Query Results from the ADS Database
Retrieved 51 abstracts, starting with number 1. Total number selected: 26417.
TY - Journal
T1 - Characterization of preserved primitive fine-grained material from the Jupiter family comet 81P/Wild 2 -- A new link between comets and CP-IDPs
A1 - Stodolna, Julien
A1 - Gainsforth, Zack
A1 - Butterworth, Anna L.
A1 - Westphal, Andrew J.
JO - Earth and Planetary Science Letters
VL - 388
Y1 - 2014/2/1
SP - 367
EP - 373
UR - http://adsabs.harvard.edu/abs/2014E%26PSL.388..367S
N2 - We report the presence of preserved primitive fine-grained material
containing an enstatite whisker with the crystallographic
characteristics of a primary condensate in a sample of the
Jupiter-family comet Wild 2, returned to earth by NASA's Stardust
mission. The preserved primitive material is composed of silica-rich
amorphous material embedded with iron sulfides and silicates. It is in
close association with a type II chondrule-like object in the track
C2052,2,74 (Ogliore et al., 2012). The close association of a chondrule
and a primary condensate shows they must have formed in different
environments and probably met in the comet-forming region. The first
observation of an enstatite whisker with properties indicating primary
condensation in a comet is a new link between comets and Chondritic
Porous IDPs (CP-IDPs).
DO - 10.1016/j.epsl.2013.12.018
SN - 0012-821X
ER -
TY - Journal
T1 - Comet 1P/Halley Multifluid MHD Model for the Giotto Fly-by
A1 - Rubin, M.
A1 - Combi, M. R.
A1 - Daldorff, L. K. S.
A1 - Gombosi, T. I.
A1 - Hansen, K. C.
A1 - Shou, Y.
A1 - Tenishev, V. M.
A1 - Tóth, G.
A1 - van der Holst, B.
A1 - Altwegg, K.
JO - The Astrophysical Journal
VL - 781
Y1 - 2014/2/1
SP - 86
KW - comets: individual: Halley/ magnetohydrodynamics: MHD/ methods: numerical/ plasmas/ solar wind
UR - http://adsabs.harvard.edu/abs/2014ApJ...781...86R
N2 - The interaction of comets with the solar wind has been the focus of many
studies including numerical modeling. We compare the results of our
multifluid MHD simulation of comet 1P/Halley to data obtained during the
flyby of the European Space Agency's Giotto spacecraft in 1986. The
model solves the full set of MHD equations for the individual fluids
representing the solar wind protons, the cometary light and heavy ions,
and the electrons. The mass loading, charge-exchange, dissociative
ion-electron recombination, and collisional interactions between the
fluids are taken into account. The computational domain spans over
several million kilometers, and the close vicinity of the comet is
resolved to the details of the magnetic cavity. The model is validated
by comparison to the corresponding Giotto observations obtained by the
Ion Mass Spectrometer, the Neutral Mass Spectrometer, the Giotto
magnetometer experiment, and the Johnstone Plasma Analyzer instrument.
The model shows the formation of the bow shock, the ion pile-up, and the
diamagnetic cavity and is able to reproduce the observed temperature
differences between the pick-up ion populations and the solar wind
protons. We give an overview of the global interaction of the comet with
the solar wind and then show the effects of the Lorentz force
interaction between the different plasma populations.
DO - 10.1088/0004-637X/781/2/86
SN - 0004-637X
ER -
TY - Journal
T1 - Far-ultraviolet Observations of Comet C/2001 Q4 (NEAT) with FIMS/SPEAR
A1 - Lim, Y.-M.
A1 - Min, K.-W.
A1 - Feldman, P. D.
A1 - Han, W.
A1 - Edelstein, J.
JO - The Astrophysical Journal
VL - 781
Y1 - 2014/2/1
SP - 80
KW - comets: individual: C/2001 Q4/ ultraviolet: planetary systems
UR - http://adsabs.harvard.edu/abs/2014ApJ...781...80L
N2 - We present the results of far-ultraviolet observations of comet C/2001
Q4 (NEAT) that were made with the Far-Ultraviolet Imaging Spectrograph
on board the Korean satellite STSAT-1. The observations were conducted
in two campaigns during its perihelion approach between 2004 May 8 and
15. Based on the scanning mode observations in the wavelength band of
1400-1700 Å, we have constructed an image of the comet with an
angular size of 5°×5°, which corresponds to the central
coma region. Several important fluorescence emission lines were detected
including S I multiplets at 1429 and 1479 Å, C I multiplets at
1561 and 1657 Å, and the CO
A1Pi-X1Sigma+ Fourth Positive
system; we have estimated the production rates of the corresponding
species from the fluxes of these emission lines. The estimated
production rate of CO was Q CO = (2.65 ± 0.63) ×
1028 s--1, which is 6.2%-7.4% of the water
production rate and is consistent with earlier predictions. The average
carbon production rate was estimated to be QC = ~1.59
× 1028 s--1, which is ~60% of the CO
production rate. However, the observed carbon profile was steeper than
that predicted using the two-component Haser model in the inner coma
region, while it was consistent with the model in the outer region. The
average sulfur production rate was QS = (4.03±1.03)
× 1027 s--1, which corresponds to ~1%
of the water production rate.
DO - 10.1088/0004-637X/781/2/80
SN - 0004-637X
ER -
TY - Journal
T1 - Meteor showers on Earth from sungrazing comets
A1 - Sekhar, A.
A1 - Asher, D. J.
