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Galactic Line Science (with ALMA Band 1)

School of Physics and Astronomy FACULTY OF MATHEMATICS & PHYSICAL SCIENCES. Galactic Line Science (with ALMA Band 1). Paola Caselli. Outline. Molecular cloud and cloud cores HC 3 N Deuterium fractionation S-bearing molecules SiO P-bearing molecules Complex molecules Summary.

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Galactic Line Science (with ALMA Band 1)

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  1. School of Physics and Astronomy FACULTY OF MATHEMATICS & PHYSICAL SCIENCES Galactic Line Science(with ALMA Band 1) Paola Caselli

  2. Outline • Molecular cloud and cloud cores • HC3N • Deuterium fractionation • S-bearing molecules • SiO • P-bearing molecules • Complex molecules • Summary

  3. Molecular clouds and cloud cores CO(1-0) Taurus-Auriga NH3 cores (Benson & Myers 1989) Caselli et al. 2002a 5 pc TMC-2 N2H+(1-0) 13CO Mizuno et al. 1995 C18O Onishi et al. 1998 M ~ 5 M 0.1 pc M ~ 5x104 M

  4. HC3N(4-3) at 36.4 GHz CO(1-0) ALMA Q-band primary beam: 2.3 angular resolution: 8.4 (compact configurstion)

  5. Evidences of freeze-out: deuterium fractionation Velocity gradients and specific angular momentum in nearby cores Crapsi et al. 2007 VLA VLA PdBI 2 km s-1 pc-1 9 km s-1 pc-1 L(NH3) ~ 5x1021 cm2 s-1 L(NH2D) ~ 3x1020 cm2 s-1 The loss of L towards the small scales is consistent with observations in more evolved sources (Belloche et al. 2002).

  6. Evidences of freeze-out: deuterium fractionation Dense core studies in high-mass star forming regions Fragmentation at the earliest stages of massive star formation: ~ 0.04 pc cores have been resolved with the VLA towards G28.34+0.06 (1.7 at 4.8 kpc). Similar studies could be done using HC3N(4-3) [critical density a few times larger that that of NH3(1,1)]. Zhang, Wang, Pillai & Rathborne (2009)

  7. Early- and late-type molecules HC3N , N2 N2H+ Suzuki et al. 1992

  8. N2 Early- and late-type molecules tCO ~ nC/[n(H2)] ~ 105yr Sternberg & Dalgarno 1995 CO HC3N , N2 N + H3+ NH+ + H2  N2H+ N + OH  NO + H NO + N  N2 + O tN2~ 106 yr in UV-shielded clouds

  9. The importance of the environment NH3 and CCS in Perseus cores: CCS almost absent in clustered proto- and pre-stellar cores  Chemical evolution depends on the environment. Foster et al. 2009

  10. The importance of the environment The majority of the cores are embedded in molecular clouds  “chemically young” material continue to flow in during core contraction and collapse. C18O(2-1) CCS ~0.05-0.3 km/s within 0.2 pc (Swift, Welch & Di Francesco 2005) ~0.05-0.3 km/s within 0.3 pc (Schnee, Caselli, Goodman et al. 2007)

  11. HC3N(4-3) as temperature probe Well separated hyperfine components allow accurate determination of intrinsic v.   Fuller & Myers 1993

  12. N2  N2D+ + H2 H2D+ + CO  DCO+ + H2 Deuterium Fractionation at T < 20 K H3+ + HD  H2D+ + H2 + 230 K Watson 1974 Millar et al. 1989 H2D+ / H3+increases if the abundance of gas phase neutral species (in particular CO) decreases(Dalgarno & Lepp 1984; Roberts & Millar 2000)

  13. Deuterium Fractionation at T < 70 K (Millar, Bennet & Herbst 1989; Roueff, Parise & Herbst 2007) CH3+ + HD  CH2D+ + H2 + 390 K C2H2+ + HD  C2HD+ + H2 + 550 K CH2D+ + N  DCN+ + H2 DCN+ + H2  DCNH+ + H DCNH+ + e-  DCN + H This can explain the large DCN/HCN abundance ratio observed toward the Orion Bar (~1%; Leurini et al. 2006) and toward the Orion Hot Core (0.1-0.3%; Schilke et al. 1992; Roberts et al. 2002).

