J/AJ/158/196 Near-Earth Object Survey (MANOS) spectroscopy (Devogele+, 2019)
Visible spectroscopy from the Mission Accessible Near-Earth Object Survey
(MANOS): taxonomic dependence on asteroid size.
Devogele M., Moskovitz N., Thirouin A., Gustaffson A., Magnuson M.,
Thomas C., Willman M., Christensen E., Person M., Binzel R., Polishook D.,
DeMeo F., Hinkle M., Trilling D., Mommert M., Burt B., Skiff B.
<Astron. J., 158, 196 (2019)>
=2019AJ....158..196D 2019AJ....158..196D (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Minor planets ; Photometry ; Spectra, optical
Keywords: catalogs - minor planets, asteroids: general - surveys
Abstract:
The Mission Accessible Near-Earth Object Survey (MANOS) aims to observe
and characterize small (mean absolute magnitude H∼25 mag) Near-Earth
Objects (NEOs) that are accessible by spacecraft (mean Δ∼5.7 km/s)
and that make close approaches with the Earth (mean Minimum Orbital
Intersection Distance MOID ∼0.03 au). We present here the first results
of the MANOS visible spectroscopic survey. The spectra were obtained
from August 2013 to March 2018 at Lowell Observatory's Discovery Channel
4.3 m telescope, and both Gemini North and South facilities. In total,
210 NEOs have been observed and taxonomically classified. Our taxonomic
distribution shows significant variations with respect to surveys of larger
objects. We suspect these to be due to a dependence of Main Belt source
regions on object size. Compared to previous surveys of larger objects,
we report a lower fraction of S+Q-complex asteroids of 43.8±4.6%. We
associate this decrease with a lack of Phocaea family members at very
small size. We also report higher fractions of X-complex and A-type
asteroids of 23.8±3.3% and 3.8±1.3% respectively due to an increase
of Hungaria family objects at small size. We find a strong correlation
between the Q/S ratio and perihelion distance. We suggest this correlation
is due to planetary close encounters with Venus playing a major role
in turning asteroids from S to Q-type. This hypothesis is supported by
a similar correlation between the Q/S ratio and Venus MOID.
Description:
We obtained 178 spectra of NEOs using the Gemini Multi-Object
Spectrographs (GMOS) in the long-slit mode at both 8.1 m Gemini North
(134 objects) and South (44 objects) telescopes. These instruments provide
spectral observations from 0.36 to 0.94 µm. The third instrument we
employed was the DeVeny spectrograph at Lowell Observatory's 4.3 m DCT.
The DeVeny spectrograph was first known as the KPNO White Spectrograph
at the Kitt Peak National Observatory (KPNO). It was acquired by Lowell
Observatory in 1998 and used with the 72" Perkins telescope from 2005
to 2015, after which it was modified and installed on the DCT instrument
cube (Bida et al. 2014SPIE.9147E..2NB).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 86 210 Observationnal circumstances and spectral analysis
results
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See also:
J/AJ/152/163 : Mission Accessible Near-Earth Objects Survey (Thirouin+, 2016)
J/ApJS/239/4 : Near-Earth Object Survey (MANOS): 4yrs photometry
(Thirouin+, 2018)
Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- ID Object identifier
12- 15 F4.1 mag HMagmean [19.3/29.6] Mean H band absolute magnitude
17- 26 A10 "date" Date Date of the observation
28- 31 F4.1 mag Vmag [14.9/21.2] NEO V band magnitude
33- 37 F5.1 --- Delta [0.5/133.1] Object-observer distance Δ (1)
39- 42 F4.2 --- NEO-Air [1.01/2.1] NEO airmass
44- 53 A10 --- SA Solar analog used
55- 58 F4.2 --- SA-Air [1.0/1.88] SA airmass
60- 65 F6.4 AU MOID [0/0.1543] Mean Minimum Orbital Intersection
Distance
67- 70 F4.1 km/s Deltav [3.9/15.5] Differential velocity Δv (2)
72- 76 F5.1 deg Phase [1.3/105.4] Phase
78- 82 A5 --- Fac Facility (3)
84- 86 A3 --- Taxon Taxonomy
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Note (1): The object-observer distance at the moment of the observation,
expressed in Lunar distance.
Note (2): Defined as the impulse needed for a spacecraft to maneuver from low
Earth orbit to a rendezvous with the asteroid in its orbit.
Note (3): Facility as follows:
DCT = Lowell Observatory's 4.3 m Discovery Channel Telescope;
GMOSN = 8.1 m Gemini North telescope on Mauna Kea, Hawaii;
GMOSS = 8.1 m Gemini South telescope on Cerro Pachon, Chile.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 15-Jan-2020