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These studies aimed to further understand the antiviral effects of safe, visible light and demonstrate a therapeutic effect of an investigational treatment device for outpatients with mild to moderate COVID-19. RD-X19 is a handheld medical device precisely engineered to emit blue light through the oral cavity to target the oropharynx and surrounding tissues. At doses that are well-tolerated in an in vitro human epithelial tissue model, the monochromatic visible light delivered by RD-X19 results in light-initiated expression of IL-1α and IL-1β cytokines with corresponding inhibition of SARS-CoV-2 replication. A randomized, double-blind, sham-controlled early feasibility study using the investigational device enrolled 31 subjects with a positive SARS-CoV-2 antigen test and possessing at least two moderate COVID-19 signs and symptoms. Subjects were randomized 2:1 (RD-X19 to sham), treated twice daily for four days, and evaluated over one week. Prespecified outcome measures included assessments of SARS-CoV-2 viral load and clinical assessments of COVID-19. There were no local application site reactions and no device-related adverse events. The time-weighted average change in log viral load throughout the study demonstrated a favorable reduction for RD-X19 compared to sham and at the end of study the mean change in log10 viral load was -3.29 for RD-X19 and -1.81 for sham at Day 8, demonstrating a treatment benefit of -1.48 [95% confidence internal (CI), -2.88 to -0.071]. Among the clinical outcome measures, differences between RD-X19 and sham were also observed, with a 57-hour reduction of median time to sustained resolution of COVID-19 signs and symptoms.

We are upgrading and refurbishing the first-generation adaptive-secondary mirror (ASM)-based AO system on the 6.5-m MMT in Arizona, in an NSF MSIP-funded program that will create a unique facility specialized for exoplanet characterization. This update includes a third-generation ASM with embedded electronics for low power consumption, two pyramid wavefront sensors (optical and near-IR), and an upgraded ARIES science camera for high-resolution spectroscopy (HRS) from 1-5 μm and MMT-POL science camera for sensitive polarization mapping. Digital electronics have been incorporated into each of the 336 actuators, simplifying hub-level electronics and reducing the total power to 300 W, down from 1800 W in the legacy system — reducing cooling requirements from active coolant to passive ambient cooling. An improved internal control law allows for electronic damping and a faster response. The dual pyramid wavefront sensors allow for a choice between optical or IR wavefront sensing depending on guide star magnitude, color, and extinction. The HRS upgrade to ARIES enables crosscorrelation of molecular templates to extract atmospheric parameters of exoplanets. The combination of these upgrades creates a workhorse instrument for exoplanet characterization via AO and HRS to separate planets from their host stars, with broad wavelength coverage and polarization to probe a range of molecular species in exoplanet atmospheres., SPIE Astronomical Telescopes + Instrumentation, December 14-18, 2020, Online Only, United States, Series: Proceedings of SPIE

We report mid- to far-infrared imaging and photomety from 7 to 37 microns with SOFIA/FORCAST and 2 micron adaptive optics imaging with LBTI/LMIRCam of a large sample of red supergiants (RSGs) in four Galactic clusters; RSGC1, RSGC2=Stephenson 2, RSGC3, and NGC 7419. The red supergiants in these clusters cover their expected range in luminosity and initial mass from approximately 9 to more than 25 Solar masses. The population includes examples of very late-type RSGs such as MY Cep which may be near the end of the RSG stage, high mass losing maser sources, yellow hypergiants and post-RSG candidates. Many of the stars and almost all of the most luminous have spectral energy distributions (SEDs) with extended infrared excess radiation at the longest wavelengths. To best model their SEDs we use DUSTY with a variable radial density distribution function to estimate their mass loss rates. Our mass loss rate -- luminosity relation for 42 RSGs basically follows the classical de Jager curve, but at luminosities below 10^5 Solar luminosities we find a significant population of red supergiants with mass loss rate below the de Jager relation. At luminosities above 10^5 Solar luminosities there is a rapid transition to higher mass loss rates that approximates and overlaps the de Jager curve. We recommend that instead of using a linear relation or single curve, the empirical mass loss rate -- luminosity relation is better represented by a broad band. Interestingly, the transition to much higher mass loss rates at about 10^5 Lsun corresponds approximately to an initial mass of 18 --20 Msun which is close to the upper limit for RSGs becoming Type II SNe., Accepted for publication in the Astronomical Journal

The red hypergiant VY CMa and the more typical red supergiant Betelgeuse provide clear observational evidence for discrete, directed gaseous outflows in their optical and infrared imaging, spectra, and light curves. In the very luminous VY CMa, mass loss estimates from the infrared bright knots and clumps, not only dominate its measured overall mass loss, but explain it. In the lower luminosity Betelgeuse, similar mass estimates of its circumstellar condensations show that they contribute significantly to its measured mass loss rate. We present new measurements for both stars and discuss additional evidence for gaseous ejections in other red supergiants. Gaseous outflows are the dominant mass loss mechanism for the most luminous RSGs and an important contributor to the more typical red supergiants like Betelgeuse. We conclude that gaseous outflows, related to magnetic fields and surface activity, comparable to coronal mass ejections, are a major contributor to mass loss from red supergiants and the missing component in discussions of their mass loss mechanism., Comment: To appear in the Astronomical Journal

Imaging and spectroscopy of the knots, clumps, and extended arcs in the complex ejecta of VY CMa confirm a record of high mass loss events over the past few hundred years. HST/STIS spectroscopy of numerous small knots close to the star allow us to measure their radial velocities from the strong K I emission and determine their separate motions, spatial orientations, and time since ejecta. Their ages concentrate around 70, 120, 200 and 250 years ago. A K I emission knot only 50 mas from the star ejected as recently as 1985 -- 1995 may coincide with an H2O maser. Comparison with VY CMa's historic light curve from 1800 to the present, shows several knots with ejection times that correspond with extended periods of variability and deep minima. The similarity of this correspondence in VY CMa with the remarkable recent dimming of Betelgeuse and an outflow of gas is apparent. The evidence for similar outflows from the surface of a more typical red supergiant suggests that discrete ejections are more common and surface or convective activity is a major source of mass loss for red supergiants., Accepted for publication in the Astronomical Journal

