N. Dellorusso et al., CARBONYL SULFIDE IN COMETS C 1996 B2 (HYAKUTAKE) AND C/1995 O1 (HALE-BOPP) - EVIDENCE FOR AN EXTENDED SOURCE IN HALE-BOPP/, Icarus (New York, N.Y. 1962), 135(2), 1998, pp. 377-388
Carbonyl sulfide was detected in Comet Hale-Bopp (C/1995 O1) using hig
h dispersion infrared spectroscopy at the NASA Infrared Telescope Faci
lity on Mauna Kea, Hawaii. Six lines (P10, P11, P12, P14, P15, and P17
) of the nu(3) fundamental band near 4.85 mu m were detected on UT Apr
il 16.0, April 30.0, and May 1.2, 1997, and two additional lines (P18
and P22) were detected on April 30.0. Water was detected directly thro
ugh emission lines of its nu(1)-nu(2) hot band on UT April 16.0, April
30.0, and May 1.2, with a rotational temperature of 93 +/- 16 K on Ma
y 1.2. Adopting a rotational temperature of 100 K for OCS, our derived
production rates are (3.80 +/- 0.67) and (1.77 +/- 0.85) x 10(28) mol
ecules s(-1) on April 16.0 and May 1.2, respectively. The measured pro
duction rates imply mixing ratios (Q(OCS)/Q(H2O)) of (4.58 +/- 0.77) a
nd (2.76 +/- 1.34) x 10(-3) on April 16.0 and May 1.2, respectively. C
omparison of spatial profiles for OCS, H2O, and the dust continuum der
ived from spectra taken less than 1 h apart suggests that on April 16.
0 a significant amount of OCS (similar to 70% of the total) was releas
ed as an extended source. On April 30.0 and May 1.2 the quality of the
data prevent a firm conclusion regarding an extended source contribut
ion. If the nature of the OCS source did not change between April 16.0
and May 1.2, the weighted mean mixing ratio is (4.13 +/- 0.77) x 10(-
3). We searched for lines P1 through P8 of the nu(3) band of OCS in Co
met Hyakutake (C/1996 B2) on UT March 24.5, 1996. Our upper limit (3 s
igma) for the OCS production rate in Hyakutake is 1.0 x 10(27) molecul
es s(-1) (Q(OCS)/Q(H2O) < 5.3 x 10(-3)). (C) 1998 Academic Press.