JO - Monthly Notices of the Royal Astronomical Society
VL - 437
Y1 - 2014/1/1
SP - L71
EP - L75
KW - celestial mechanics/ comets: general/ comets: individual: C/2012 S1 (ISON)/ comets: individual: C/1680 V1 (Newton's comet)/ meteorites/ meteors/ meteoroids
UR - http://adsabs.harvard.edu/abs/2014MNRAS.437L..71S
N2 - Sungrazing comets have always captured a lot of interest and curiosity
among the general public as well as scientists since ancient times. The
perihelion passage of comet C/2012 S1 (ISON) at the end of this year (on
2013 November 28) is an eagerly awaited event. In this work, we do a
mathematical study to check whether meteoroids ejected from this comet
during its journey around the Sun can produce spectacular meteor
phenomena on Earth. Our calculations show that although the orbital
elements of this comet are much more favourable than for most sungrazers
to have its descending node near the Earth's orbit, even ejection
velocities as high as 1 km s-1 do not induce sufficient nodal
dispersion to bring meteoroids to Earth intersection during present
times. A similar result applies to Newton's comet C/1680 V1 which has
surprisingly similar orbital elements, although it is known to be a
distinct comet from C/2012 S1. Our analysis also shows that for
meteoroids ejected from all known sungrazing groups during recent
epochs, only the Marsden family (with required ejection velocities of
some hundreds of m s-1) can produce meteor phenomena during
present times. In a broader sense, we indicate why we do not observe
visually brilliant meteor showers from frequently observed sungrazers.
DO - 10.1093/mnrasl/slt143
C1 - eprint: arXiv:1310.3171
SN - 0035-8711
ER -
TY - Journal
T1 - Resonant behavior of comet Halley and the Orionid stream
A1 - Sekhar, A.
A1 - Asher, D. J.
JO - Meteoritics and Planetary Science
VL - 49
Y1 - 2014/1/1
SP - 52
EP - 62
UR - http://adsabs.harvard.edu/abs/2014M%26PS...49...52S
N2 - Comet 1P/Halley has the unique distinction of having a very
comprehensive set of observational records for almost every perihelion
passage from 240 B.C. This has helped to constrain theoretical models
pertaining to its orbital evolution. Many previous works have shown the
active role of mean motion resonances (MMR) in the evolution of various
meteoroid streams. Here, we look at how various resonances, especially
the 1:6 and 2:13 MMR with Jupiter, affect comet 1P/Halley and thereby
enhance the chances of meteoroid particles getting trapped in resonance,
leading to meteor outbursts in some particular years. Comet Halley
itself librated in the 2:13 resonance from 240 B.C. to 1700 A.D. and in
the 1:6 resonance from 1404 B.C. to 690 B.C., while stream particles can
survive for time scales of the order of 10,000 yr and 1,000 yr in the
1:6 and 2:13 resonances, respectively. This determines the long-term
dynamical evolution and stream structure, influencing the occurrence of
Orionid outbursts. Specifically, we are able to correlate the occurrence
of enhanced meteor phenomena seen between 1436-1440, 1933-1938, and
2006-2010 with the 1:6 resonance and meteor outbursts in 1916 and 1993
with the 2:13 resonance. Ancient as well as modern observational records
agree with these theoretical simulations to a very good degree.
DO - 10.1111/maps.12117
C1 - eprint: arXiv:1303.2928
SN - 1086-9379
ER -
TY - Journal
T1 - Dust production of comet 21P/Giacobini-Zinner using broadband photometry
A1 - Blaauw, Rhiannon C.
A1 - Suggs, Robert M.
A1 - Cooke, William J.
JO - Meteoritics and Planetary Science
VL - 49
Y1 - 2014/1/1
SP - 45
EP - 51
UR - http://adsabs.harvard.edu/abs/2014M%26PS...49...45B
N2 - Presented here are results from photometric analysis on broadband images
taken of comet 21P/Giacobini-Zinner from May 24, 2011 to October 24,
2011. As the parent body of the Draconids, a meteor shower known for
outbursting, 21P was studied for its dust production activity, Afrho,
focusing on how it changes with heliocentric distance. An expected
increase in dust production with a decrease in heliocentric distance was
observed. The comet went from heliocentric distance of 3.05 -1.77 AU
during the observed time that corresponded to an apparent magnitude of
19.61 to 15.72 and Afrho of 16.48 cm to 284.17 cm. These values can be
extrapolated to estimate a peak Afrho value at perihelion of 3824 cm.
The images were obtained using a 0.5-meter f/8.1 Ritchey-Chrétien
telescope located in Mayhill, New Mexico.
DO - 10.1111/maps.12115
SN - 1086-9379
ER -
TY - Journal
T1 - Dust coma of comet C/2009 P1 (Garradd) by imaging polarimetry
A1 - Hadamcik, E.
A1 - Sen, A. K.
A1 - Levasseur-Regourd, A. C.
A1 - Roy Choudhury, S.
A1 - Lasue, J.
A1 - Gupta, R.
A1 - Botet, R.
