Ammonia and other parent molecules in comet 10P/Tempel 2 from Herschel/HIFI and ground-based radio observations

0.24 MB·English

by  N. Biver

Astronomy&Astrophysicsmanuscriptno.ammonia˙10p˙v3 (cid:13)c ESO2012
January23,2012
Ammonia and other parent molecules in comet 10P/Tempel 2 from
⋆
Herschel/HIFI and ground-based radio observations
N.Biver1,J.Crovisier1,D.Bockele´e-Morvan1,S.Szutowicz2,D.C.Lis3,P.Hartogh4,M.deVal-Borro4,R.Moreno1,
J.Boissier5,6,M.Kidger7,M.Ku¨ppers7,G.Paubert8,N.DelloRusso9,R.Vervack9,H.Weaver9,andHssOteam
1 LESIA, Observatoire de Paris, CNRS, UPMC, Universite´ Paris-Diderot, 5 place Jules Janssen, 92195 Meudon, France. e-mail:
[email protected]
2 SpaceResearchCentre,PAS,Warszawa,Poland
3 Caltech,Pasadena,CA,USA
2
4 MaxPlanckInstitutfu¨rSonnensystemforschung,Katlenburg-Lindau,Germany
1
5 IstitutodiRadioastronomia-INAF,Bologna,Italy
0
6 ESO,GarchingbeiMu¨nchen,Germany
2
7 ESAC,VillafrancadelCastillo,Spain

n 8 IRAM,Avd.DivinaPastora,7,18012Granada,Spain
a 9 JHU/APL,Laurel,Maryland,USA
J
DraftJanuary23,2012
0
2
ABSTRACT

]
P TheJupiter-familycomet10P/Tempel2wasobservedduringits2010returnwiththeHerschelSpaceObservatory.Wepresenthere
E theobservation ofthe JK (10–00)transitionofNH3 at572GHzinthiscomet withtheHeterodyneInstrument fortheFarInfrared
(HIFI)ofHerschel.Wealsoreportonradioobservationsofothermolecules(HCN,CH OH,H SandCS)obtainedduringthe1999
. 3 2
h returnof thecomet withtheCSO telescopeand theJCMT, and during its2010 return withtheIRAM30-m telescope. Molecular
p abundancesrelativetowaterare0.09%,1.8%,0.4%,and0.08%forHCN,CH OH,H S,andCS,respectively.Anabundanceof0.5%
3 2
- forNH isobtained,whichissimilartothevaluesmeasuredinothercomets.Thehyperfinestructureoftheammonialineisresolved
o 3
forthefirsttimeinanastronomicalsource.Stronganisotropyintheoutgassingispresentinallobservationsfrom1999to2010and
r
t ismodelledtoderivetheproductionrates.
s
a Keywords.comets:individual:10P/Tempel2–radiolines–submillimetre–techniques:spectroscopic
[

1
v 1. Introduction Ammoniawasalsoobservedfromitsν and/orν vibrational
1 3
8 bands near 3 µm in comets 6P/d’Arrest, 73P/Schwassmann-
1 With an abundance of ≈ 0.5% relative to water, ammo- Wachmann 3, C/1995 O1 (Hale-Bopp),C/2002 T7 (LINEAR),
3 nia is a major repository of nitrogen in cometary volatiles C/2004 Q2 (Machholz), C/2006 P1 (McNaught), and
4 (Bockele´e-Morvanetal. 2004). Thephotodissociationproducts 103P/Hartley 2 (Kawakita&Mumma 2011, and references
. ofNH ,NH andNH,areroutinelyobservedinthevisiblespec-
1 3 2 therein).
0 tra of comets (Feldmanetal. 2004). The direct observation of
2 ammonia is difficult because it is a short-lived molecule (life- Comet 10P/Tempel 2 is a Jupiter-family comet discovered
1 time ≈ 5000s at 1 AU from the Sun) andbecause its lines are in1873byWilhelmTempel.Itsorbitalperiodis5.5years;thus
v: eitherweakoraffectedbytelluricabsorption. alternate perihelion passages are favourable. Its behaviour has
i In previous radio observations of NH3, the inversion tran- alreadybeenwelldocumented,2010beingtheyearofthe22nd
X sitions near 24 GHz were tentatively detected with ground- return to perihelion observed for this comet. Prior to 1994, its
r based radio telescopes in C/1983 H1 (IRAS-Araki-Alcock) perihelion distance was shorter (≈ 1.31–1.39AU vs 1.48 AU),
a (Altenhoffetal. 1983), but not in 1P/Halley (Birdetal. 1987). resultingin a closerapproachto theEarthandthecometbeing
They were then definitely detected in C/1996 B2 (Hyakutake) moreactiveatperihelion.Afterthe1999apparition,theorbitof
(Palmeretal. 1996) and C/1995 O1 (Hale-Bopp) (Birdetal. thecometslightlychangedandtheperiheliondistancedecreased
1997;Hirotaetal.1999)andtentativelydetectedin153P/Ikeya- againto1.42AU.
