Spectroscopy of near-Earth asteroids

Michelsen, R.; Nathues, A.; Lagerkvist, C.‐I.

doi:10.1051/0004-6361:20040443

Cited by 14 publications

(8 citation statements)

References 25 publications

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“…All spectra look featureless for λ < 800 nm and their reddening slopes are summarised in Table 5. Michelsen et al (2006) observed a strong phase reddening in NEO spectra at α > 60 • . Our observations were performed at α ≤ 53 • , thus the phase reddening should not hinder our comparison between asteroids.…”

Section: Spectroscopymentioning

confidence: 87%

2P/Encke, the Taurid complex NEOs and the Maribo and Sutter’s Mill meteorites

Tubiana

Snodgrass

Michelsen

et al. 2015

A&A

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Aims. 2P/Encke is a short period comet that was discovered in 1786 and has been extensively observed and studied for more than 200 years. The Taurid meteoroid stream has long been linked with 2P/Encke owing to a good match of their orbital elements, even though the comet's activity is not strong enough to explain the number of observed meteors. Various small near-Earth objects (NEOs) have been discovered with orbits that can be linked to 2P/Encke and the Taurid meteoroid stream. Maribo and Sutter's Mill are CM type carbonaceous chondrite that fell in Denmark on January 17, 2009 and April 22, 2012, respectively. Their pre-atmospheric orbits place them in the middle of the Taurid meteoroid stream, which raises the intriguing possibility that comet 2P/Encke could be the parent body of CM chondrites. Methods. To investigate whether a relationship between comet 2P/Encke, the Taurid complex associated NEOs, and CM chondrites exists, we performed photometric and spectroscopic studies of these objects in the visible wavelength range. We observed 2P/Encke and 10 NEOs on August 2, 2011 with the FORS instrument at the 8.2 m Very Large Telescope on Cerro Paranal (Chile). Results. Images in the R filter, used to investigate the possible presence of cometary activity around the nucleus of 2P/Encke and the NEOs, show that no resolved coma is present. None of the FORS spectra show the 700 nm absorption feature due to hydrated minerals that is seen in the CM chondrite meteorites. All objects show featureless spectra with moderate reddening slopes at λ < 800 nm. Apart for 2003 QC 10 and 1999 VT 25 , which show a flatter spectrum, the spectral slope of the observed NEOs is compatible with that of 2P/Encke. However, most of the NEOs show evidence of a silicate absorption in lower S/N data at λ > 800 nm, which is not seen in 2P/Encke, which suggests that they are not related. Conclusions. Despite similar orbits, we find no spectroscopic evidence for a link between 2P/Encke, the Taurid complex NEOs and the Maribo and Sutter's Mill meteorites. However, we cannot rule out a connection to the meteorites either, as the spectral differences may be caused by secondary alteration of the surfaces of the NEOs.

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Section: Spectroscopymentioning

confidence: 87%

2P/Encke, the Taurid complex NEOs and the Maribo and Sutter’s Mill meteorites

Tubiana

Snodgrass

Michelsen

et al. 2015

A&A

Self Cite

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“…The NTT is capable of differential tracking, however previous studies found that for exposure times longer than ∼ 10 minutes, NEAs tend to move out of the slit (Michelsen et al, 2006). Therefore, exposures were limited to 600 s. In the case of the 2.2 m telescope, due to its excellent tracking capability the exposure time for the asteroids was 900 s.…”

Section: Visible Spectramentioning

confidence: 99%

“…The data reduction was performed using ESO-MIDAS following the same procedure described in (e.g., Michelsen et al, 2006;Nathues, 2010). The steps involved in the reduction process are: (1) sky background removal by subtracting A from B and B from A, (2) flat-field correction, (3) median filtering for removal of cosmic hits, (4) extraction of the one-dimensional spectra, (5) wavelength calibration using Helium and Argon arc spectra (for the NTT data) and HgHeRb arc spectra (for the Calar Alto data), (6) extinction correction (for the NTT data), using La Silla's mean extinction curve (Tüg, 1977), (7) co-adding of individual spectra to increase the S/N, (8) division of the asteroids spectrum by the spectrum of a solar analog star, and (9) normalization of the spectra to unity at 0.55 µm.…”