JO - Meteoritics and Planetary Science
VL - 49
Y1 - 2014/1/1
SP - 36
EP - 44
UR - http://adsabs.harvard.edu/abs/2014M%26PS...49...36H
N2 - Comet C/2009 P1 (Garradd) was observed by imaging polarimetry for nearly
5 months from October 2011 to March 2012, over an intermediate phase
angle range (28°-35°). Two months before perihelion and one
month after, dust particles seem to be ejected all around the optocenter
and jets extend to distances greater than 40,000 km. An increase of
activity is noticed in intensity and polarization after perihelion. Two
months before perihelion and one month after, the dust emission seems to
be all around the optocenter. Two and three months after perihelion the
jets are mainly toward the solar direction with an extension of more
than 20,000 km projected on the sky. The values of the aperture
polarization are comparable to those of other comets. On the
polarization maps in October 2011 and January 2012 the higher
polarization zones extend in large regions perpendicularly to the solar
direction where jets are also observed. In February and March 2012, the
polarization in the jets is larger in the solar direction than in the
surrounding coma. By its activity visible on intensity images and
polarization maps at large distances from the nucleus, comet Garradd
probably belongs to the high-Pmax class of comets.
DO - 10.1111/maps.12114
SN - 1086-9379
ER -
TY - Journal
T1 - Negative ion chemistry in the coma of comet 1P/Halley
A1 - Cordiner, M. A.
A1 - Charnley, S. B.
JO - Meteoritics and Planetary Science
VL - 49
Y1 - 2014/1/1
SP - 21
EP - 27
UR - http://adsabs.harvard.edu/abs/2014M%26PS...49...21C
N2 - Negative ions (anions) were identified in the coma of comet 1P/Halley
during in situ Electron Electrostatic Analyzer measurements performed by
the Giotto spacecraft in 1986. These anions were detected with masses in
the range 7-110 amu, but with insufficient mass resolution to permit
unambiguous identification. We present details of a new
chemical-hydrodynamic model for the coma of comet Halley that
includes---for the first time---atomic and molecular anions, in
addition to a comprehensive hydrocarbon chemistry. Anion number
densities are calculated as a function of radius in the coma, and
compared with the Giotto results. Important anion production mechanisms
are found to include radiative electron attachment, polar
photodissociation, dissociative electron attachment, and proton
transfer. The polyyne anions C4H- and
C6H- are found to be likely candidates to explain
the Giotto anion mass spectrum in the range 49-73 amu. The
CN- anion probably makes a significant contribution to the
mass spectrum at 26 amu. Larger carbon-chain anions such as
C8H- can explain the peak near 100 amu provided
there is a source of large carbon-chain-bearing molecules from the
cometary nucleus.
DO - 10.1111/maps.12082
SN - 1086-9379
ER -
TY - Journal
T1 - The Oort Cloud and long-period comets
A1 - Rickman, Hans
JO - Meteoritics and Planetary Science
VL - 49
Y1 - 2014/1/1
SP - 8
EP - 20
UR - http://adsabs.harvard.edu/abs/2014M%26PS...49....8R
N2 - This review starts with a brief historical overview of the subject,
after which some recent papers attempting to improve the understanding
of comet injection from the Oort Cloud and the origin of new comets are
discussed. Special attention is paid to the importance of
nongravitational effects in comet orbit determination, the synergy
between stellar encounters and the galactic tides for the injection
dynamics, and the role of planetary perturbations. The field is thus
shown to be advancing rapidly, and brief comments on possible
implications for studying the origin of the cloud are made.
DO - 10.1111/maps.12080
SN - 1086-9379
ER -
TY - Journal
T1 - Gas and dust productions of Comet 103P/Hartley 2 from millimetre observations: Interpreting rotation-induced time variations
A1 - Boissier, Jérémie
A1 - Bockelée-Morvan, Dominique
A1 - Biver, Nicolas
A1 - Colom, Pierre
A1 - Crovisier, Jacques
A1 - Moreno, Raphael
A1 - Zakharov, Vladimir
A1 - Groussin, Olivier
A1 - Jorda, Laurent
A1 - Lis, Darek C.
JO - Icarus
VL - 228
Y1 - 2014/1/1
SP - 197
EP - 216
UR - http://adsabs.harvard.edu/abs/2014Icar..228..197B
N2 - Comet 103P/Hartley 2 made a close approach to the Earth in October 2010.
It was the target of an extensive observing campaign including ground-
and orbit-based observatories and was visited by the Deep Impact
spacecraft in the framework of its mission extension EPOXI. We present
observations of HCN and CH3OH emission lines conducted with
the IRAM Plateau de Bure interferometer on 22--23, 28 October and
4, 5 November 2010 at 1.1, 1.9 and 3.4 mm wavelengths. The thermal
emission from the dust coma and nucleus is detected simultaneously.
Interferometric images with unprecedented spatial resolution of
˜100 to ˜500 km are obtained. A sine--wave like
variation of the thermal continuum is observed in the 23 October data,
that we associate with the nucleus thermal light curve. The nucleus
contributes up to 30--55% of the observed continuum emission. The
dust thermal emission is used to measure the dust production rate. The
inferred large dust-to-gas ratio (in the range 2--6) can be
explained by the unusual activity of the comet for its size, which
allows decimeter size particles and large boulders to be entrained by
the gas due to the small nucleus gravity. The rotational temperature of
CH3OH is measured with beam radii from ˜150 km to
˜1500 km. We attribute the increase from ˜35 K to ˜46
K with increasing beam size to radiative processes. The HCN production
rate displays strong rotation-induced temporal variations, varying from
Ëœ0.3 × 1025 s-1 to Ëœ2.0
× 1025 s-1 in the 4--5 November
period. The HCN production curve, as well as the CO2 and
H2O production curves measured by EPOXI, are interpreted with
a geometric model which takes into account the complex rotational state
of 103P/Hartley 2 and its shape. The HCN and H2O production
curves are in phase, showing that these molecules have common sources.