Zhang(Birdetal.2002;Hatchelletal.2005).
Ammoniarotationallinesareexpectedtobemuchstronger, Comet10P/Tempel2hasarelativelylargenucleus(≈16×8
buttheyfallinthesubmillimetricspectralrangeandhavetobe km; Jewitt&Luu 1989; Lamyetal. 2009), and a well-studied
observedfromspace.TheJ (1 –0 )lineat572.5GHzwasfirst rotation period of ≈ 8.95 h, found to be increasing with time
K 0 0
detectedinC/2001Q4(NEAT)andC/2002T7(LINEAR)with (Knightetal. 2011). Given its relatively low outgassing rate,
theOdinsatellite(Biveretal.2007). onlyasmallfractionofitsnucleusisactive.Strongseasonalef-
fectsareobserved:theactivityrisesveryrapidlyduringthelast
⋆ Herschel is an ESA space observatory with science instruments threemonthsbeforeperihelionandpeaksaboutonemonthafter.
providedbyEuropean-ledPrincipalInvestigatorconsortiaandwithim- A prominentdustjetclose to thenorthpole hasbeenobserved
portantparticipationfromNASA. inimagesateachperihelion.
1
HssOteam:Ammoniaincomet10P/Tempel2withHerschel
We report on an observation of the 572.5 GHz line of am-
monia in comet 10P/Tempel2, which was part of the study of
this comet with the Herschel Space Observatory. Preliminary
reports were given by Biveretal. (2010) and Szutowiczetal.
(2011).Additionalanalysesoftheobservationsofwaterwiththe
HeterodyneInstrumentfortheFarInfrared(HIFI)inthiscomet
will be presented by Szutowiczetal. (2012inpreparation).
Several water lines were also detected with the Photodetector
Array Camera and Spectrometer (PACS) and the Spectral and
PhotometricImagingReceiver(SPIRE)instrumentsofHerschel
andwillbepresentedinafuturepaper.
In support of Herschel observations, 10P/Tempel 2 was
observed from the ground at millimetric wavelengths with
the Institut de radioastronomie millime´trique (IRAM) 30-m
telescope. We also present observations obtained at the an-
tepenultimate perihelion passage (in 1999), with the Caltech
SumillimeterObservatory(CSO)telescopeandtheJamesClerk
Maxwell Telescope (JCMT), which helped to prepare the Fig.1.WaterH2O(110–101)lineobservedincomet10P/Tempel2
Herschelobservations. withHerschelusingtheHRSon19July2010.
2. Observations
The1999perihelionofcomet10P/Tempel2wason8September
atr = 1.48AU.Theperigeetookplaceon12Julyat0.65AU.
h
HCN was observedat JCMT on 4 and 6 September,and again
on1and2October.HCNwasalsoobservedatCSO on11and
12September(Fig.3)andCH OHonthe12thonly.
3
The 2010 perihelion was on 4 July at r = 1.42 AU and
h
perigee took place on 26 August at ∆ = 0.65 AU. The comet
wasobservedwiththeIRAM30-mradio-telescopebetween7.2
and 11.4 July 2010 UT. The first two nights suffered from bad
weather and the third was completely lost, but days 4 and 5
yielded good data (Figs. 4–6). Table 1 provides the list of de-
tectedlines.