  14. Deuterated molecules in Band 1 DC3N(4-3) and (5-4) HC3N(4-3) Not much follow up since the 80s (Howe et al. 1994).. DC3N may preferentially trace recently cooled material in dense regions and its detail mapping could help in understanding core formation. Langer et al. 1980 DC3N/HC3N ~ 0.05-0.1

  15. Deuterated molecules in Q-band With ALMA Band 1: DC5N(13-12)  (17-16) HC5N(12-11)  (16-15) …Among other things, cyanopolyynes (HC2n+1N) are thought to have links to the carbenes (H2Cn) found in carbonaceous chondrites. Their detection in protoplanetary disks would be interesting… Schoerb et al. 1981 DC5N/HC5N ~ 0.02

  16. S-bearing molecules H2CS(101-000) - 34.3 GHz OCS(3-2) - 36.5 GHz HDCS(101-000) - 31.0 GHz CS(1-0) - 49.0 GHz C34S(1-0) - 48.2 GHz Together with other observations of S-bearing species and deuterium fractionation in H2S (HDS, van Dishoeck et al. 1995; D2S, Vastel et al. 2003), thioformaldehyde will help to put constraints on Sulphur chemistry. Marcelino, Cernicharo et al. 2005

  17. P-bearing molecules HCP in IRC+10216 With Band 1: HCP(1-0) - 40.0 GHz HPO(1-0) - 40.5 GHz H2CP(1-0) - 32.9 GHz DCP(1-0) - 34.0 GHz PNO(3-2) - 37.1 GHz HC3P(6-5) - 31.9 GHz Already detected: HCP (2-1)  (7-6) (Agundez et al. 2007) CP(2-1) and (5-4) (Guelin et al. 1990) PN(2-1), (3-2) and (5-4) (Turner & Bally 1987) PH3 tentative detection in IRC+10216 (Agundez et al. 2008) Phosphorus (second-row element, same valence as N), comes in the composition of a variety of molecules essentials for living systems (Maciá 2005). Agundez et al. 2007

  18. Evidences of freeze-out: deuterium fractionation Infrared Dark Clouds 3´ MJy Sr-1 g cm-2 Mass Surface Density Spitzer IRAC 8μm (Butler & Tan 2009; Peretto & Fuller 2009)

  19. Evidences of freeze-out: deuterium fractionation SiO in Infrared Dark Clouds With Band 1: SiO(1-0) - 43.4 GHz [29SiO(1-0) - 42.9 GHz, Goddi+09] G035.39-00.33 Jimenez-Serra, Caselli, Tan + in prep.

  20. Amino acetonitrile in SgrB2(N) (Belloche et al. 2008) H H O C C N H H O H Glycine - the simplest amino acid Complex Organic Molecules Known Interstellar Molecules (Total: 151 as of today)

  21. How do complex molecules form? (e.g. Garrod et al. 2008) protostellar dust heating, X-rays (mantle processing and evaporation) dust (mantles and cores) sputtering + vaporization along protostellar outflows

  22. How do complex molecules form? But Marcelino et al. (2007) found propylene (CH2CHCH3) in the cold core TMC-1 (also rich in cyanopolyynes)… Observations in Band 1 (with several hydrocarbons and cyanopolyynes transitions - Kaifu et al. 2004) could help in understanding interstellar gas-phase and surface processes. Among other interesting transitions: C2H5CN(111-000) + isotopologues, many low energy O,C,N-bearing complex molecules (Hollis et al.) + glycine (NH2CH2COOH) transitions…

  23. Complex molecules in protoplanetary disks? Aikawa & Herbst 1999; Markwick & Charnley 2003; Aikawa & Nomura 2006; Bergin et al. 2007; Dutrey et al. 2007; Meijerink, Poelman et al. 2008; Semenov et al. 2008 Henning & Semenov 2008

  24. Summary • HC3N observations and surveys: complementary to mm and submm as well as NH3 (VLA) observations (larger scale, chemically young material). • Observations of interesting deuterated molecules • (cold and dense material). • S chemistry: H2CS(101-000) (molecular clouds and star forming regions). • Si in dense clouds: SiO(1-0). • P chemistry: HCP(1-0), HPO(1-0) (stellar envelopes and interstellar medium). • Complex organic molecules in dense clouds and protoplanetary disks

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