Bibcode
DOI
Dello Russo, N.; Vervack, R. J., Jr.; Weaver, H. A.; Montgomery, M. M.; Deshpande, R.; Fernández, Y. R.; Martin, E. L.
Bibliographical reference
The Astrophysical Journal, Volume 680, Issue 1, pp. 793-802.
Advertised on:
6
2008
Journal
Citations
53
Refereed citations
50
Description
The volatile abundances in comet 17P/Holmes were measured on three dates
(UT 2007 October 27.6 and 31.3 and November 2.3) using high-dispersion
(λ/Δλ~2.5×104) infrared
spectroscopy with NIRSPEC at the W. M. Keck Observatory and CSHELL at
the NASA Infrared Telescope Facility. Compared to other comets, the
relative gas production rates in the coma show an enhancement of
C2H6, HCN, and C2H2 with
respect to H2O, by factors of ~2-3. CH3OH was also
detected with an abundance relative to H2O that is similar to
or perhaps slightly enhanced compared to the values observed in other
comets. The apparent enrichment of some volatiles in the coma of
17P/Holmes does not necessarily imply an unusual composition for its
nucleus because fractionation effects may be important at the relatively
large heliocentric distance (Rh=2.45 AU) at which our
observations were performed. Rotational temperatures were determined for
H2O, HCN, C2H6, and
C2H2 in the coma on UT October 27.6 and found to
be between 60 and 80 K. We used lines in both the ν5 and
ν7 bands to obtain the best constraints yet achieved for
the rotational temperature of C2H6. The spatial
distributions of all measured volatiles in the coma are consistent with
each other and suggest at most only a minor contribution from
sublimating icy grains within our aperture. The overall gas production
rate declined by approximately a factor of 7 between UT October 27.6 and
November 2.3 with no significant change measured in the relative
production rates of C2H6 and H2O during
this time.