Comet 10P was also observed in 2010 with the
Herschel Space Observatory (Pilbrattetal. 2010) using
HIFI (deGraauwetal. 2010), within the framework of the
Fig.2. Ammonia J (1 –0 ) line observed in comet
Water and related chemistry in the Solar System (HssO) K 0 0
10P/Tempel 2 with Herschel using the HRS on 19 July
project (Hartoghetal. 2009). Several water rotational lines
2010. The position and relative intensities of the hyperfine
were observed and mapped from 15 June to 29 July 2010
components are shown with a synthetic spectrum overplotted
(Szutowiczetal. 2011, 2012inpreparation). The observation
that takes into account hyperfine structure and asymmetric
of ammonia took place on 19.1 July 2010 UT when the comet
outgassing(seetext).
was at r = 1.43 AU and at ∆ = 0.71 AU from Herschel. The
h
J (1 –0 ) transition of NH at 572.5 GHz and the 1 –1
K 0 0 3 10 01
line of H O at 557 GHz were observed simultaneously in
2
the frequency-switching mode, the former in the upper side rotationaltemperatureofmethanollinesandtheoutgassingpat-
band and the latter in the lower side band of the band 1b tern and expansionvelocityare constrainedby the line shapes.
receiver of HIFI. A total of 54 min of integration time were Collisionswith electronsare taken intoaccountasmodelledin
spent on the comet, split into five observations every 2 h to Zakharovetal. (2007) with a density scaling factor xne of 0.5
cover a full rotation of the nucleus. Water and ammonia were (Biveretal.2006).
observed both with the low-resolution spectrometer (WBS, All lines (Figs. 3–5) show a strong asymmetry (mean
resolution 0.58 kms−1) and the highest resolution mode of the Dopplershiftaround−0.3to−0.4kms−1,Table1)andneedto
high-resolution spectrometer (HRS autocorrelator, resolution be modelled with asymmetric outgassing. The strong blueshift
0.074kms−1)andbothpolarizationswereaveraged(Figs1,2). anda phaseangle(≈42◦)smallerthan90◦ suggestthata large
partoftheoutgassingisdominatedbyarelativelynarrowjeton
the day-sidethat is notfar fromthe directionto the Earth.The
3. Results openingofthejetandthefractionofoutgassingitcontainswere
constrainedby the Dopplershifts of the lines and optimizedto
3.1.Modellingthedata
fit the line shapes. The half width at half maximum (HWHM)
Thesameexcitationandoutgassingpatternmodelhasbeenused of the lines on the negative and positive sides suggests expan-
toanalysealldata.ThedensitydistributionisbasedontheHaser sionvelocitiesof0.9and0.5kms−1 onthedayandnightsides,
model,with photodissociationratesat 1 AU, β ≈ 1.88×10−5 respectively.
0
s−1 in 1999andβ = 1.60×10−5 s−1 in 2010,forHCN, based The rotational temperature of methanol was found to be
0
on the solar activity.The gastemperatureis constrainedby the 16±7 K, 32±8, and 25±4 K on 7–8 September 1999, and
2
HssOteam:Ammoniaincomet10P/Tempel2withHerschel
Table1.Molecularobservationsincomet10P/Tempel2
UTdate <r > <∆> Integ.time Line Intensity Velocityshiftb Prod.rate
h
[mm/dd.dd] [AU] [AU] [min]a [K kms−1] [kms−1] [molec.s−1]
