J/ApJ/759/49 Jovian Trojan asteroids with WISE/NEOWISE: taxonomy (Grav+, 2012)
WISE/NEOWISE observations of the Jovian Trojan population: taxonomy.
Grav T., Mainzer A.K., Bauer J.M., Masiero J.R., Nugent C.R.
<Astrophys. J., 759, 49 (2012)>
=2012ApJ...759...49G 2012ApJ...759...49G
ADC_Keywords: Infrared sources ; Minor planets ; Surveys
Keywords: infrared: planetary systems; minor planets, asteroids: general
Abstract:
We present updated/new thermal model fits for 478 Jovian Trojan
asteroids observed with the Wide-field Infrared Survey Explorer
(WISE). Using the fact that the two shortest bands used by WISE,
centered on 3.4 and 4.6µm, are dominated by reflected light, we
derive albedos of a significant fraction of these objects in these
bands. While the visible albedos of both the C-, P-, and D-type
asteroids are strikingly similar, the WISE data reveal that the albedo
at 3.4µm is different between C-/P- and D-types. The albedo at
3.4µm can thus be used to classify the objects, with C-/P-types
having values less than 10% and D-types have values larger than 10%.
Classifying all objects larger than 50km shows that the D-type objects
dominate both the leading cloud (L4), with a fraction of 84%, and
trailing cloud (L5), with a fraction of 71%-80%. The two clouds thus
have very similar taxonomic distribution for these large objects, but
the leading cloud has a larger number of these large objects,
L4/L5=1.34. The taxonomic distribution of the Jovian Trojans is
found to be different from that of the large Hildas, which is
dominated by C- and P-type objects. At smaller sizes, the fraction of
D-type Hildas starts increasing, showing more similarities with the
Jovian Trojans. If this similarity is confirmed through deeper
surveys, it could hold important clues to the formation and evolution
of the two populations. The Jovian Trojans does have similar taxonomic
distribution to that of the Jovian irregular satellites, but lacks the
ultra red surfaces found among the Saturnian irregular satellites and
Centaur population.
Description:
WISE is a NASA Medium-class Explorer mission which survey the entire
sky in four infrared wavelengths, 3.4, 4.6, 12, and 22um (denoted W1,
W2, W3, and W4, respectively). The solar-system-specific portion of
the WISE project, known as NEOWISE, collected observations of more
than 158000 asteroids, including Jovian Trojans. The survey started on
2010 January 14 and the mission exhausted its secondary tank cryogen
on 2010 August 5. After the exhaustion of the primary cryogen tank on
2010 September 29, the survey was continued until 2011 February 1 as
the NEOWISE Post-Cryogenic Mission using only bands W1 and W2.
Both the WISE and NEOWISE portions of the survey and instructions on
retrieval of data from the WISE databases are described in complete
detail in Mainzer et al. (2011ApJ...731...53M 2011ApJ...731...53M) and Grav et al. (2011,
Cat. J/ApJ/742/40).
Comparing to Grav et al. 2011, we introduce in this paper two major
modifications to the fits: (1) we no longer assume that the albedo is
the same in the W1 and W2 bands and (2) pass1 post-cryogenic data are
incorporated into the fits when available (see section 2).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 103 478 *Thermal model fits
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Note on table1.dat: This table contains the preliminary thermal fit results
based on the First Pass version of the WISE data processing as described in
the text. The NEOWISE project plans to produce an updated final catalog
of physical properties based on the Second Pass processing of the WISE
data using the updated version of the WISE Science Data System, with a
goal of delivering this updated catalog to NASA's Planetary Data System.
Error values presented here represent the statistical errors on the model
fits, including Monte Carlo modeling of uncertainties for the WISE magnitudes,
H, G, and beaming and pIR when these two parameters cannot be fit. Two
calibration papers (Mainzer et al, 2011ApJ...736..100M 2011ApJ...736..100M and
Mainzer et al, 2011ApJ...737L...9M 2011ApJ...737L...9M) discuss the absolute calibration of the
WISE data for small Solar system bodies and should be consulted before
comparing with data derived from other sources. The quoted precision for each
parameter follows the object with the most significant figures for the error
on that value in the table. Readers are encouraged to check the WISE
Explanatory Supplement (Cutri et al. 2011wise.rept....1C) for details and
updates.
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See also:
B/astorb : Orbits of Minor Planets (Bowell+ 2014)
II/311 : WISE All-Sky Data Release (Cutri+ 2012)
J/ApJ/744/197 : WISE/NEOWISE observations of Hilda asteroids (Grav+, 2012)
J/ApJ/743/156 : NEOWISE obs. of NEOs: preliminary results (Mainzer+, 2011)
J/ApJ/742/40 : Jovian Trojans asteroids with WISE/NEOWISE (Grav+, 2011)
J/ApJ/741/68 : Main Belt asteroids with WISE/NEOWISE. I. (Masiero+, 2011)
J/AJ/134/1133 : Fraction of contact binary trojan asteroids (Mann+, 2007)
http://sbn.psi.edu/pds/resource/sdsstax.html : Asteroid SDSS data sets
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- MPC Trojan name; MPC format
11- 15 F5.2 mag HMag Absolute H band magnitude
18- 21 F4.2 --- G Slope parameter
25- 30 F6.2 km Diam [8/148] Diameter
34- 37 F4.2 km e_Diam Statistical error in Diam
41- 45 F5.3 --- pV [0.03/0.2] Optical geometrical albedo
47- 51 F5.3 --- e_pV Statistical error in pV
54- 58 F5.3 --- eta [0.6/1.4] Beaming parameter η
(takes into account the thermal inertia)
60- 64 F5.3 --- e_eta Statistical error in eta
67- 71 F5.3 --- Alb1 [0.05/0.4] W1 band albedo
73- 77 F5.3 --- e_Alb1 Statistical error in Alb1
80- 84 F5.3 --- Alb2 [0.02/0.4] W2 band albedo
86- 90 F5.3 --- e_Alb2 Statistical error in Alb2
93- 94 I2 --- N1 [0/28] Number of WISE W1 band (3.4um) observations
96- 97 I2 --- N2 [0/28] Number of WISE W2 band (4.6um) observations
99-100 I2 --- N3 [1/31] Number of WISE W3 band (12um) observations
102-103 I2 --- N4 [0/32] Number of WISE W4 band (22um) observations
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 10-Jul-2014