The ˜1.7 h delay, in average, of the HCN and H2O
production curves with respect to the CO2 production curve
suggests that HCN and H2O are mainly produced by subliming
icy grains. The scale length of production of HCN is determined to be on
the order of 500--1000 km, implying a mean velocity of
100--200 m s-1 for the icy grains producing HCN.
From the time evolution of the insolation of the nucleus, we show that
the CO2 production is modulated by the insolation of the
small lobe of the nucleus. The three-cycle pattern of the production
curves reported earlier is best explained by an overactivity of the
small lobe in the longitude range 0--180°. The good correlation
between the insolation of the small lobe and CO2 production
is consistent with CO2 being produced from small depths below
the surface. The time evolution of the velocity offset of the HCN lines,
as well as the displacement of the HCN photocenter in the
interferometric maps, are overall consistent with this interpretation.
Other localized sources of gas on the nucleus surface are also
suggested.
DO - 10.1016/j.icarus.2013.10.010
C1 - eprint: arXiv:1310.2600
SN - 0019-1035
ER -
TY - Journal
T1 - Pre- and post-perihelion observations of C/2009 P1 (Garradd): Evidence for an oxygen-rich heritage?
A1 - DiSanti, Michael A.
A1 - Villanueva, Geronimo L.
A1 - Paganini, Lucas
A1 - Bonev, Boncho P.
A1 - Keane, Jacqueline V.
A1 - Meech, Karen J.
A1 - Mumma, Michael J.
JO - Icarus
VL - 228
Y1 - 2014/1/1
SP - 167
EP - 180
UR - http://adsabs.harvard.edu/abs/2014Icar..228..167D
N2 - We conducted pre- and post-perihelion observations of Comet C/2009 P1
(Garradd) on UT 2011 October 13 and 2012 January 8, at heliocentric
distances of 1.83 and 1.57 AU, respectively, using the high-resolution
infrared spectrometer (NIRSPEC) at the Keck II 10-m telescope on Mauna
Kea, HI. Pre-perihelion, we obtained production rates for nine primary
volatiles (native ices): H2O, CO, CH3OH,
CH4, C2H6, HCN,
C2H2, H2CO, and NH3.
Post-perihelion, we obtained production rates for three of these
(H2O, CH4, and HCN) and sensitive upper limits for
three others (C2H2, H2CO, and
NH3). CO was enriched and C2H2 was
depleted, yet C2H6 and CH3OH were close
to their current mean values as measured in a dominant group of Oort
cloud comets. This may indicate processing of its pre-cometary ices in a
relatively oxygen-rich environment.
DO - 10.1016/j.icarus.2013.09.001
SN - 0019-1035
ER -
TY - Journal
T1 - Photometry of Comet C/2011 L4 (PANSTARRS) at 4.4--4.2 AU heliocentric distances
A1 - Ivanova, Oleksandra
A1 - Borysenko, Serhii
A1 - Golovin, Alex
JO - Icarus
VL - 227
Y1 - 2014/1/1
SP - 202
EP - 205
UR - http://adsabs.harvard.edu/abs/2014Icar..227..202I
N2 - We present an analysis of the photometric data of Comet C/2011 L4
(PANSTARRS) observed at heliocentric distance of 4.4--4.2 AU. The
Comet C/2011 L4 (PANSTARRS) shows one significant activity, despite of
its quite large heliocentric distance. The color indexes, dust mass-loss
rates and radius of the comet are measured.
DO - 10.1016/j.icarus.2013.08.026
SN - 0019-1035
ER -
TY - Journal
T1 - Probing Oort Cloud and Local Interstellar Medium Properties via Dust Produced in Cometary Collisions
A1 - Howe, Alex R.
A1 - Rafikov, Roman R.
JO - The Astrophysical Journal
VL - 781
Y1 - 2014/1/1
SP - 52
KW - celestial mechanics/ comets: general/ ISM: general/ Oort Cloud
UR - http://adsabs.harvard.edu/abs/2014ApJ...781...52H
N2 - The Oort cloud remains one of the most poorly explored regions of the
solar system. We propose that its properties can be constrained by
studying a population of dust grains produced in collisions of comets in
the outer solar system. We explore the dynamics of mum-sized grains
outside the heliosphere (beyond ~250 AU), which are predominantly
affected by the magnetic field of the interstellar medium (ISM) flow
past the Sun. We derive analytic models for the production and motion of
small particles as a function of their birth location in the cloud and
calculate the particle flux and velocity distribution in the inner solar
system. These models are verified by direct numerical simulations. We
show that grains originating in the Oort cloud have a unique
distribution of arrival directions, which should easily distinguish them
from both interplanetary and interstellar dust populations. We also
demonstrate that the distribution of particle arrival velocities is
uniquely determined by the mass distribution and dust production rate in
the cloud. Cometary collisions within the cloud produce a flux of
mum-sized grains in the inner solar system of up to several
m--2 yr--1. The next generation dust
detectors may be sensitive enough to detect and constrain this dust
population, which will illuminate the Oort cloud's properties. We also
show that the recently detected mysterious population of large
(mum-sized) unbound particles, which seems to arrive with the ISM
flow, is unlikely to be generated by collisions of comets in the Oort
cloud.
DO - 10.1088/0004-637X/781/1/52
C1 - eprint: arXiv:1310.2933
SN - 0004-637X
ER -
TY - Journal
T1 - Hubble Space Telescope Pre-perihelion ACS/WFC Imaging Polarimetry of Comet Ison (c/2012 s1) at 3.81 AU
A1 - Hines, Dean C.
