The role of cosmic rays in the formation of interstellar and circumstellar molecules

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1 The role of cosmic rays in the formation of interstellar and circumstellar molecules Maria Elisabetta Palumbo INAF Osservatorio Astrofisico di Catania

2 Molecules in space About 160 molecules have been detected in space (

3 Ices in the Solar System Planet Satellite Observed Species Planet Satellite Observed Species Jupiter Io SO 2, H 2 S, H 2 O Europa H 2 O, SO 2, CO 2, H 2 O 2 Ganymede H 2 O, O 2, O 3, CO 2 Callisto H 2 O, SO 2, CO 2 Saturn Mimas H 2 O Enceladus H 2 O Tethys H 2 O Dione H 2 O, O 3 Rhea H 2 O, O 3 Hyperion H 2 O Iapetus H 2 O Uran Miranda Ariel Umbriel Titania Oberon Neptune Triton Pluto* Pluto Charon H 2 O H 2 O H 2 O H 2 O H 2 O N 2,CH 4,CO,CO 2,H 2 O N 2, CH 4, CO, H 2 O H 2 O * After IAU resolution, in 2006, Pluto is a dwarf planet and is recognized as the prototype of trans-neptunian objects.

4 Observations of dense molecular clouds

5 Solid-phase species in dense molecular clouds Field star High-mass young stellar object Elias 16

6 Abundance of solid-phase molecules (with respect to H 2 O=100) It is generally accepted that other molecules are also present in icy grain mantles

7 Origin of interstellar molecules Gas-phase reactions Solid phase Grain-surface reactions Energetic processing of icy mantles (molecules released to the gas phase after desorption of ices)

8 Icy grain mantles UV photons Freeze out of gas phase species (CO) Grain surface reactions (H 2 O, CH 3 OH, CH 4, H 2 S) cosmic ions Energetic processing of icy mantles (CO 2, OCS)

9 Energetic processing High density and high extinction stellar radiation does not penetrate molecular clouds Interaction of cosmic rays with molecular clouds low-energy cosmic rays electrons UV photons E = kev - MeV E = kev E = ev

10 Effects of energetic processing kev-mev ions UV photons frozen gases Sputtering Structural Chemistry Implantation Residue changes Laboratory experiments

11 Laboratories worldwide Energetic processing driven chemistry University of Hawaii, Honolulu (USA) NASA/Ames Research Center (USA) NASA/Goddard Space Flight Center (USA) University of Virginia, Charlottesville (USA) AT&T Bell Lab, NJ (USA) Leiden Observatory (NL) University of Paris, Orsay (F) CIMAP-CIRIL-Ganil, Caen (F) Forschungszentrum Jülich (D) Catania Astrophysical Observatory (I) etc.

12 Laboratorio di Astrofisica Sperimentale Catania Ion beam Vacuum chamber FTIR spectrometer

13 Vacuum chamber IR spectroscopy Analysis: Raman spectroscopy

14 Experimental procedure Substrate (Si, KBr, CsI) T= K Background (mid-infrared) at 16 K (KBr substrate) IR beam

15 Experimental procedure Sample T= K IR beam Mid-IR spectrum of the sample as deposited (CH 3 OH at 16 K)

16 Experimental procedure Irradiation of the sample T= K Ions (kev - MeV)

17 Experimental procedure Irradiated sample T= K IR beam Mid-IR spectrum of the sample after irradiation (CH 3 OH kev H + at 16 K) CO 2 CO CH 4 H 2 CO

18 Experimental procedure

19 Solid CO Loeffler, Baratta, Palumbo, Strazzulla, Baragiola, 2005, A&A 435, 587

20 optical depth optical depth Comparison with IR observations wavelength ( m) Elias 16 H 2 O on carbon grains at 15 K CO +200 kev H + at 15 K fit Elias 16 (field star) Mennella, Baratta, Palumbo, Bergin, 2006, ApJ 643, wavelength (µm) NGC 7538 IRS9 H 2 O on carbon grains at 15 K CH 3 OH + 30 kev di He + at 15 K CO kev di H + at 15 K CO kev di H + at 80 K fit wavenumber (cm -1 ) NGC7538 IRS9 (high-mass YSO) Ioppolo, Palumbo, Baratta, Mennella, 2009, A&A 493, wavenumber (cm -1 )

21 optical depth Chemistry in solid CO CO kev H + CO CO wavenumber (cm -1 )

22 optical depth Formation of carbon chains wavelength ( m) CO 2 12 CO as deposited +200 kev H + C 3 O 2 13 CO 0.1 C 3 O C 5 O 2 CO at 16 K C 7 O 2 C7 O 2 13 CO 2 C 3 O 2 C 5 C 5 O 2 C 2 O C 4 O 0.0 C 3 C wavenumber (cm -1 ) Palumbo, Leto, Siringo, Trigilio, 2008, ApJ 685, 1033

