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We consider discrete subgroups of the group of orientation preserving isometries of the $m$-dimensional hyperbolic space, whose limit set is a $(m-1)$-dimensional real sphere, acting on the $n$-dimensional complex projective space for $n\geq m$, via an embedding from the group of orientation preserving isometries of the $m$-dimensional hyperbolic space to the group of holomorphic isometries of the $n$-dimensional complex hyperbolic space. We describe the Kulkarni limit set of any of these subgroups under the embedding as a real semi-algebraic set. Also, we show that the Kulkarni region of discontinuity can only have one or three connected components. We use the Sylvester's law of inertia when $n=m$. In the other cases, we use some suitable projections of the the $n$-dimensional complex projective space to the $m$-dimensional complex projective space.

We report the first detection of the S(1) pure rotational line of ortho-H2 at 17.04 um in an asymptotic giant branch star, using observations of IRC+10216 with the Echelon-cross-echelle Spectrograph (EXES) mounted on the Stratospheric Observatory for Infrared Astronomy (SOFIA). This line, which was observed in a very high sensitivity spectrum (RMS noise ~0.04% of the continuum), was detected in the wing of a strong telluric line and displayed a P Cygni profile. The spectral ranges around the frequencies of the S(5) and S(7) ortho-H2 transitions were observed as well but no feature was detected in spectra with sensitivities of 0.12% and 0.09% regarding the continuum emission, respectively. We used a radiation transfer code to model these three lines and derived a mass-loss rate of 2.43(0.21)E-05 M_sun/yr without using the CO abundance. The comparison of this rate with previous estimates derived from CO observations suggests that the CO abundance relative to H2 is 6.7(1.4)E-04. From this quantity and previously reported molecular abundances, we estimate the O/H and C/H ratios to be 3.3(0.7)E-04 and >5.2(0.9)E-04, respectively. The C/O ratio is >1.5(0.4). The absence of the S(5) and S(7) lines of ortho-H2 in our observations can be explained by the opacity of hot dust within 5R* from the center of the star. We estimate the intensity of the S(0) and S(2) lines of para-H2 to be ~0.1% and 0.2% of the continuum, respectively, which are below the detection limit of EXES., Comment: 7 pages, 4 figures, accepted for publication in ApJ Letters

High spectral resolution observations toward the low mass-loss rate C-rich, J-type AGB star Y CVn have been carried out at 7.5, 13.1 and 14.0 um with SOFIA/EXES and IRTF/TEXES. Around 130 HCN and H13CN lines of bands v2, 2v2, 2v2-v2, 3v2-2v2, 3v2-v2, and 4v2-2v2 have been identified involving lower levels with energies up to ~3900 K. These lines have been complemented with the pure rotational lines J=1-0 and 3-2 of the vibrational states up to 2v2 acquired with the IRAM 30 m telescope, and with the continuum taken with ISO. We have analyzed the data with a ro-vibrational diagram and a code which models the absorption and emission of the circumstellar envelope of an AGB star. The continuum is produced by the star with a small contribution from dust grains comprising warm to hot SiC and cold amorphous carbon. The HCN abundance distribution seems to be anisotropic. The ejected gas is accelerated up to the terminal velocity (~8 km/s) from the photosphere to ~3R* but there is evidence of higher velocities (>9-10 km/s) beyond this region. In the vicinity of Y CVn, the line widths are as high as ~10 km/s, which implies a maximum turbulent velocity of 6 km/s or the existence of other physical mechanisms probably related to matter ejection that involve higher gas expansion velocities than expected. HCN is rotationally and vibrationally out of LTE throughout the whole envelope. A difference of about 1500 K in the rotational temperature at the photosphere is needed to explain the observations at 7.5 and 13-14 um. Our analysis finds a total HCN column density that ranges from ~2.1E+18 to 3.5E+18 cm^{-2}, an abundance with respect to H2 of 3.5E-05 to 1.3E-04, and a 12C/13C isotopic ratio of ~2.5 throughout the whole envelope., Comment: 24 pages, 11 figures, 3 tables, accepted for publication in A&A