A1 - Videen, Gorden
A1 - Zubko, Evgenij
A1 - Muinonen, Karri
A1 - Shkuratov, Yuriy
A1 - Kaydash, Vadim G.
A1 - Knight, Matthew M.
A1 - Sitko, Michael L.
A1 - Lisse, Carey M.
A1 - Mutchler, Max
A1 - Hammer, Derek
A1 - Yanamandra-Fisher, Padmavati A.
JO - The Astrophysical Journal Letters
VL - 780
Y1 - 2014/1/1
SP - L32
KW - comets: general/ comets: individual: C/2012 S1 (ISON)/ instrumentation: polarimeters/ techniques: polarimetric
UR - http://adsabs.harvard.edu/abs/2014ApJ...780L..32H
N2 - We present polarization images of Comet ISON (C/2012 S1) taken with the
Hubble Space Telescope (HST) on UTC 2013 May 8 (r h = 3.81
AU, Delta = 4.34 AU), when the phase angle was alpha ≈
12.°16. This phase angle is approximately centered in the negative
polarization branch for cometary dust. The region beyond 1000 km (~0.32
arcsec ≈ 6 pixels) from the nucleus shows a negative polarization
amplitude of p% ~ --1.6%. Within 1000 km of the nucleus, the
polarization position angle rotates to be approximately perpendicular to
the scattering plane, with an amplitude p% ~ +2.5%. Such positive
polarization has been observed previously as a characteristic feature of
cometary jets, and we show that Comet ISON does indeed harbor a jet-like
feature. These HST observations of Comet ISON represent the first
visible light, imaging polarimetry with subarcsecond spatial resolution
of a Nearly Isotropic Comet beyond 3.8 AU from the Sun at a small phase
angle. The observations provide an early glimpse of the properties of
the cometary dust preserved in this Oort-Cloud comet.
DO - 10.1088/2041-8205/780/2/L32
C1 - eprint: arXiv:1311.4896
SN - 0004-637X
ER -
TY - Journal
T1 - Toward a Unique Nitrogen Isotopic Ratio in Cometary Ices
A1 - Rousselot, Philippe
A1 - Pirali, Olivier
A1 - Jehin, Emmanuël
A1 - Vervloet, Michel
A1 - Hutsemékers, Damien
A1 - Manfroid, Jean
A1 - Cordier, Daniel
A1 - Martin-Drumel, Marie-Aline
A1 - Gruet, Sébastien
A1 - Arpigny, Claude
A1 - Decock, Alice
A1 - Mousis, Olivier
JO - The Astrophysical Journal Letters
VL - 780
Y1 - 2014/1/1
SP - L17
KW - comets: general/ line: identification/ molecular data/ techniques: spectroscopic
UR - http://adsabs.harvard.edu/abs/2014ApJ...780L..17R
N2 - Determination of the nitrogen isotopic ratios in different bodies of the
solar system provides important information regarding the solar system's
origin. We unambiguously identified emission lines in comets due to the
15NH2 radical produced by the photodissociation of
15NH3. Analysis of our data has permitted us to
measure the 14N/15N isotopic ratio in comets for a
molecule carrying the amine (-NH) functional group. This ratio, within
the error, appears similar to that measured in comets in the HCN
molecule and the CN radical, and lower than the protosolar value,
suggesting that N2 and NH3 result from the
separation of nitrogen into two distinct reservoirs in the solar nebula.
This ratio also appears similar to that measured in Titan's atmospheric
N2, supporting the hypothesis that, if the latter is
representative of its primordial value in NH3, these bodies
were assembled from building blocks sharing a common formation location.
DO - 10.1088/2041-8205/780/2/L17
SN - 0004-637X
ER -
TY - Journal
T1 - Analysis of Asteroid (216) Kleopatra Using Dynamical and Structural Constraints
A1 - Hirabayashi, Masatoshi
A1 - Scheeres, Daniel J.
JO - The Astrophysical Journal
VL - 780
Y1 - 2014/1/1
SP - 160
KW - celestial mechanics/ comets: general/ methods: analytical/ methods: numerical/ minor planets/ asteroids: general/ minor planets/ asteroids: individual: 216 Kleopatra
UR - http://adsabs.harvard.edu/abs/2014ApJ...780..160H
N2 - This paper evaluates a dynamically and structurally stable size for
Asteroid (216) Kleopatra. In particular, we investigate two different
failure modes: material shedding from the surface and structural failure
of the internal body. We construct zero-velocity curves in the vicinity
of this asteroid to determine surface shedding, while we utilize a limit
analysis to calculate the lower and upper bounds of structural failure
under the zero-cohesion assumption. Surface shedding does not occur at
the current spin period (5.385 hr) and cannot directly initiate the
formation of the satellites. On the other hand, this body may be close
to structural failure; in particular, the neck may be situated near a
plastic state. In addition, the neck's sensitivity to structural failure
changes as the body size varies. We conclude that plastic deformation
has probably occurred around the neck part in the past. If the true size
of this body is established through additional measurements, this method
will provide strong constraints on the current friction angle for the
body.
DO - 10.1088/0004-637X/780/2/160
C1 - eprint: arXiv:1312.4976
SN - 0004-637X
ER -
TY - Journal
T1 - Uncorrelated Volatile Behavior during the 2011 Apparition of Comet C/2009 P1 Garradd
A1 - Feaga, Lori M.
A1 - A'Hearn, Michael F.
A1 - Farnham, Tony L.
A1 - Bodewits, Dennis
A1 - Sunshine, Jessica M.