Section: Visible Spectramentioning

confidence: 99%

Surface composition and taxonomic classification of a group of near-Earth and Mars-crossing asteroids

Sanchez

Michelsen

Reddy

et al. 2013

Icarus

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In the past, constraining the surface composition of near-Earth asteroids (NEAs) has been difficult due to the lack of high quality near-IR spectral data (0.7-2.5 µm) that contain mineralogically diagnostic absorption bands. Here we present visible (∼ 0.43-0.95 µm) and nearinfrared (∼ 0.7-2.5 µm) spectra of nine NEAs and five Mars-crossing asteroids (MCs). The YT1) as a V-type was made on the basis of its near-infrared spectrum since no visible spectrum is available for this asteroid. A mineralogical analysis was performed on six of the asteroids (those for which near-IR spectra were obtained or previously available). We found that three asteroids (241662 (2000 KO44), 19764 (2000 NF5), 138404 (2000) have mafic silicate compositions consistent with ordinary chondrites, while three others (4055 Magellan, 164121 (2003 YT1), 5407 (1992 AX)) are pyroxene-dominated basaltic achondrite assemblages. In the case of 5407 (1992 AX) we found that its basaltic surface composition contrasts its taxonomic classification as a S-type.

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“…We stress, however, that phase reddening is not yet well understood (see Dahlgren et al 1997;Michelsen et al 2006;Sanchez et al 2012, and references therein), especially for primitive asteroid types. Lumme & Bowell (1981), for example, report a mean phase reddening for C-type asteroids of (0.15 ± 0.12)%/10 3 Å/degree in B − V, while Dahlgren et al (1997) find that the phase reddening effect is negligible for the taxonomic P and D classes.…”

Section: Spectral Analysis and Discussionmentioning

confidence: 83%

Ultraviolet to near-infrared spectroscopy of the potentially hazardous, low delta-V asteroid (175706) 1996 FG3

Perna

Dotto

Barucci

et al. 2013

A&A

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Context. Primitive near-Earth asteroids (NEAs) are important subjects of study for current planetary research. Their investigation can provide crucial information on topics such as the formation of the solar system, the emergence of life, and the mitigation of the risk of asteroid impact. Sample return missions from primitive asteroids have been scheduled or are being studied by space agencies, including the MarcoPolo-R mission selected for the assessment study phase of ESA M3 missions. Aims. We want to improve our knowledge of the surface composition and physical nature of the potentially hazardous, low delta-V asteroid (175706) 1996 FG3, backup target of MarcoPolo-R. This intriguing object shows an as-yet unexplained spectral variability. Methods. We performed spectroscopic observations of 1996 FG3 using the visible spectrograph DOLORES at the Telescopio Nazionale Galileo (TNG), and the UV-to-NIR X-Shooter instrument at the ESO Very Large Telescope (VLT). Results. We find featureless spectra and we classify 1996 FG3 as a primitive Xc-type in the Bus-DeMeo taxonomy. Based on literature comparison, we confirm the spectral variability of this object at near-infrared (NIR) wavelengths, and find that spectral variations exist also for the visible spectral region. Phase reddening cannot explain such variations. Obtained with the same observational conditions for the whole 0.3-2.2 µm range, our X-Shooter spectrum allowed a proper comparison with the RELAB meteorite database. A very good fit is obtained with the very primitive C2 Tagish Lake carbonaceous chondrite (pressed powder), confirming 1996 FG3 as a suitable target for a sample return mission from primitive NEAs. Conclusions. We hypothesize a compacted/cemented surface for 1996 FG3, like that observed by the Hayabusa mission on (25143) Itokawa, with the possible presence of regions showing different degrees of surface roughness. This variegation could be related to the binary nature of 1996 FG3, but to check this hypothesis further observations are necessary.

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Spectroscopy of near-Earth asteroids

Cited by 14 publications

References 25 publications

2P/Encke, the Taurid complex NEOs and the Maribo and Sutter’s Mill meteorites

2P/Encke, the Taurid complex NEOs and the Maribo and Sutter’s Mill meteorites

Surface composition and taxonomic classification of a group of near-Earth and Mars-crossing asteroids

Ultraviolet to near-infrared spectroscopy of the potentially hazardous, low delta-V asteroid (175706) 1996 FG3

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