We report the first detection of galactic spiral structure by means of thermal emission from magnetically aligned dust grains. Our 89 $��$m polarimetric imaging of NGC 1068 with the High-resolution Airborne Wideband Camera/Polarimeter (HAWC+) on NASA's Stratospheric Observatory for Infrared Astronomy (SOFIA) also sheds light on magnetic field structure in the vicinity of the galaxy's inner-bar and active galactic nucleus (AGN). We find correlations between the 89 $��$m magnetic field vectors and other tracers of spiral arms, and a symmetric polarization pattern as a function of the azimuthal angle arising from the projection and inclination of the disk field component in the plane of the sky. The observations can be fit with a logarithmic spiral model with pitch angle of $16.9^{+2.7}_{-2.8}$$^{\circ}$ and a disk inclination of $48\pm2^{\circ}$. We infer that the bulk of the interstellar medium from which the polarized dust emission originates is threaded by a magnetic field that closely follows the spiral arms. Inside the central starburst disk ($, 13 pages, 7 figures, Accepted for publication by ApJ

We report near simultaneous imaging using LMIRCam on the LBTI of the quadruply imaged lensed quasar HS 0810+2554 at wavelengths of 2.16, 3.7 and $4.78~\mu$m with a Full Width Half Max (FWHM) spatial resolution of $0^{\prime\prime}\!\!.13$, $0^{\prime\prime}\!\!.12$ and $0^{\prime\prime}\!\!.15$ respectively, comparable to HST optical imaging. In the $\rm{z} = 1.5$ rest frame of the quasar, the observed wavelengths correspond to 0.86, 1.48, and $1.91~\mu$m respectively. The two brightest images in the quad, A and B, are clearly resolved from each other with a separation of $0.187^{\prime\prime}$. The flux ratio of these two images (A/B) trends from 1.79 to 1.23 from 2.16 to $4.78~\mu$m. The trend in flux ratio is consistent with the $2.16~\mu$m flux originating from a small sized accretion disk in the quasar that experiences only microlensing. The excess flux above the contribution from the accretion disk at the two longer wavelengths originates from a larger sized region that experiences no microlensing. A simple model employing multiplicative factors for image B due to stellar microlensing $(m)$ and sub-structure millilensing $(M)$ is presented. The result is tightly constrained to the product $m\times M=1.79$. Given the observational errors, the 60\% probability contour for this product stretches from $m= 2.6$, $M = 0.69$ to $m= 1.79$, $M = 1.0$, where the later is consistent with microlensing only., Comment: accepted AJ

et al., We present J′ and K′ imaging linear polarimetric adaptive optics observations of NGC 1068 using MMT-Pol on the 6.5-m MMT. These observations allow us to study the torus from a magnetohydrodynamical (MHD) framework. In a 0.5 arcsec (30 pc) aperture at K′, we find that polarization arising from the passage of radiation from the inner edge of the torus through magnetically aligned dust grains in the clumps is the dominant polarization mechanism, with an intrinsic polarization of 7.0 ± 2.2 per cent. This result yields a torus magnetic field strength in the range of 4–82 mG through paramagnetic alignment, and 139+11−20−20+11 mG through the Chandrasekhar–Fermi method. The measured position angle (P.A.) of polarization at K′ is found to be similar to the P.A. of the obscuring dusty component at few parsec scales using infrared interferometric techniques. We show that the constant component of the magnetic field is responsible for the alignment of the dust grains, and aligned with the torus axis on to the plane of the sky. Adopting this magnetic field configuration and the physical conditions of the clumps in the MHD outflow wind model, we estimate a mass outflow rate ≤0.17 M⊙ yr−1 at 0.4 pc from the central engine for those clumps showing near-infrared dichroism. The models used were able to create the torus in a time-scale of ≥105 yr with a rotational velocity of ≤1228 km s−1 at 0.4 pc. We conclude that the evolution, morphology and kinematics of the torus in NGC 1068 can be explained within a MHD framework., ELR and CP acknowledge support from the University of Texas at San Antonio. CP acknowledges support from NSF-0904421 grant. CP and TJJ acknowledge support from NSF-0704095 grant. AA-H acknowledges financial support from the Spanish Plan Nacional de Astronomía y Astrofisíca under grant AYA2012-31447. RN acknowledges support by FONDECYT grant No. 3140436. CRA is supported by a Marie Curie Intra European Fellowship within the 7th European Community Framework Programme (PIEF-GA-2012-327934).

We present Far-Infrared polarimetry observations of M82 at 53 and $154~\mu \rm{m}$ and NGC 253 at $89~\mu \rm{m}$, which were taken with HAWC+ in polarimetry mode on the Stratospheric Observatory for Infrared Astronomy (SOFIA). The polarization of M82 at $53~\mu \rm{m}$ clearly shows a magnetic field geometry perpendicular to the disk in the hot dust emission. For M82 the polarization at $154~\mu \rm{m}$ shows a combination of field geometry perpendicular to the disk in the nuclear region, but closer to parallel to the disk away from the nucleus. The fractional polarization at $53~\mu \rm{m}$ $(154~\mu \rm{m})$ ranges from 7% (3%) off nucleus to 0.5% (0.3%) near the nucleus. A simple interpretation of the observations of M82 invokes a massive polar outflow, dragging the field along, from a region $\sim 700$~pc in diameter that has entrained some of the gas and dust, creating a vertical field geometry seen mostly in the hotter $(53~\mu \rm{m})$ dust emission. This outflow sits within a larger disk with a more typical planar geometry that more strongly contributes to the cooler $(154~\mu \rm{m})$ dust emission. For NGC 253, the polarization at $89~\mu \rm{m}$ is dominated by a planar geometry in the tilted disk, with weak indication of a vertical geometry above and below the plane from the nucleus. The polarization observations of NGC 253 at $53~\mu \rm{m}$ were of insufficient S/N for detailed analysis., Comment: 6 Figures, 20 pages, ApJL accepted

