Science.gov

Sample records for m82 faint supernova

  1. Hubble Monitors Supernova In Nearby Galaxy M82

    NASA Image and Video Library

    2017-09-27

    This is a Hubble Space Telescope composite image of a supernova explosion designated SN 2014J in the galaxy M82. At a distance of approximately 11.5 million light-years from Earth it is the closest supernova of its type discovered in the past few decades. The explosion is categorized as a Type Ia supernova, which is theorized to be triggered in binary systems consisting of a white dwarf and another star — which could be a second white dwarf, a star like our sun, or a giant star. Astronomers using a ground-based telescope discovered the explosion on January 21, 2014. This Hubble photograph was taken on January 31, as the supernova approached its peak brightness. The Hubble data are expected to help astronomers refine distance measurements to Type Ia supernovae. In addition, the observations could yield insights into what kind of stars were involved in the explosion. Hubble’s ultraviolet-light sensitivity will allow astronomers to probe the environment around the site of the supernova explosion and in the interstellar medium of the host galaxy. Because of their consistent peak brightness, Type Ia supernovae are among the best tools to measure distances in the universe. They were fundamental to the 1998 discovery of the mysterious acceleration of the expanding universe. A hypothesized repulsive force, called dark energy, is thought to cause the acceleration. Among the other major NASA space-based observatories used in the M82 viewing campaign are Spitzer Space Telescope, Chandra X-ray Observatory, Nuclear Spectroscopic Telescope Array (NuSTAR), Fermi Gamma-ray Space Telescope, Swift Gamma Ray Burst Explorer, and the Stratospheric Observatory for Infrared Astronomy (SOFIA). Image Credit: NASA, ESA, A. Goobar (Stockholm University), and the Hubble Heritage Team (STScI/AURA) NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics

  2. Radio evolution of supernova SN 2008iz in M 82

    NASA Astrophysics Data System (ADS)

    Kimani, N.; Sendlinger, K.; Brunthaler, A.; Menten, K. M.; Martí-Vidal, I.; Henkel, C.; Falcke, H.; Muxlow, T. W. B.; Beswick, R. J.; Bower, G. C.

    2016-08-01

    We report on multi-frequency Very Large Array (VLA) and Very Long Baseline Interferometry (VLBI) radio observations for a monitoring campaign of supernova SN 2008iz in the nearby irregular galaxy M 82. We fit two models to the data, a simple time power-law, S ∝ tβ, and a simplified Weiler model, yielding decline indices of β = -1.22 ± 0.07 (days 100-1500) and -1.41 ± 0.02 (days 76-2167), respectively. The late-time radio light-curve evolution shows flux-density flares at ~970 and ~1400 days that are a factor of ~2 and ~4 higher than the expected flux, respectively. The later flare, except for being brighter, does not show signs of decline at least from results examined so far (2014 January 23; day 2167). We derive the spectral index, α, S ∝ να for frequencies 1.4 to 43 GHz for SN 2008iz during the period from ~430 to 2167 days after the supernova explosion. The value of α shows no signs of evolution and remains steep ≈-1 throughout the period, unlike that of SN 1993J, which started flattening at ~day 970. From the 4.8 and 8.4 GHz VLBI images, the supernova expansion is seen to start with a shell-like structure that becomes increasingly more asymmetric, then breaks up in the later epochs, with bright structures dominating the southern part of the ring. This structural evolution differs significantly from SN 1993J, which remains circularly symmetric over 4000 days after the explosion. The VLBI 4.8 and 8.4 GHz images are used to derive a deceleration index, m, for SN 2008iz, of 0.86 ± 0.02, and the average expansion velocity between days 73 and 1400 as (12.1 ± 0.2) × 103 km s-1. From the energy equipartition between magnetic field and particles, we estimate the minimum total energy in relativistic particles and the magnetic fields during the supernova expansion and also find the magnetic field amplification factor for SN 2008iz to be in the range of 55-400. The VLBI images (FITS files) are only available at the CDS via anonymous ftp to http

  3. Dust Extinction toward Supernova 2014J in M82

    NASA Astrophysics Data System (ADS)

    Gao, Jian; Jiang, B. W.; Li, Aigen; Li, Jun; Wang, Xiaofeng

    2015-08-01

    Type Ia supernovae (SNe Ia) are powerful cosmological “standardizable candles” and the most precise distance indicators. However, the ultimate limiting factor in their use for precision cosmology rests on our ability to correct for the dust extinction toward them. SN 2014J in the starburst galaxy M82, the closest detected SN Ia in three decades, provides unparalleled opportunities to study the dust extinction. In order to derive the extinction as a function of wavelength, we model the color excesses toward SN 2014J observationally derived over a wide wavelength range in terms of dust models consisting of a mixture of silicate and graphite. The resulting extinction laws steeply rise toward the far ultraviolet, even steeper than that of the Small Magellanic Cloud (SMC). We infer a visual extinction of AV≈1.9 mag, a reddening of E(B-V)≈1.1 mag, and a total-to-selective extinction ratio of RV≈1.7, consistent with that previously derived from photometric, spectroscopic and polarimetric observations. The size distributions of the dust in the interstellar medium toward SN 2014J are skewed toward substantially smaller grains than that of the Milky Way and the SMC.

  4. Peering into the heart of the M82 starburst: Type II supernova remnants and a possible relic GRB?

    NASA Astrophysics Data System (ADS)

    Fenech, Danielle Marie; Beswick, Robert; Muxlow, Tom; Argo, Megan

    2015-08-01

    M82 is considered the archetypal starburst galaxy and at a distance of ~3.6 Mpc is one of the closest examples of its kind. It therefore provides a unique opportunity to study a star-forming environment in detail and particularly the discrete products of star-formation such as supernova remnants (SNR) and HII regions. Supernovae and supernova remnants play an important role in the feedback of energy and material into the surrounding interstellar medium as evidenced in M82 by the galactic superwind driven by the numerous supernovae, SNR and massive stellar winds.Radio observations can be used to see into the core of the star-forming region in the centre of M82 as they are unaffected by the gas and dust associated with such an intense starburst environment. Since their discovery in the 1970s, radio observations have been used to study and monitor the evolution of the ~100 supernova remnants at the heart of this galaxy.We present multi-epoch millarcsecond resolution images of the most compact supernova remnants in M82, spanning 25 years of evolution. In particular, we will discuss one of the quintessential SNR 43.31+59.2 as well as the unusual object 41.95+57.5 and its potential as a GRB afterglow.

