Young moving groups (YMGs) are coeval, comoving groups of stars which have migrated from their birthsites after formation. In the substellar regime, YMG members are key benchmarks to empirically define brown dwarf evolution with age and to study the lowest mass end of the initial mass function. We have combined Pan-STARRS1 (PS1) proper motions with optical+IR photometry from PS1, 2MASS and WISE to perform a large-scale (≈30,000 deg2) systematic search for substellar members down to ≈10 MJup. We have obtained near-IR spectroscopy of a large sample of ultracool candidate YMG members to assess their youth via gravity-sensitive absorption features. We have identified several new intermediate-gravity candidate members of the AB Dor Moving Group, potentially greatly expanding the substellar membership. These new candidate members bridge the gap between the known low-mass stellar and planetary-mass members and yield valuable insight into the spectral characteristics of young brown dwarfs.

We use a WISE-2MASS-Pan-STARRS1 galaxy catalog to search for a supervoid in the direction of the Cosmic Microwave Background Cold Spot. We obtain photometric redshifts using our multicolor data set to create a tomographic map of the galaxy distribution. The radial density profile centred on the Cold Spot shows a large low density region, extending over 10's of degrees. Motivated by previous Cosmic Microwave Background results, we test for underdensities within two angular radii, 5°, and 15°. Our data, combined with an earlier measurement by Granett et al. 2010, are consistent with a large Rvoid=(192 ± 15)h−1 Mpc (2σ) supervoid with δ ≃ −0.13 ± 0.03 centered at z=0.22 ± 0.01. Such a supervoid, constituting a ∼3.5 σ fluctuation in the ΛCDM model, is a plausible cause for the Cold Spot.

We present ASCA SIS observations of the wind-blown bubble NGC 6888. Because the ASCA SIS is sensitive to higher energy photons and has a higher spectral resolution compared to the ROSAT PSPC, we are able to detect a T ≈ 8×106 K plasma component besides the T ≈ 1.5×106 K component known from previous PSPC observations. The existence of a high-temperature component, the observed limb-brightened X-ray surface brightness profile, and the observed level of X-ray surface brightness cannot be satisfactorily explained by currently available models. Reducing heat conduction at the contact discontinuity may raise the central temperature and produce a limb-brightening; however, the expected X-ray surface brightness is still considerably higher than the observed surface brightness.