We report new polarimetric and photometric maps of the massive star-forming region OMC-1 using the HAWC+ instrument on the Stratospheric Observatory for Infrared Astronomy (SOFIA). We present continuum polarimetric and photometric measurements of this region at 53, 89, 154, and 214 microns at angular resolutions of 5.1, 7.9, 14.0, and 18.7 arcseconds for the four bands, respectively. The photometric maps enable the computation of improved SEDs for the region. We find that at the longer wavelengths, the inferred magnetic field configuration matches the `hourglass' configuration seen in previous studies, indicating magnetically-regulated star formation. The field morphology differs at the shorter wavelengths. The magnetic field inferred at these wavelengths traces the bipolar structure of the explosive Becklin-Neugebauer (BN)/Kleinman-Low (KL) outflow emerging from OMC-1 behind the Orion Nebula. Using statistical methods to estimate the field strength in the region, we find that the explosion dominates the magnetic field near the center of the feature. Farther out, the magnetic field is close to energetic equilibrium with the ejecta and may be providing confinement to the explosion. The correlation between polarization fraction and the local polarization angle dispersion indicates that the depolarization as a function of unpolarized intensity is a result of intrinsic field geometry as opposed to decreases in grain alignment efficiency in denser regions., Comment: 28 pages, 14 figures, ApJ, accepted

Aims. Polarisation observations of circumstellar dust and molecular (thermal and maser) lines provide unique information about dust properties and magnetic fields in circumstellar envelopes of evolved stars. Methods. We use Atacama Large Millimeter/submillimeter Array (ALMA) Band 5 science verification observations of the red supergiant VY CMa to study the polarisation of SiO thermal/maser lines and dust continuum at ∼1.7 mm wavelength. We analyse both linear and circular polarisation and derive the magnetic field strength and structure, assuming the polarisation of the lines originates from the Zeeman effect, and that of the dust originates from aligned dust grains. We also discuss other effects that could give rise to the observed polarisation. Results. We detect, for the first time, significant polarisation (∼3%) of the circumstellar dust emission at millimeter wavelengths. The polarisation is uniform with an electric vector position angle of ∼8°. Varying levels of linear polarisation are detected for the J = 4 - 328SiO v = 0, 1, 2, and 29SiO v = 0, 1 lines, with the strongest polarisation fraction of ∼30% found for the 29SiO v = 1 maser. The linear polarisation vectors rotate with velocity, consistent with earlier observations. We also find significant (up to ∼1%) circular polarisation in several lines, consistent with previous measurements. We conclude that the detection is robust against calibration and regular instrumental errors, although we cannot yet fully rule out non-standard instrumental effects. Conclusions. Emission from magnetically aligned grains is the most likely origin of the observed continuum polarisation. This implies that the dust is embedded in a magnetic field >13 mG. The maser line polarisation traces the magnetic field structure. The magnetic field in the gas and dust is consistent with an approximately toroidal field configuration, but only higher angular resolution observations will be able to reveal more detailed field structure. If the circular polarisation is due to Zeeman splitting, it indicates a magnetic field strength of ∼1-3 Gauss, consistent with previous maser observations.

The E and B Experiment (EBEX) was a long-duration balloon-borne cosmic microwave background polarimeter that flew over Antarctica in 2013. We describe the experiment's optical system, receiver, and polarimetric approach, and report on their in-flight performance. EBEX had three frequency bands centered on 150, 250, and 410 GHz. To make efficient use of limited mass and space we designed a 115 cm$^{2}$sr high throughput optical system that had two ambient temperature mirrors and four anti-reflection coated polyethylene lenses per focal plane. All frequency bands shared the same optical train. Polarimetry was achieved with a continuously rotating achromatic half-wave plate (AHWP) that was levitated with a superconducting magnetic bearing (SMB). Rotation stability was 0.45 % over a period of 10 hours, and angular position accuracy was 0.01 degrees. This is the first use of a SMB in astrophysics. The measured modulation efficiency was above 90 % for all bands. To our knowledge the 109 % fractional bandwidth of the AHWP was the broadest implemented to date. The receiver that contained one lens and the AHWP at a temperature of 4 K, the polarizing grid and other lenses at 1 K, and the two focal planes at 0.25 K performed according to specifications giving focal plane temperature stability with fluctuation power spectrum that had $1/f$ knee at 2 mHz. EBEX was the first balloon-borne instrument to implement technologies characteristic of modern CMB polarimeters including high throughput optical systems, and large arrays of transition edge sensor bolometric detectors with mutiplexed readouts., Comment: 49 pages, 32 figures, submitted to The Astrophysical Journal Supplement

New MMT/MIRAC (9-11 {\mu}m), SOFIA/FORCAST (11-37 {\mu}m), and Herschel/PACS (70 and 160 {\mu}m) infrared (IR) imaging and photometry is presented for three famous OH/IR red supergiants (NML Cyg, VX Sgr, and S Per) and two normal red supergiants (RS Per and T Per). We model the observed spectral energy distributions (SEDs) using radiative transfer code DUSTY. Azimuthal average profiles from the SOFIA/FORCAST imaging, in addition to dust mass distribution profiles from DUSTY, constrain the mass-loss histories of these supergiants. For all of our observed supergiants, the DUSTY models suggest that constant mass-loss rates do not produce enough dust to explain the observed infrared emission in the stars' SEDs. Combining our results with Shenoy et al. (2016) (Paper I) we find mixed results with some red supergiants showing evidence for variable and high mass-loss events while others have constant mass loss over the past few thousand years., Comment: 29 pages, 15 figures, 3 tables. Accepted to AJ