  5. OPTICAL SPECTROSCOPY OF SUPERNOVA REMNANTS IN M81 AND M82

    SciTech Connect

    Lee, Myung Gyoon; Sohn, Jubee; Lee, Jong Hwan; Lim, Sungsoon; Jang, In Sung; Ko, Youkyung; Koo, Bon-Chul; Hwang, Narae; Kim, Sang Chul; Park, Byeong-Gon

    2015-05-01

    We present spectroscopy of 28 supernova remnant (SNR) candidates as well as one H ii region in M81 and two SNR candidates in M82. Twenty-six of the M81 candidates turn out to be genuine SNRs, and two in M82 may be shocked condensations in the galactic outflow or SNRs. The distribution of [N ii]/Hα ratios of M81 SNRs is bimodal. M81 SNRs are divided into two groups in the spectral line ratio diagrams: an [O iii]-strong group and an [O iii]-weak group. The latter are larger and may have faster shock velocities. [N ii]/Hα ratios of the SNRs show a strong correlation with [S ii]/Hα ratios. They show a clear radial gradient in their [N ii]/Hα and [S ii]/Hα ratios: dLog ([N ii]/Hα)/dLog R = −0.018 ± 0.008 dex kpc{sup −1} and dLog ([S ii]/Hα)/dLog R = −0.016 ± 0.008 dex kpc{sup −1}, where R is the deprojected galactocentric distance. We estimate the nitrogen and oxygen abundances of the SNRs from comparison with shock-ionization models. We obtain a value for the nitrogen radial gradient of dLog(N/H)/dLog R= −0.023 ± 0.009 dex kpc{sup −1}, and find little evidence for an oxygen gradient. This nitrogen abundance shows a gradient that is a few times flatter than those of the planetary nebulae and H ii regions. We find that five SNRs are matched with X-ray sources. Their X-ray hardness colors are consistent with thermal SNRs.

  6. Interstellar-medium Mapping in M82 through Light Echoes around Supernova 2014J

    NASA Astrophysics Data System (ADS)

    Yang, Yi; Wang, Lifan; Baade, Dietrich; Brown, Peter. J.; Cracraft, Misty; Höflich, Peter A.; Maund, Justyn; Patat, Ferdinando; Sparks, William B.; Spyromilio, Jason; Stevance, Heloise F.; Wang, Xiaofeng; Wheeler, J. Craig

    2017-01-01

    We present multiple-epoch measurements of the size and surface brightness of the light echoes from supernova (SN) 2014J in the nearby starburst galaxy M82. Hubble Space Telescope (HST) ACS/WFC images were taken ˜277 and ˜416 days after B-band maximum in the filters F475W, F606W, and F775W. Observations with HST WFC3/UVIS images at epochs ˜216 and ˜365 days are included for a more complete analysis. The images reveal the temporal evolution of at least two major light-echo components. The first one exhibits a filled ring structure with position-angle-dependent intensity. This radially extended, diffuse echo indicates the presence of an inhomogeneous interstellar dust cloud ranging from ˜100 to ˜500 pc in the foreground of the SN. The second echo component appears as an unresolved luminous quarter-circle arc centered on the SN. The wavelength dependence of scattering measured in different dust components suggests that the dust producing the luminous arc favors smaller grain sizes, while that causing the diffuse light echo may have sizes similar to those of the Milky Way dust. Smaller grains can produce an optical depth consistent with that along the supernova-Earth line of sight measured by previous studies around maximum light. Therefore, it is possible that the dust slab from which the luminous arc arises is also responsible for most of the extinction toward SN 2014J. The optical depths determined from the Milky Way-like dust in the scattering matters are lower than the optical depth produced by the dust slab.

  7. Physical Dust Models for the Extinction toward Supernova 2014J in M82

    NASA Astrophysics Data System (ADS)

    Gao, Jian; Jiang, B. W.; Li, Aigen; Li, Jun; Wang, Xiaofeng

    2015-07-01

    Type Ia supernovae (SNe Ia) are powerful cosmological “standardizable candles” and the most precise distance indicators. However, a limiting factor in their use for precision cosmology rests on our ability to correct for the dust extinction toward them. SN 2014J in the starburst galaxy M82, the closest detected SN Ia in three decades, provides unparalleled opportunities to study the dust extinction toward an SN Ia. In order to derive the extinction as a function of wavelength, we model the color excesses toward SN 2014J, which are observationally derived over a wide wavelength range, in terms of dust models consisting of a mixture of silicate and graphite. The resulting extinction laws steeply, rise toward the far-ultraviolet, even steeper than that of the SMC. We infer a visual extinction of {A}V≈ 1.9 {mag}, a reddening of E(B-V)≈ 1.1 {mag}, and a total-to-selective extinction ratio of RV ≈ 1.7, consistent with that previously derived from photometric, spectroscopic, and polarimetric observations. The size distributions of the dust in the interstellar medium toward SN 2014J are skewed toward substantially smaller grains than that of the Milky Way and the SMC.

  8. SWIFT ULTRAVIOLET OBSERVATIONS OF SUPERNOVA 2014J IN M82: LARGE EXTINCTION FROM INTERSTELLAR DUST

    SciTech Connect

    Brown, Peter J.; Smitka, Michael T.; Wang, Lifan; Krisciunas, Kevin; Breeveld, Alice; Kuin, N. Paul; Page, Mat; De Pasquale, Massimiliano; Hartmann, Dieter H.; Milne, Peter A.; Siegel, Michael

    2015-05-20

    We present optical and ultraviolet (UV) photometry and spectra of the very nearby and highly reddened supernova (SN) 2014J in M82 obtained with the Swift Ultra-Violet/Optical Telescope (UVOT). Comparison of the UVOT grism spectra of SN 2014J with Hubble Space Telescope observations of SN2011fe or UVOT grism spectra of SN 2012fr are consistent with an extinction law with a low value of R{sub V} ∼1.4. The high reddening causes the detected photon distribution in the broadband UV filters to have a much longer effective wavelength than for an unreddened SN. The light curve evolution is consistent with this shift and does not show a flattening due to photons being scattered back into the line of sight (LOS). The light curve shapes and color evolution are inconsistent with a contribution scattered into the LOS by circumstellar dust. We conclude that most or all of the high reddening must come from interstellar dust. We show that even for a single dust composition, there is not a unique reddening law caused by circumstellar scattering. Rather, when considering scattering from a time-variable source, we confirm earlier studies that the reddening law is a function of the dust geometry, column density, and epoch. We also show how an assumed geometry of dust as a foreground sheet in mixed stellar/dust systems will lead to a higher inferred R{sub V}. Rather than assuming the dust around SNe is peculiar, SNe may be useful probes of the interstellar reddening laws in other galaxies.

  9. Compact radio sources in the starburst galaxy M82 and the Sigma-D relation for supernova remnants

    NASA Technical Reports Server (NTRS)

    Huang, Z. P.; Thuan, T. X.; Chevalier, R. A.; Condon, J. J.; Yin, Q. F.

    1994-01-01

    We have obtained an 8.4 GHz Very Large Array (VLA) A-array map of the starburst galaxy M82 with a resolution Full Width at Half Maximum (FWHM) approximately 0.182 sec. About 50 compact radio sources in the central region of M82 were detected with a peak surface brightness approximately greater than 10(exp -17) W/Hz/sq m/sr. Comparison with previous observations shows that most sources are declining in flux. Three previously visible sources have faded into the background of our map (approximately less than 0.2 mJy/beam), while a few sources, including the second and third brightest radio sources in M82, may have increased slightly in flux over the last decade. No new radio supernova was found. The birth rate of the compact radio sources is estimated to be 0.11 + or - 0.05/yr. We attribute the population of such bright, small supernova remnants (SNRs) in M82 to the high pressure in the central region that can truncate the mass loss during a red supergiant phase or allow dense ionized clouds to be present. The compact radio sources obey a Sigma(radio surface brightness) - D(diameter) relation which is remarkably similar to that followed by supernova remnants in the Galaxy and the Magellanic Clouds and by two of the strongest known extragalactic radio supernovae: SN 1986J and SN 1979C. A least-squares fit to the SNR data gives: Sigma(sub 8.4 GHz) (W/Hz/sq m/sr) = 4.4 x 10(exp -16) D(sub pc)(exp -3.5 +/- 0.1) covering seven orders of magnitude in Sigma. Possible selection effects are discussed and a theoretical discussion of the correlation is presented.