We report on the detection of hot CO2 in the O-rich AGB star R Leo based on high spectral resolution observations in the range 12.8-14.3 um carried out with the Echelon-cross-Echelle Spectrograph (EXES) mounted on the Stratospheric Observatory for Infrared Astronomy (SOFIA). We have found ~240 CO2 emission lines in several vibrational bands. These detections were possible thanks to a favorable Doppler shift that allowed us to avoid contamination by telluric CO2 features. The highest excitation lines involve levels at an energy of ~7000 K. The detected lines are narrow (average deconvolved width ~2.5 km/s) and weak (usually <10% the continuum). A ro-vibrational diagram shows that there are three different populations, warm, hot, and very hot, with rotational temperatures of ~550, 1150, and 1600 K, respectively. From this diagram, we derive a lower limit for the column density of ~2.2E+16 cm^{-2}. Further calculations based on a model of the R Leo envelope suggest that the total column density can be as large as 7.0E+17 cm^{-2} and the abundance with respect to H2 ~2.5E-05. The detected lines are probably formed due to de-excitation of CO2 molecules from high energy vibrational states, which are essentially populated by the strong R Leo continuum at 2.7 and 4.2 um., Comment: 8 pages, 5 figures, accepted for publication in A&A

We have observed the massive protostar AFGL 2136 IRS 1 in multiple wavelength windows in the near-to-mid-infrared at high ($\sim3$ km s$^{-1}$) spectral resolution using VLT+CRIRES, SOFIA+EXES, and Gemini North+TEXES. There is an abundance of H$_2$O absorption lines from the $\nu_1$ and $\nu_3$ vibrational bands at 2.7 $\mu$m, from the $\nu_2$ vibrational band at 6.1 $\mu$m, and from pure rotational transitions near 10-13 $\mu$m. Analysis of state-specific column densities derived from the resolved absorption features reveals that an isothermal absorbing slab model is incapable of explaining the relative depths of different absorption features. In particular, the strongest absorption features are much weaker than expected, indicating optical depth effects resulting from the absorbing gas being well-mixed with the warm dust that serves as the "background" continuum source at all observed wavelengths. The velocity at which the strongest H$_2$O absorption occurs coincides with the velocity centroid along the minor axis of the compact disk in Keplerian rotation recently observed in H$_2$O emission with ALMA. We postulate that the warm regions of this dust disk dominate the continuum emission at near-to-mid infrared wavelengths, and that H$_2$O and several other molecules observed in absorption are probing this disk. Absorption line profiles are not symmetric, possibly indicating that the warm dust in the disk that produces the infrared continuum has a non-uniform distribution similar to the substructure observed in 1.3 mm continuum emission., Comment: 30 pages, 12 figures, 3 tables, ApJ accepted

The luminous Type IIn SN 2010jl shows strong signs of interaction between the SN ejecta and dense circumstellar material. Dust may be present in the unshocked ejecta, the cool, dense shell between the shocks in the interaction region, or in the circumstellar medium. We present and model new optical and infrared photometry and spectroscopy of SN 2010jl from 82 to 1367 days since explosion. We evaluate the photometric and spectroscopic evolution using the radiative transfer codes MOCASSIN and DAMOCLES, respectively. We propose an interaction scenario and investigate the resulting dust formation scenarios and dust masses. We find that SN 2010jl has been continuously forming dust based on the evolution of its infrared emission and optical spectra. There is evidence for pre-existing dust in the circumstellar medium as well as new dust formation in the cool, dense shell and/or ejecta. We estimate that 0.005--0.01M$_{\odot}$ of predominantly carbon dust grains has formed in SN 2010jl by ~1400d post-outburst., Comment: Accepted by ApJ. Author accepted manuscript. Accepted on 26/03/2020. Deposited on 03/04/20. 21 pages, 10 figures