The supernova impostor PSN J09132750+7627410 in NGC 2748 reached a maximum luminosity of approximately -14 mag. It was quickly realized that its was not a true supernova, but another example of a non-terminal giant eruption. PSN J09132750+7627410 is distinguished by multiple P Cygni absorption minima in the Balmer emission lines that correspond to outflow velocities of -400, -1100, and -1600 km/s. Multiple outflows have been observed in only a few other objects. In this paper we describe the evolution of the spectrum and the P Cygni profiles for three months past maximum, the post-maximum formation of a cool, dense wind, and the identification of a possible progenitor. One of the possible progenitors is an infrared source. Its pre-eruption spectral energy distribution suggests a bolometric luminosity of -8.3 mag and a dust temperature of 780 degrees K. If it is the progenitor it is above the AGB limit unlike the intermediate luminosity red transients. The three P Cygni profiles could be due to ejecta from the current eruption, the wind of the progenitor, or previous mass loss events. We suggest that they were all formed as part of the same high mass loss event and are due to material ejected at different velocities or energies. We also suggest that multiple outflows during giant eruptions may be more common than reported., To appear in the Astrophysical Journal

Polarimetry at far-infrared wavelengths is a key tool for studying physical processes on size scales ranging from interstellar dust grains to entire galaxies. A multi-wavelength continuum polarimeter at these wavelengths will allow studies of thermal dust polarization in an effort to constrain the grains’ physical properties and test grain alignment theory. High spatial resolution (5–30 arcsec) and sensitive observations will measure the influence of magnetic fields on infrared cirrus clouds, the envelopes and disks of YSOs, outflows from both low- and high-mass star forming regions, and the relative strength of magnetic, gravitational, and turbulent effects in star- and cloud-formation.

Images of the circumstellar ejecta associated with the post-red supergiant IRC +10420 show a complex ejecta with visual evidence for episodic mass loss. In this paper we describe the transverse motions of numerous knots, arcs and condensations in the inner ejecta measured from second epoch {\it HST/WFPC2} images. When combined with the radial motions for several of the features, the total space motion and direction of the outflows show that they were ejected at different times, in different directions, and presumably from separate regions on the surface of the star. These discrete structures in the ejecta are kinematically distinct from the general expansion of the nebula and their motions are dominated by their transverse velocities. They are apparently all moving within a few degrees of the plane of the sky. We are thus viewing IRC +10420 nearly pole-on and looking nearly directly down onto its equatorial plane. We also discuss the role of surface activity and magnetic fields on IRC +10420's recent mass loss history., 16 pages, 6 figures

Recent supernova and transient surveys have revealed an increasing number of non-terminal stellar eruptions. Though the progenitor class of these eruptions includes the most luminous stars, little is known of the pre-supernova mechanics of massive stars in their most evolved state, thus motivating a census of possible progenitors. From surveys of evolved and unstable luminous star populations in nearby galaxies, we select a sample of yellow and red supergiant candidates in M31 and M33 for review of their spectral characteristics and spectral energy distributions. Since the position of intermediate and late-type supergiants on the color-magnitude diagram can be heavily contaminated by foreground dwarfs, we employ spectral classification and multi-band photometry from optical and near-infrared surveys to confirm membership. Based on spectroscopic evidence for mass loss and the presence of circumstellar dust in their SEDs, we find that $30-40\%$ of the yellow supergiants are likely in a post-red supergiant state. Comparison with evolutionary tracks shows that these mass-losing, post-RSGs have initial masses between $20-40\,M_{\odot}$. More than half of the observed red supergiants in M31 and M33 are producing dusty circumstellar ejecta. We also identify two new warm hypergiants in M31, J004621.05+421308.06 and J004051.59+403303.00, both of which are likely in a post-RSG state., Accepted for publication in ApJ. 34 pages, 11 figures

We present high-angular (0.17$-$0.35 arcsec) resolution imaging polarimetric observations of Mrk 231 in the 3.1 $\mu$m filter using MMT-Pol on the 6.5-m MMT, and in the 8.7 $\mu$m, 10.3 $\mu$m, and 11.6 $\mu$m filters using CanariCam on the 10.4-m Gran Telescopio CANARIAS. In combination with already published observations, we compile the 1$-$12 $\mu$m total and polarized nuclear spectral energy distribution (SED). The total flux SED in the central 400 pc is explained as the combination of 1) a hot (731 $\pm$ 4 K) dusty structure, directly irradiated by the central engine, which is at 1.6 $\pm$ 0.1 pc away and attributed to be in the pc-scale polar region, 2) an optically-thick, smooth and disk-like dusty structure (`torus') with an inclination of 48 $\pm$ 23$^{\circ}$ surrounding the central engine, and 3) an extinguished (A$_{\mbox{V}} =$ 36 $\pm$ 5 mag) starburst component. The polarized SED decreases from 0.77 $\pm$ 0.14 per cent at 1.2 $\mu$m to 0.31 $\pm$ 0.15 per cent at 11.6 $\mu$m and follows a power-law function, $\lambda^{\sim0.57}$. The polarization angle remains constant ($\sim$108$^{\circ}$) in the 1$-$12 $\mu$m wavelength range. The dominant polarization mechanism is explained as scattering off hot dust grains in the pc-scale polar regions., Comment: 9 pages, 2 figures. Accepted for publication in MNRAS

Images of the complex circumstellar nebula associated with the famous red supergiant VY CMa show evidence for multiple and asymmetric mass loss events over the past 1000 yrs. Doppler velocities of the arcs and knots in the ejecta showed that they are not only spatially distinct but also kinematically separate from the surrounding diffuse material. In this paper we describe second epoch HST/WFPC2 images to measure the transverse motions which when combined with the radial motions provide a complete picture of the kinematics of the ejecta including the total space motions and directions of the outflows. Our results show that the arcs and clumps of knots are moving at different velocities, in different directions, and at different angles relative to the plane of the sky and to the star, confirming their origin from eruptions at different times and from physically separate regions on the star. We conclude that the morphology and kinematics of the arcs and knots are consistent with a history of mass ejections not aligned with any presumed axis of symmetry. The arcs and clumps represent relatively massive outflows and ejections of gas very likely associated with large -- scale convective activity and magnetic fields.

