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The deep search of O 2 in interstellar space

The deep search of O 2 in interstellar space. L. Pagani Observatoire de Paris-Meudon. COSMIC ABUNDANCES. Oxygen recycling. Simplified oxygen chemistry in gas phase (from Prasad et al. 1987). How much of O 2 ?. 50 % of O in CO. C/O » 0.4. 50 % of O in O 2. CO/ O 2 » 2.

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The deep search of O 2 in interstellar space

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  1. The deep search of O2 in interstellar space L. Pagani Observatoire de Paris-Meudon

  2. COSMIC ABUNDANCES

  3. Oxygen recycling Simplified oxygen chemistry in gas phase (from Prasad et al. 1987)

  4. How much of O2 ? 50 % of O in CO C/O » 0.4 50 % of O in O2 CO/ O2» 2 Cooling agent for dark clouds (Goldsmith & Langer 1978, ApJ 222, 881)

  5. Clavel et al. 1978, A&A 65, 435

  6. Goldsmith & Langer 1978, ApJ 222, 881

  7. From 1985 to 1997 : First searches from the ground O18O (234 GHz, NJ : 2101, Galactic sources) • Goldsmith et al,. 1985, ApJ 289, 613 • Liszt & van den Bout, 1985, ApJ 291, 178 • Pagani et al., 1993, A&A 274, L13 • Fuente et al., 1993, A&A 275, 558 • Maréchal et al., 1997, A&A 318, 252O2/CO < 0.1 (3 s) O16O (119 GHz, NJ : 1110, z > 0.02,  < 116 GHz) • Liszt, 1985, ApJ 298, 281L • Combes et al., 1991, A&A 248, 607 • Liszt, 1992, ApJ 386, 139 • Combes et al., 1997, A&A 327, L17O2/CO < 0.006 (3 s)

  8. 16O18O Search with POM-2 16O18O (NJ:21-01) line at 234 GHz is observable from the ground NGC 2264 (C18O and O18O) O2/CO < 0.09

  9. 16O18O Search with POM-2 L183, first false (tentative) detection…

  10. PIROG 8, a Balloon Experiment Launch He filling 60 cm telescope 425/440 GHz SIS receiver O2 (NJ:32-12) and 13CO (J:4-3) After Landing…

  11. Olofsson et al., 1998 A&A 339, L81 NGC 7538 13CO(4-3) NGC 7538 C18O and O2 W51 13CO(4-3) and O2 O2/CO < 0.04

  12. SWAS : O2 @ 487 GHz(NJ : 33-12) • SWAS did not detect O2 in quiescent cloud cores - • abundance limit of 3 x 10-7 rel. to H2 • (Goldsmith et al. 2000, ApJ 539, L123)

  13. Second false (tentative) detection in r Oph A SWAS Odin Goldsmith et al. 2002, ApJ 576, 814

  14. Odin, a Satellite with a 119 GHz rec. Swedish Satellite with contributions from France, Canada and Finland 1.1 m off-axis telescope, Schottky receivers, passively cooled

  15. Still no O2! (O2) < 5-10 -8

  16. No O2 in SMC (O2) < 1.3 -6 C/O = 0.16 and lower metallicity Wilson et al. 2005, A&A 403, L5

  17. Third false detection or real detection ? in r Oph A (again !) N(O2) = 8.4E14 cm-2 (O2) = 2.3E-8

  18. Ted Bergin's view of O2 chemistry Atomic Oxygen depletes on grains

  19. What reasons for O2 deficiency ? • Larger C/O ratio : 0.8 ? More ? • Deeper penetration of UV rays ? • Turbulence taking C+ deep inside ? • Turbulence + higher H abundance ? • Something wrong with the reaction rates ? (no! O + OH, I. Sims) • Depletion onto grains ? ((O2) (ice) < 1.5 10-5) • Reaction with PAHs ? (Joblin, Zermatt conf. 9/2003)… • See papers : • Vandenbussche et al. 1999, A&A 346, L57 • Goldsmith et al. 2000, ApJ 539, L123 • Bergin et al. 2000, ApJ 539, L129 • Casu et al. 2001, MNRAS 325, 826 • Spaan & van Dishoek, 2001, ApJ 548, L517 • Roberts & Herbst, 2002, A&A 395, 233 • Willacy et al., 2002, ApJ 573, L119

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