We present an analysis of the evolution of circumstellar dust and molecules in the environment of the very late thermal pulse object V4334 Sgr (Sakurai's Object) over a $\sim20$-year period, drawing on ground-, airborne- and space-based infrared photometry and spectroscopy. The dust emission, which started in 1997, resembles a blackbody that cooled from $\sim1200$K in 1998 August to $\sim180$K in 2016 July. The dust mass, assuming amorphous carbon, was $\sim5\times10^{-10}$M$_\odot$ in 1998 August, and we estimate that the total dust mass was $\sim2\times10^{-5}$M$_\odot$ by $\sim2016$. The appearance of a near infrared excess in 2008 suggests a new episode of (or renewed) mass loss began then. We infer lower limits on the bolometric luminosity of the embedded star from that of the dust shell, which rose to $\sim16000$L$_\odot$ before declining to $\sim3000$L$_\odot$. There is evidence for weak 6-7$\mu$m absorption, which we attribute to hydrogenated amorphous carbon formed in material ejected by Sakurai's Object during a mass ejection phase that preceded the 1997 event. We detect small hydrocarbon and other molecules in the spectra, and trace the column densities in hydrogen cyanide (HCN) and acetylene (C$_2$H$_2$). We use the former to determine the $^{12}$C/$^{13}$C ratio to be $6.4\pm0.7$, 14 times smaller than the Solar System value.

Dust and starlight are modeled for the KINGFISH project galaxies. With data from 3.6 micron to 500 micron, models are strongly constrained. For each pixel in each galaxy we estimate (1) dust surface density; (2) q_PAH, the dust mass fraction in PAHs; (3) distribution of starlight intensities heating the dust; (4) luminosity emitted by the dust; and (5) dust luminosity from regions with high starlight intensity. The models successfully reproduce both global and resolved spectral energy distributions. We provide well-resolved maps for the dust properties. As in previous studies, we find q_PAH to be an increasing function of metallicity, above a threshold Z/Z_sol approx 0.15. Dust masses are obtained by summing the dust mass over the map pixels; these "resolved" dust masses are consistent with the masses inferred from model fits to the global photometry. The global dust-to-gas ratios obtained from this study correlate with galaxy metallicities. Systems with Z/Z_sol > 0.5 have most of their refractory elements locked up in dust, whereas when Z/Z_sol < 0.3 most of these elements tend to remain in the gas phase. Within galaxies, we find that q_PAH is suppressed in regions with unusually warm dust with nu L_nu(70 um) > 0.4L_dust. With knowledge of one long-wavelength flux density ratio (e.g., f_{160}/f_{500}), the minimum starlight intensity heating the dust (U_min) can be estimated to within ~50%. For the adopted dust model, dust masses can be estimated to within ~0.07 dex accuracy using the 500 micron luminosity nu L_nu(500) alone. There are additional systematic errors arising from the choice of dust model, but these are hard to estimate. These calibrated prescriptions may be useful for studies of high-redshift galaxies., Comment: ApJ, accepted

We present mid-infrared SOFIA/EXES spectroscopy of Europa, seeking direct evidence of the presence of water vapor arising from plumes venting from the surface of Europa. We place quantitatively useful upper limits on the strength of water vibrational-rotational emission lines. Conversion to water mass limits is dependent on the rotational temperature of the vapor. For low rotational temperature, the limits lie below the inferred water mass from previous HST plume observations. For higher temperatures, the limits are comparable. We also present coordinated HST transit observations obtained close in time to the SOFIA observations. There is evidence for a feature close to the location of the previously seen feature north of the crater Pwyll in one of the HST images, although it was not observable by EXES given its location. We conclude that if a water plume had been active at the time of the SOFIA observation, with the strength implied by previous HST observations, then under the right Earth atmospheric and geometric conditions, the plume could have been detected by EXES, however no IR water vibrational-rotational emission was detected., Comment: Accepted by Astrophysical Journal Letters, Dec. 26, 2018