We use imaging polarimetry taken with the HST/ACS/HRC to explore the three dimensional structure of the circumstellar dust distribution around the red supergiant VY Canis Majoris. The polarization vectors of the nebulosity surrounding VY CMa show a strong centro-symmetric pattern in all directions except directly East and range from 10% - 80% in fractional polarization. In regions that are optically thin, and therefore likely have only single scattering, we use the fractional polarization and photometric color to locate the physical position of the dust along the line-of-sight. Most of the individual arc-like features and clumps seen in the intensity image are also features in the fractioanl polarization map. These features must be distinct geometric objects. If they were just local density enhancements, the fractional polarization would not change so abruptly at the edge of the feature. The location of these features in the ejecta of VY CMa using polarimetry provides a determination of their 3D geometry independent of, but in close agreement with, the results from our study of their kinematics (Paper I).

We use second epoch images taken with WFPC2 on the HST and imaging polarimetry taken with the HST/ACS/HRC to explore the three dimensional structure of the circumstellar dust distribution around the red supergiant VY Canis Majoris. Transverse motions, combined with radial velocities, provide a picture of the kinematics of the ejecta, including the total space motions. The fractional polarization and photometric colors provide an independent method of locating the physical position of the dust along the line-of-sight. Most of the individual arc-like features and clumps seen in the intensity image are also features in the fractional polarization map, and must be distinct geometric objects. The location of these features in the ejecta of VY CMa using kinematics and polarimetry agree well with each other, and strongly suggest they are the result of relatively massive ejections, probably associated with magnetic fields.

We present new images of the giant molecular cloud W3 obtained with the Infrared Array Camera (IRAC) and the Multiband Imaging Photometer for Spitzer (MIPS) on board the Spitzer Space Telescope. The images encompass the star forming regions W3 Main, W3(OH), and a region that we refer to as the Central Cluster, which encloses the emission nebula IC 1795. We present a star count analysis of the point sources detected in W3. The star count analysis shows that the stellar population of the Central Cluster, when compared to that in the background, contains an over density of sources. The Central Cluster also contains an excess of sources with colors consistent with Class II young stellar objects (YSOs). An analysis of the color-color diagrams also reveals a large number of Class II YSOs in the Central Cluster. Our results suggest that an earlier epoch of star formation created the Central Cluster, created a cavity, and triggered the active star formation in the W3 Main and W3(OH) regions. We also detect a new outflow and its candidate exciting star.

We have constructed a cryogenic induction motor to turn the rotor of a superconducting magnetic bearing (SMB). Both the motor and the SMB are operated at liquid He temperatures. We give a model for the motor and present measurements of its operation. The rotation speed is very stable. Over 8 h it shows an RMS variation of only 0.005 Hz from a mean of 2 Hz. The speed variation within one period of rotation is 3% ± 1% implying that the angular position of the rotor can be determined to an accuracy of 1° for all angles of rotation even if angular position is encoded only once every period. Friction and heat dissipation in this motor is dominated by eddy currents. We discuss the application of the motor to astrophysical polarimetry.

We present observations of the giant HII region complex N159 in the LMC using IRAC on the {\it Spitzer Space Telescope}. One of the two objects previously identified as protostars in N159 has an SED consistent with classification as a Class I young stellar object (YSO) and the other is probably a Class I YSO as well, making these two stars the youngest stars known outside the Milky Way. We identify two other sources that may also be Class I YSOs. One component, N159AN, is completely hidden at optical wavelengths, but is very prominent in the infrared. The integrated luminosity of the entire complex is L $\approx 9\times10^6$L$_{\odot}$, consistent with the observed radio emission assuming a normal Galactic initial mass function (IMF). There is no evidence for a red supergiant population indicative of an older burst of star formation. The N159 complex is 50 pc in diameter, larger in physical size than typical HII regions in the Milky Way with comparable luminosity. We argue that all of the individual components are related in their star formation history. The morphology of the region is consistent with a wind blown bubble $\approx 1-2Myr-old that has initiated star formation now taking place at the rim. Other than its large physical size, star formation in N159 appears to be indistinguishable from star formation in the Milky Way.

We have previously presented a design for a cosmic microwave background (CMB) polarimeter in which a cryogenically cooled half-wave plate rotates by means of a high-temperature superconducting (HTS) bearing. Here, a prototype bearing, consisting of a commercially available ring-shaped permanent magnet and an array of YBCO bulk HTS material, has been constructed. We measured its coefficient of friction and vibrational property as a function of several parameters, including temperature between 15 and 83 K, rotation frequency between 0.3 and 3.5 Hz, levitation distance between 6 and 10 mm and ambient pressure of Torr. We concluded that the low rotational drag of the HTS bearing would allow rotations for long periods with minimal input power and negligible wear and tear, thus making this technology suitable for a future satellite mission.

e present Near Infrared imaging polarimetry of three regions of massive star formation, G$192.16 - 3.82$, Cepheus A, and W42. In W42 we have discovered a new bipolar nebula located at the far side of the HII region behind the visible cluster of exciting stars. The axis of this new nebula is aligned with the magnetic field threading the entire cluster region. Polarization in the bipolar outflow nebulosity associated with G192.16 is consistent with a single illuminating source, too faint to be detected at $2 \micron$. Polarization in the reflection nebulosity associated with Ceph A requires more than one illuminating source, although HW2 is clearly dominant. In all three objects, the magnetic field in the outflow at distances greater than $\sim 0.2$ pc is radial. In G192.16 the magnetic field geometry closer than $\sim 0.2$ pc to the embedded star appears chaotic. For G192.16 the outflow is not aligned with the surrounding magnetic field, which lies in the galactic plane. In Ceph A, the outflow axis could be interpreted as being aligned with the galactic plane, but the magnetic field threading the region is not. Only in the case of W42 is the magnetic field threading the HII region aligned with the mean field in the surrounding galactic plane.

