Detection of cyanopolyynes in the protostellar shock L1157-B1

Transcription

1 Detection of cyanopolyynes in the protostellar shock L1157-B1 Edgar Mendoza IAG/USP, S~ao Paulo B. Lefloch, C. Ceccarelli, A. Al-Edhari, J. Lepine, C. Codella, L. Podio, S. Viti, H. M. Boechat-Roberty, C. Kahane, R. Bachiller, M. Benedettini International Symposium and Workshop on Astrochemistry Campinas 07/07/2016

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3 Index Cyanopolyynes in interstellar conditions ASAI: Line identification Formation of HC 3 N in L1157-B1 Summarizing

4 Cyanopolyynes in interstellar conditions Bell et al. (1997) determined a decrement between successive cyanopolyynes in TMC-1 Synthesis starting with small precursors C 2 H + 2, HCN, C 2H, HNC Freeman et al. (1978) 2016.

5 The source: L1157-B1 L1157-mm is a low-mass Class 0 protostar ( 250 pc) (left) Santangelo et al (right) Map of L1157-B1 with HC 3 N J=16-15 L1157-B1, the brightest shock, is located at the second cavity in the south hemisphere L1157-B1 is a young object, its dynamical age is 4000 yr Several chemical species have been observed at mm wavelengths: H 2 CO, CH 3 OH, NH 2 CHO, CH 3 CN, H 2 S... Interferometric image of L1157-B1 HC 3 N J=16-15 ( arcsec) Bachiller et al. (2001); Lefloch et al. (2012); Benedettini et al. (2013); Podio et al. (2014)

6 Physical components in B1 g 1 : T kin 250 K g 2 : T kin 70 K g 3 : T kin 25 K The source: L1157-B1 Busquet et al. (2014) and Lefloch et al. (2012)

7 Index Cyanopolyynes in interstellar conditions ASAI: Line identification Formation of HC 3 N in L1157-B1 Summarizing

8 The ASAI large program Astrochemical Surveys At Iram: 350 hours of observation at IRAM-30m (PIs: Lefloch & Bachiller 2014) Sources: Samples that cover all the evolutionary phases of solar type protostars Frequencies observed through ASAI: 3 mm: GHz 2 mm: GHz 1.3 mm: GHz 0.8 mm: GHz

9 Data reduction: Systematic study of HCN, HC 3 N and HC 5 N The data reduction was performed using the GILDAS/CLASS90 package. The CDMS and JPL spectroscopy databases were used to identify lines The telescope and receiver paramenters:

10 HC 3 N Cold component from HC 3 N J=8-7 to J=19-18 T rot = 16 K N = 3 ± cm 2 Hot component from HC 3 N J=23-22 to J=32-31 T rot = 48 K N = 6 ± cm 2 Detection of HC 3 N and HC 5 N

11 Detection of HC 3 N and HC 5 N HC 5 N Cold component from HC 3 N J=8-7 to J=19-18 T rot = 16 K N = 3 ± cm 2 Hot component from HC 5 N J=36-35 to J=42-41 T rot 110 K N = cm 2

12 Spectral line profile The high sensitivity of ASAI allowed to analyse the line profiles of HCN J=3-2, HCN J=1-0 and H 13 CN J=2-1 ( ) v I(v) exp v 0 v 0 12 km/s v 0 4 km/s v 0 2 km/s Lefloch et al. (2012) Gómez-Ruiz et al. (2015) Physical components 1. Component g1: T k = 210 K, N(CO)= cm 2, size Component g2: T k = 64 K, N(CO)= cm 2, size Component g3: T k = 23 K, N(CO)= cm 2, size 25

13 HC 3 N isotopologues in B1: a subtle evidence H 13 CCCN Freq HC 13 CCN Freq HCC 13 CN Freq J MHz J MHz J MHz Rotational temperatures around 15 K N(H 13 CCCN) N(H 13 CCCN) cm 2 ; N(HCC 13 CN) cm 2

14 Molecular abundances (preliminary results) Abundances derived from LTE and LVG calculations Component T kin n(h 2 ) N(CO) [HCN] [HNC] [HC 3 N] [HC 5 N] (K) 10 6 cm cm g g g Next step: chemistry 1. What kind of processes govern the HC 3 N formation? 2. Can we find a match between the observations and chemical models? 3. Task: Chemical modelling of the physical components of B1