Orion BN has a large proper motion and radial velocity with respect to the gas and other stars in the region where it is presumed to have formed. Multiple dynamical interaction scenarios have been proposed to explain this motion. In one case BN is thought to have interacted with stars in the Trapezium cluster, while in another it is thought to have interacted with source I while deeply embedded in molecular gas. If there is dense gas that has been retained in close proximity to BN, it may be evidence that the latter scenario is favored. We observed BN at high spectral resolution in three windows near 6 $\mu$m using SOFIA/EXES targeting the $\nu_2$ vibrational band of H$_2$O. Absorption from only three transitions of H$_2$O is detected, and through kinematic analysis is associated with cool, dense foreground gas, not BN itself. We find no evidence for H$_2$O absorption or emission at the systemic velocity of BN., Comment: 8 pages, 3 figures, 1 table, accepted for publication in ApJL SOFIA special issue

SN 2011ja was a bright (I = -18.3) Type II supernova occurring in the nearby edge on spiral galaxy NGC 4945. Flat-topped and multi-peaked H-alpha and H-beta spectral emission lines appear between 64 - 84 days post-explosion, indicating interaction with a disc-like circumstellar medium inclined 30-45 degrees from edge-on. After day 84 an increase in the H- and K-band flux along with heavy attenuation of the red wing of the emission lines are strong indications of early dust formation, likely located in the cool dense shell created between the forward shock of the SN ejecta and the reverse shock created as the ejecta plows into the existing CSM. Radiative transfer modeling reveals both ~1.5 x 10^-4 Msun of pre-existing dust located ~ 10^16.7 cm away and ~ 5 x 10^-5 Msun of newly formed dust. Spectral observations after 1.5 years reveal the possibility that the fading SN is located within a young (3-6 Myr) massive stellar cluster, which when combined with tentative 56Ni mass estimates of 0.2 Msun may indicate a massive (> 25 Msun) progenitor for SN 2011ja., Comment: 13 pages, 8 figures, submitted to MNRAS awaiting final referee report

We present a study of the infrared/submm emission of the LMC star forming complex N158-N159-N160. Combining observations from the Spitzer Space Telescope (3.6-70um), the Herschel Space Observatory (100-500um) and LABOCA (870um) allows us to work at the best angular resolution available now for an extragalactic source. We observe a remarkably good correlation between SPIRE and LABOCA emission and resolve the low surface brightnesses emission. We use the Spitzer and Herschel data to perform a resolved Spectral Energy Distribution (SED) modelling of the complex. Using MBB, we derive a global emissivity index beta_c of 1.47. If beta cold is fixed to 1.5, we find an average temperature of 27K. We also apply the Galliano et al. (2011) modelling technique (and amorphous carbon to model carbon dust) to derive maps of the star formation rate, the mean starlight intensity, the fraction of PAHs or the dust mass surface density of the region. We observe that the PAH fraction strongly decreases in the HII regions. This decrease coincides with peaks in the mean radiation field intensity map. The dust surface densities follow the FIR distribution, with a total dust mass of 2.1x10^4 Msolar (2.8 times less than when using graphite grains) in the resolved elements we model. We find a non-negligible amount of dust in the molecular cloud N159 South (showing no massive SF). We also investigate the drivers of the Herschel/PACS and SPIRE submm colours as well as the variations in the gas-to-dust mass ratio (G/D) and the XCO conversion factor in the region N159. We finally model individual regions to analyse variations in the SED shape across the complex and the 870um emission in more details. No measurable submm excess emission at 870um seems to be detected in these regions., Comment: Accepted for publication in MNRAS; 23 pages, 11 figures, 2 tables