A1 - Gersch, Alan M.
A1 - Protopapa, Silvia
A1 - Yang, Bin
A1 - Drahus, Michal
A1 - Schleicher, David G.
JO - The Astronomical Journal
VL - 147
Y1 - 2014/1/1
SP - 24
KW - comets: general/ comets: individual: C/2009 P1 Garradd/ infrared: planetary systems/ techniques: spectroscopic
UR - http://adsabs.harvard.edu/abs/2014AJ....147...24F
N2 - The High Resolution Instrument Infrared Spectrometer (HRI-IR) on board
the Deep Impact Flyby spacecraft detected H2O,
CO2, and CO in the coma of the dynamically young Oort Cloud
comet C/2009 P1 (Garradd) post-perihelion at a heliocentric distance of
2 AU. Production rates were derived for the parent volatiles, Q
H2O = 4.6 ± 0.8 × 1028, Q
CO2 = 3.9 ± 0.7 × 1027, and Q
CO = 2.9 ± 0.8 × 1028 molecules
s--1, and are consistent with the trends seen by other
observers and within the error bars of measurements acquired during a
similar time period. When compiled with other observations of Garradd's
dominant volatiles, unexpected behavior was seen in the release of CO.
Garradd's H2O outgassing, increasing and peaking
pre-perihelion and then steadily decreasing, is more typical than that
of CO, which monotonically increased throughout the entire apparition.
Due to the temporal asymmetry in volatile release, Garradd exhibited the
highest CO to H2O abundance ratio ever observed for any comet
inside the water snow line at ~60% during the HRI-IR observations. Also,
the HRI-IR made the only direct measurement of CO2, giving a
typical cometary abundance ratio of CO2 to H2O of
8% but, with only one measurement, no sense of how it varied with
orbital position.
DO - 10.1088/0004-6256/147/1/24
C1 - eprint: arXiv:1311.4802
SN - 0004-6256
ER -
TY - Journal
T1 - The Unexpectedly Bright Comet C/2012 F6 (Lemmon) Unveiled at Near-infrared Wavelengths
A1 - Paganini, Lucas
A1 - DiSanti, Michael A.
A1 - Mumma, Michael J.
A1 - Villanueva, Geronimo L.
A1 - Bonev, Boncho P.
A1 - Keane, Jacqueline V.
A1 - Gibb, Erika L.
A1 - Boehnhardt, Hermann
A1 - Meech, Karen J.
JO - The Astronomical Journal
VL - 147
Y1 - 2014/1/1
SP - 15
KW - astrochemistry/ comets: general/ comets: individual: C/2012 F6 (Lemmon)/ molecular processes/ Oort Cloud/ planets and satellites: formation
UR - http://adsabs.harvard.edu/abs/2014AJ....147...15P
N2 - We acquired near-infrared spectra of the Oort cloud comet C/2012 F6
(Lemmon) at three different heliocentric distances (R h)
during the comet's 2013 perihelion passage, providing a comprehensive
measure of the outgassing behavior of parent volatiles and cosmogonic
indicators. Our observations were performed pre-perihelion at R
h = 1.2 AU with CRIRES (on 2013 February 2 and 4), and
post-perihelion at R h = 0.75 AU with CSHELL (on March 31 and
April 1) and R h = 1.74 AU with NIRSPEC (on June 20). We
detected 10 volatile species (H2O, OH* prompt emission,
C2H6, CH3OH, H2CO, HCN, CO,
CH4, NH3, and NH2), and obtained upper
limits for two others (C2H2 and HDO).
One-dimensional spatial profiles displayed different distributions for
some volatiles, confirming either the existence of polar and apolar
ices, or of chemically distinct active vents in the nucleus. The
ortho-para ratio for water was 3.31 ± 0.33 (weighted mean of
CRIRES and NIRSPEC results), implying a spin temperature >37 K at the
95% confidence limit. Our (3sigma) upper limit for HDO corresponds to
D/H < 2.45 × 10--3 (i.e., <16 Vienna
Standard Mean Ocean Water, VSMOW). At R h = 1.2 AU (CRIRES),
the production rate for water was Q(H2O) = 1.9 ± 0.1
× 1029 s--1 and its rotational
temperature was T rot ~ 69 K. At R h = 0.75 AU
(CSHELL), we measured Q(H2O) = 4.6 ± 0.6 ×
1029 s--1 and T rot = 80 K on
March 31, and 6.6 ± 0.9 × 1029
s--1 and T rot = 100 K on April 1. At R
h = 1.74 AU (NIRSPEC), we obtained Q(H2O) = 1.1
± 0.1 × 1029 s--1 and T
rot ~ 50 K. The measured volatile abundance ratios classify
comet C/2012 F6 as rather depleted in C2H6 and
CH3OH, while HCN, CH4, and CO displayed abundances
close to their median values found among comets. H2CO was the
only volatile showing a relative enhancement. The relative paucity of
C2H6 and CH3OH (with respect to
H2O) suggests formation within warm regions of the nebula.
However, the normal abundance of HCN and hypervolatiles CH4
and CO, and the enhancement of H2CO, may indicate a possible
heterogeneous nucleus of comet C/2012 F6 (Lemmon), possibly as a result
of radial mixing within the protoplanetary disk.
Based on observations obtained at the European Southern Observatory at
Cerro Paranal, Chile, under program 290.C-5016, at the NASA's Infrared
Telescope Facility, program 2013A_071, and Keck Observatory, program
H233NS, at Mauna Kea, Hawaii.