We present near-infrared (2.2 μm) imaging polarimetry and near-infrared photometry for recent comets. The 2.2 μm polarization as a function of phase angle is 1%–2% higher than typical comet visual narrowband red polarization. This implies a general, but weak, trend to higher polarization at wavelengths longer than 0.7 μm. As found with visual narrowband red polarimetry, comets appear to divide into a high- and a low-polarization class at 2.2 μm as well. The high-polarization class is characterized by moderate to strong mid-infrared silicate emission, while the low-polarization class is characterized by weak to absent silicate emission. In contrast to C/1995 O1 (Hale-Bopp) and some other dusty comets, no significant grain population radial gradient is seen in any of the polarization maps for the six comets in our sample with near-infrared imaging polarimetry. Our analysis of previously published Hale-Bopp data shows that the polarization at 40° phase angle varies by only about a factor of 1.6 from 0.3 to 2.2 μm and is nearly flat from 0.7 to 2.2 μm. Any model of comet dust must reproduce this weak wavelength dependence.

We present spectroscopic observations of the classical nova CP Crucis (Nova Crux 1996) obtained with the Infrared Space Observatory Short Wavelength Spectrometer (ISO SWS) and the Anglo-Australian Telescope using both the Infrared Imaging Spectrograph and the Royal Greenwich Observatory Spectrograph. From the expansion parallax, we find that CP Crucis lies at a distance of 2.6 ± 0.5 kpc and reached a maximum MV of -8.7 at 0.96 days after discovery. We find abundance enhancements versus solar by mass of 75, 17, and 27 for N, O, and Ne, respectively. Additionally, we constrain the Mg abundance in the ejecta to be approximately solar. Abundance analysis suggests CP Crucis is an old Population I binary system. Combining the strong N and Ne abundances with the relatively low Mg abundance and a Ne/O ratio of 0.5, we propose that CP Crucis is an example of the "missing link" between CO and ONeMg novae.

We present measurements of the interstellar polarization at 1.65 μm of stars shining through the filamentary dark cloud GF 9. Unlike many dark clouds, the interstellar polarization through GF 9 increases significantly with increasing extinction through the cloud. We find the magnetic field geometry in GF 9–core is very smooth, in agreement with results from far-infrared polarimetry by Clemens, Kraemer, & Ciardi (published in 1999). Our much more limited results for GF 9–filament are consistent with a disordered field, also in agreement with the far-infrared polarimetry. Comparison of the near-infrared and far-infrared position angles suggests that there is a moderate rotation in the projected magnetic field direction from the exterior to the interior of GF 9–core.

Measurements of the polarization of the cosmic microwave background (CMB) radiation are expected to significantly increase our understanding of the early universe. We present a design for a CMB polarimeter in which a cryogenically cooled half wave plate rotates by means of a high-temperature superconducting (HTS) bearing. The design is optimized for implementation in MAXIPOL, a balloon-borne CMB polarimeter. A prototype bearing, consisting of commercially available ring-shaped permanent magnet and an array of YBCO bulk HTS material, has been constructed. We measured the coefficient of friction as a function of several parameters including temperature between 15 and 80 K, rotation frequency between 0.3 and 3.5 Hz, levitation distance between 6 and 10 mm, and ambient pressure between 10^{-7} and 1 torr. The low rotational drag of the HTS bearing allows rotations for long periods of time with minimal input power and negligible wear and tear thus making this technology suitable for a future satellite mission., 6 pages, IEEE-Transactions of Applied Superconductivity, 2003, Vol. 13, in press

We present results of a campaign to obtain near-infrared images of evolved classical nova shells by using the Near-Infrared Camera and Multi-Image Spectrometer (NICMOS) on the Hubble Space Telescope. Images were obtained in six filters from 1.87 to 2.37 μm. Three of our four targets, QV Vulpeculae (Nova Vul 1987), QU Vulpeculae (Nova Vul 1984 No. 2), and V1974 Cygni (Nova Cyg 1992) exhibit pronounced shell emission in the narrowband Paα (F187N) filter. In the other five filters, the shells are only marginally detected with the exception of QU Vul, which exhibits spatially extended low surface brightness emission in the medium-band filter (F222M) centered near 2.22 μm. Spatially extended emission from V723 Cassiopeiae (Nova Cas 1995) was not detected above the image noise in any filter. The observed ejecta geometries lend further support to the suggestion that the speed class of a nova may correlate with the shape of the shells. The NICMOS images, in combination with ground-based spectroscopic determination of the ejecta expansion velocities, enable us to estimate the expansion parallaxes for V1974 Cyg, QU Vul, and QV Vul. Of note, the expansion velocity (in milliarcseconds per day) determined for V1974 Cyg has remained constant over the 4 year period (1993–1998) after onset of the optical thin phase. Lastly, more structures in the shell of V1974 Cyg have appeared since 1993.