We derive the distribution of the synchrotron spectral index across NGC6946 and investigate the correlation between the radio continuum (synchrotron) and far-infrared (FIR) emission using the KINGFISH Herschel PACS and SPIRE data. The radio--FIR correlation is studied as a function of star formation rate, magnetic field strength, radiation field strength, and the total gas surface brightness. The synchrotron emission follows both star-forming regions and the so-called magnetic arms present in the inter-arm regions. The synchrotron spectral index is steepest along the magnetic arms ($\alpha_n \sim 1$), while it is flat in places of giant H{\sc ii} regions and in the center of the galaxy ($\alpha_n \sim 0.6-0.7$). The map of $\alpha_n$ provides an observational evidence for aging and energy loss of cosmic ray electrons propagating in the disk of the galaxy. Variations in the synchrotron--FIR correlation across the galaxy are shown to be a function of both star formation and magnetic fields. We find that the synchrotron emission correlates better with cold rather than with warm dust emission, when the interstellar radiation field is the main heating source of dust. The synchrotron--FIR correlation suggests a coupling between the magnetic field and the gas density. NGC6946 shows a power-law behavior between the total (turbulent) magnetic field strength B and the star formation rate surface density $\Sigma_{\rm SFR}$ with an index of 0.14\,(0.16)$\pm$0.01. This indicates an efficient production of the turbulent magnetic field with the increasing gas turbulence expected in actively star forming regions. The scale-by-scale analysis of the synchrotron--FIR correlation indicates that the ISM affects the propagation of old/diffused cosmic ray electrons, resulting in a diffusion coefficient of $D_0=4.6\times 10^{28}$\,cm$^2$\,s$^{-1}$ for 2.2\,GeV CREs., Comment: 23 pages, 13 figures, accepted for publication in Astronomy & Astrophysics Journal

We present kiloparsec (kpc) spatial resolution maps of the CO-to-H2 conversion factor (alpha_co) and dust-to-gas ratio (DGR) in 26 nearby, star-forming galaxies. We have simultaneously solved for alpha_co and DGR by assuming that the DGR is approximately constant on kpc scales. With this assumption, we can combine maps of dust mass surface density, CO integrated intensity and HI column density to solve for both alpha_co and DGR with no assumptions about their value or dependence on metallicity or other parameters. Such a study has just become possible with the availability of high resolution far-IR maps from the Herschel key program KINGFISH, 12CO J=(2-1) maps from the IRAM 30m large program HERACLES and HI 21-cm line maps from THINGS. We use a fixed ratio between the (2-1) and (1-0) lines to present our alpha_co results on the more typically used 12CO J=(1-0) scale and show using literature measurements that variations in the line ratio do not effect our results. In total, we derive 782 individual solutions for alpha_co and DGR. On average, alpha_co = 3.1 Msun pc^-2 (K km s^-1)^-1 for our sample with a standard deviation of 0.3 dex. Within galaxies we observe a generally flat profile of alpha_co as a function of galactocentric radius. However, most galaxies exhibit a lower alpha_co in the central kpc---a factor of ~2 below the galaxy mean, on average. In some cases, the central alpha_co value can be factors of 5 to 10 below the standard Milky Way (MW) value of alpha_co,MW =4.4 Msun pc^-2 (K km s^-1)^-1. While for alpha_co we find only weak correlations with metallicity, DGR is well-correlated with metallicity, with an approximately linear slope. Finally, we present several recommendations for choosing an appropriate alpha_co for studies of nearby galaxies., Comment: accepted to ApJ July 9, 2013, 63 pages, 2-column ApJ format, p38-63 are an image atlas

We characterize the dust in NGC628 and NGC6946, two nearby spiral galaxies in the KINGFISH sample. With data from 3.6um to 500um, dust models are strongly constrained. Using the Draine & Li (2007) dust model, (amorphous silicate and carbonaceous grains), for each pixel in each galaxy we estimate (1) dust mass surface density, (2) dust mass fraction contributed by polycyclic aromatic hydrocarbons (PAH)s, (3) distribution of starlight intensities heating the dust, (4) total infrared (IR) luminosity emitted by the dust, and (5) IR luminosity originating in regions with high starlight intensity. We obtain maps for the dust properties, which trace the spiral structure of the galaxies. The dust models successfully reproduce the observed global and resolved spectral energy distributions (SEDs). The overall dust/H mass ratio is estimated to be 0.0082+/-0.0017 for NGC628, and 0.0063+/-0.0009 for NGC6946, consistent with what is expected for galaxies of near-solar metallicity. Our derived dust masses are larger (by up to a factor 3) than estimates based on single-temperature modified blackbody fits. We show that the SED fits are significantly improved if the starlight intensity distribution includes a (single intensity) "delta function" component. We find no evidence for significant masses of cold dust T<12K. Discrepancies between PACS and MIPS photometry in both low and high surface brightness areas result in large uncertainties when the modeling is done at PACS resolutions, in which case SPIRE, MIPS70 and MIPS160 data cannot be used. We recommend against attempting to model dust at the angular resolution of PACS., Comment: To be published in Apj, September 2012. See the full version at http://www.astro.princeton.edu/~ganiano/Papers/

