1. 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

2. 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?

3. 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 IRAS (Cazaux et al. 2003).

4. 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.

5. 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

6. 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.

7. 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.

8. 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?).

9. 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

10. 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

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

12. 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).

13. Continuum emission

14. 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

15. 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.

16. 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).

17. 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.