New Silhouette Disks with Reflection Nebulae and Outflows in the Orion Nebula and M43

We report the detection of several new circumstellar disks seen in silhouette in the outskirts of the Orion nebula and M43, detected as part of our Halpha survey of Orion with the HST/ACS. Several of the disks show bipolar reflection nebulae, microjets, or temporal variability. Two disks in our sample are large and particularly noteworthy: A nearly edge-on disk, d216-0939, is located several arcminutes northwest of M43 and resembles the famous HH30 disk/jet system in Taurus. It drives the 0.15 pc long bipolar outflow HH667, and exhibits a remarkable asymmetric reflection nebula. With a diameter of 1200 AU, it is as large as the giant edge-on silhouette disk d114-426 in the core of the Orion Nebula. The large disk d253-1536 is located in a binary system embedded within an externally-ionized giant proplyd in M43. The disk exhibits distortions which we attribute to tidal interactions with a companion. The bipolar jet HH668 emerges orthogonal to the disk, and a bow shock lies 54'' south of this binary system along the outflow axis. Proper motions over 1.4 yr confirm that these emission knots are moving away from d253-1536, with speeds as high as 330 km/s in the HH668 microjet, and slower motion farther from the star.Comment: 19 pages, Fig 2 in color, accepted by A

Protostellar Outflows in L1340

We have searched the L1340 A, B, and C clouds for shocks from protostellar outflows using the H_2 2.122 μm near-infrared line as a shock tracer. Substantial outflow activity has been found in each of the three regions of the cloud (L1340 A, L1340 B, and L1340 C). We find 42 distinct shock complexes (16 in L1340 A, 11 in L1340 B, and 15 in L1340 C). We were able to link 17 of those shock complexes into 12 distinct outflows and identify candidate source stars for each. We examine the properties (A_V, T_(bol), and L_(bol)) of the source protostars and compare them to the properties of the general population of Class 0/I and flat spectral energy distribution protostars and find that there is an indication, albeit at low statistical significance, that the outflow-driving protostars are drawn from a population with lower A_V, higher L_(bol), and lower T_(bol) than the general population of protostars

The Brightening of Re50N: Accretion Event or Dust Clearing?

The luminous Class I protostar HBC 494, embedded in the Orion A cloud, is associated with a pair of reflection nebulae, Re50 and Re50N, which appeared sometime between 1955 and 1979. We have found that a dramatic brightening of Re50N has taken place sometime between 2006 and 2014. This could result if the embedded source is undergoing a FUor eruption. However, the near-infrared spectrum shows a featureless very red continuum, in contrast to the strong CO bandhead absorption displayed by FUors. Such heavy veiling, and the high luminosity of the protostar, is indicative of strong accretion but seemingly not in the manner of typical FUors. We favor the alternative explanation that the major brightening of Re50N and the simultaneous fading of Re50 is caused by curtains of obscuring material that cast patterns of illumination and shadows across the surface of the molecular cloud. This is likely occurring as an outflow cavity surrounding the embedded protostar breaks through to the surface of the molecular cloud. Several Herbig-Haro objects are found in the region.Comment: 8 pages, accepted by Ap

Protostellar Outflows in L1340

We have searched the L1340 A, B, and C clouds for shocks from protostellar outflows using the H_2 2.122 μm near-infrared line as a shock tracer. Substantial outflow activity has been found in each of the three regions of the cloud (L1340 A, L1340 B, and L1340 C). We find 42 distinct shock complexes (16 in L1340 A, 11 in L1340 B, and 15 in L1340 C). We were able to link 17 of those shock complexes into 12 distinct outflows and identify candidate source stars for each. We examine the properties (A_V, T_(bol), and L_(bol)) of the source protostars and compare them to the properties of the general population of Class 0/I and flat spectral energy distribution protostars and find that there is an indication, albeit at low statistical significance, that the outflow-driving protostars are drawn from a population with lower A_V, higher L_(bol), and lower T_(bol) than the general population of protostars

And in the Darkness Bind Them: Equatorial Rings, B[e] Supergiants, and the Waists of Bipolar Nebulae