1999perihelionpassage:
JCMT 09/04.2–06.3 1.482 0.816 157 HCN(4–3) 0.058±0.012 −0.86±0.23 0.5±0.1×1025
CSO 09/11.2–12.3 1.482 0.851 133 HCN(3–2) 0.106±0.012 −0.20±0.08 1.4±0.2×1025
CSO 09/12.32 1.482 0.855 72 CH OH(4 −4 A-+) 0.080±0.018 +0.19±0.15
3 1 0
CH OH(2 −2 A-+) 0.119±0.016 −0.10±0.08 3.7±1.0×1026
3 1 0
JCMT 10/01.3–02.3 1.500 0.980 67 HCN(3–2) 0.090±0.019 −0.57±0.18 0.9±0.2×1025
2010perihelionpassage:
IRAM 07/07.28 1.423 0.745 126 HCN(1–0) 0.057±0.013 −0.16±0.16 1.6±0.4×1025
IRAM 07/08.26 1.423 0.742 131 HCN(1–0) 0.054±0.009 −0.44±0.14 1.5±0.2×1025
IRAM 07/10.22 1.424 0.734 103 HCN(3–2) 0.410±0.033 −0.30±0.05 1.5±0.1×1025
IRAM 07/10.34 1.424 0.734 42 HCN(1–0) 0.044±0.016 −0.65±0.33 1.2±0.4×1025
IRAM 07/11.17 1.424 0.731 61 HCN(3–2) 0.427±0.036 −0.41±0.05 1.6±0.2×1025
IRAM 07/11.28 1.424 0.731 131 HCN(1–0) 0.068±0.010 −0.49±0.13 1.8±0.3×1025
IRAM 07/07.2-08.4 1.423 0.743 257 CH OH(1 −1 E) 0.028±0.010
3 0 −1
CH OH(2 −2 E) 0.044±0.010
3 0 −1
CH OH(3 −3 E) 0.032±0.010
3 0 −1
CH OH(4 −4 E) 0.050±0.010 −0.41±0.10c 3.2±0.8×1026
3 0 −1
CH OH(5 −5 E) 0.030±0.010
3 0 −1
CH OH(6 −6 E) 0.036±0.010
3 0 −1
CH OH(7 −7 E) 0.008±0.010
3 0 −1
IRAM 07/11.26 1.424 0.731 98 CH OH(1 −1 E) 0.024±0.008
3 0 −1
CH OH(2 −2 E) 0.046±0.008
3 0 −1
CH OH(3 −3 E) 0.050±0.008
3 0 −1
CH OH(4 −4 E) 0.041±0.008 −0.42±0.08c 3.2±0.4×1026
3 0 −1
CH OH(5 −5 E) 0.030±0.008
3 0 −1
CH OH(6 −6 E) 0.017±0.008
3 0 −1
CH OH(7 −7 E) 0.011±0.008
3 0 −1
IRAM 07/10.34 1.424 0.734 42 H S(1 −1 ) 0.065±0.021 −0.43±0.26 7.1±2.3×1026
2 10 01
IRAM 07/11.34 1.424 0.730 33 CS(3–2) 0.049±0.011 −0.02±0.14 1.5±0.3×1025
IRAM 07/11.34 1.424 0.730 33 CH CN(8 -7 )K=0,1,2d <0.062 <0.8×1025
3 K K
HIFI 07/18.9–19.3 1.431 0.708 54 H O(1 –1 ) 5.509±0.005 −0.062±0.001 2.2±0.1×1028
2 10 01
HIFI 07/18.9–19.3 1.431 0.708 54 NH (1 –0 ) 0.072±0.005 −0.43±0.06e 10.0±0.7×1025
3 0 0
Note:aTotalintegrationtime,ON+OFF,orONinfrequencyswitchingmode(JCMTandHIFI);
bReferencelinefrequencies(exceptedforNH –seetexte)weretakenfromCDMS(Mu¨lleretal. 2005);
3
cvaluebasedontheaverageofthe6strongestlines;
dSumofthethreetransitionsJ =8 –7 ,8 –7 ,and8 –7 ;
K 0 0 1 1 2 2
eDopplershiftmeasuredwithrespecttothebarycentricpositionofthehyperfinestructureofthelineat572498.160MHz.
11July2010(Fig.6),respectively.Thesevaluesarecompatible 2.2×1028molec.s−1 (Table1).Thissimplisticmodellingofthe
withagastemperatureT =25K,butacloserinspectionofthe anisotropicoutgassingofcomet10P/Tempel2willbeimproved
rot
relativeintensitiesofthelinesrevealsthatthenight-sidetemper- in a future paper (Szutowiczetal. 2012inpreparation), but is
ature(v>0kms−1)T =21±5Kislowerthanintheday-side sufficientto deriveaccurate productionratesand relativeabun-
rot
jet:T = 31±4K.WewilluseT = 30Kinthesunwardjet dances.Whenisotropicoutgassingisassumedandthegastem-
rot rot
andT =20Kelsewhere. peraturesetto25K,wederiveproductionrates≈15%higherfor
rot
theshort-livedmoleculeslikeH SandNH ,or≈45%higherfor
A good fit is obtained with 44% of the outgassing in a 2 3
othermolecules.
