Deuterated molecules: a chemical filter for recently evaporated gas Francesco Fontani (INAF-OAA) C. Codella, C. Ceccarelli, B. Lefloch, M.E. Palumbo … et al.

Formation of D-molecules H HD H 2 D + + H K 1. If T ≤ 20 K H 2 D + /H 3 + increases in cold gas (>> D/H cosmic abundance ~10 -5 ) CH HD CH 2 D + + H K C 2 H HD C 2 HD + + H K H CO HCO + + H 2 H 2 D + + CODCO + + H 2 2. If CO freezes-out (i.e. n≥10 5 cm -3 ) H 3 + and H 2 D + combine with other neutrals, X, Increasing [XD + ]/[XH + ] ratios (e.g., X=N 2  N 2 D + /N 2 H + ~0.1) Roberts & Millar 89; Gerlich+02; Asvany+04; Gerlich & Schlemmer 02; Flower If o-/p-H 2 is low H 2 D + /H 3 + is high H HD H 2 D + + o-H 2 Internal energy of o-H 2 170K higher than p-H 2

H 2 D + + CN  DCN + + H 2  HCND + + e -  DNC + H H 2 D + + N 2  N 2 D + + H 2 H 2 D + + NH 3  NH 3 D + + H 2 ; NH 3 D + + e -  NH 2 D + H Gas: Ion-molecule reactions Grains: hydrogenation forms saturated species…and their deuterated forms! Watson & Salpeter 1972; Hasegawa et al. 1992; Caselli et al. 1993; Turner 2001; Roueff et al. 2007; Caselli & Ceccarelli 2012; Ceccarelli et al. 2012, PPVI O  OH  H 2 O / HDO C  CH  CH 2  CH 3  CH 4 / CH 3 D N  NH  NH 2  NH 3 / NH 2 D CO  HCO  H 2 CO / HDCO  H 3 CO  CH 3 OH / CH 2 DOH H 2 D + + H 2 CO  H 2 DCO + + H 2 ; H 2 DCO + + e -  HDCO + H Formation of D-molecules: gas vs grain

B1 shock B2B2 Gueth et al. (1998), Benedettini et al. (2007), Codella et al. (2009) all highest velocity tracers converge here ! The L1157-B1 chemically rich bow-shock Powered by a Class 0 source (d = 250 pc) Most chemically rich outflow known so far: SiO, SO, NH 3, CH 3 OH, H 2 O, and many other molecules! Precessing molecular outflow associated with bow shocks seen in CO (Gueth et al. 1996) and H 2 (Neufeld et al. 2009): B1 is the brightest shocked region.

Deuterated molecules in L1157-B1! Codella+12, ApJ, 757, L9  L1157-B1 surveyed as part of the Herschel/CHESS and IRAM-30m/ASAI Large Programmes (Ceccarelli+10, in: 78 – 350 GHz (IRAM-30m) 500 – 2000 GHz (Herschel)  12 lines of deuterated molecules detected  Column densities of HDO, HDCO and CH 2 DOH consistent with “multi-layer” ices formed before the passage of the shock, and released into the gas by grain sputtering!

 PdBI angular resolution ~ 2.4”  HDCO emission delineates V-like region: the interface between shock and ambient material !!!  Similar to CH 3 CN (Codella+09) Fontani, Codella, Ceccarelli, LeFloch, Viti & Benedettini 2014, ApJL, 788, 43  ….and CH 3 CHO (Codella+15) First clear evidence of HDCO as shock tracer

L1157 (Spitzer) Bow-shock B1 protostar First clear evidence of HDCO as shock tracer

 PdBI angular resolution ~ 2.4”  CH 2 DOH emission faint and clumpy  ….likewise CH 3 OH (Benedettini+12)…  BUT DIFFICULT TO DEFINE AN EMITTING REGION! CH 2 DOH in L1157-B1: SHOCK TRACER?

Fontani+2014, ApJL,

Deuterated fractions in L1157-B1 WALL ARCH HEAD TOTAL Dfrac(H 2 CO) = Dfrac(CH 3 OH) within the errors

Fontani+2014, ApJL, 788, 43  ARCH and HEAD cover similar areas, and have similar temperatures (Codella+09);  H 2 CO formed in the gas similar: N gas arch ≈ N gas head ≈ N tot head  H 2 CO released from the grains different: N grain arch >> N grain head ~ 0  N tot arch – N tot head ≈ N grain arch  deuterated fraction on grains is: N tot (HDCO) arch /N grain (H 2 CO) arch ≅ 0.1 “clean” estimate of HDCO/H 2 CO on grain mantles!

HH 212: HDCO in a rotating cavity! ALMA cycle-1 (PI: Codella); Fontani et al., in prep. HDCO (red and blue) Codella et al. (2014) 3200 A.U. 220 A.U.

H 2 CO/CH 3 OH in L1157-B1: laboratory vs observations Palumbo et al., in prep. DOSE = ice age * CR flux Assuming ζ = 3x s -1 (Podio et al. 2014), the age is ~ 10 6 years

Deuterated molecules in shocks: summary and conclusions (1) The cavities of protostellar shocks are rich in HDCO. HDCO and CH 2 DOH emission associated with the interface between shock and ambient gas in L1157-B1 and HH 212  associated with grain sputtering – shock tracers (2) “clean” measurement of HDCO/H 2 CO on GRAIN MANTLES (~0.1) (3) “age” of grain processing from HDCO/CH 3 OH? To be confirmed Deuterated molecules are “chemical filters” for material formed on grain mantles and recently evaporated/desorbed

IRAC 8  m (grey) CO(2-1) (contours) (Looney et al. 2007, Bachiller et al. 2001) B1 shock B2B2 Powered by a Class 0 source (d = 250 pc) Most chemically rich outflow known so far: SiO, SO, NH 3, CH 3 OH, H 2 O, and many other molecules! PdBI CO(1-0)+ SiO(2-1)+CS(2-1) (Gueth et al. 1996, 1998, Benedettini et al. 2007) Herschel-PACS H 2  m (Nisini et al. 2010) Precessing molecular outflow associated with bow shocks seen in CO (Gueth et al. 1996) and H 2 (Neufeld et al. 2009): B1 is the brightest shocked region. The L1157-B1 chemically rich bow-shock