For the Class 0 protostar, L1527, we compare 131 polarization vectors from SCUPOL/JCMT, SHARP/CSO and TADPOL/CARMA observations with the corresponding model polarization vectors of four ideal-MHD, non-turbulent, cloud core collapse models. These four models differ by their initial magnetic fields before collapse; two initially have aligned fields (strong and weak) and two initially have orthogonal fields (strong and weak) with respect to the rotation axis of the L1527 core. Only the initial weak orthogonal field model produces the observed circumstellar disk within L1527. This is a characteristic of nearly all ideal-MHD, non-turbulent, core collapse models. In this paper we test whether this weak orthogonal model also has the best agreement between its magnetic field structure and that inferred from the polarimetry observations of L1527. We found that this is not the case; based on the polarimetry observations the most favored model of the four is the weak aligned model. However, this model does not produce a circumstellar disk, so our result implies that a non-turbulent, ideal-MHD global collapse model probably does not represent the core collapse that has occurred in L1527. Our study also illustrates the importance of using polarization vectors covering a large area of a cloud core to determine the initial magnetic field orientation before collapse; the inner core magnetic field structure can be highly altered by a collapse and so measurements from this region alone can give unreliable estimates of the initial field configuration before collapse., Comment: 43 pages, 9 figures, 4 tables. Accepted by the Astrophysical Journal

Polarimetry of starlight observed through dust and observations of polarized thermal emission from this dust are some of the few ways to observe the presence of magnetic fields in the interstellar medium. Not only is the strength and overall geometry of the magnetic field important in physical processes in the ISM, the turbulent component to the field also plays an important role. Turbulence in the field is directly tied to turbulence in the gas and consequently to the dynamics of the gas, on both large and small scales. Using interstellar polarization to measure parameters relating to turbulence in the magnetic field is necessarily an indirect process. In this chapter we explore several techniques and results for using polarimetry to explore the turbulent component of the magnetic field in the Galaxy.

We present observations of the classical nova V1425 Aquilae (Nova Aquila 1995) with the Infrared Space Observatory's (ISO) Short Wavelength Spectrometer, the Isaac Newton Telescope's Intermediate Dispersion Spectrograph, and the International Ultraviolet Explorer's Short-Wavelength Primary Spectrograph. Analysis of He II (1640 A) development constrains the white dwarf turnoff to ~400 days after outburst. Photoionization modeling of the optical and ISO spectra obtained during the late nebular phase constrains the mass of the ejecta between 2.5–4.2 × 10-5 M⊙. This modeling also suggests C and O in the ejecta were enhanced by a factor of ~9, and N was enhanced by a factor of ~100 with respect to solar, while Ne was only slightly enhanced. Based upon these analyses, we determine that the white dwarf in the V1425 Aql system has a CO composition and is at a distance of 3.0 ± 0.4 kpc.

We present 1.2-18.3 μm photometry of comet 1995 01 (Hale-Bopp). Our observations spanned nearly 4 months pre- and post-perihelion. The dust grain size-dependent parameters of superheat, 10 μm silicate excess, and albedo are used to make determinations about the Hale-Bopp coma grain population. The evolution of the coma grain size distribution is tracked by measuring these parameters over a range of heliocentric distances. We also observed several regions in the Hale-Bopp coma revealing significant gradients in the measured color temperature suggesting differences in the dust grain size distribution. Finally, we compare the grain size-dependent parameters to those of 11 other bright comets. The extreme values of these parameters displayed by Hale-Bopp suggest it had a smaller mean dust grain size than those associated with the other comets.

The extended infrared emission from Sharpless 106 shows complex structure in ground-based images obtained at wavelengths from 3 to 20 μm. The structure of the ionization fronts and photodissociation regions are resolved in Brα emission at 4.05 μm and emission from polycyclic aromatic hydrocarbons at 3.29 μm, with the H I emission residing interior to the hydrocarbon emission. The mid-infrared observations at 10 to 20 μm reveal the distribution of continuum emission from warm dust in the nebula. These images have a higher spatial resolution than previous mid-infrared maps, but they support earlier findings of a relatively constant dust color temperature of ~135 K in the extended dust, excluding the dust near the self-luminous sources IRS 2 and 4. All infrared images presented here show a dark lane bisecting the nebula, which probably results from shadowing of light from the central engine rather than line-of-sight extinction. If this shadow is caused by a compact disk around IRS 4, its ionized inner edge would be within the radio photosphere of the stellar wind at wavelengths longer than about 1.5 cm. There appears to be a faint point source seen at near-infrared wavelengths that is coincident with the position of a bright far-infrared source. This source is adjacent to some bright near-infrared nebulosity but is not clearly detected in thermal infrared dust emission.

Imaging polarimetry at 1.65 and 2.2 $\mu $m is presented for the classic starburst galaxy M82 and the advanced merger system Cen A. Polarimetry at near IR wavelengths allows the magnetic field geometry in galaxies to be probed much deeper into dusty regions than optical polarimetry. In M82, the magnetic field throughout the nucleus has a polar geometry, presumably due to the massive vertical flow that is a result of the intense star formation there. Fully two thirds of the line of sight dust through to the center of M82 contains a vertical magnetic field. In Cen A, the prominent dust lane shows a normal planar field geometry. There is no indication of significant disturbance in the field geometry in the dust lane and the polarization strength is near normal for the amount of extinction. Either the magnetic field geometry was well maintained during the merger, or it reestablished itself very easily.

We present 2.2 μm ( K ) imaging infrared (IR) polarimetry of Comet Hale–Bopp at three different epochs: 1996 April and August and 1997 April. We also present 1.5- and 1.7-μm imaging polarimetry and photometry from 1.7 to 3.8 μm in 1997 April. In 1996 April and August the comet was ≤ 0.5% polarized in the K band. By 1997 April the comet was strongly polarized from 1.5 to 2.2 μm—more polarized than is typical for a comet at optical wavelengths. This suggests that the grains or grain aggregates are behaving more like Rayleigh particles at λ=1.5 μm. The percentage polarization was not uniform across the coma. It was higher in the jet, in particular at the leading edge of the jet and in the more distant (older) jet arc or halo. This behavior is most easily explained by a population of small grains present in the jet that are continuing to break up several hours after release from the nucleus. The 1.7- to 3.8-μm color images of the comet are consistent with this conclusion, although changes in the grain population in the jet between epochs are also probably a factor.