  10. Compact radio sources in the starburst galaxy M82 and the Sigma-D relation for supernova remnants

    NASA Technical Reports Server (NTRS)

    Huang, Z. P.; Thuan, T. X.; Chevalier, R. A.; Condon, J. J.; Yin, Q. F.

    1994-01-01

    We have obtained an 8.4 GHz Very Large Array (VLA) A-array map of the starburst galaxy M82 with a resolution Full Width at Half Maximum (FWHM) approximately 0.182 sec. About 50 compact radio sources in the central region of M82 were detected with a peak surface brightness approximately greater than 10(exp -17) W/Hz/sq m/sr. Comparison with previous observations shows that most sources are declining in flux. Three previously visible sources have faded into the background of our map (approximately less than 0.2 mJy/beam), while a few sources, including the second and third brightest radio sources in M82, may have increased slightly in flux over the last decade. No new radio supernova was found. The birth rate of the compact radio sources is estimated to be 0.11 + or - 0.05/yr. We attribute the population of such bright, small supernova remnants (SNRs) in M82 to the high pressure in the central region that can truncate the mass loss during a red supergiant phase or allow dense ionized clouds to be present. The compact radio sources obey a Sigma(radio surface brightness) - D(diameter) relation which is remarkably similar to that followed by supernova remnants in the Galaxy and the Magellanic Clouds and by two of the strongest known extragalactic radio supernovae: SN 1986J and SN 1979C. A least-squares fit to the SNR data gives: Sigma(sub 8.4 GHz) (W/Hz/sq m/sr) = 4.4 x 10(exp -16) D(sub pc)(exp -3.5 +/- 0.1) covering seven orders of magnitude in Sigma. Possible selection effects are discussed and a theoretical discussion of the correlation is presented.

  11. SN 2014J at M82 - I. A middle-class Type Ia supernova by all spectroscopic metrics

    NASA Astrophysics Data System (ADS)

    Galbany, L.; Moreno-Raya, M. E.; Ruiz-Lapuente, P.; González Hernández, J. I.; Méndez, J.; Vallely, P.; Baron, E.; Domínguez, I.; Hamuy, M.; López-Sánchez, A. R.; Mollá, M.; Catalán, S.; Cooke, E. A.; Fariña, C.; Génova-Santos, R.; Karjalainen, R.; Lietzen, H.; McCormac, J.; Riddick, F. C.; Rubiño-Martín, J. A.; Skillen, I.; Tudor, V.; Vaduvescu, O.

    2016-03-01

    We present the intensive spectroscopic follow up of the Type Ia supernova (SN Ia) 2014J in the starburst galaxy M82. Twenty-seven optical spectra have been acquired from 2014 January 22 to September 1 with the Isaac Newton and William Herschel Telescopes. After correcting the observations for the recession velocity of M82 and for Milky Way and host galaxy extinction, we measured expansion velocities from spectral line blueshifts and pseudo-equivalent width of the strongest features in the spectra, which gives an idea on how elements are distributed within the ejecta. We position SN 2014J in the Benetti, Branch et al. and Wang et al. diagrams. These diagrams are based on properties of the Si II features and provide dynamical and chemical information about the SN ejecta. The nearby SN 2011fe, which showed little evidence for reddening in its host galaxy, is shown as a reference for comparisons. SN 2014J is a border-line object between the Core-normal and Broad-line groups, which corresponds to an intermediate position between low-velocity gradient and high-velocity gradient objects. SN 2014J follows the R(Si II)-Δm15 correlation, which confirms its classification as a relatively normal SN Ia. Our description of the SN Ia in terms of the evolution of the pseudo-equivalent width of various ions as well as the position in the various diagrams put this specific SN Ia into the overall sample of SN Ia.

  12. Recent Hubble Space Telescope Imaging of the Light Echoes of Supernova 2014J in M 82 and Supernova 2016adj in Centaurus A

    NASA Astrophysics Data System (ADS)

    Lawrence, Stephen S.; Hyder, Ali; Sugerman, Ben; Crotts, Arlin P. S.

    2017-06-01

    We report on our ongoing use of Hubble Space Telescope (HST) imaging to monitor the scattered light echoes of recent heavily-extincted supernovae in two nearby, albeit unusual, galaxies.Supernova 2014J was a highly-reddened Type Ia supernova that erupted in the nearby irregular star-forming galaxy M 82 in 2014 January. It was discovered to have light echo by Crotts (2016) in early epoch HST imaging and has been further described by Yang, et al. (2017) based on HST imaging through late 2014. Our ongoing monitoring in the WFC3 F438W, F555W, and F814W filters shows that, consistent with Crotts (2106) and Yang, et al. (2017), throughout 2015 and 2016 the main light echo arc expanded through a dust complex located approximately 230 pc in the foreground of the supernova. This main light echo has, however, faded dramatically in our most recent HST imaging from 2017 March. The supernova itself has also faded to undetectable levels by 2017 March.Supernova 2016adj is a highly-reddened core-collapse supernova that erupted inside the unusual dust lane of the nearby giant elliptical galaxy Centaurus A (NGC 5128) in 2016 February. It was discovered to have a light echo by Sugerman & Lawrence (2016) in early epoch HST imaging in 2016 April. Our ongoing monitoring in the WFC3 F438W, F547M, and F814W filters shows a slightly elliptical series of light echo arc segments hosted by a tilted dust complex ranging approximately 150--225 pc in the foreground of the supernova. The supernova itself has also faded to undetectable levels by 2017 April.References: Crotts, A. P. S., ApJL, 804, L37 (2016); Yang et al., ApJ, 834, 60 (2017); Sugerman, B. and Lawrence, S., ATel #8890 (2016).

  13. ESTIMATING THE FIRST-LIGHT TIME OF THE TYPE IA SUPERNOVA 2014J IN M82

    SciTech Connect

    Zheng, WeiKang; Shivvers, Isaac; Filippenko, Alexei V.; Clubb, Kelsey I.; Fox, Ori D.; Graham, Melissa L.; Kelly, Patrick L.; Mauerhan, Jon C.; Itagaki, Koichi

    2014-03-01

    The Type Ia supernova (SN Ia) 2014J in M82 (d ≈ 3.5 Mpc) was serendipitously discovered by S. Fossey's group on 2014 January 21 UT and has been confirmed to be the nearest known SN Ia since at least SN 1986G. Although SN 2014J was not discovered until ∼7 days after first light, both the Katzman Automatic Imaging Telescope at Lick Observatory and K. Itagaki obtained several prediscovery observations of SN 2014J. With these data, we are able to constrain the object's time of first light to be January 14.75 UT, only 0.82 ± 0.21 days before our first detection. Interestingly, we find that the light curve is well described by a varying power law, much like SN 2013dy, which makes SN 2014J the second example of a changing power law in early-time SN Ia light curves. A low-resolution spectrum taken on January 23.388 UT, ∼8.70 days after first light, shows that SN 2014J is a heavily reddened but otherwise spectroscopically normal SN Ia.