narrow jet (opening angle 37◦ or 0.1 × 4π steradian) with
gas velocity of 0.9 kms−1, and the remaining 90% of the sky
contain 56% of the outgassing at 0.5 kms−1, as illustrated in
Fig. 7. The synthetic line shapes obtained with this modelling 3.2.Ammonia
provide a reasonable fit to the observed lines (Figs. 2, 4 and
5). We used the same model to analyse the H O 557 GHz The ammonia J (1 –0 ) line at 572.5GHz is clearly detected
2 K 0 0
line (Fig. 1) and determine the water production rate Q (Fig. 2). The hyperfine structure of the ammonia line is simi-
H2O
at the time of the NH observations. However, we assumed lar to that of the J (1–0) HCN line: three components F (2–
3
x = 0.15 in the excitation model. This value best explains 1), F (1–1) and F (0–1) with relative intensities 5, 3 and 1,
ne
the brightness distribution of the 557 GHz line observed on and relative velocities at 0.0, +0.64 and −0.97 km s−1, respec-
19July(Szutowiczetal.2011,2012inpreparation)andiscon- tively,withrespecttotheF(2–1)frequencyof572498.371MHz
sistent with values found in other comets (Biveretal. 2007; (Cazzolietal. 2009). Thisstructure is resolvedin the observed
Hartoghetal.2010).Themodelreproducesboththelineinten- spectrumofNH (Fig.2).Thesyntheticlineprofile,basedona
3
sity and the Doppler shift of the water line if we set Q to modelused to fit the opticallythin molecularlines observedat
H2O
3
HssOteam:Ammoniaincomet10P/Tempel2withHerschel
Fig.3. HCN J(3–2) line at 265.886 GHz observed in comet Fig.5. HCN J(1–0) line at 88.632 GHz observed in comet
10P/Tempel2withtheCSOon11–12September1999.Thepo- 10P/Tempel2withtheIRAM30-mtelescopeon7–11July2010.
sitions and relative intensities of the hyperfinecomponentsare Thepositionandrelativeintensitiesofthehyperfinecomponents
drawnasdetailedinFig.4. areshownandasyntheticspectrumconsideringasymmetricout-
gassing(seetext)isoverplotted.
Fig.4. HCN J(3–2) line at 265.886 GHz observed in comet
10P/Tempel 2 with the IRAM 30-m telescope on 10–11 July Fig.6. CH OH lines at 157 GHz observed in comet
3
2010.Thepositionandrelativeintensitiesofthehyperfinecom- 10P/Tempel2withtheIRAM30-mtelescopeon11July2010.
ponentsareshownandasyntheticspectrumincludingasymmet-
ricoutgassing(seetext)andhyperfinestructureisoverplotted.
we did not consider that the ν +ν , and ν + ν bands partly
3 4 2 3
deexcite via ν . Since these combination bands are weak, this
3
IRAM(Figs4and 5,Section3.1),agreeswellwiththeobserved approximationshouldnotaffectsignificantlytherotationalpop-
profile. ulations.Theradialevolutionofthepopulationofthesixlowest
The time variation of the line intensity is marginal(±17%, ortholevelsofNH isshowninFig.8.
3
ata 1.5–σlevelof significance).The ammoniaproductionrate The NH photodissociation rate is β = 1.8×10−4 s−1 for
3 0
was derived with the previously described collision and out- the quietSun at r = 1 AU (Huebneretal. 1992). Because the
h
gassing pattern model. We assumed a total cross-section of NH lifetime is relatively short, radiative processes do not sig-
3
2×10−14 cm−2 forthecollisionswithneutrals.Collisionswith nificantlyaffecttheexcitationoftherotationallevelsforcomets
electrons were modelled in the same way as for the other with high outgassing rates. Indeed NH photodissociates be-
3
molecules(e.g.Zakharovetal.2007),i.e.weusedtheBornap- fore reaching the rarefied coma where IR pumping and radia-
proximation for the computation of the cross-sections and set tivedecaydominateovercollisionalexcitation.Formoderately
x = 0.5. Infrared pumping through the six strongest (ν , ν , active comets like 10P/Tempel 2, these processes are signifi-
ne 1 2
ν ,ν ,ν +ν ,andν +ν )vibrationalbandswastakenintoac- cant:neglectingIRpumpingwouldoverestimatetheproduction
3 4 3 4 2 3
countusingtheGEISAdatabase(Jacquinet-Hussonetal.2008). rate by a factor 2.5 and assuming thermal equilibrium would
Table 2 lists the pumping rates for the main infrared bands of underestimate it by a factor 1.7. On the other hand, neglect-
ammonia. The six bands included in our model comprise 95% ingtheanisotropyoftheoutgassingwouldincreasetheproduc-
oftheinfraredpumping.Ourexcitationratesagreewiththoseof tionratebyonly14%.Thederivedammoniaproductionrateis
Kawakita&Mumma(2011).Whencomputingthefluorescence 1.0×1026 molec.s−1. The contemporaneouswater production
ofthe vibrationalbandsdownto the fundamentalgroundstate, being≈2.2×1028molec.s−1(Table1),weobtain[NH ]/[H O]
3 2
4
HssOteam:Ammoniaincomet10P/Tempel2withHerschel
Fig.8.RotationalpopulationsofthelowestortholevelsofNH
Fig.7. Outgassing pattern used to interpret 10P/Tempel 2 ob- 3
in the coma of comet 10P/Tempel 2 (r = 1.431 AU, Q =
servations. The length of the vectors pointing away from 2.2×1028 molec.s−1, v = 0.7 kmsh−1), taking into acHc2oOunt
the nucleus are proportional to the expansion velocity (scale exp
collisions with neutrals at T = 25 K, collisions with electrons
bar). The shaded area in dark represents the earthward jet at
0.9 kms−1containing 44% of the outgassing with a T = 30 K (responsibleforthefeatureatthecontactsurfaceat≈1000km),
radiativedecayandinfraredpumping.
