J/ApJ/924/L9 596 Scheila NIR spectra before & after impact (Hasegawa+, 2022)
The appearance of a "fresh" surface on 596 Scheila as a consequence of the
2010 impact event.
Hasegawa S., Marsset M., DeMeo F.E., Bus S.J., Ishiguro M., Kuroda D.,
Binzel R.P., Hanus J., Nakamura A.M., Yang B., Vernazza P.
<Astrophys. J., 924, L9 (2022)>
=2022ApJ...924L...9H 2022ApJ...924L...9H
ADC_Keywords: Minor planets; Solar system; Spectra, infrared
Keywords: Small Solar System bodies ; Asteroids ; Main belt asteroids ;
Asteroid surfaces
Abstract:
Dust emission was detected on main-belt asteroid 596 Scheila in 2010
December and was attributed to the collision of a few-tens-of-meters
projectile on the surface of the asteroid. In such an impact, the
ejected material from the collided body is expected to mainly come
from its fresh, unweathered subsurface. Therefore, it is expected that
the surface of 596 was partially or entirely refreshed during the 2010
impact. By combining spectra of 596 from the literature and our own
observations, we show that the 2010 impact event resulted in a
significant slope change in the near-infrared (0.8-2.5µm) spectrum
of the asteroid, from moderately red (T type) before the impact to red
(D type) after the impact. This provides evidence that red
carbonaceous asteroids become less red with time due to space
weathering, in agreement with predictions derived from laboratory
experiments on the primitive Tagish Lake meteorite, which is
spectrally similar to 596. This discovery provides the very first
telescopic confirmation of the expected weathering trend of asteroids
spectrally analog to Tagish Lake and/or anhydrous chondritic porous
interplanetary dust particles. Our results also suggest that the
population of implanted objects from the outer solar system is much
larger than previously estimated in the main belt, but many of these
objects are hidden below their space-weathered surfaces.
Description:
NIR spectroscopic observations of 596 Scheila were conducted at two
distinct epochs: 2002 June 1 and 2011 February 7, with Spex on the 3m
InfraRed Telescope Facility (IRTF) located on Maunakea, Hawaii. Data
from the first epoch of observation were published and analyzed by
DeMeo+ (2009Icar..202..160D 2009Icar..202..160D) while data from the second epoch were
never published. In this paper, we describe the observations and data
reduction performed for the data acquired on 2011 February 7.
See Section 2.
We compared the spectra of 596 Scheila obtained before and after the
2010 impact to search for any spectral change induced by this event.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig1.dat 20 824 Comparison of 596's NIR spectra before and after
the 2010 impact event
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See also:
II/118 : UBVRI standards around Celestial Equator (Landolt 1983)
J/ApJ/741/68 : Main Belt asteroids with WISE/NEOWISE. I. (Masiero+, 2011)
J/PASJ/63/1117 : Asteroid catalog using AKARI (AcuA). V1. (Usui+, 2011)
J/AJ/152/54 : Sp. of main-belt Ch/Cgh-type asteroids (Vernazza+, 2016)
J/PASJ/71/1 : AKARI Near Infrared Asteroid Spectral Catalog V1 (Usui+, 2019)
J/A+A/654/A48 : V-band photometry of asteroids from ASAS-SN (Hanus+, 2021)
J/A+A/654/A56 : Largest main belt asteroids data (Vernazza+, 2021)
Byte-by-byte Description of file: fig1.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Time Time relative to impact ("After" or "Before")
8- 13 F6.4 um lambda [0.43/2.48] Wavelength
15- 20 F6.4 --- NRef [0.86/1.96] Normalized reflectance
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 25-Aug-2023