 in absorption(towards Hypercompact HII regions): velocity profile. Radiative transfer models needed to interpret line profile. NH3(1,1) in absorption should allow us to detect and measure clump-scale infall Observations of various tracers and at different angular resolutions (0.1-1 pc): velocity field  conservation of angular momentum?

  17. My current work Observations Single-dish 13CO and C18O on-the-fly observations of 11 sources with IRAM’s 30m radiotelescope in Granada (HERA receiver) Observed in September 2006

  18. IRAM 30m telescope + HERA www.iram.es 30m radiotelescope (IRAM, Granada) HERA receiver: 2 arrays of 3x3 pixels with 24” spacing tunable between 215 and 272 GHz beamwidth varies between 12” and 9”

  19. My current work Observations Single-dish 13CO and C18O on-the-fly observations of 11 sources with IRAM’s 30m radiotelescope in Granada (HERA receiver) Observed in September 2006 Aims: Search for molecular outflows and embedded massive (proto)stars Characterise properties of outflow and their powering sources NH3 VLA observations (A configuration) towards 2 different sources, August 2007: infall? (not reduced yet)

  20. My current work Data reduction and mapping

  21. My current work Data reduction and mapping

  22. My current work Data reduction and mapping

  23. To be continued…

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