15 Index Cyanopolyynes in interstellar conditions ASAI: Line identification Formation of HC 3 N in L1157-B1 Summarizing

16 Chemical modelling: Formation of HC 3 N Phases Nahoon (Wakelam et al. 2012) was employed to compute the chemical abundances of HC3N and its precursors as a function of time. Dark-cloud conditions: T = 10 K, A v 10 mag, n(h 2 ) 10 4 cm 3, ζ = s 1 High temperature phase: T 3000 K, A v 5-10 mag, n(h 2 ) 10 5 cm 3 Physical conditions of g2: T 70 K and A v 5-10 mag Initial abundances Specie Abundance He 0.14 N O C S Si Fe Na Mg

17 Chemistry in the physical component g 2 1 st Step 2 nd Step Chemistry Elemental abundances Abundanes in steady-state e.g. Podio et al. 2014; Wakelam & Herbst 2008 (t = yr) Physics n(h) = cm 3 n(h) = cm 3 T = 10 K T = 70 K A v = 10 mag A v = 10 mag ξ = s 1 ξ = s

18 Chemistry in the physical component g 2 1 st Step 2 nd Step Chemistry Elemental abundances Abundanes in steady-state e.g. Podio et al. 2014; Wakelam & Herbst 2008 (t = yr) Physics n(h) = cm 3 n(h) = cm 3 T = 10 K T = 70 K A v = 10 mag A v = 10 mag ξ = s 1 ξ = s

19 Chemistry in the physical component g 2 1 st Step 2 nd Step Chemistry Elemental abundances Abundanes in steady-state e.g. Podio et al. 2014; Wakelam & Herbst 2008 (t = yr) Physics n(h) = cm 3 n(h) = cm 3 T = 10 K T = 70 K A v = 10 mag A v = 10 mag ξ = s 1 ξ = s

20 Chemistry in the physical component g 2 1 st Step 2 nd Step Chemistry Elemental abundances Abundanes in steady-state e.g. Podio et al. 2014; Wakelam & Herbst 2008 (t = yr) Physics n(h) = cm 3 n(h) = cm 3 T = 10 K T = 70 K A v = 10 mag A v = 10 mag ξ = s 1 ξ = s

21 Chemistry in the physical component g 2

22 High temperature phase We kept the physical conditions except temperature. Models including: T =1000 K T =2000 K T =3000 K

23 High temperature phase We kept the physical conditions except temperature. Models including: T =1000 K T =2000 K T =3000 K

24 Reactions working at high temperature

25 Sputtering of CH 4 Sakai et al. 2012; Codella et al Large quantities of CH4 have been found around L1157-mm X(CH4) What is the influence on the abundances when is injected CH4?

26 Sputtering of CH 4 Sakai et al. 2012; Codella et al Large quantities of CH4 have been found around L1157-mm X(CH4) What is the influence on the abundances when is injected CH4?

27 Sputtering of CH 4

28 Index Cyanopolyynes in interstellar conditions ASAI: Line identification Formation of HC 3 N in L1157-B1 Summarizing

29 Summarizing We confirmed through ASAI/IRAM-30m the presence of HC 3 N and HC 5 N in L1157-B1 Detection of HC 3 N from J=9-8 to J=32-31, HC 5 N from J=32-31 to J= The spectral line profiles of HNC J=1-0, HCN J=1-0 and HC 3 N = 9-8 evidenced the contribution of the g2 and g3 physical components, as reported by Lefloch et al and Gómez-Ruiz et al Component T kin N(CO) [HCN] [HNC] [HC 3 N] [HC 5 N] (K) cm g g g

30 Summarizing We confirmed through ASAI/IRAM-30m the presence of HC 3 N and HC 5 N in L1157-B1 Detection of HC 3 N from J=9-8 to J=32-31, HC 5 N from J=32-31 to J= The spectral line profiles of HNC J=1-0, HCN J=1-0 and HC 3 N = 9-8 evidenced the contribution of the g2 and g3 physical components, as reported by Lefloch et al and Gómez-Ruiz et al Component T kin N(CO) [HCN] [HNC] [HC 3 N] [HC 5 N] (K) cm g g g