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Here we present the results of an airborne 3-5.4$\mu$m spectroscopic study of three young, Carbon-rich planetary nebulae IC 5117, PNG 093.9-00.1, and BD $+$30 3639. These observations were made using the grism spectroscopy mode of the FLITECAM instrument during airborne science operations onboard NASA's Stratospheric Observatory for Infrared Astronomy (SOFIA). The goal of this study is to characterize the 3.3 $\mu$m and 5.25 $\mu$m PAH dust emission in planetary nebulae and study the evolution of PAH features within evolved stars before their incorporation into new stellar systems in star-forming regions. Targets were selected from IRAS, KAO and ISO source lists, and were previously observed with FLITECAM on the 3-meter Shane telescope at Lick Observatory to allow direct comparison between the ground and airborne observations. We measure PAH emission equivalent width and central wavelength, classify the shape of the PAH emission, and determine the PAH/Aliphatic ratio for each target. The 3.3 $\mu$m PAH emission feature is observed in all three objects. PNG 093.9-00.1 exhibits NGC 7027-like aliphatic emission in the 3.4 to 3.6 $\mu$m region while IC 5117 and BD +30 3639 exhibit less aliphatic structure. All three PNs additionally exhibit PAH emission at 5.25 $\mu$m., Comment: 17 Pages, 3 figures

SOFIA HAWC+ polarimetry at $154~\micron$ is reported for the face-on galaxy M51 and the edge-on galaxy NGC 891. For M51, the polarization vectors generally follow the spiral pattern defined by the molecular gas distribution, the far-infrared (FIR) intensity contours, and other tracers of star formation. The fractional polarization is much lower in the FIR-bright central regions than in the outer regions, and we rule out loss of grain alignment and variations in magnetic field strength as causes. When compared with existing synchrotron observations, which sample different regions with different weighting, we find the net position angles are strongly correlated, the fractional polarizations are moderately correlated, but the polarized intensities are uncorrelated. We argue that the low fractional polarization in the central regions must be due to significant numbers of highly turbulent segments across the beam and along lines of sight in the beam in the central 3 kpc of M51. For NGC 891, the FIR polarization vectors within an intensity contour of 1500 $\rm{MJy~sr^{-1}}$ are oriented very close to the plane of the galaxy. The FIR polarimetry is probably sampling the magnetic field geometry in NGC 891 much deeper into the disk than is possible with NIR polarimetry and radio synchrotron measurements. In some locations in NGC 891 the FIR polarization is very low, suggesting we are preferentially viewing the magnetic field mostly along the line of sight, down the length of embedded spiral arms. There is tentative evidence for a vertical field in the polarized emission off the plane of the disk., Comment: AJ, Accepted, In Press

We report on polarimetric maps made with HAWC+/SOFIA toward Rho Oph A, the densest portion of the Rho Ophiuchi molecular complex. We employed HAWC+ bands C (89 $\mu$m) and D (154 $\mu$m). The slope of the polarization spectrum was investigated by defining the quantity R_DC = p_D/p_C, where p_C and p_D represent polarization degrees in bands C and D, respectively. We find a clear correlation between R_DC and the molecular hydrogen column density across the cloud. A positive slope (R_DC > 1) dominates the lower density and well illuminated portions of the cloud, that are heated by the high mass star Oph S1, whereas a transition to a negative slope (R_DC < 1) is observed toward the denser and less evenly illuminated cloud core. We interpret the trends as due to a combination of: (1) Warm grains at the cloud outskirts, which are efficiently aligned by the abundant exposure to radiation from Oph S1, as proposed in the radiative torques theory; and (2) Cold grains deep in the cloud core, which are poorly aligned due to shielding from external radiation. To assess this interpretation, we developed a very simple toy model using a spherically symmetric cloud core based on Herschel data, and verified that the predicted variation of R_DC is consistent with the observations. This result introduces a new method that can be used to probe the grain alignment efficiency in molecular clouds, based on the analysis of trends in the far-infrared polarization spectrum., Comment: Accepted by ApJ (July 18 2019)

