Complex organic molecules in hot corinos Sandrine Bottinelli Laboratoire d’AstrOphysique de Grenoble (France) / Institute for Astronomy (Hawaii) Cecilia Ceccarelli (LAOG), Jonathan Williams (IfA) and Roberto Neri (IRAM) Outline: I – Background II – 30m observations of NGC1333-IRAS4A III – PdB observations of IRAS16293 IV – Conclusions

Hot core: first stage in the evolution of massive protostars Compact (<0.1 pc), warm (>100 K), dense (>107 cm-3) regions. Rich chemistry: Saturated molecules, Complex organic molecules (oxygen-, nitrogen-, sulfur-bearing). 1st discovered around Orion-KL (Morris et al. 1980). Nowadays, >20 massive hot cores. Many studies: e.g. Friedel et al. (this morning), Comito et al. (Friday morning). Hot cores around Class 0?

Importance of hot corinos Protoplanetary disks Hot corinos (this work) Comets (e.g. Bockelée-Morvan, Wednesday) From Ehrenfreund & Charnley 2000, ARA&A, 38, 427 1st hot corino discovered in IRAS16293-2422 (Cazaux et al. 2003).

Questions and goals Is IRAS16293 an exception or is the hot corino phase common in the evolution of low-mass protostars?  Search for complex molecules towards other Class 0. Is the chemistry in hot corinos similar to that in massive hot cores?  Compare abundances. What are the formation mechanisms of these complex molecules?  Interferometry, laboratory work, chemical modeling.

30m observations of NGC1333-IRAS4A (Bottinelli et al. 2004a, ApJ 615, 354) Perseus (220 pc), 6 L, binary 440 AU separation Observations at 1, 2 and 3mm

Spectra HCOOCH3-A (4), HCOOCH3-E (6), HCOOH (2), CH3CN (9) IRAS4A HCOOCH3-A (4), HCOOCH3-E (6), HCOOH (2), CH3CN (9) Upper limits for CH3OCH3 and C2H5CN.

Rotational diagrams HCOOCH3-A/E: x ~ 310-8 Trot = 36 K IRAS4A HCOOCH3-A/E: x ~ 310-8 Trot = 36 K HCOOH: 510-9, 10K CH3CN: 210-9, 27 K Assuming source size 0.5" (Maret et al. 2004) and N(H2) = 1.61024 cm-2.

Comparison with previous results IRAS4A Lack of CH3OH and N-bearing molecules in hot corinos  difference in grain mantle composition? Similar abundance ratio for O-bearing molecules, except CH3OH  H2CO could be mother molecule. Similar abundance ratio for O-bearing molecules, except CH3OH  H2CO could be mother molecule. Similar abundance ratios for N-bearing molecules  common mother molecule (NH3?). Similar abundance ratios for N-bearing molecules  common mother molecule (NH3?).

PdB observations of IRAS16293-2422 (Bottinelli et al. 2004b, ApJ 617, L69)  Oph (160 pc), 27 L, binary 800 AU separation Continuum 1 and 3mm 5 lines CH3CN at ~110 GHz 4 lines HCOOCH3 (2 –A, 2 –E) at ~227 GHz

Line emission Beam: (a) 4.7"×1.6" (c) 2.2"×0.9" IRAS16293 110 GHz 227 GHz Beam: (a) 4.7"×1.6" (c) 2.2"×0.9" Contour levels: (a) 15 mJy/beam (c) 20 mJy/beam

Comparison with 30m IRAS16293 Confirms hot corinos are compact with sizes <1.5" (A) and <0.8" (B).

SMA observations IRAS16293 ~345 GHz, beam ~ 2.7"  1.3" (Kuan et al. 2004, ApJ 616, L27). ~300 GHz, beam ~ 1.9"  0.9" (Chandler et al. 2005, ApJ in press).

Continuum emission

Spectra IRAS16293 64,0-54,0 60,0-50,0 61,0-51,0 62,0-52,0 63,0-53,0 202,19-192,18 A E 201,19-191,18 CN 2-1

2 scenarios VLSR (A,B) = 3.9 km/s. IRAS16293 2 scenarios 1 VLSR (A,B) = 3.9 km/s. MA ~ MB, B more compact. Lines optically thick towards B. MA ~ 1M MB < MA Vsin i = 1.2 km/s 830 AU 2 VLSR (A) = 3.9 km/s and VLSR (B) = 2.7 km/s.

Chemical modeling Coupling between chemistry, dynamics and radiative transfer is computationally intensive, but many efforts to tackle different aspects: chemical evolution in protostellar envelopes (e.g. Rodgers & Charnley 2003; Doty et al. (2004); laboratory studies (e.g. Horn et al. 2004); molecular line profiles (e.g. Lee et al. 2004); chemical clocks (e.g. Wakelam et al. 2004, previous talk); grain surface reactions (e.g. Weaver & Blake this afternoon). Problem = difficult to reconcile theory and observations for gas-phase formation of complex molecules (e.g. for HCOOCH3 - Horn et al. 2004).

Conclusions Hot corinos exist and have been imaged. IRAS16293 not alone (however still don’t know how common hot corinos are). Open questions: What are the formation mechanisms of these molecules? Evolution, link with comets?  to answer, continue the effort through combining modeling and observations.