J/A+A/559/A48 Mm-spectra of comets C/2001 Q2 and C/2002 T7 (de Val-Borro+ 2013)
A survey of volatile species in Oort cloud comets C/2001 Q2 (NEAT) and
C/2002 T7 (LINEAR) at millimeter wavelengths.
de Val-Borro M., Kuppers M., Hartogh P., Rezac L., Biver N.,
Bockelee-Morvan D., Crovisier J., Jarchow C., Villanueva G.L.
<Astron. Astrophys. 559, A48 (2013)>
=2013A&A...559A..48D 2013A&A...559A..48D
ADC_Keywords: Comets ; Spectra, millimetric/submm
Keywords: comets: individual: C/2002 T7 (LINEAR) -
comets: individual: C/2001 Q2 (NEAT) - molecular processes -
submillimeter: planetary systems - techniques: spectroscopic
Abstract:
The chemical composition of comets can be inferred using spectroscopic
observations in submillimeter and radio wavelengths.
We aim to compare the production rates ratio of several volatiles in
two comets, C/2001 Q4 (NEAT) and C/2002 T7 (LINEAR), which are
generally regarded as dynamically new comets likely to originate in
the Oort cloud. This type of comets is considered to be composed of
primitive material that has not undergone considerable thermal
processing.
The line emission in the coma was measured in the comets, C/2001 Q4
(NEAT) and C/2002 T7 (LINEAR), that were observed on five consecutive
nights, 7-11 May 2004, at heliocentric distances of 1.0 and 0.7AU,
respectively, by means of high resolution spectroscopic observations
using the 10-m Submillimeter Telescope (SMT) at the Arizona Radio
Observatory (ARO). Both objects became very bright and reached
naked-eye visibility during their perihelion passage in the spring of
2004.
Description:
Table 3 contains the observed flux densities integrated over velocity,
Doppler velocity shifts and production rates in comet C/2001 Q4 (NEAT)
measured with the SMT in 7-11 May 2004. Statistical uncertainties are
shown in brackets after the respective values in units of the last
significant digits.
Table 4 contains the observed flux densities integrated over velocity,
Doppler velocity shifts and production rates in comet C/2002 T7
(LINEAR) measured with the SMT in 8-11 May 2004. Statistical
uncertainties are shown in brackets after the respective values in
units of the last significant digits.
Table 7 contains the line variability of the HCN (3-2) transition in
C/2001 Q4 (NEAT).
Table 8 contains the line variability of the HCN (3-2) transition in
C/2002 T7 (LINEAR).
The reduced FITS files include frequency, velocity and flux columns in
units of GHz, km/s and calibrated main beam brightness temperature
(K). The format of the name of the FITS files is
sourcemoleculedate_backend.fits where the date is given in
fractional UT days.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
objects.dat 84 2 Comet information (from B/comets catalog)
table3.dat 129 41 *Observed flux densities integrated over velocity
in comet C/2001 Q4 (NEAT)
table4.dat 129 51 *Observed flux densities integrated over velocity
in comet C/2002 T7 (LINEAR)
table7.dat 42 60 Line variability of the HCN (3-2) transition
in C/2001 Q4 (NEAT)
table8.dat 42 156 Line variability of the HCN (3-2) transition
in C/2002 T7 (LINEAR)
list.dat 70 26 List of FITS reduced spectra
fits/* . 65 Individual FITS reduced spectra
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Note on table3.dat: Doppler velocity shifts and production rates in comet
C/2001 Q4 (NEAT) measured with the SMT in 7-11 May 2004.
Note on table4.dat: in comet C/2002 T7 (LINEAR) observed with the SMT in
8-11 May 2004.
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See also:
B/comet : Database of the orbital elements of comets (Rocher, 2007+)
Byte-by-byte Description of file: objects.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- IAU IAU code for the comet
11- 16 A6 --- Type IAU class (NEAT or LINEAR)
18- 26 F9.1 d Ep Epoch of the computed elements (JD)
28- 36 F9.7 AU q Perihelion distance
38- 46 F9.7 --- e Orbit eccentricity
48- 57 F10.6 deg i Inclination of the orbit
59- 62 F4.2 mag H1 Constant term for magnitude
64- 73 A10 --- File1 Name of the file with flux densities
75- 84 A10 --- File2 Name of the file with line variability
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Byte-by-byte Description of file: table[34].dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Mol Molecule
8- 12 F5.2 d Date Mid-time of the observations recorded as
decimal days in May 2004
14- 26 A13 --- Trans Transition
27 A1 --- n_Trans [*] * indicate blended lines
29- 38 F10.6 GHz Freq [225/272] Transition frequency (1)
40- 43 A4 --- Backend Backend name (AOSA, AOSB or CTSB)
45- 49 F5.3 K rms rms noise in units of main beam brightness
temperature (TmB)
51 A1 --- l_Iflux Limit flag on Iflux
52- 56 F5.3 K.km/s Iflux Observed flux density integrated over
velocity (line intensity) (2)
58- 62 F5.3 K.km/s e_Iflux ? rms uncertainty on Iflux
64- 70 E7.2 m/s DV ? Velocity offset (3)
72- 78 E7.2 m/s e_DV ? rms uncertainty on DV
79- 82 F4.2 km/s Vexp ? Expansion velocity
84- 87 F4.2 km/s e_Vexp ? rms uncertainty on Vexp
89 A1 --- l_Q Limit flag on Q
90- 97 E8.3 mol/s Q ? Production rate (4)
99-106 E8.2 mol/s e_Q ? rms uncertainty on Q
108-129 A22 --- FileName Name of the spectrum file in subdirectory fits
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Note (1): The line frequencies were obtained from the latest online edition of
the JPL Molecular Spectroscopy Catalog (Pickett et al. 1998).
Note (2): Line intensities and production rates of H2CO measured with the
CTSB are derived 3σ upper limits
Note (3): The velocity offsets are computed with respect to the optocenters of
the complete components for blended lines
Note (4): For table3.dat: Production rates derived for a gas kinetic
temperature of 54K, expansion velocity of 0.73km/s, electron density scaling
factor of xne=0.2 and a pointing offset of 2".
For table4.dat: Production rates computed for Tkin=119K, Vexp=0.90km/s,
xne=0.2, and a pointing offset of 2".
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Byte-by-byte Description of file: table7.dat table8.dat
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Bytes Format Units Label Explanations
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1- 6 F6.3 d Date Mid-time of the observations recorded as
decimal days in May 2004
8- 11 A4 --- Backend Backend name (AOSA, AOSB or CTSB)
13- 16 F4.2 K.km/s Iflux Observed flux density integrated over
velocity (line intensity)
18- 21 F4.2 K.km/s e_Iflux ? rms uncertainty on Iflux
23- 29 E7.2 m/s DV ? Velocity offset (1)
31- 37 E7.2 m/s e_DV ? rms uncertainty on DV
39- 42 I4 K Tsys System temperature
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Note (1): The velocity offsets are computed with respect to the optocenters of
the complete components for blended lines
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 22 A22 --- FileName Name of FITS file in subdirectory fits
25- 70 A46 --- Title Title of the file
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Acknowledgements:
Miguel de Val-Borro, valborro(at)princeton.edu
(End) Miguel de Val-Borro [Princeton Univ.], Patricia Vannier [CDS] 22-Aug-2013