  14. Supernova 2014J at M82 - II. Direct analysis of a middle-class Type Ia supernova

    NASA Astrophysics Data System (ADS)

    Vallely, Patrick; Moreno-Raya, M. E.; Baron, E.; Ruiz-Lapuente, Pilar; Domínguez, I.; Galbany, Lluís; González Hernández, J. I.; Méndez, J.; Hamuy, M.; López-Sánchez, A. R.; Catalán, S.; Cooke, E.; Fariña, C.; Génova-Santos, R.; Karjalainen, R.; Lietzen, H.; McCormac, J.; Riddick, F.; Rubiño-Martín, J. A.; Skillen, I.; Tudor, V.; Vaduvescu, O.

    2016-08-01

    We analyse a time series of optical spectra of SN 2014J from almost two weeks prior to maximum to nearly four months after maximum. We perform our analysis using the SYNOW code, which is well suited to track the distribution of the ions with velocity in the ejecta. We show that almost all of the spectral features during the entire epoch can be identified with permitted transitions of the common ions found in normal supernovae (SNe) Ia in agreement with previous studies. We show that 2014J is a relatively normal SN Ia. At early times the spectral features are dominated by Si II, S II, Mg II, and Ca II. These ions persist to maximum light with the appearance of Na I and Mg I. At later times iron-group elements also appear, as expected in the stratified abundance model of the formation of normal Type Ia SNe. We do not find significant spectroscopic evidence for oxygen, until 100 d after maximum light. The +100 d identification of oxygen is tentative, and would imply significant mixing of unburned or only slight processed elements down to a velocity of 6000 kms-1. Our results are in relatively good agreement with other analyses in the infrared. We briefly compare SN 2011fe to SN 2014J and conclude that the differences could be due to different central densities at ignition or differences in the C/O ratio of the progenitors.

  15. Interstellar-medium Mapping in M82 and Circumstellar Environment Constraints through Light Echoes Around Supernova 2014J

    NASA Astrophysics Data System (ADS)

    Yang, Yi; Wang, Lifan

    2017-01-01

    We present multiple-epoch measurements of the size and surface brightness of the light echoes from supernova (SN) 2014J in the nearby starburst galaxy M82. Hubble Space Telescope (HST) ACS/WFC images were taken ˜277 and ˜416 days after B-band maximum in the filters F475W, F606W, and F775W. Linear polarimetry of the SN 2014J has also been acquired. The images reveal the temporal evolution of at least two major light-echo components. The first one exhibits a filled ring structure with position-angle-dependent intensity. This radially extended, diffuse echo indicates the presence of an inhomogeneous interstellar dust cloud ranging from ˜100 pc to ˜500 pc in the foreground of the SN. The second echo component appears as an unresolved luminous quarter-circle arc centered on the SN. The wavelength dependence of scattering measured in different dust components suggests that the dust producing the luminous arc favors smaller grain sizes, while that causing the diffuse light echo may have sizes similar to those of the Milky Way dust. Smaller grains can produce an optical depth consistent with that along the supernova-Earth line of sight measured by previous studies around maximum light. Therefore, it is possible that the dust slab, from which the luminous arc arises, is also responsible for most of the extinction towards SN 2014J. The optical depths produced by the diffuse Milky Way-like dust in the scattering matters are lower than that produced by the dust slab. Apart from the resolved light echoes, the polarization of the SN 2014J point source measured at day 277 shows conspicuous deviations from other epochs and this can be identified as due to at least 10-6 Msun of dust located at a distance of ~5×1017 cm away from the SN. The presence of this CS dust may set strong constraints on the progenitor system that led to the explosion of SN 2014J.

  16. OPTICAL AND NEAR-INFRARED POLARIMETRY OF HIGHLY REDDENED Type Ia SUPERNOVA 2014J: PECULIAR PROPERTIES OF DUST IN M82

    SciTech Connect

    Kawabata, K. S.; Akitaya, H.; Itoh, R.; Moritani, Y.; Yamanaka, M.; Maeda, K.; Nogami, D.; Ui, T.; Kawabata, M.; Mori, K.; Takaki, K.; Ueno, I.; Chiyonobu, S.; Harao, T.; Matsui, R.; Miyamoto, H.; Nagae, O.; Nomoto, K.; Suzuki, N.; Tanaka, M.; and others

    2014-11-01

    We present optical and near-infrared multi-band linear polarimetry of the highly reddened Type Ia supernova (SN) 2014J that appeared in M82. SN 2014J exhibits large polarization at shorter wavelengths, e.g., 4.8% in the B band, which decreases rapidly at longer wavelengths, while the position angle of the polarization remains at approximately 40° over the observed wavelength range. These polarimetric properties suggest that the observed polarization is likely predominantly caused by the interstellar dust within M82. Further analysis shows that the polarization peaks at a wavelengths much shorter than those obtained for the Galactic dust. The wavelength dependence of the polarization can be better described by an inverse power law rather than by the Serkowski law for Galactic interstellar polarization. These points suggest that the nature of the dust in M82 may be different from that in our Galaxy, with polarizing dust grains having a mean radius of <0.1 μm.

  17. Expectations for the Hard X-Ray Continuum and Gamma-Ray Line Fluxes from the Type Ia Supernova SN 2014J in M82

    NASA Astrophysics Data System (ADS)

    The, Lih-Sin; Burrows, Adam

    2014-05-01

    The hard X-ray continuum and gamma-ray lines from a Type Ia supernova dominate its integrated photon emissions and can provide unique diagnostics of the mass of the ejecta, the 56Ni yield and spatial distribution, its kinetic energy and expansion speed, and the mechanism of explosion. Such signatures and their time behavior "X-ray" the bulk debris field in direct fashion, and do not depend on the ofttimes problematic and elaborate UV, optical, and near-infrared spectroscopy and radiative transfer that have informed the study of these events for decades. However, to date no hard photons have ever been detected from a Type Ia supernova in explosion. With the advent of the supernova SN 2014J in M82, at a distance of ~3.5 Mpc, this situation may soon change. Both NuSTAR and INTEGRAL have the potential to detect SN 2014J, and, if spectra and light curves can be measured, would usefully constrain the various explosion models published during the last ~30 yr. In support of these observational campaigns, we provide predictions for the hard X-ray continuum and gamma-line emissions for 15 Type Ia explosion models gleaned from the literature. The model set, containing as it does deflagration, delayed detonation, merger detonation, pulsational delayed detonation, and sub-Chandrasekhar helium detonation models, collectively spans a wide range of properties, and hence signatures. We provide a brief discussion of various diagnostics (with examples), but importantly make the spectral and line results available electronically to aid in the interpretation of the anticipated data.