temperature,whilethelightlyshadedarearepresentstheremain-
ingpartoftheskywithlowervelocity(0.5kms−1)andtemper-
ature(20K).
Table3.Molecularabundancesincomet10P/Tempel2
Table2.Ammoniainfraredbandparametersandexcitationrates
Molecule Q/Q Q/Q Q/Q
HCN HCN H2O
in1999 in2010 in2010
vibrationalband frequency Aa gaat1AU used HCN 1 1 0.09±0.01%
ν ν
[cm−1] [s−1] [s−1] CH OH 20±5 21±3 1.8±0.2%
3
ν 3337 7.7 3.3×10−5 yes H S 4.6±1.6 0.39±0.13%
1 2
ν ≈950 16.2 27.7×10−5 yes CS 0.9±0.2 0.08±0.02%
2
2ν2 ≈1700 0.5 0.5×10−5 no CH3CN <0.5 <0.04%
3ν2 ≈2600 0.1 0.05×10−5 no NH3 - 0.46±0.04%
ν +ν 4315 1.6 0.5×10−5 no
1 2
ν 3450 3.8 1.5×10−5 yes
3
ν 1630 8.7 8.5×10−5 yes
4
ν +ν 2600 0.02 0.01×10−5 no
2 4
ν3+ν4 5000 15 3.7×10−5 yes time of IRAM observations in 2010 (i.e. ≈ 9 days earlier than
ν +ν 4960 0.6 0.2×10−5 no
1 4 the NH observation), the derived molecular abundances are
ν +ν 4450 9 2.6×10−5 yes 3
2 3 given in Table 3. These abundancesare typical of short-period
2ν 3240 2.7 0.4×10−5 no
4 comets, with CH OH and H S abundances in the middle-low
Note: a “Band” (as defined in Crovisier&Encrenaz 1983) Einstein 3 2
part of the observedrange (Crovisieretal. 2009a,b). The aver-
coefficients and total excitation rates (from GEISA database
agecometary[CS]/[HCN]ratioiscloseto0.8atr =1AU,with
(Jacquinet-Hussonetal.2008))computedat40K. h
ar−0.8dependence(Biveretal.2006,2011).Theobservedvalue
h
in10P/Tempel2isonthehighsidegiventhatwewouldexpect
=0.46±0.04%.Thisvalueisverysimilartotheabundancemea- a valuearound0.6atrh = 1.42AU. Ammoniaisthe dominant
suredinothercomets(Kawakita&Watanabe2002;Biveretal. source of nitrogen in the cometary ices (≈ 80%). Other possi-
2007;Kawakita&Mumma2011). ble sources of nitrogen in comets are HNC, and HC3N, which
The ortho-to-para ratio (OPR) of ammonia is not directly werealways belowtheHCN abundancein allcometsinwhich
measuredin comets;it is inferredfromthat of the NH radical theyweredetectedorsearchedfor(e.g.,Bockele´e-Morvanetal.
2
andfoundtobetypically1.1to1.2,correspondingtospintem- 2004). Note thateventhoughHC3N was notsearchedin depth
peratures ≈ 30 K (Kawakitaetal. 2001; Shinnakaetal. 2010, incomet10P,low-resolutionspectraon11.3Julyprovideanup-
2011).Whenanalysingourmeasurement,whereonlyorthoNH3 per limit on the HC3N J(16–15)line, which yieldsin any case
wasobserved,weassumedOPR=1(statisticalratio).Therefore, QHC3N <0.3×QNH3.
our determinationof the productionrate may be overestimated In 1999 the comet had a higher activity on 12 September
by5to10%. whenCH OHwasobservedandHCNreachedamaximum.At
3
otherdates,however,itwasatleast50%lessactivethanin2010.