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

We present observations of NGC 1068 covering the $19.7-53.0$ $\mu$m wavelength range using FORCAST and HAWC+ onboard SOFIA. Using these observations, high-angular resolution infrared (IR) and sub-mm observations, we find an observational turn-over of the torus emission in the $30-40$ $\mu$m wavelength range with a characteristic temperature of $70-100$ K. This component is clearly different from the diffuse extended emission in the narrow line and star formation regions at 10-100 $\mu$m within the central 700 pc. We compute $2.2-432$ $\mu$m 2D images using the best inferred \textsc{clumpy} torus model based on several nuclear spectral energy distribution (SED) coverages. We find that when $1-20$ $\mu$m SED is used, the inferred result gives a small torus size ($<4$ pc radius) and a steep radial dust distribution. The computed torus using the $1-432$ $\mu$m SED provides comparable torus sizes, $5.1^{+0.4}_{-0.4}$ pc radius, and morphology to the recently resolved 432 $\mu$m ALMA observations. This result indicates that the $1-20$ $\mu$m wavelength range is not able to probe the full extent of the torus. The characterization of the turn-over emission of the torus using the $30-60$ $\mu$m wavelength range is sensitive to the detection of cold dust in the torus. The morphology of the dust emission in our 2D image at 432 $\mu$m is spatially coincident with the cloud distribution, while the morphology of the emission in the $1-20$ $\mu$m wavelength range shows an elongated morphology perpendicular to the cloud distribution. We find that our 2D \textsc{clumpy} torus image at 12 $\mu$m can produce comparable results to those observed using IR interferometry., Comment: 12 pages, 7 Figures, Accepted for publication in ApJ

We use a modified version of MOOG to generate large grids of synthetic spectra in an attempt to derive quantitative abundances for three CVs (GK Per, RU Peg, and SS Cyg) by comparing the models to moderate resolution (R $\sim$ 25,000) $K$-band spectra obtained with NIRSPEC on Keck. For each of the three systems we find solar, or slightly sub-solar values for [Fe/H], but significant deficits of carbon: for SS Cyg we find [C/Fe] = $-$0.50, for RU Peg [C/Fe] = $-$0.75, and for GK Per [C/Fe] = $-$1.00. We show that it is possible to use lower resolution (R $\sim$ 2,000) spectra to quantify carbon deficits. We examine realistic veiling scenarios and find that emission from H I or CO cannot reproduce the observations., Comment: Accepted in the Astronomical Journal

Here we report on the first successful exoplanet transit observation with the Stratospheric Observatory for Infrared Astronomy (SOFIA). We observed a single transit of the hot Jupiter HD 189733 b, obtaining two simultaneous primary transit lightcurves in the B and z' bands as a demonstration of SOFIA's capability to perform absolute transit photometry. We present a detailed description of our data reduction, in particular the correlation of photometric systematics with various in-flight parameters unique to the airborne observing environment. The derived transit depths at B and z' wavelengths confirm a previously reported slope in the optical transmission spectrum of HD 189733 b. Our results give new insights to the current discussion about the source of this Rayleigh scattering in the upper atmosphere and the question of fixed limb darkening coefficients in fitting routines., Comment: 40 pages, 7 figures, accepted for publication in JATIS

We present medium resolution near-infrared (NIR) spectra, covering 1.1 to 3.4 microns, of the normal Type Ia supernova (SN Ia) SN 2014J in M82 obtained with the FLITECAM instrument aboard SOFIA approximately 17-25 days after maximum B light. Our 2.8-3.4 micron spectra may be the first ~3 micron spectra of a SN Ia ever published. The spectra spanning the 1.5-2.7 micron range are characterized by a strong emission feature at ~1.77 microns with a full width at half maximum of ~11,000-13,000 km/s. We compare the observed FLITECAM spectra to the recent non-LTE delayed detonation models of Dessart et al. (2014) and find that the models agree with the spectra remarkably well in the 1.5-2.7 micron wavelength range. Based on this comparison we identify the ~1.77 micron emission peak as a blend of permitted lines of Co II. Other features seen in the 2.0 - 2.5 micron spectra are also identified as emission from permitted transitions of Co II. However, the models are not as successful at reproducing the spectra in the 1.1 - 1.4 micron range or between 2.8 and 3.4 microns. These observations demonstrate the promise of SOFIA by allowing access to wavelength regions inaccessible from the ground, and serve to draw attention to the usefulness of the regions between the standard ground-based NIR passbands for constraining SN models., Comment: 23 pages, including 7 figures; Accepted by ApJ

We have used the PACS instrument on the Herschel Space Observatory to observe eight cataclysmic variables at 70 and 160 microns. Of these eight objects, only AM Her was detected. We have combined the Herschel results with ground-based, Spitzer, and WISE observations to construct spectral energy distributions for all of the targets. For the two dwarf novae in the sample, SS Cyg and U Gem, we find that their infrared luminosities are completely dominated by their secondary stars. For the two highly magnetic "polars" in our survey, AM Her and EF Eri, we find that their mid-infrared excesses, previously attributed to circumbinary dust emission, can be fully explained by cyclotron emission. The WISE light curves for both sources show large, orbitally modulated variations that are identically phased to their near-IR light curves. We propose that significant emission from the lowest cyclotron harmonics (n