  18. Expectations for the hard x-ray continuum and gamma-ray line fluxes from the typE IA supernova SN 2014J in M82

    SciTech Connect

    The, Lih-Sin; Burrows, Adam E-mail: burrows@astro.princeton.edu

    2014-05-10

    The hard X-ray continuum and gamma-ray lines from a Type Ia supernova dominate its integrated photon emissions and can provide unique diagnostics of the mass of the ejecta, the {sup 56}Ni yield and spatial distribution, its kinetic energy and expansion speed, and the mechanism of explosion. Such signatures and their time behavior 'X-ray' the bulk debris field in direct fashion, and do not depend on the ofttimes problematic and elaborate UV, optical, and near-infrared spectroscopy and radiative transfer that have informed the study of these events for decades. However, to date no hard photons have ever been detected from a Type Ia supernova in explosion. With the advent of the supernova SN 2014J in M82, at a distance of ∼3.5 Mpc, this situation may soon change. Both NuSTAR and INTEGRAL have the potential to detect SN 2014J, and, if spectra and light curves can be measured, would usefully constrain the various explosion models published during the last ∼30 yr. In support of these observational campaigns, we provide predictions for the hard X-ray continuum and gamma-line emissions for 15 Type Ia explosion models gleaned from the literature. The model set, containing as it does deflagration, delayed detonation, merger detonation, pulsational delayed detonation, and sub-Chandrasekhar helium detonation models, collectively spans a wide range of properties, and hence signatures. We provide a brief discussion of various diagnostics (with examples), but importantly make the spectral and line results available electronically to aid in the interpretation of the anticipated data.

  19. SUPERNOVA 2003ie WAS LIKELY A FAINT TYPE IIP EVENT

    SciTech Connect

    Arcavi, Iair; Gal-Yam, Avishay; Sergeev, Sergey G.

    2013-04-15

    We present new photometric observations of supernova (SN) 2003ie starting one month before discovery, obtained serendipitously while observing its host galaxy. With only a weak upper limit derived on the mass of its progenitor (<25 M{sub Sun }) from previous pre-explosion studies, this event could be a potential exception to the ''red supergiant (RSG) problem'' (the lack of high-mass RSGs exploding as Type IIP SNe). However, this is true only if SN2003ie was a Type IIP event, something which has never been determined. Using recently derived core-collapse SN light-curve templates, as well as by comparison to other known SNe, we find that SN2003ie was indeed a likely Type IIP event. However, with a plateau magnitude of {approx} - 15.5 mag, it is found to be a member of the faint Type IIP class. Previous members of this class have been shown to arise from relatively low-mass progenitors (<12 M{sub Sun }). It therefore seems unlikely that this SN had a massive RSG progenitor. The use of core-collapse SN light-curve templates is shown to be helpful in classifying SNe with sparse coverage. These templates are likely to become more robust as large homogeneous samples of core-collapse events are collected.

  20. Fainting

    MedlinePlus

    ... tunnel vision) or noises are fading into the background. Causes Fainting may occur while or after you: ... a seizure or heart rhythm disturbance), and to figure out the cause of the fainting episode. If ...

  1. A very faint core-collapse supernova in M85.

    PubMed

    Pastorello, A; Della Valle, M; Smartt, S J; Zampieri, L; Benetti, S; Cappellaro, E; Mazzali, P A; Patat, F; Spiro, S; Turatto, M; Valenti, S

    2007-10-18

    An anomalous transient in the early Hubble-type (S0) galaxy Messier 85 (M85) in the Virgo cluster was discovered by Kulkarni et al. on 7 January 2006 that had very low luminosity (peak absolute R-band magnitude M(R) of about -12) that was constant over more than 80 days, red colour and narrow spectral lines, which seem inconsistent with those observed in any known class of transient events. Kulkarni et al. suggest an exotic stellar merger as the possible origin. An alternative explanation is that the transient in M85 was a type II-plateau supernova of extremely low luminosity, exploding in a lenticular galaxy with residual star-forming activity. This intriguing transient might be the faintest supernova that has ever been discovered.

  2. A faint type of supernova from a white dwarf with a helium-rich companion.

    PubMed

    Perets, H B; Gal-Yam, A; Mazzali, P A; Arnett, D; Kagan, D; Filippenko, A V; Li, W; Arcavi, I; Cenko, S B; Fox, D B; Leonard, D C; Moon, D-S; Sand, D J; Soderberg, A M; Anderson, J P; James, P A; Foley, R J; Ganeshalingam, M; Ofek, E O; Bildsten, L; Nelemans, G; Shen, K J; Weinberg, N N; Metzger, B D; Piro, A L; Quataert, E; Kiewe, M; Poznanski, D

    2010-05-20

    Supernovae are thought to arise from two different physical processes. The cores of massive, short-lived stars undergo gravitational core collapse and typically eject a few solar masses during their explosion. These are thought to appear as type Ib/c and type II supernovae, and are associated with young stellar populations. In contrast, the thermonuclear detonation of a carbon-oxygen white dwarf, whose mass approaches the Chandrasekhar limit, is thought to produce type Ia supernovae. Such supernovae are observed in both young and old stellar environments. Here we report a faint type Ib supernova, SN 2005E, in the halo of the nearby isolated galaxy, NGC 1032. The 'old' environment near the supernova location, and the very low derived ejected mass ( approximately 0.3 solar masses), argue strongly against a core-collapse origin. Spectroscopic observations and analysis reveal high ejecta velocities, dominated by helium-burning products, probably excluding this as a subluminous or a regular type Ia supernova. We conclude that it arises from a low-mass, old progenitor, likely to have been a helium-accreting white dwarf in a binary. The ejecta contain more calcium than observed in other types of supernovae and probably large amounts of radioactive (44)Ti.

  3. Fainting

    MedlinePlus

    ... brain does not get enough oxygen. You lose consciousness, or “pass out,” for a brief time (usually ... syncope, exertional syncope, fainting, hyperventilation, hypovolemic syncope, lose consciousness, loss of consciousness, micturition syncope, orthostatic syncope, pass ...

  4. Rapidly evolving faint transients from stripped-envelope electron-capture supernovae

    NASA Astrophysics Data System (ADS)

    Moriya, Takashi J.; Eldridge, J. J.

    2016-09-01

    We investigate the expected rates and bolometric light-curve properties of stripped-envelope electron-capture supernovae (ECSNe) using stellar models from the Binary Population and Spectral Synthesis code. We find that 0.8 per cent (Z = 0.020) and 1.2 per cent (Z = 0.004) of core-collapse supernovae are stripped-envelope ECSNe. Their typical ejecta masses are estimated to be about 0.3 M⊙(Z = 0.020) and 0.6 M⊙ (Z = 0.004). Assuming ECSN explosion properties from numerical explosion simulations, an explosion energy of 1.5 × 1050 erg and a 56Ni mass of 2.5 × 10-3 M⊙, we find that stripped-envelope ECSNe have a typical rise time of around 7 d (Z = 0.020) or 13 d (Z = 0.004) and peak luminosity of around 1041 ergs-1 (-13.8 mag, Z = 0.020) or 7 × 1040 erg s-1 (-13.4 mag, Z = 0.004). Their typical ejecta velocities are around 7000 km s-1 (Z = 0.020) or 5000 km s-1 (Z = 0.004). Thus, stripped-envelope ECSNe are observed as rapidly evolving faint transients with relatively small velocities. SN 2008ha-like supernovae, which are the faintest kind of SN 2002cx-like (also known as Type Iax) supernovae, may be related to stripped-envelope ECSNe.