This is likely due to a larger perihelion distance (1.48 vs 1.42
3.3.Molecularabundancesfromgroundbaseddata
AU). Meanwhile, the [CH OH]/[HCN] ratio did not change in
3
Table1providesproductionratesinferredforHCNandCH OH 11 years after two orbitsaround the Sun and the prominentjet
3
in 1999, and for HCN, CH OH, CS, H S and CH CN in feature was still there: the line asymmetry is still present and
3 2 3
2010.Based on contemporaneouswater productionof ≈ 1.8× visibleimagesshowedasimilarnorthwardsjetstructure(Biver
1028 molec.s−1(Szutowiczetal. 2012inpreparation) at the personalcommunication)atbothapparitions.
5
HssOteam:Ammoniaincomet10P/Tempel2withHerschel
4. Conclusion Jacquinet-Husson, N., Scott, N. A., Che´din, A., et al. 2008,
J.Quant.Spec.Radiat.Transf.,109,1043
Ammoniawasdirectlyobservedincomet10/Tempel2through Hartogh,P.,Lellouch,E.,Crovisier,J.,etal.2009,Planet.SpaceSci.,57,1596
its fundamental rotational line. The hyperfine structure of the Hartogh,P.,Crovisier,J.,deVal-Boro,M.,etal.2010,A&A,518,L150
lineisresolvedforthefirsttimeinanastronomicalobject,thanks Hatchell,J.,Bird,M.K.,vanderTak,F.F.S.,&Sherwood,W.A.,2005,A&A,
439,777
tothenarrowwidthofthecometaryline.Theabundanceofam-
Hirota, T., Yamamoto, S., Kawaguchi, K., Sakamoto, A., & Ukita, N. 1999,
moniaisfoundtobe0.46±0.04%relativetowater.Thisissimi- A&A,520,895
lartovaluesmeasuredinothercomets,makingammoniathema- Huebner,W.F.,Keady,J.J.,&Lyon,S.P.1992,Ap&SS,195,1
jorsourceofnitrogenincometaryices.TheabundancesofHCN, Jewitt,D.,&Luu,J.1989,AJ,97,1766
Kawakita,H.,Watanabe,J.-i.,Ando,H.,etal.2001,Science,294,1089
CH OH,CS,andH Saretypicalofshort-periodcomets,though
3 2 Kawakita,H.,&Mumma,M.J.2011,ApJ,727,91
onthemid-lowrange.Thecometdisplayedstronglyblueshifted
Kawakita,H.,&Watanabe,J.-i.2002,ApJ,572,L177
lines indicative of a strong asymmetry in the outgassing. This Knight,M.M.,Farnham,T.L.,Schleicher, D.G.,Schwieterman,E.W.2011,
asymmetryispresentforallspecies,whichalsosuggestsacom- AJ,141,2
mon source for all and compositional homogeneity. Based on Lamy,P.L.,Toth,I.,Weaver,H.A.,A’Hearn,M.F.,&Jorda,L.2009,A&A,
508,1045
simple modelling, about half of the outgassing is in a narrow
Mu¨ller,H.S.P.,Schlo¨der,F.,StutzkiJ.&Winnewisser,G.2005,J.Mol.Struct.
sunward jet with a higher outgassing speed (0.9 kms−1) than 742,215(http://www.astro.uni-koeln.de/cdms/)
outsidethejet(0.5kms−1). Palmer,P.,Wootten,A.,Butler,B.,etal.1996,BAAS,28,927
Pilbratt,G.L.,Riedinger,J.R.,Passvogel,T.,etal.2010,A&A,518,L1
Shinnaka,Y.,Kawakita,H.,Kobayashi,H.,&Kanda,Y.-I.2010,PASJ,62,263
Acknowledgements. HIFI has been designed and built by a consortium of Shinnaka,Y.,Kawakita,H.,Kobayashi,H.,etal.2011,ApJ,729,81
institutes and university departments from across Europe, Canada and the Szutowicz,S.,Biver,N.,Bockelee-Morvan,D.,etal.EPSC-DPSJointMeeting,
United States under the leadership of SRON Netherlands Institute for Space 2-7 October 2011, Nantes, France 2011, EPSC Abstracts Vol. 6, EPSC-
Research, Groningen, The Netherlands and with major contributions from DPS2011-1213
Germany, France and the US. Consortium members are: Canada: CSA, Szutowicz,S.,etal.,inpreparation
U. Waterloo; France: CESR, LAB, LERMA, IRAM; Germany: KOSMA, Zakharov,V.,Bockele´e-Morvan, D.,Biver, N.,Crovisier, J.,&Lecacheux, A.
