We have selected an all-sky (|b| ≥ 25 • ) 12 µm flux-limited sample of 893 galaxies from the IRAS Faint Source Catalog, Version 2 (FSC-2). This new sample contains 2.3 times as many objects as an earlier selection (Spinoglio & Malkan 1989) based on the IRAS Point Source Catalog, Version 2. We have obtained accurate total fluxes in the IRAS wavebands by using the ADDSCAN procedure for all objects with FSC-2 12 µm fluxes greater than 0.15 Jy and increasing flux densities from 12 to 60 µm, and defined the sample by imposing a survey limit of 0.22 Jy on the total 12 µm flux. Its completeness is verified, by means of the classical Log N − Log S and V /V max tests, down to 0.30 Jy, below which we have measured the incompleteness down to the survey limit, using the Log N − Log S plot, for our statistical analysis. We have obtained redshifts (mostly from catalogs) for virtually all (98.4%) the galaxies in the sample.Using existing catalogs of active galaxies, we defined a subsample of 118 objects consisting of 53 Seyfert 1s and quasars, 63 Seyfert 2s, and 2 blazars-∼ 13% of the full sample), which is the largest unbiased sample of Seyfert galaxies ever assembled. Since the 12 µm flux has been shown to be about one-fifth of the bolometric flux for Seyfert galaxies and quasars, the subsample of Seyferts (including quasars and blazars) is complete not only to 0.30 Jy at 12 µm but also with respect to a bolometric flux limit of ∼ 2.0 × 10 −10 erg s −1 cm −2 . The average value of V /V max for the full sample, corrected for incompleteness at low fluxes, is 0.51 ± 0.04, expected for a complete sample of uniformly distributed galaxies, while the value for the Seyfert galaxy subsample is 0.46 ± 0.10, suggesting that several more galaxies are yet to be identified as Seyferts in our sample. We have derived 12 µm and far-infrared luminosity functions for the AGN, as well as for the entire sample. The AGN luminosity functions are more complete than those of the optically selected CfA Seyfert galaxies for all luminosities and AGN types.We extracted from our sample a complete subsample of 235 galaxies fluxlimited (8.3 Jy) at 60 µm. The 60 µm luminosity function computed for this subsample is in satisfactory agreement with the ones derived from the bright galaxy sample (BGS;Soifer et al. 1987) and the deep high-galactic latitude sample (Lawrence et al. 1986), both selected at 60 µm. Over the high luminosity range where our sample and the BGS overlap, however, our space densities are systematically lower by a factor of ∼ 1.5, whereas at low luminosities our space densities are higher by about the same amount. Comparable results are obtained when comparing the far-IR luminosity function of our entire sample with the one derived from the BGS. This is not unexpected, because of the bias towards high-luminosity spirals caused by selection at 60 µm.

Aperture photometry from our own observations and the literature is presented for the 12 µm Galaxies in the near infrared J, H and K bands and, in some cases, in the L band. These data are corrected to "total" near-infrared magnitudes, (with a typical uncertainty of 0.3 magnitudes) for a direct comparison with our IRAS fluxes which apply to the entire galaxy. The corrected data are used to derive integrated total NIR and FIR luminosities. We then combine these with blue photometry and an estimate of the flux contribution from cold dust at wavelengths longward of 100 µm to derive the first bolometric luminosities for a large sample of galaxies.The presence of nonstellar radiation at 2-3 µm correlates very well with nonstellar IRAS colors. This enables us to identify a universal Seyfert nuclear continuum from near-to far-infrared wavelengths. Thus there is a sequence of infrared colors which runs from a pure "normal galaxy" to a pure Seyfert/quasar nucleus. Seyfert 2 galaxies fall close to this same sequence, although only a few extreme narrow-line Seyferts have quasar-like colors, and these show strong evidence of harboring an obscured Broad Line Region. A corollary is that the host galaxies of Seyfert nuclei have normal near-to

The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. CitationHamilton, V.E., et al., "Evidence for widespread hydrated minerals on asteroid (101955) Bennu." Nature astronomy 3, 4 (2019): p.

Christensen, P. R.; Drouet d'Aubigny, C. Y.; Hamilton, V. E.; Reuter, D. C.; Rizk, B.; Simon, A. A.; Asphaug, E.; Bandfield, J. L.; Barnouin, O. S.; Barucci, M. A.; Bierhaus, E. B.; Binzel, R. P.; Bottke, W. F.; Bowles, N. E.; Campins, H.; Clark, B. C.; Clark, B. E.; Connolly, H. C.; Daly, M. G.; Leon, J. de; Delbo', M.; Deshapriya, J. D. P.; Elder, C. M.; Fornasier, S.; Hergenrother, C. W.; Howell, E. S.; Jawin, E. R.; Kaplan, H. H.; Kareta, T. R.; Le Corre, L.; Li, J.-Y.; Licandro, J.; Lim, L. F.; Michel, P.; Molaro, J.; Nolan, M. C.; Pajola, M.; Popescu, M.; Garcia, J. L. Rizos; Ryan, A.; Schwartz, S. R.; Shultz, N.; Siegler, M. A.; Smith, P. H.; Tatsumi, E.; Thomas, C. A.; Walsh, K. J.; Wolner, C. W. V.; Zou, X.-D. and Lauretta, D. S. (2019). Properties of rubble-pile asteroid (101955) Bennu from OSIRIS-REx imaging and thermal analysis. Nature Astronomy, 3 pp. 341-351. For guidance on citations see FAQs.Length of main text: 2956 words Length of methods: 3605 words Length of legends: 565 words Number of references: 53 main text, 69 including methods and supplementary information (refs 67 to 69 are cited in the SI only) , we show that asteroid (101955) Bennu's surface is globally rough, dense with boulders and low in albedo. The number of boulders is surprising given Bennu's moderate thermal inertia, suggesting that simple models linking thermal inertia to particle size do not adequately capture the complexity relating these properties. At the same time, we find evidence for a wide range of particle sizes with distinct albedo characteristics. Our findings imply that ages of Bennu's surface particles span from the disruption of the asteroid's parent body (boulders) to recent in situ production (micron-scale particles).