DO - 10.1088/0004-6256/147/1/15
SN - 0004-6256
ER -
TY - Journal
T1 - Observational results for eight long-period comets observed far from the Sun
A1 - Mazzotta Epifani, E.
A1 - Perna, D.
A1 - Di Fabrizio, L.
A1 - Dall'Ora, M.
A1 - Palumbo, P.
A1 - Snodgrass, C.
A1 - Licandro, J.
A1 - Della Corte, V.
A1 - Tozzi, G. P.
JO - Astronomy and Astrophysics
VL - 561
Y1 - 2014/1/1
SP - 6
KW - comets: general
UR - http://adsabs.harvard.edu/abs/2014A%26A...561A...6M
N2 - Context. With this work we start a systematic analysis of the distant
activity of several long-period comets in order to investigate the
evolution of activity throughout the solar system and explore
differences between comets that pass their perihelion at far or very
close distances from the Sun.
Aims: We present observational data
for eight long-period comets, observed for the first time beyond r = 5
AU. Three targets have been characterised on their inward orbital
branch. The others have passed their perihelion at quite large
heliocentric distances (rq from 4.5 to 7.5 AU).
Methods: We analyse multicolour broadband images (V,R, and I filters)
taken at the Telescopio Nazionale Galileo to characterise the dust coma
of the comets and investigate their morphology, photometry, colours, and
dust production.
Results: The morphological analysis shows many
differences among the sample, from the large twisted structure present
in the coma of comet C/2005 L3 to the regular coma envelope of C/2010
R1. The colour of the dust coma of all the comets is redder than the
Sun. The Afrho value (measured in a reference aperture of radius rho
= 104 km) ranges from 114 ± 2 (C/2005 S4) to 5091
± 47 (C/2005 L3) cm, depicting a scenario of bodies from
moderately to very active. This is confirmed by the first-order
quantitative estimate of the dust mass-loss rate for the comets that was
obtained from the photometric data: assuming a grain velocity of v = 20
m/s, the dust production rate is comparable with, or even significantly
larger than, that measured for many short-period ("old") comets at much
smaller heliocentric distances.
Based on observations collected at the Italian Telescopio Nazionale
Galileo (TNG), operated on the island of La Palma by the Centro Galileo
Galilei of the INAF (Istituto Nazionale di Astrofisica) at the Spanish
Observatorio del Roque de los Muchachos of the Instituto de
Astrofísica de Canarias.
DO - 10.1051/0004-6361/201321290
SN - 0004-6361
ER -
TY - Journal
T1 - Operation of CONSERT aboard Rosetta during the descent of Philae
A1 - Hegler, Sebastian
A1 - Statz, Christoph
A1 - Hahnel, Ronny
A1 - Plettemeier, Dirk
A1 - Herique, Alain
A1 - Kofman, Wlodek
JO - Planetary and Space Science
VL - 89
Y1 - 2013/12/1
SP - 151
EP - 158
UR - http://adsabs.harvard.edu/abs/2013P%26SS...89..151H
N2 - This paper presents a study investigating the performance of using the
CONSERT instrument aboard the Rosetta spacecraft as a radar sounder
during the Separation--Descent--Landing (SDL) phase of the
Rosetta mission. Gathering scientifically valuable data during this
phase will support CONSERT's primary target, the reconstruction of the
3D permittivity distribution within the comet
67P/Churyumov--Gerasimenko, by providing a permittivity map of the
surface around the landing site. Simulation results will show the
performance of the instrument, using a realistic setup including the
antenna characteristics of both orbiter and landing unit as well as a
realistic orbitography for the descent phase. It will be shown that
operating the CONSERT instrument will indeed provide very valuable data,
thereby providing tremendous aid to the experiment's main objective.
Furthermore, by including knowledge of the antenna characteristics, it
is possible to calculate attitude and descent profile of the Philae
lander during descent, using the data of the line-of-sight propagation
path and the echoes reflected from the comet's surface.
DO - 10.1016/j.pss.2013.09.015
SN - 0032-0633
ER -
TY - Journal
T1 - Polarimetric studies of comet C/2009 P1 (Garradd)
A1 - Das, H. S.
A1 - Medhi, B. J.
A1 - Wolf, S.
A1 - Bertrang, G.
A1 - Deb Roy, P.
A1 - Chakraborty, A.
JO - Monthly Notices of the Royal Astronomical Society
VL - 436
Y1 - 2013/12/1
SP - 3500
EP - 3506
KW - polarization/ scattering/ comets: general/ dust/ extinction
UR - http://adsabs.harvard.edu/abs/2013MNRAS.436.3500D
N2 - We present the optical imaging polarimetric observations of comet C/2009
P1 (Garradd) at three different phase angles e.g. 28.2°, 28.1°
and 21.6°. The observations were carried out using the Inter
University Centre for Astronomy and Astrophysics (IUCAA) Faint Object
Spectrograph and Camera mounted on Cassegrain focus of the 2 m telescope
of IGO, IUCAA, Pune, in Rcomet, R photometric bands, on 2012
March 21 and 22 and Aryabhatta Research Institute of observational
sciencES (ARIES) Imaging Polarimeter mounted on Cassegrain focus of the
1.04 m Sampurnanand Telescope of ARIES, Nainital, in R photometric band,
on 2012 May 23. We show the presence of a jet activity in the
rotational-gradient-treated image of comet Garradd at phase angle
28.1°. These jets are mainly oriented towards the Sun and extended
up to ˜5100 km from the cometary photocentre. The antisolar
extension of the jet seems to be fainter, which is extended up to
˜1800 km. It is found that the comet Garradd shows negative
polarization at phase angle 21.6°. The degree of polarization
derived for Garradd is in good agreement with other comets at nearly
similar phase angles e.g. comets 67P/Churyumov-Gerasimenko, 22P/Kopff,
1P/Halley, C/1990 K1 (Levy), 4P/Faye and C/1995 O1 (Hale-Bopp) at phase
angle Ëœ28°, and 47P/Ashbrook-Jackson at phase angle
Ëœ21.6°, respectively. It is also found that the degree of
polarization of dusty coma of comet Garradd at phase angle
Ëœ28° is high but not as high as in the case of comet
Hale-Bopp.