  5. FAINT POPULATION III SUPERNOVAE AS THE ORIGIN OF THE MOST IRON-POOR STARS

    SciTech Connect

    Ishigaki, Miho N.; Tominaga, Nozomu; Kobayashi, Chiaki; Nomoto, Ken'ichi

    2014-09-10

    The most iron-poor stars in the Milky Way provide important observational clues to the astrophysical objects that enriched the primordial gas with heavy elements. Among them, the recently discovered iron-deficient star SMSS J031300.36–670839.3 shows a remarkable chemical composition with a non-detection of iron ([Fe/H] <–7.1) and large enhancement of carbon and magnesium relative to calcium. We investigate supernova yields of metal-free (Population III) stars to interpret the abundance pattern observed in this star. We report that the high [C/Ca] and [C/Mg] ratios and upper limits of other elemental abundances are well reproduced with the yields of core-collapse supernovae (which have normal kinetic energies of explosion E of E {sub 51} = E/10{sup 51} erg =1) and hypernovae (E {sub 51} ≥ 10) of Population III 25 M {sub ☉} or 40 M {sub ☉} stars. The best-fit models assume that the explosions undergo extensive matter mixing and fallback, leaving behind a black hole remnant. In these models, Ca is produced by static/explosive O burning and incomplete Si burning in the Population III supernova/hypernova, in contrast to the suggestion that Ca is originated from the hot-CNO cycle during pre-supernova evolution. Chemical abundances of four carbon-rich iron-poor stars with [Fe/H] <–4.5, including SMSS J031300.36–670839.3, are consistently explained by faint supernova models with ejected masses of {sup 56}Ni less than 10{sup –3} M {sub ☉}.

  6. Faint Population III Supernovae as the Origin of the Most Iron-poor Stars

    NASA Astrophysics Data System (ADS)

    Ishigaki, Miho N.; Tominaga, Nozomu; Kobayashi, Chiaki; Nomoto, Ken'ichi

    2014-09-01

    The most iron-poor stars in the Milky Way provide important observational clues to the astrophysical objects that enriched the primordial gas with heavy elements. Among them, the recently discovered iron-deficient star SMSS J031300.36-670839.3 shows a remarkable chemical composition with a non-detection of iron ([Fe/H] <-7.1) and large enhancement of carbon and magnesium relative to calcium. We investigate supernova yields of metal-free (Population III) stars to interpret the abundance pattern observed in this star. We report that the high [C/Ca] and [C/Mg] ratios and upper limits of other elemental abundances are well reproduced with the yields of core-collapse supernovae (which have normal kinetic energies of explosion E of E 51 = E/1051 erg =1) and hypernovae (E 51 >= 10) of Population III 25 M ⊙ or 40 M ⊙ stars. The best-fit models assume that the explosions undergo extensive matter mixing and fallback, leaving behind a black hole remnant. In these models, Ca is produced by static/explosive O burning and incomplete Si burning in the Population III supernova/hypernova, in contrast to the suggestion that Ca is originated from the hot-CNO cycle during pre-supernova evolution. Chemical abundances of four carbon-rich iron-poor stars with [Fe/H] <-4.5, including SMSS J031300.36-670839.3, are consistently explained by faint supernova models with ejected masses of 56Ni less than 10-3 M ⊙.

  7. Discovery of a Type Ia Supernova in a Faint Dwarf Galaxy

    NASA Astrophysics Data System (ADS)

    Williams, R.; Hsiao, E. Y.; Mahabal, A.; Djorgovski, S. G.; Drake, A. J.; Graham, M. J.; Graham, M. L.; Pritchet, C. J.; Parker, A.; Sadavoy, S.; Balam, D.; Catelan, M.; Beshore, E. C.; Larson, S. M.; Boattini, A.; Christensen, E.

    2008-11-01

    We have discovered a supernova in observations from CSS, Palomar 60 and the Plaskett Telescope starting from 22 Nov UT. The discovery has the following parameters:

    CSS081122:094326+251021 2008-11-22 UT 10:18:11 RA 09:43:26.22 Dec 25:10:21.9 Mag 16.4 Type SN Iaz=0.027
    CSS081122:094326+251021 is associated with a very faint anonymous galaxy seen in SDSS DR7 images (mags: u= 23.2, g=22.7, r=22.8, i=22.7, z=23.6).

  8. THE OLD ENVIRONMENT OF THE FAINT CALCIUM-RICH SUPERNOVA SN 2005cz

    SciTech Connect

    Perets, Hagai B.; Gal-yam, Avishay; Crockett, R. Mark; Sullivan, Mark; Anderson, Joseph P.; James, Phil A.; Neill, James D.; Leonard, Douglas C.

    2011-02-20

    The supernova SN 2005cz has recently attracted some attention due to the fact that it was spectroscopically similar to type Ib supernovae (SNe Ib), a class that is presumed to result from the core collapse of massive stars, yet it occurred in an elliptical galaxy, where one expects very few massive stars to exist. Two explanations for this remarkable event were put forward. Perets et al. associate SN 2005cz with the class of Ca-rich, faint SNe Ib, which likely result from old double-white-dwarf systems with an He-rich secondary. On the other hand, Kawabata et al. suggest that SN 2005cz is indeed a core-collapse event (in a binary system), albeit of a star at the lower end of the mass range, 10-12 M{sub sun}. The existence of this star in its elliptical host is explained as resulting from low-level star formation (SF) activity in that galaxy. Here we present extensive observations of the location of SN 2005cz, sensitive to a variety of SF tracers, including optical spectroscopy, H{alpha} emission, UV emission, and Hubble Space Telescope photometry. We show that NGC 4589, the host galaxy of SN 2005cz, does not show any signatures of a young stellar population or recent SF activity either close to or far from the location of SN 2005cz.

  9. Faint supernovae and supernova impostors: case studies of SN 2002kg/NGC 2403-V37 and SN 2003gm

    NASA Astrophysics Data System (ADS)

    Maund, J. R.; Smartt, S. J.; Kudritzki, R.-P.; Pastorello, A.; Nelemans, G.; Bresolin, F.; Patat, F.; Gilmore, G. F.; Benn, C. R.

