We present 11 candidate late-type companions to nearby stars identified with data from the Wide-field Infrared Survey Explorer (WISE) and the Two Micron All Sky Survey (2MASS). Eight of the candidates are likely to be companions based on their common proper motions with the primaries. The remaining three objects are rejected as companions, one of which is a free-floating T7 dwarf. Spectral types are available for five of the companions, which consist of M2V, M8.5V, L5, T8, and T8. Based on their photometry, the unclassified companions are probably two mid-M dwarfs and one late-M/early-L dwarf. One of the T8 companions, WISE J142320.84+011638.0, has already been reported by Pinfield and coworkers. The other T8 companion, ULAS J095047.28+011734.3, was discovered by Burningham and coworkers through the United Kingdom Infrared Telescope Infrared Deep Sky Survey, but its companionship has not been previously recognized in the literature. The L5 companion, 2MASS J17430860+8526594, is a new member of a class of L dwarfs that exhibit unusually blue near-IR colors. Among the possible mechanisms that have been previously proposed for the peculiar colors of these L dwarfs, low metallicity does not appear to be a viable explanation for 2MASS J17430860+8526594 since our spectrum of the primary suggests that its metallicity is not significantly subsolar.

The Faint Intergalactic Medium Redshifted Emission Balloon (FIREBall) is a mission designed to observe faint emission from the circumgalactic medium of moderate-redshift (z ∼ 0.7) galaxies for the first time. FIREBall observes a component of galaxies that plays a key role in how galaxies form and evolve, likely contains a significant amount of baryons, and has only recently been observed at higher redshifts in the visible. Here we report on the 2018 flight of the FIREBall-2 Balloon telescope, which occurred on 2018 September 22 from Fort Sumner, New Mexico. The flight was the culmination of a complete redesign of the spectrograph from the original FIREBall fiber-fed integral field unit to a wide-field multiobject spectrograph. The flight was terminated early owing to a hole in the balloon, and our original science objectives were not achieved. The overall sensitivity of the instrument and telescope was 90,000 LU, due primarily to increased noise from stray light. We discuss the design of the FIREBall-2 spectrograph, including modifications from the original FIREBall payload, and provide an overview of the performance of all systems. We were able to successfully flight-test a new pointing control system, a UV-optimized, delta-doped, and coated electron multiplying CCD, and an aspheric grating. The FIREBall-2 team is rebuilding the payload for another flight attempt in the fall of 2021, delayed from 2020 as a result of COVID-19.

The interaction between inflowing gas clouds and galactic outflows at the interface where the galactic disk transitions into the circumgalactic medium is an important process in galaxy fueling, yet remains poorly understood. Using a series of tall-box hydrodynamic Enzo simulations, we have studied the interaction between smooth gas inflow and supernovae-driven outflow at the disk-halo interface with pc-scale resolution. A realistic wind of outflowing material is generated by supernovae explosions in the disk, while inflowing gas is injected at the top boundary of the simulation box with an injection velocity ranging from 10 − 100 km s −1 . We find that cooling and hydrodynamic instabilities drive the injected gas to fragment into cold (∼ 10 3 K) cloud clumps with typical densities of ∼ 1 cm −3 . These clumps initially accelerate before interacting and partially mixing with the outflow and decelerating to velocities in the 50-100 km s −1 range. When the gas clumps hit the disk, 10% − 50% of the injected material is able to accrete (depending on the injection velocity). Clumps originating from gas injected with a higher initial velocity approach the disk with greater ram pressure, allowing them to penetrate through the disk in low density regions. We use (equilibrium) Cloudy photoionization models to generate absorption and emission signatures of gas accretion, finding that our mock HI and Hα observables are prominent and generally consistent with measurements in the Milky Way. We do not predict enhanced emission/absorption for higher ionization states such as OVI.

WISE J104915.57−531906.1 A+B and WISE J085510.83−071442.5 were recently discovered as the third and fourth closest known systems to the Sun, respectively (2.0 and 2.3 pc). The former consists of a L8+T0.5 binary and the latter is a probable Y dwarf and is the coldest known brown dwarf (∼ 250 K). We present a search for common proper motion companions to these brown dwarfs using multi-epoch mid-infrared images from the Spitzer Space Telescope. We have also obtained near-infrared adaptive optics images of WISE J104915.57−531906.1 A+B with the Very Large Telescope to search for companions at smaller separations than reached by Spitzer. No new companions are detected in either system. At projected separations of 25-420 ′′ (50-840 AU) for WISE J104915.57−531906.1 A+B and 4-420 ′′ (9-970 AU) for WISE J085510.83−071442.5, the Spitzer images are sensitive to companions with M 4.5 21.6 and 21.9, respectively, which correspond to masses of 1 M Jup for ages of ≥ 1 Gyr and temperatures of 150 K. The detection limit in the adaptive optics images of WISE J104915.57−531906.1 A+B is ∆H ∼ 10 at 3-15 ′′ (6-30 AU), or 7 M Jup for ≥ 1 Gyr.

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