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J/A+A/603/A55       WISE/NEOWISE Mars-crossing asteroids      (Ali-Lagoa+, 2017)

Sizes and albedos of Mars-crossing asteroids from WISE/NEOWISE data Ali-Lagoa V., Delbo M. <Astron. Astrophys. 603, A55 (2017)> =2017A&A...603A..55A (SIMBAD/NED BibCode)
ADC_Keywords: Minor planets ; Photometry, infrared ; Morphology Keywords: minor planets, asteroids: general - surveys - infrared: planetary systems Abstract: Mars-crossing asteroids (MCs) are a dynamically unstable group between the main belt and the near-Earth populations. Characterising the physical properties of a large sample of MCs can help to understand the original sources of many near-Earth asteroids, some of which may produce meteorites on Earth. Our aim is to provide diameters and albedos of MCs with available WISE/NEOWISE data. We used the near-Earth asteroid thermal model to find the best-fitting values of equivalent diameter and, whenever possible, the infrared beaming parameter. With the diameter and tabulated asteroid absolute magnitudes we also computed the visible geometric albedos. We determined the diameters and beaming parameters of 404 objects observed during the fully cryogenic phase of the WISE mission, most of which have not been published elsewhere. We also obtained 1572 diameters from data from the 3-Band and posterior non-cryogenic phases using a default value of beaming parameter. The average beaming parameter is 1.2±0.2 for objects smaller than 10km, which constitute most of our sample. This is higher than the typical value of 1.0 found for the whole main belt and is possibly related to the fact that WISE is able to observe many more small objects at shorter heliocentric distances, i.e. at higher phase angles. We argue that this is a better default value for modelling Mars-crossing asteroids from the WISE/NEOWISE catalogue and discuss the effects of this choice on the diameter and albedo distributions. We find a double-peaked distribution for the visible geometric albedos, which is expected since this population is compositionally diverse and includes objects in the major spectral complexes. However, the distribution of beaming parameters is homogeneous for both low- and high-albedo objects. Description: We fitted the near-Earth asteroid thermal model of Harris (1998, Icarus, 131, 29) to WISE/NEOWISE thermal infrared data (see, e.g., Mainzer et al. 2011ApJ...736..100M, and Masiero et al. 2014, Cat. J/ApJ/791/121). The table contains the best-fitting values of size and beaming parameter. We note that the beaming parameter is a strictly positive quantity, but a negative sign is given to indicate whenever we could not fit it and had to assume a default value. We also provide the visible geometric albedos computed from the diameter and the tabulated absolute magnitudes. Minimum relative errors of 10, 15, and 20 percent should be considered for size, beaming parameter and albedo in those cases for which the beaming parameter could be fitted. Otherwise, the minimum relative errors in size and albedo increase to 20 and 40 percent (see, e.g., Mainzer et al. 2011ApJ...736..100M). The asteroid absolute magnitudes and slope parameters retrieved from the Minor Planet Center (MPC) are included, as well as the number of observations used in each WISE band (nW2, nW3, nW4) and the corresponding average values of heliocentric and geocentric distances and phase angle of the observations. The ephemerides were retrieved from the MIRIADE service ( File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 99 2399 Best-fitting values of size and infrared beaming parameter and corresponding geometric visible albedos of Mars-crossing asteroids observed by WISE/NEOWISE
See also: J/ApJ/791/121 : NIR albedos of main-belt asteroids (Masiero+, 2014) J/A+A/591/A14 : PCF, SpecB or SDSSB asteroids parameters (Ali-Lagoa+, 2016) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 7 A7 --- Object Asteroid designation (MPC-packed format) 12- 16 F5.2 mag H Asteroid absolute magnitude (MPC) 21- 24 F4.2 --- G Slope parameter (MPC) 29- 33 F5.2 km D Equivalent diameter 36- 40 F5.3 --- pV Visible geometric albedo 43- 47 F5.2 --- eta Infrared beaming parameter (negative sign indicates that it was not fitted but fixed at the corresponding positive value) (1) 50- 51 I2 --- nW2 Number of data fitted in band W2 54- 55 I2 --- nW3 Number of data fitted in band W3 58- 59 I2 --- nW4 Number of data fitted in band W4 62- 68 F7.5 AU r Average heliocentric distance 71- 77 F7.5 AU Delta Average geocentric distance 80- 87 F8.5 deg alpha Average phase angle 90- 99 F10.4 d MJD Modified Julian Date
Note (1): The beaming parameter is a strictly positive quantity, so entries with negative values indicate that the beaming parameter was fixed to the corresponding positive value.
Acknowledgements: Victor Ali-Lagoa, vali(at) MPE, Garching bei Munchen, Germany
(End) Victor Ali-Lagoa [MPE, Germany], Patricia Vannier [CDS] 12-Jul-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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