DO - 10.1093/mnras/stt1827
C1 - eprint: arXiv:1309.6960
SN - 0035-8711
ER -
TY - Journal
T1 - Observations of Comet P/2003 T12 = 2012 A3 (SOHO) at large phase angle in STEREO-B
A1 - Hui, M.-T.
JO - Monthly Notices of the Royal Astronomical Society
VL - 436
Y1 - 2013/12/1
SP - 1564
EP - 1575
KW - methods: data analysis/ techniques: photometric/ techniques: polarimetric/ comets: individual: P/2003 T12 = 2012 A3 (SOHO)
UR - http://adsabs.harvard.edu/abs/2013MNRAS.436.1564H
N2 - Comet P/2003 T12 = 2012 A3 (SOHO) was observed by the satellite STEREO-B
during the period 2012 January 13-27. During its apparition, it ventured
into the highest phase angle ever observed for a comet, and the
forward-scattering enhancement in brightness was marked, as large as
˜8.5 mag. Therefore, it provided a precious opportunity to examine
the compound Henyey-Greenstein (HG) comet-dust light-scattering model
and it also offered valuable polarization data under an unprecedented
observing geometry. Our analysis reveals that the compound HG model fits
the observations very well until the phase angle exceeds
Ëœ173°, where the brightness surge of the comet was obviously
steeper than the prediction by the model. We have found that the reason
for the greater steepness cannot be explained by contaminations from the
proximal tail. Instead, the model of Mie spheres with radii greater than
1 mum, having a power-law distribution of power index ˜3,
matches the observation very well, providing a best-fitting complex
refractive index mu = 1.38 + i 0.006. The dust size was found to be
consistent with the analysis of the comet's syndyne lines. The debiased
polarization of the coma was ˜0 per cent in the phase angle range
from 172.9° to 177.6°. . No convincing evidence of temporal
variation of the polarization was detected.
DO - 10.1093/mnras/stt1683
SN - 0035-8711
ER -
TY - Journal
T1 - Iron valence state of fine-grained material from the Jupiter family comet 81P/Wild 2 -- A coordinated TEM/STEM EDS/STXM study
A1 - Stodolna, Julien
A1 - Gainsforth, Zack
A1 - Leroux, Hugues
A1 - Butterworth, Anna L.
A1 - Tyliszczak, Tolek
A1 - Jacob, Damien
A1 - Westphal, Andrew J.
JO - Geochimica et Cosmochimica Acta
VL - 122
Y1 - 2013/12/1
SP - 1
EP - 16
UR - http://adsabs.harvard.edu/abs/2013GeCoA.122....1S
N2 - The oxidation state of transition metal elements is an indicator of the
environmental conditions during formation and history of
extraterrestrial materials. We studied the iron valence state of
fine-grained material from a bulbous track extracted from the Stardust
cometary collector. It likely originated from primitive material of the
comet Wild 2. We used synchrotron-based Scanning Transmission X-ray
Microscopy (STXM) to collect Fe L3-XANES spectra at a spatial
resolution of about 20 nm. Maps of Fe valence state were combined with
the elemental maps recorded by energy dispersive X-ray spectroscopy
(EDS) with a transmission electron microscope (TEM), on the same areas
and with a comparable electron probe size (5--20 nm). As for most
Stardust fine-grained material, the samples are severely damaged by the
hypervelocity impact in the aerogel collector blocks. They show of a
wide range of oxidation state at a micrometer scale, from Fe metal to
Fe3+. This heterogeneity of oxidation state can be due to the
extreme conditions of the collection. Two major parameters can favor
changes in redox state. The first is the high temperature regime, known
to be highly heterogeneous and to have locally reached extreme values
(up to 2000 K). The second is the local chemical environment. It may
contain elements that could favor a reduction or oxidation reaction
within the flash-heated Wild 2 fragments. Comparison of maps by STXM and
EDS shows evidence for several correlation trends between element
concentrations and the iron valence state. These observations, together
with the study of a melted rim of a larger particle, suggest that the
redox state was not completely redistributed within the impact melts.
These local signatures are compatible with precursors that could have
been close to primitive matrix material of chondrites or to chondritic
interplanetary dust particles. On average, the fine-grained material
from Wild 2 displays a molar fraction (Fe2+oxide +
Fe3+oxide)/(total Fe) equal to 0.80 ± 0.10.
It appears more oxidized than the average value measured for the comet,
when done on larger particles (Westphal et al., 2009). This fine-grained
material from Wild 2 does not seem to have sampled reducing environments
in the solar nebulae in contrast with the larger particles of Wild 2.
This observation confirms the high degree of diversity of materials in
Wild 2 and is in good agreement with the dual distribution of high
temperature minerals and matrices in carbonaceous chondrites.
DO - 10.1016/j.gca.2013.08.006
SN - 0016-7037
ER -