We examine Herschel Space Observatory images of one nearby prototypical outer ring galaxy, NGC 1291, and show that the ring becomes more prominent at wavelengths longer than 160um. The mass of cool dust in the ring dominates the total dust mass of the galaxy, accounting for at least 70% of it. The temperature of the emitting dust in the ring (T=19.5+/-0.3K) is cooler than that of the inner galaxy (T=25.7+/-0.7K). We discuss several explanations for the difference in dust temperature, including age and density differences in the stellar populations of the ring versus the bulge., Comment: Accepted to ApJ, 9 pages, 6 figures

New far-infrared and sub-millimeter photometry from the Herschel Space Observatory is presented for 61 nearby galaxies from the Key Insights on Nearby Galaxies: A Far-Infrared Survey with Herschel (KINGFISH) sample. The spatially-integrated fluxes are largely consistent with expectations based on Spitzer far-infrared photometry and extrapolations to longer wavelengths using popular dust emission models. Dwarf irregular galaxies are notable exceptions, as already noted by other authors, as their 500um emission shows evidence for a sub-millimeter excess. In addition, the fraction of dust heating attributed to intense radiation fields associated with photo-dissociation regions is found to be (21+/-4)% larger when Herschel data are included in the analysis. Dust masses obtained from the dust emission models of Draine & Li are found to be on average nearly a factor of two higher than those based on single-temperature modified blackbodies, as single blackbody curves do not capture the full range of dust temperatures inherent to any galaxy. The discrepancy is largest for galaxies exhibiting the coolest far-infrared colors., Comment: Accepted for publication in ApJ

The KINGFISH project (Key Insights on Nearby Galaxies: a Far-Infrared Survey with Herschel) is an imaging and spectroscopic survey of 61 nearby (d < 30 Mpc) galaxies, chosen to cover a wide range of galaxy properties and local interstellar medium (ISM) environments found in the nearby Universe. Its broad goals are to characterize the ISM of present-day galaxies, the heating and cooling of their gaseous and dust components, and to better understand the physical processes linking star formation and the ISM. KINGFISH is a direct descendant of the Spitzer Infrared Nearby Galaxies Survey (SINGS), which produced complete Spitzer imaging and spectroscopic mapping and a comprehensive set of multi-wavelength ancillary observations for the sample. The Herschel imaging consists of complete maps for the galaxies at 70, 100, 160, 250, 350, and 500 microns. The spectal line imaging of the principal atomic ISM cooling lines ([OI]63um, [OIII]88um, [NII]122,205um, and [CII]158um) covers the subregions in the centers and disks that already have been mapped in the mid-infrared with Spitzer. The KINGFISH and SINGS multi-wavelength datasets combined provide panchromatic mapping of the galaxies sufficient to resolve individual star-forming regions, and tracing the important heating and cooling channels of the ISM, across a wide range of local extragalactic ISM environments. This paper summarizes the scientific strategy for KINGFISH, the properties of the galaxy sample, the observing strategy, and data processing and products. It also presents a combined Spitzer and Herschel image atlas for the KINGFISH galaxies, covering the wavelength range 3.6 -- 500 microns. All imaging and spectroscopy data products will be released to the Herschel user generated product archives., Comment: 52 pages, 10 figures, 2 tables. Accepted for publication in PASP. A pdf copy of the image atlas can be downloaded separately at the KINGFISH public website, http://www.ast.cam.ac.uk/sites/default/files/Kingfish_reduced.pdf