23 C 3 O 2, C 2 O and C 3 O CO kev H + T=16 K Palumbo et al. 2008

24 optical depth optical depth optical depth CO:N 2 mixtures CO : N 2 = 1 : 1 as deposited kev H + CO 2 C 3 O N 2 O T = 16 K CO 0.05 C 3 O 2 Sicilia et al. in preparation wavenumber (cm -1 ) CO : N 2 = 1 : 1 as deposited kev H + NO 0.10 NO 2 CO : N 2 = 1 : 1 as deposited kev H + C 2 O 0.01 OCN 0.05 N 2 O O wavenumber (cm -1 ) wavenumber (cm -1 )

25 time (10 7 years) time (10 7 years) CO : N 2 = 8 : 1 CO : N 2 = 1 : 1 CO : N 2 = 1 : CO : N 2 = 1 : 1 CO : N 2 = 1 : y = a (1 - e - D ) N 2 O / (CO) i y = a (1 - e - D ) NO 2 / (CO) i Dose (ev/16 u) Dose (ev/16 u) time (10 7 years) NO / (CO) i CO : N 2 = 8 : 1 CO : N 2 = 1 : 1 CO : N 2 = 1 : 8 fit curve y = a (1 - e - D ) Nitrogen oxides Dose (ev/16 u) Sicilia et al. in preparation

26 Experimental results After irradiation of CO and CO:N 2 ice mixtures: CO 2 /CO i 0.1 (Ioppolo et al. 2009) carbon-chain oxides/co i 2-3 x 10-3 (Palumbo et al. 2008) NO/CO i N 2 O/CO i 1-4 x 10-3 NO 2 /CO i 1-3 x 10-2 (Sicilia et al. in preparation)

27 optical depth Sublimation CO + 1.5x kev H + cm T=16 K T=40 K T=50 K T=80 K wavenumber (cm -1 ) Palumbo, Leto, Siringo, Trigilio, 2008, ApJ 685, 1033

28 Carbon chain oxides in the ISM gas phase C 2 O and C 3 O detected towards TMC-1CP cold molecular cloud (Brown et al. 1985) L1498 IRAS starless core (Palumbo et al. in preparation) hot corino (Ceccarelli, priv. comm.) Elias 18 class II protostar (Palumbo et al. 2008) These sources cover different phase of low-mass star formation. Observations towards L1498 and Elias 18 triggered by laboratory results. We expect ALMA will detect carbon-chain oxides towards a large number of sources. C 2 O/H 2 = C 3 O/H 2 = (e.g., Brown et al. 1985; Ohishi et al. 1991; Palumbo et al. 2008)

29 column density/co column density Origin of C 2 O and C 3 O Gas phase reactions Ion irradiation of CO-rich icy mantles In IS clouds: CO/H 2 = (Frerking et al. 1982) C 2 O/CO = C 3 O/CO = ExperimentaI highest values C 2 O/CO = C 3 O/CO = Assuming: High depletion (1 MeV) = 1 cm -2 s -1 (Mennella et al. 2003) time (10 6 years) C 3 O C 2 O fluence ( kev H + cm -2 ) Observed C 2 O and C 3 O can be formed after years (Palumbo et al. 2008)

30 Nitrogen oxides in the ISM Sagittarius B2 (Halfen et al. 2001) NO/H N 2 O/H (two orders of magnitude higher than predicted by chemical models) NO 2 /H 2 < 3.3 x 10-9 CO depletion at n H 10 4 cm -3 N depletion at n H 10 6 cm -3 Nitrogen oxides formed in the solid phase after ion irradiation of icy grain mantles and released to the gas phase after desorption of icy mantles. We expect ALMA will detect nitrogen oxides towards a large number of sources.

31 C 3 O in carbon star IRC Tenenbaum et al. 2006, ApJ 649, L17 IRC is an asymptotic giant branch star C 3 O column density = 1.2x10 12 cm -2 an order of magnitude higher than predicted Other detected O-bearing molecules: H 2 O (Melnick et al. 2001; Hasegawa et al. 2006) OH (Ford et al. 2003) H 2 CO (Ford et al. 2004) C 3 O origin in IRC Gas phase reactions (Tenenbaum et al. 2006) Sublimation of icy bodies (Melnick et al. 2001)

32 Search for carbon-chain oxides in icy Solar System objects (Comets, Pluto and Kuiper Belt objects) Tentative detection of carbon suboxide (C 3 O 2 ) in comet Halley (Huntress et al. 1991; Crovisier et al. 1991). We would need almost a Hale-Bopp like comet to be able to detect some C 3 O lines with ALMA (Jeremie Boissier, priv. comm.) New Horizons ( Launched in January 2006, will encounter Pluto-Charon in 2015 and other Kuiper Belt objects in

33 Acknowledgments Giuseppe Baratta Carla Buemi Saro Di Benedetto Vincenzo Greco Farahjabeen Islam Zuzana Kanuchova Giuseppe Leto Paolo Leto Matteo Munari Ivana Sangiorgio Gianni Strazzulla Corrado Trigilio Grazia Umana

Magnetospheric Ion Implantation in the Icy Moons of Giant Planets

Magnetospheric Ion Implantation in the Icy Moons of Giant Planets Giovanni Strazzulla INAF Osservatorio Astrofisico di Catania NWO visitor (May-July 2012) gianni@oact.inaf.it; http://web.ct.astro.it/weblab/