J/A+A/568/L7 Reflectance spectra of 12 Trojans and Hildas (Marsset+, 2014)
Similar origin for low and high albedo jovian Trojans and Hildas?
Marsset M., Vernazza P., Gourgeot F., Dumas C., Birlan M., Lamy P.,
Binzel R.P.
<Astron. Astrophys. 568, L7 (2014)>
=2014A&A...568L...7M 2014A&A...568L...7M
ADC_Keywords: Solar system ; Minor planets ; Spectroscopy
Keywords: minor planets, asteroids: individual (Jovian Trojans and Hildas) -
techniques: spectroscopic
Abstract:
Hilda asteroids and Jupiter Trojans are two low-albedo (pv∼0.07)
populations for which the Nice model predicts an origin in the
primordial Kuiper Belt region. However, recent surveys by WISE and the
Spitzer Space Telescope (SST) have revealed that ∼2% of these objects
possess high albedos (pv≥0.15), which might indicate interlopers
--that is, objects not formed in the Kuiper Belt-- among these two
populations. Here, we report spectroscopic observations in the visible
and/or near-infrared spectral ranges of twelve high-albedo (pv>0.15)
Hilda asteroids and Jupiter Trojans. These twelve objects have
spectral properties similar to those of the low-albedo population,
which suggests a similar composition and hence a similar origin for
low- and high-albedo Hilda asteroids and Jupiter Trojans. We therefore
propose that most high albedos probably result from statistical bias
or uncertainties that affect the WISE and SST measurements. However,
some of the high albedos may be true and the outcome of some
collision-induced resurfacing by a brighter material that could
include water ice. Future work should attempt to investigate the
nature of this supposedly bright material. The lack of interlopers in
our sample allows us to set an upper limit of 0.4% at a confidence
level of 99.7% on the abundance of interlopers with unexpected
taxonomic classes (e.g., A-, S-, V-type asteroids) among these two
populations.
Description:
We present 17 reflectance spectra of 12 high albedo (pv>0.14) Jovian
Trojans (8 objects) and Hildas (4 objects) obtained with the ESO/VLT
Echelle spectrograph X-SHOOTER in the 0.3-2.2um spectral range
(14 spectra) and with the NASA/IRTF spectrograph SpeX in the 0.8-2.5um
spectral range (3 spectra). X-SHOOTER spectra were normalized to unity
at 0.55um and SpeX spectra were normalized to unity at 2.2um . The
spectra presented in this work were collected between April and
December 2013.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 116 12 List of studied jovian Trojans and Hildas
1162_1.dat 19 10000 X-SHOOTER spectrum of Hilda (1162) 1930 AC
1162_2.dat 19 564 SpeX spectrum of Hilda (1162) 1930 AC
3290_1.dat 19 10000 1st X-SHOOTER spectrum of Hilda (3290) 1973 SZ1
3290_2.dat 19 10000 2nd X-SHOOTER spectrum of Hilda (3290) 1973 SZ1
5023.dat 19 10000 X-SHOOTER spectrum of Trojan (5023) 1985 TG3
9713.dat 19 10000 X-SHOOTER spectrum of Trojan (9713) 1973 SP1
11249_1.dat 19 10000 1st X-SHOOTER spectrum of Hilda (11249) 1971 FD
11249_2.dat 19 564 2nd X-SHOOTER spectrum of Hilda (11249) 1971 FD
13331.dat 19 10000 X-SHOOTER spectrum of Trojan (13331) 1998 SU52
14669.dat 19 564 SpeX spectrum of Hilda (14669) 1999 DC
15529.dat 19 10000 X-SHOOTER spectrum of Trojan (15529) 2000 AA80
24452.dat 19 10000 X-SHOOTER spectrum of Trojan (24452) 2000 QU167
32430.dat 19 10000 X-SHOOTER spectrum of Trojan (32430) 2000 RQ83
63284_1.dat 19 10000 1st X-SHOOTER spectrum of Trojan (63284) 2001 DM46
63284_2.dat 19 10000 2nd X-SHOOTER spectrum of Trojan (63284) 2001 DM46
65227_1.dat 19 10000 1st X-SHOOTER spectrum of Trojan (65227) 2002 ES46
65227_2.dat 19 10000 2nd X-SHOOTER spectrum of Trojan (65227) 2002 ES46
--------------------------------------------------------------------------------
See also:
B/astorb : Orbits of Minor Planets (Bowell+ 2014)
Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- Ast Asteroid number
7- 25 A19 --- Name Asteroid name
27- 31 F5.2 mag H Absolute magnitude H parameter (1)
34- 37 F4.1 km Diam ?=- IRAS diameter (1)
39- 47 F9.6 deg i Inclination (1)
49- 58 F10.8 --- e Eccentricity (1)
60- 69 F10.8 AU a Semimajor axis (1)
71- 80 A10 "Y-M-D" Date1 Date of first observation
82- 92 A11 --- File1 Name of the file with the reflectance spectrum
95-104 A10 "Y-M-D" Date2 Date of second observation
106-116 A11 --- File2 Name of second file with the reflectance spectrum
--------------------------------------------------------------------------------
Note (1): Data from The Asteroid Orbital Elements Database, Cat. B/astorb.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: [123569]*.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.7 um lambda [0.32/2.56] Wavelength λ
10- 19 F10.7 --- Flux Normalized reflectance
--------------------------------------------------------------------------------
Acknowledgements:
Michael Marsset, mmarsset(at)eso.org
(End) Michael Marsset [ESO, Chile], Patricia Vannier [CDS] 23-Jul-2014