MPIfR, MPS; Ireland: NUI Maynooth; Italy: ASI, IFSI-INAF, Osservatorio 2007,A&A,473,303
AstrofisicodiArcetri-INAF;Netherlands:SRON,TUD;Poland:CAMK,CBK;
Spain: Observatorio Astrono´mico Nacional (IGN), Centro de Astrobiolog´ıa
(CSIC-INTA); Sweden: Chalmers University of Technology – MC2, RSS &
GARD;OnsalaSpaceObservatory;SwedishNationalSpaceBoard,Stockholm
University–StockholmObservatory;Switzerland:ETHZurich,FHNW;USA:
Caltech,JPL,NHSC.WearegratefultotheIRAMstaffandtootherobservers
for their assistance during the observations. IRAM is an international insti-
tuteco-fundedbytheCentrenationaldelarecherchescientifique(CNRS),the
Max Planck Gesellschaft and the Instituto Geogra´fico Nacional, Spain. This
research has been supported by the CNRS and the Programme national de
plane´tologie de l’Institut des sciences de l’univers (INSU). The CSO is sup-
portedbyNational Science Foundation grantAST-0540882.TheJamesClerk
Maxwell Telescope is operated by The Joint Astronomy Centre on behalf of
the Science and Technology Facilities Council of the United Kingdom, the
Netherlands Organisation for Scientific Research, and the National Research
CouncilofCanada.Theresearchleadingtotheseresultsreceivedfundingfrom
theEuropeanCommunity’sSeventhFrameworkProgramme(FP7/2007–2013)
under grant agreement No. 229517. S.S. was supported by MNiSW (grant
181/N-HSO/2008/0).
References
Altenhoff,W.J.,Batrla,W.K.,Huchtmeier,W.K.,etal.1983,A&A,125,L19
Bird, M.K.,Huchtmeier, W.K.,vonKap-Herr, A.,Schmidt, J.&Walmsley,
C.M.1987,inCometaryRadioAstronomy,edW.M.Irvine,F.P.Schloerb,
& L. E. Tacconi-Garman, (Green Bank, WV, National Radio Astronomy
Observatory),85
Bird,M.K.,Huchtmeier,W.K.,Gensheimer,P.,etal.1997,A&A,325,L5
Bird,M.K.,Hatchell,J.,vanderTak,F.F.S.,Crovisier,J.&Bockele´e-Morvan,
D. 2002, In Proceedings of Asteroids, Comets, Meteors - ACM 2002, ed.
BarbaraWarmbein,ESASP-500,697
Biver,N.,Bockele´e-Morvan,D.,Crovisier,J.,etal.2006,A&A,449,1255
Biver,N.,Bockele´e-Morvan,D.,Crovisier,J.,etal.2007,Planet.SpaceSci.,55,
1058
Biver,N.,Szutowicz,S.,Bockele´e-Morvan,D.,etal.2010,BAAS,42,946
Biver,N.,Bockele´e-Morvan,D.,Colom,P.,etal.2011,A&A,A142
Bockele´e-Morvan, D.,Crovisier,J.,Mumma,M.J.,&Weaver,H.A.2004,in
CometsII,ed.M.C.Festou,H.U.Keller,&H.A.Weaver(Univ.ofArizona
Press),391
Cazzoli,G.,Dore,L.,&Puzzarini,C.2009,A&A,507,1707
Crovisier,J.,&Encrenaz,Th.1983,A&A,126,170
Crovisier, J., Biver, N., Bockele´e-Morvan, D., & Colom, P. 2009a,
Planet.SpaceSci.,57,1162
Crovisier, J., Biver, N., Bockele´e-Morvan, D., et al. 2009b, Earth Moon and
Planets,105,267
deGraauw,T.,Helmich,F.P.,Phillips,T.G.,etal.2010,A&A,518,L6
Feldman, P. D., Cochran, A. L., & Combi, M. R. 2004, in Comets II, ed.
M.C.Festou,H.U.Keller,&H.A.Weaver(Univ.ofArizonaPress),425
6