    2006-06-01

    Photometric and spectroscopic observations of the faint Supernovae (SNe) 2002kg and 2003gm, and their precursors, in NGC 2403 and NGC 5334, respectively, are presented. The properties of these SNe are discussed in the context of previously proposed scenarios for faint SNe: low-mass progenitors producing underenergetic SNe; SNe with ejecta constrained by a circumstellar medium; and outbursts of massive Luminous Blue Variables (LBVs). The last scenario has been referred to as `Type V SNe', `SN impostors' or `fake SNe'. The faint SN 2002kg reached a maximum brightness of MV = -9.6, much fainter than normal Type II SNe. The precursor of SN 2002kg is confirmed to be, as shown in previous work, the LBV NGC 2403-V37. Late-time photometry of SN 2002kg shows it to be only 0.6 mag fainter at 500 d than at the epoch of discovery. Two spectra of SN 2002kg, with an approximately 1-yr interval between observations, show only minor differences. Strong FeII lines are observed in the spectra of SN 2002kg, similar to both the LBV NGC 2363-V1 and the Type IIn SN 1995G. The spectrum of SN 2002kg does show strong resolved [NII] at λλ6549,6583 Å. The identified progenitor of SN 2003gm is a bright yellow star, consistent with a F5-G2 supergiant, similar to the identified progenitor of SN 2004et. SN 2003gm, at the epoch of discovery, was of similar brightness to the possible fake SN 1997bs and the Type IIP SNe 1999br and 2005cs. Photometrically SN 2003gm shows the same decrease in brightness, over the same time period as SN 1997bs. The light curve and the spectral properties of SN 2003gm are also consistent with some intrinsically faint and low-velocity Type II SNe. The early-time spectra of SN 2003gm are dominated by Balmer emission lines, which at the observed resolution, appear similar to SN 2000ch. On the basis of the post-discovery photometric and spectroscopic observations presented here, we suggest that SN 2003gm is a similar event to SN 1997bs, although the SN/LBV nature of

  10. PESSTO monitoring of SN 2012hn: further heterogeneity among faint Type I supernovae

    NASA Astrophysics Data System (ADS)

    Valenti, S.; Yuan, F.; Taubenberger, S.; Maguire, K.; Pastorello, A.; Benetti, S.; Smartt, S. J.; Cappellaro, E.; Howell, D. A.; Bildsten, L.; Moore, K.; Stritzinger, M.; Anderson, J. P.; Benitez-Herrera, S.; Bufano, F.; Gonzalez-Gaitan, S.; McCrum, M. G.; Pignata, G.; Fraser, M.; Gal-Yam, A.; Le Guillou, L.; Inserra, C.; Reichart, D. E.; Scalzo, R.; Sullivan, M.; Yaron, O.; Young, D. R.

    2014-01-01

    We present optical and infrared monitoring data of SN 2012hn collected by the Public European Southern Observatory Spectroscopic Survey for Transient Objects. We show that SN 2012hn has a faint peak magnitude (MR ˜ -15.65) and shows no hydrogen and no clear evidence for helium in its spectral evolution. Instead, we detect prominent Ca II lines at all epochs, which relates this transient to previously described `Ca-rich' or `gap' transients. However, the photospheric spectra (from -3 to +32 d with respect to peak) of SN 2012hn show a series of absorption lines which are unique and a red continuum that is likely intrinsic rather than due to extinction. Lines of Ti II and Cr II are visible. This may be a temperature effect, which could also explain the red photospheric colour. A nebular spectrum at +150 d shows prominent Ca II, O I, C I and possibly Mg I lines which appear similar in strength to those displayed by core-collapse supernovae (SNe). To add to the puzzle, SN 2012hn is located at a projected distance of 6 kpc from an E/S0 host and is not close to any obvious star-forming region. Overall SN 2012hn resembles a group of faint H-poor SNe that have been discovered recently and for which a convincing and consistent physical explanation is still missing. They all appear to explode preferentially in remote locations offset from a massive host galaxy with deep limits on any dwarf host galaxies, favouring old progenitor systems. SN 2012hn adds heterogeneity to this sample of objects. We discuss potential explosion channels including He-shell detonations and double detonations of white dwarfs as well as peculiar core-collapse SNe.

  11. Discovery of two new supernovae and a possible AGN/luminous SN IIn in the Pan-STARRS1 3Pi faint galaxy supernova survey

    NASA Astrophysics Data System (ADS)

    Valenti, S.; Kankare, E.; Mattila, S.; Pastorello, A.; Smartt, S.; Smith, K.; Kotak, R.; Ward, M.; Gezari, S.; Chornock, R.; A.; Bresolin, F.; Kudritzki, R.; Tonry, J.; Magnier, E.; Chambers, K.; Kaiser, N.; Morgan, J.; Burgett, W.; Heasley, J.; Sweeney, W.; Waters, C.; Flewelling, H.; Price, P. A.

    2010-09-01

    report the discovery of two new supernovae and a possible AGN/luminous SN IIn in the Pan-STARRS 1 "3Pi Faint galaxy supernova survey". During the course of the PS1 3Pi sky survey, PS1-1000791 was detected on Aug 14.40 (UT) (Coord: 20:45:13.089 -06:56:11.090, J2000) at g=19.4 and detected again on Aug 19.33 at r=18.64 within 0.9 arcsec of the faint SDSS galaxy (J204513.14-065611.2). A spectrum of PS1-1000791 was obtained at the Nordic Optical Telescope (+ALFOSC+Gr4; range 350-950nm) on Aug 30.0 (UT).

  12. The search for faint radio supernova remnants in the outer Galaxy: five new discoveries

    NASA Astrophysics Data System (ADS)

    Gerbrandt, Stephanie; Foster, Tyler J.; Kothes, Roland; Geisbüsch, Jörn; Tung, Albert

    2014-06-01

    Context. High resolution and sensitivity large-scale radio surveys of the Milky Way are critical in the discovery of very low surface brightness supernova remnants (SNRs), which may constitute a significant portion of the Galactic SNRs still unaccounted for (ostensibly the "missing SNR problem"). Aims: The overall purpose here is to present the results of a systematic, deep data-mining of the Canadian Galactic plane Survey (CGPS) for faint, extended non-thermal and polarized emission structures that are likely the shells of uncatalogued SNRs. Methods: We examine 5 × 5 degree mosaics from the entire 1420 MHz continuum and polarization dataset of the CGPS after removing unresolved "point" sources and subsequently smoothing them. Newly revealed extended emission objects are compared to similarly prepared CGPS 408 MHz continuum mosaics, as well as to source-removed mosaics from various existing radio surveys at 4.8 GHz, 2.7 GHz, and 327 MHz, to identify candidates with non-thermal emission characteristics. We integrate flux densities at each frequency to characterise the radio spectra behaviour of these candidates. We further look for mid- and high-frequency (1420 MHz, 4.8 GHz) ordered polarized emission from the limb brightened "shell"-like continuum features that the candidates sport. Finally, we use IR and optical maps to provide additional backing evidence. Results: Here we present evidence that five new objects, identified as filling all or some of the criteria above, are strong candidates for new SNRs. These five are designated by their Galactic coordinate names G108.5+11.0, G128.5+2.6, G149.5+3.2, G150.8+3.8, and G160.1-1.1. The radio spectrum of each is presented, highlighting their steepness, which is characteristic of synchrotron radiation. CGPS 1420 MHz polarization data and 4.8 GHz polarization data also provide evidence that these objects are newly discovered SNRs. These discoveries represent a significant increase in the number of SNRs known in the outer

  13. Evidence for an Expanding Molecular Superbubble in M 82

    NASA Astrophysics Data System (ADS)

    Weiss, A.; Walter, F.; Neininger, N.; Klein, U.