We present HST Wide Field Planetary Camera 2 images of the very massive eclipsing binary RY Scuti. The HST Hα image shows a very complex ionized nebula roughly 1'' in size. Several interesting structures are revealed, including what appears to be a pair of concentric ionized rings above and below the equatorial plane of the system, located at the inner edge of a more extended dust torus. We reexamine some essential physical characteristics of the nebula, such as a possible magnetic field and the complicated mass-loss geometry of this near-Eddington limit contact binary. The effects of a rotating illumination source are considered to explain the brightness distribution in the rings. We suggest a model for the origin of the mass and detailed structure in the nebula. This model invokes a previous mass ejection that is shaped by nonspherical interacting winds and possibly magnetic fields.

We present thermal infrared images of the unusual multiple stellar system HD 98800, which contains two double-star systems (A and B) separated by ≈08 in the north/south direction. This system may have formed in a recent burst of star formation in a very low mass cloud in the local solar neighborhood. Our images resolve the A and B components. Both A and B emit roughly equal fluxes at 4.71 μm, where radiation is primarily photospheric. The northern component (B) is about 3.7 times brighter than the southern component (A) at 9.78 μm where the radiation is due to thermal emission from dust, showing that 78% of the circumstellar dust in the system resides around component B. The two primary components are nearly identical K5 V pre-main-sequence stars, both with very significant amounts of dust emission. The dust system around the B component may have size, temperature, and possible structure analogous to those of a primitive zodiacal cloud.

Observations of the classical nova QU Vul (1984) were carried out in the infrared, optical, and radio regimes between days 3791 and 4262 after discovery. For the first time a spatial extension of the shell around QU Vul could be unambiguously established from our IR and optical observations. At 2.2 μm, a shell size of about 08 was found, which corresponds to a linear diameter of (4.5 ± 0.4) × 1016 cm on day 4124 assuming QU Vul is 3.6 kpc distant. The mass of the shell is (4 ± 1.5) × 10-4 M⊙ with the assumption that a free-free emission process is the dominant emission mechanism in the shell. This shell mass is larger than found for any nova.

We present the results of spectrophotometry from 1.3 to 4.2 μm of 45 IRAS sources in the list of Campbell, Persson, & Matthews that have been presumed to be luminous young stellar objects because of their infrared colors and large IRAS fluxes. About 70% of the objects show 3.1 μm H2O ice absorption or 3.3 μm unidentified infrared emission, or both. Among those with 3.1 μm H2O ice absorption, three objects seem to have a distinct absorption near 3.4 μm, and their absorption profiles are different than the optical depth profiles of young stellar objects in the literature. In the HKL two-color diagram, objects with ice absorption occupy the same region as previously known young stellar objects with the ice feature, and those with unidentified infrared emission overlap with Herbig Ae/Be stars. We interpret the distribution in the HKL two-color diagram as indicating the evolutionary sequence of intermediate- to high-mass young stars.

Comets, such as C/1995 O1 (Hale-Bopp), are important to studies of the origins of the solar system because they are believed to be frozen reservoirs of the most primitive pre-solar dust grains and ices. Here, we report 1.2–18.5 μm infrared (IR) spectrophotometric and polarimetric observations of comet Hale-Bopp. Our measurements of the spectral energy distribution (SED) and IR polarization near perhelion passage suggest that emission from the coma was dominated by scattering and thermal emission from sub-micron sized dust grains. Hale-Bopp's surprising brightness may have been largely a result of the properties of its coma grains rather than the size of its nucleus. The thermal emission continuum from the grains had a superheat of S = Tcolor/TBB ≥ 1.7, the peak of the 10 μm silicate emission feature was 1.7 mags above the carbon grain continuum, and the albedo (reflectivity) of the grains was ≥ 0.4 at a scattering angles, θ ≥ 135°

We present near infrared polarimetry data of background stars shining through a selection of starless cores taken in the $K$ band, probing visual extinctions up to $A_{V} \sim 48$. We find that $P_K/{\tau _K}$ continues to decline with increasing $A_{V}$ with a power law slope of roughly -0.5. Examination of published submillimeter (submm) polarimetry of starless cores suggests that by $A_{V} \gtrsim 20$ the slope for $P$ vs. $\tau$ becomes $\sim -1$, indicating no grain alignment at greater optical depths. Combining these two data sets, we find good evidence that, in the absence of a central illuminating source, the dust grains in dense molecular cloud cores with no internal radiation source cease to become aligned with the local magnetic field at optical depths greater than $A_V \sim 20$. A simple model relating the alignment efficiency to the optical depth into the cloud reproduces the observations well., Comment: 33 pages, 5 figures

We present 1.20-18.5 μm infrared (IR) spectrophotometric measurements of comet C/1995 O1 (Hale-Bopp) during 1997 February 15 and 20 UT. The spectral energy distribution (SED) was dominated by scattering and thermal emission from submicron sized dust grains that were unusually small. Hale-Bopp's surprising brightness may have been largely a result of the properties of its coma grains rather than the size of its nucleus. The thermal emission continuum from the grains had a superheat of S=Tcolor/TBB ≈ 1.84, the peak of the 10 μm silicate emission feature was 1.81 mag above the carbon grain continuum, and the albedo (reflectivity) of the grains was ≈ 0.41 at a scattering angle of θ ≈ 144°. These are the highest values for these empirical parameters ever observed in 20 years of optical/IR measurements of bright comets. The observations indicate that the optically important grains dominating the visual scattering and near-IR emission from the coma had an average radius of a≤0.4 μm. The strong silicate feature is produced by grains with a similar size range. These dust radii are comparable to the radii of the grains that condense in the outflows of some novae ("stardust") but still about 10 times larger than the average radius of the grains that produce the general interstellar extinction.

We present the 1.2-4.2 fiia spectroscopy of stars found in an objective prism survey of the galactic plane by Stephenson (1992, AAA 55.002.010). These stars were thought by Stephenson to be heavily reddened by interstellar absorption. However, almost all of them have turned out to be late-type stars with clear 2.3 //m CO absorption, which means that they are intrinsically red as well. A few stars have Ay ~ 9, but most of them are only moderately reddened {Ay = 1-5).