We report the discovery of the first He I*λ10830 broad absorption line quasar FBQS J1151+3822. Using new infrared and optical spectra, as well as the SDSS spectrum, we extracted the apparent optical depth profiles as a function of velocity of the 3889Å and 10830Å He I* absorption lines. Since these lines have the same lower levels, inhomogeneous absorption models could be used to extract the average true He I* column density; the log of that number was 14.9. The total hydrogen column density was obtained using Cloudy models. A range of ionization parameters and densities were allowed, with the lower limit on the ionization parameter of log U = −1.4 determined by the requirement that there be sufficient He I*, and the upper limit on the density of log n = 8 determined by the lack of Balmer absorption. Simulated UV spectra showed that the ionization parameter could be further constrained in principle using a combination of low and high ionization lines (such as Mg II and P V), but the only density-sensitive line predicted to be observable and not significantly blended was C IIIλ1176. We estimated the outflow rate and kinetic energy, finding them to be consistent but on the high side compared with analysis of other objects. Assuming that radiative line driving is the responsible acceleration mechanism, a force multipler model was constructed. A dynamical argument using the model results strongly constrained the density to be log n ≥∼ 7. Consequently, the log hydrogen column density is constrained to be between 21.7 and 22.9, the mass outflow rate to be between 11 and 56 solar masses per year, the ratio of the mass outflow rate to the accretion rate to be between 1.2 and 5.8, and the kinetic energy to be between 1 and 5×10 44 erg s −1 . We discuss the advantages of using He I* to detect high-column-density BALQSOs and and measure their properties. We find that the large λf ik ratio of 23.3 between the 10830Å and 3889Å components makes He I* analysis sensitive to a large range of high column densities. We discuss the prospects for finding other He I*λ10830 BALQSOs and examine the advantages of studying the properties of a sample identified using He I*.

We present near-and mid-infrared photometry and spectroscopy from PAIRI-TEL, IRTF, and Spitzer of a metallicity-unbiased sample of 117 cool, hydrogenatmosphere white dwarfs from the Palomar-Green survey and find five with excess radiation in the infrared, translating to a 4.3 +2.7 −1.2 % frequency of debris disks. This is slightly higher than, but consistent with the results of previous surveys. Using an initial-final mass relation, we apply this result to the progenitor stars of our sample and conclude that 1 − 7M stars have at least a 4.3% chance of hosting planets; an indirect probe of the intermediate-mass regime eluding conventional exoplanetary detection methods. Alternatively, we interpret this result as a limit on accretion timescales as a fraction of white dwarf cooling ages; white dwarfs accrete debris from several generations of disks for ∼10Myr. The average total mass accreted by these stars ranges from that of 200km asteroids to Ceres-sized objects, indicating that white dwarfs accrete moons and dwarf planets as well as Solar System asteroid analogues.

We report the discovery of very high energy (VHE) gamma-ray emission from the direction of the SNR G54.1+0.3 using the VERITAS ground-based gamma-ray observatory. The TeV signal has an overall significance of 6.8σ and appears pointlike given the resolution of the instrument. The integral flux above 1 TeV is 2.5% of the Crab Nebula flux and significant emission is measured between 250 GeV and 4 TeV, well described by a power-law energy spectrum dN/dE ∼ E −Γ with a photon index Γ = 2.39 ± 0.23 stat ± 0.30 sys. We find no evidence of time variability among observations spanning almost two years. Based on the location, the morphology, the measured spectrum, the lack of variability, and a comparison with similar systems previously detected in the TeV band, the most likely counterpart of this new VHE gamma-ray source is the pulsar wind nebula (PWN) in the SNR G54.1+0.3. The measured X-ray to VHE gamma-ray luminosity ratio is the lowest among all the nebulae supposedly driven by young rotation-powered pulsars, which could indicate a particle-dominated PWN.

A recent cross-correlation between the SDSS DR7 White Dwarf Catalog with the Wide-Field Infrared Survey Explorer (WISE ) all-sky photometry at 3.4, 4.6, 12, and 22 microns performed by Debes et al. (2011) resulted in the discovery of 52 candidate dusty white dwarfs (WDs). The 6 WISE beam allows for the possibility that many of the excesses exhibited by these WDs may be due to contamination from a nearby source, however. We present MMT+SWIRC Jand H-band imaging observations (0.5-1.5 PSF) of 16 of these candidate dusty WDs and confirm that four have spectral energy distributions (SEDs) consistent with a dusty disk and are not accompanied by a nearby source contaminant. The remaining 12 WDs have contaminated WISE photometry and SEDs inconsistent with a dusty disk when the contaminating sources are not included in the photometry measurements. We find the frequency of disks around single WDs in the WISE ∩ SDSS sample to be 2.6-4.1%. One of the four new dusty WDs has a mass of 1.04 M (progenitor mass 5.4 M ) and its discovery offers the first confirmation that massive WDs (and their massive progenitor stars) host planetary systems.

We present the discovery of an unusual, tidally-distorted extremely low mass white dwarf (WD) with nearly solar metallicity. Radial velocity measurements confirm that this is a compact binary with an orbital period of 2.6975 hrs and a velocity semi-amplitude of K = 108.7 km s −1 . Analysis of the hydrogen Balmer lines yields an effective temperature of T eff = 8380 K and a surface gravity of log g = 6.21 that in turn indicate a mass of M = 0.16 M ⊙ and a cooling age of 4.2 Gyr. In addition, a detailed analysis of the observed metal lines yields abundances of log (Mg/H) = −3.90, log (Ca/H) = −5.80, log (Ti/H) = −6.10, log (Cr/H) = −5.60, and log (Fe/H) = −4.50, similar to the sun. We see no evidence of a debris disk from which these metals would be accreted though the possibility cannot entirely be ruled out. Other potential mechanisms to explain the presence of heavy elements are discussed. Finally, we expect this system to ultimately undergo unstable mass transfer and merge to form a ∼ 0.3-0.6 M ⊙ WD in a few Gyr.