We investigate the Pick problem for the polydisk and unit ball using dual algebra techniques. Some factorization results for Bergman spaces are used to describe a Pick theorem for any bounded region in $\mathbb{C}^d$., Comment: v2, minor revisions. 7 pages

Suppose $\fA$ is an algebra of operators on a Hilbert space $H$ and $A_1,..., A_n \in \fA$. If the row operator $[A_1,..., A_n] \in B(H^{(n)},H)$ has a right inverse in $B(H, H^{(n)})$, the Toeplitz corona problem for $\fA$ asks if a right inverse can be found with entries in $\fA$. When $H$ is a complete Nevanlinna-Pick space and $\fA$ is a weakly-closed algebra of multiplication operators on $H$, we show that under a stronger hypothesis, the corona problem for $\fA$ has a solution. When $\fA$ is the full multiplier algebra of $H$, the Toeplitz corona theorems of Arveson, Schubert and Ball-Trent-Vinnikov are obtained. A tangential interpolation result for these algebras is developed in order to solve the Toeplitz corona problem., Comment: 13 pages

We present K-band spectroscopy of short period, "sub-gap" cataclysmic variable (CV) systems obtained using ISAAC on the VLT. We show the infrared spectra (IR) for nine systems below the 2-3 hour period gap: V2051 Oph, V436 Cen, EX Hya, VW Hyi, Z Cha, WX Hyi, V893 Sco, RZ Leo, and TY PsA. We are able to clearly detect the secondary star in all but WX Hyi, V893 Sco, and TY PsA. We present the first direct detection of the secondary stars of V2051 Oph, V436 Cen, and determine new spectral classifications for EX Hya, VW Hyi, Z Cha, and RZ Leo. We find that the CO band strengths of all but Z Cha appear normal for their spectral types, in contrast to their longer period cousins above the period gap. This brings the total number of CVs and pre-CVs with moderate resolution (R >~ 1500) IR spectroscopy to sixty-one systems: nineteen pre-CVs, thirty-one non-magnetic systems, and eleven magnetic or partially magnetic systems. We discuss the trends seen in the IR abundance patterns thus far, and highlight a potential link between anomalous abundances seen in the IR with the C IV/N V anomaly seen in the ultraviolet. We present a compilation of all systems with sufficient resolution IR observations to assess the CO band strengths, and, by proxy, obtain an estimate on the C abundance on the secondary star., Comment: 44 pages, 8 figures, 4 tables. Accepted for publication to ApJ

If $\fA$ is a unital weak-$*$ closed algebra of multiplication operators on a reproducing kernel Hilbert space which has the property $\bA_1(1)$, then the cyclic invariant subspaces index a Nevanlinna-Pick family of kernels. This yields an NP interpolation theorem for a wide class of algebras. In particular, it applies to many function spaces over the unit disk including Bergman space. We also show that the multiplier algebra of a complete NP space has $\bA_1(1)$, and thus this result applies to all of its subalgebras. A matrix version of this result is also established. It applies, in particular, to all unital weak-$*$ closed subalgebras of $H^\infty$ acting on Hardy space or on Bergman space., Comment: 26 pages; minor revisions; to appear in Integral Equations and Operator Theory

The prototype nova-like variable VY Sculptoris was observed by the IUE during four different optical brightness states of the system. The FUV flux level from the highest state to the lowest state declines by a factor of 28. We have carried out model accretion disk and white dwarf atmosphere fitting to the spectra. The corresponding accretion rates range from $\dot{M}= 8 \times 10^{-9}$M$_{\sun}$ yr$^{-1}$ at the highest FUV flux level down to $\dot{M}= 1.9\times 10^{-10}$M$_{\sun}$ yr$^{-1}$ at the lowest flux level. We report tentative evidence for the detection of the underlying white dwarf with $T_{\rm eff} = 45,000$K in the spectrum with the lowest flux level., Comment: Accepted for publication in the PASP (to appear in February, 2008 issue)

We present a synthetic spectral analysis of nearly the entire far ultraviolet International Ultraviolet Explorer (IUE) archive of spectra of dwarf novae in or near outburst. The study includes 46 systems of all dwarf nova subtypes both above and below the period gap. The spectra were uniformly analyzed using synthetic spectral codes for optically thick accretion disks and stellar photospheres along with the best-available distance measurements or estimates. We present newly estimated accretion rates and discuss the implications of our study for disk accretion physics and CV evolution., Comment: Accepted for publication in the ApJ, Part 1