Showing papers by "Charles A. Beichman published in 2005"
TL;DR: In this paper, the authors used the 2MASS Extended Source Catalog to obtain the total reddening on each galaxy line of sight and compared this value to the IRAS 100 µm surface brightness converted to extinction by Schlegel et al.
Abstract: We present an analysis of the dust optical properties at large scale, for the whole galactic anticenter hemisphere. We used the 2MASS Extended Source Catalog to obtain the total reddening on each galaxy line of sight and we compared this value to the IRAS 100 µm surface brightness converted to extinction by Schlegel et al. (1998, ApJ, 500, 525). We performed a careful examination and correction of the possible systematic effects resulting from foreground star contamination, redshift contribution and galaxy selection bias. We also evaluated the contribution of dust temperature variations and interstellar clumpiness to our method. The correlation of the near-infrared extinction to the far-infrared optical depth shows a discrepancy for visual extinction greater than 1 mag with a ratio AV(FIR)/AV(gal) = 1.31 ± 0.06. We attribute this result to the presence of fluffy/composite grains characterized by an enhanced far-infrared emissivity. Our analysis, applied to half of the sky, provides new insights on the dust grains nature suggesting fluffy grains are found not only in some very specific regions but in all directions for which the visual extinction reaches about 1 mag.
63 citations
TL;DR: A suite of space-based missions will determine the incidence of Earth-like planets, detect and characterize the nearest planets, search for signs of life in their atmosphere, as well as make great advances in our understanding of how planetary systems form and evolve.
Abstract: The President has identified the search for Earth-like planets around nearby stars as a critical part of NASA's long term Vision for Space Exploration. A suite of space-based missions will determine the incidence of Earth-like planets, detect and characterize the nearest planets, search for signs of life in their atmosphere, as well as make great advances in our understanding of how planetary systems form and evolve. A detailed roadmap lays out the required technology developments, the precursor scientific knowledge, and the capabilities of the relevant missions.
1 citations