Aims: In this paper, we perform detailed modelling of the Spitzer and Herschel observations of the LMC, in order to: (i) systematically study the uncertainties and biases affecting dust mass estimates; and to (ii) explore the peculiar ISM properties of the LMC. Methods: To achieve these goals, we have modelled the spatially resolved SEDs with two alternate grain compositions, to study the impact of different submillimetre opacities on the dust mass. We have rigorously propagated the observational errors (noise and calibration) through the entire fitting process, in order to derive consistent parameter uncertainties. Results: First, we show that using the integrated SED leads to underestimating the dust mass by ~50 % compared to the value obtained with sufficient spatial resolution, for the region we studied. This might be the case, in general, for unresolved galaxies. Second, we show that Milky Way type grains produce higher gas-to-dust mass ratios than what seems possible according to the element abundances in the LMC. A spatial analysis shows that this dilemma is the result of an exceptional property: the grains of the LMC have on average a larger intrinsic submm opacity (emissivity index beta~1.7 and opacity kappa_abs(160 microns)=1.6 m2/kg) than those of the Galaxy. By studying the spatial distribution of the gas-to-dust mass ratio, we are able to constrain the fraction of unseen gas mass between ~10, and ~100 % and show that it is not sufficient to explain the gas-to-dust mass ratio obtained with Milky Way type grains. Finally, we confirm the detection of a 500 microns extended emission excess with an average relative amplitude of ~15 %, varying up to 40 %. This excess anticorrelates well with the dust mass surface density. Although we do not know the origin of this excess, we show that it is unlikely the result of very cold dust, or CMB fluctuations., Comment: 33 pages, 36 figures, accepted for publication in Astronomy and Astrophysics

We report far-infrared and submillimeter observations of Supernova 1987A, the star that exploded on February 23, 1987 in the Large Magellanic Cloud, a galaxy located 160,000 lightyears away. The observations reveal the presence of a population of cold dust grains radiating with a temperature of ~17-23 K at a rate of about 220 solar luminosity. The intensity and spectral energy distribution of the emission suggests a dust mass of ~0.4-0.7 solar mass. The radiation must originate from the SN ejecta and requires the efficient precipitation of all refractory material into dust. Our observations imply that supernovae can produce the large dust masses detected in young galaxies at very high redshifts., Comment: This is the author's version of the work. It is posted here by permission of the AAAS for personal use, not for redistribution. To appear in Science; available in Science Express on 7th July, DOI:10.1126/science.1205983 at http://www.sciencemag.org/lookup/doi/10.1126/science.1205983 ; 14 pages, 2 figures, 4 tables. High resolution images are available from the authors

We describe the optical spectropolarimetric monitoring program at Steward Observatory centered around gamma-ray-bright blazars and the LAT Monitored Source List planned for Fermi Cycles 2-4. The large number of measurements made during Cycle 1 of the Fermi mission are available to the research community and the data products are summarized (see http://james.as.arizona.edu/~psmith/Fermi). The optical data include spectropolarimetry at a resolution of ~20 A, broad-band polarization and flux measurements, and flux-calibrated spectra spanning 4000-7600 A. These data provide a comprehensive view of the optical variability of an important sample of objects during the Fermi Era. In addition to broad-band flux and linear polarization monitoring, the spectra allow for the tracking of changes to the spectral index of the synchrotron continuum, importance of non-synchrotron emission features, and how and when the polarization varies with wavelength, an important clue as to the structure of the emission region or the identification of multiple nonthermal components. As an illustration, we present observations of 3C 454.3 obtained in 2009 September during an exceptionally bright gamma-ray flare. The blazar was optically bright during the flare, but except for a few short periods, it showed surprisingly low polarization (P < 5%). Opportunities exist within the Fermi research community to coordinate with our long-term optical monitoring program toward the goal of maximum scientific value to both the Fermi and associated radio VLBI monitoring of blazars., Comment: 2009 Fermi Symposium, eConf Proceedings C091122, 6 pages, 2 figures