We report the discovery of two new circumstellar ring nebulae in the western Carina Nebula. The brighter object, SBW1, resembles a lidless staring eye and encircles a B1.5 Iab supergiant. Its size is identical to the inner ring around SN1987A, but SBW1's low N abundance indicates that the star didn't pass through a RSG phase. The fainter object, SBW2, is a more distorted ring, is N-rich, and has a central star that seems to be invisible. We discuss these two new nebulae in context with rings around SN1987A, Sher25, HD168625, RY Scuti, WeBo1, SuWt2, and others. The ring bearers fall into two groups: Five rings surround hot supergiants, and all except for the one known binary are carbon copies of the ring around SN1987A. We propose a link between these rings and B[e] supergiants, where the rings derive from the same material in an earlier B[e] phase. The remaining four rings surround evolved intermediate-mass stars; all members of this ring fellowship are close binaries, hinting that binary interactions govern the forging of such rings. We estimate that there may be several thousand more dark rings in the Galaxy, but we are scarcely aware of their existence due to selection effects. The lower-mass objects might be the equatorial density enhancements often invoked to bind the waists of bipolar PNe.Comment: AJ accepted, 27 page

The Bolocam Galactic Plane Survey: II. Catalog of The Image Data

We present a catalog of 8358 sources extracted from images produced by the Bolocam Galactic Plane Survey (BGPS). The BGPS is a survey of the millimeter dust continuum emission from the northern Galactic plane. The catalog sources are extracted using a custom algorithm, Bolocat, which was designed specifically to identify and characterize objects in the large-area maps generated from the Bolocam instrument. The catalog products are designed to facilitate follow-up observations of these relatively unstudied objects. The catalog is 98% complete from 0.4 Jy to 60 Jy over all object sizes for which the survey is sensitive ( \u3c 3\u27.5). We find that the sources extracted can best be described as molecular clumps-large dense regions in molecular clouds linked to cluster formation. We find that the flux density distribution of sources follows a power law with dN/dS alpha S(-2.4+/-0.1) and that the mean Galactic latitude for sources is significantly below the midplane: \u3c b \u3e = (-0 degrees.095 +/- 0 degrees.001)

The Bolocam Galactic Plane Survey: Survey Description and Data Reduction

We present the Bolocam Galactic Plane Survey (BGPS), a 1.1 mm continuum survey at 33" effective resolution of 170 square degrees of the Galactic Plane visible from the northern hemisphere. The survey is contiguous over the range -10.5 < l < 90.5, |b| < 0.5 and encompasses 133 square degrees, including some extended regions |b| < 1.5. In addition to the contiguous region, four targeted regions in the outer Galaxy were observed: IC1396, a region towards the Perseus Arm, W3/4/5, and Gem OB1. The BGPS has detected approximately 8400 clumps over the entire area to a limiting non-uniform 1-sigma noise level in the range 11 to 53 mJy/beam in the inner Galaxy. The BGPS source catalog is presented in a companion paper (Rosolowsky et al. 2010). This paper details the survey observations and data reduction methods for the images. We discuss in detail the determination of astrometric and flux density calibration uncertainties and compare our results to the literature. Data processing algorithms that separate astronomical signals from time-variable atmospheric fluctuations in the data time-stream are presented. These algorithms reproduce the structure of the astronomical sky over a limited range of angular scales and produce artifacts in the vicinity of bright sources. Based on simulations, we find that extended emission on scales larger than about 5.9' is nearly completely attenuated (> 90%) and the linear scale at which the attenuation reaches 50% is 3.8'. Comparison with other millimeter-wave data sets implies a possible systematic offset in flux calibration, for which no cause has been discovered. This presentation serves as a companion and guide to the public data release through NASA's Infrared Processing and Analysis Center (IPAC) Infrared Science Archive (IRSA). New data releases will be provided through IPAC IRSA with any future improvements in the reduction.Comment: Accepted for publication in Astrophysical Journal Supplemen

Engaging Citizen Scientists to Keep Transit Times Fresh and Ensure the Efficient Use of Transiting Exoplanet Characterization Missions

This white paper advocates for the creation of a community-wide program to maintain precise mid-transit times of exoplanets that would likely be targeted by future platforms. Given the sheer number of targets that will require careful monitoring between now and the launch of the next generation of exoplanet characterization missions, this network will initially be devised as a citizen science project -- focused on the numerous amateur astronomers, small universities and community colleges and high schools that have access to modest sized telescopes and off-the-shelf CCDs.Comment: White Paper submitted to Astro2020 Science Call, 5 pages, 3 figures, community comments and involvement are welcome