    1999-05-01

    We present evidence for an expanding superbubble in M 82 (diameter: ~ 130 pc, expansion velocity: ~ 45 km s(-1) , mass: ~ 8*10(6 ) Msun) as traced by (12) CO(J=1 -> 0), (12) CO(J=2 -> 1), (13) CO(J=1 -> 0) and C(18) O(J=1 -> 0) observations. The superbubble is centred around the most powerful supernova remnant 41.9+58 in M 82. The CO observations show that the molecular superbubble already broke out of M 82's disk. This scenario is supported by ROSAT HRI observations which suggest that hot coronal gas originating from inside the shell is the main contributor to the diffuse X-ray outflow in M 82. We briefly discuss observations of the same region at other wavelengths (radio continuum, optical, HI, X-rays, ionized gas). From our spectral line observations, we derive a kinematic age of about 10(6) years for the superbubble. Using simple theoretical models, the total energy needed for the creation of this superbubble is of order 2*E(54) ergs (energy equivalent of 1000 'regular' type II supernova (SN) explosions and the strong stellar winds of their progenitors). The average energy input rate (0.001 SN yr(-1) ) is reasonable given the high SN rate of ~ 0.1 SN yr(-1) in the central part of M 82. As much as 10% of the energy needed to create the superbubble is still present in form of the kinetic energy of the expanding molecular shell. This newly detected expanding molecular superbubble is believed to be powered by the same objects which also lie at origin of the prominent X-ray outflow in M 82. It can therefore be used as an alternative tool to investigate the physical properties of these sources. acknowledgements: A.W. and F.W. acknowledge the Deutsche Forschungsgemeinschaft for the award of a stipendium in the Graduate School `` The Magellanic Clouds and Other Dwarf Galaxies''.

  14. Hα Emission 11 KPC Above M82

    NASA Astrophysics Data System (ADS)

    Devine, D.; Bally, J.

    1998-05-01

    We report the discovery of Hα emission extending out to a projected distance of 11 kpc from the disk of M82, which is three times farther than previously identified emission line components associated with the nuclear superwind. The Hα emission can be traced nearly continuously for ten arcminutes northwest of M82 out to an emission line structure (the ``cap''), which lies at a projected distance of 11 - 12 kpc from the M82 nucleus. The cap has a shell-like morphology and is blueshifted by 50 - 200 km s(-1) relative to the M82 nucleus. The ``cap'' may be photoionized material illuminated by Lyman continuum photons leaking out of the M82 nuclear region through the hot bipolar cavity produced by the starburst driven superwind, or it may be a bow shock formed by the impact of the superwind with either previously emitted wind material or with ambient intergalactic material and/or tidal debris left over from the collision between M81 and M82.

  15. Diffuse Galactic antimatter from faint thermonuclear supernovae in old stellar populations

    NASA Astrophysics Data System (ADS)

    Crocker, Roland M.; Ruiter, Ashley J.; Seitenzahl, Ivo R.; Panther, Fiona H.; Sim, Stuart; Baumgardt, Holger; Möller, Anais; Nataf, David M.; Ferrario, Lilia; Eldridge, J. J.; White, Martin; Tucker, Brad E.; Aharonian, Felix

    2017-06-01

    Our Galaxy hosts the annihilation of a few 1043 low-energy positrons every second. Radioactive isotopes capable of supplying such positrons are synthesized in stars, stellar remnants and supernovae. For decades, however, there has been no positive identification of a main stellar positron source, leading to suggestions that many positrons originate from exotic sources like the Galaxy's central supermassive black hole or dark matter annihilation. Here we show that a single type of transient source, deriving from stellar populations of age 3-6 Gyr and yielding ∼0.03 M ⊙ of the positron emitter 44Ti, can simultaneously explain the strength and morphology of the Galactic positron annihilation signal and the Solar System abundance of the 44Ti decay product 44Ca. This transient is likely the merger of two low-mass white dwarfs, observed in external galaxies as the sub-luminous, thermonuclear supernova known as SN 1991bg-like.

  16. Helium ignition in rotating magnetized CO white dwarfs leading to fast and faint rather than classical Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Neunteufel, P.; Yoon, S.-C.; Langer, N.

    2017-06-01

    produce events that belong to the recently identified classes of faint and fast hydrogen-free supernovae.

  17. A progenitor binary and an ejected mass donor remnant of faint type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Geier, S.; Marsh, T. R.; Wang, B.; Dunlap, B.; Barlow, B. N.; Schaffenroth, V.; Chen, X.; Irrgang, A.; Maxted, P. F. L.; Ziegerer, E.; Kupfer, T.; Miszalski, B.; Heber, U.; Han, Z.; Shporer, A.; Telting, J. H.; Gänsicke, B. T.; Østensen, R. H.; O'Toole, S. J.; Napiwotzki, R.

    2013-06-01

    Type Ia supernovae (SN Ia) are the most important standard candles for measuring the expansion history of the universe. The thermonuclear explosion of a white dwarf can explain their observed properties, but neither the progenitor systems nor any stellar remnants have been conclusively identified. Underluminous SN Ia have been proposed to originate from a so-called double-detonation of a white dwarf. After a critical amount of helium is deposited on the surface through accretion from a close companion, the helium is ignited causing a detonation wave that triggers the explosion of the white dwarf itself. We have discovered both shallow transits and eclipses in the tight binary system CD-30°11223 composed of a carbon/oxygen white dwarf and a hot helium star, allowing us to determine its component masses and fundamental parameters. In the future the system will transfer mass from the helium star to the white dwarf. Modelling this process we find that the detonation in the accreted helium layer is sufficiently strong to trigger the explosion of the core. The helium star will then be ejected at such high velocity that it will escape the Galaxy. The predicted properties of this remnant are an excellent match to the so-called hypervelocity star US 708, a hot, helium-rich star moving at more than 750 km s-1, sufficient for it to leave the Galaxy. The identification of both progenitor and remnant provides a consistent picture of the formation and evolution of underluminous SNIa.

  18. Discovery of Optical Transient in M82 : P60-M82-081119

    NASA Astrophysics Data System (ADS)

    Kasliwal, M. M.; Cenko, S. B.; Rau, A.; Ofek, E. O.; Quimby, R.; Kulkarni, S. R.

    2008-11-01

    On UT 2008 Nov 19.536, P60-FasTING (Palomar 60-inch Fast Transients In Nearby Galaxies) discovered a possible nova in M82 at RA(J2000) = 09:55:58.390 DEC(J2000) = +69:40:56.17, offset from the nucleus by 29.5"E, 10.4"N. P60-M82-081119 had a brightness of g = 20.0 +/- 0.1 at peak corresponding to Mg = -7.8 at the distance of M82 (uncorrected for extinction). There is no counterpart in SDSS or SIMBAD.

  19. Optical and near-IR observations of the faint and fast 2008ha-like supernova 2010ae

    NASA Astrophysics Data System (ADS)

    Stritzinger, M. D.; Hsiao, E.; Valenti, S.; Taddia, F.; Rivera-Thorsen, T. J.; Leloudas, G.; Maeda, K.; Pastorello, A.; Phillips, M. M.; Pignata, G.; Baron, E.; Burns, C. R.; Contreras, C.; Folatelli, G.; Hamuy, M.; Höflich, P.; Morrell, N.; Prieto, J. L.; Benetti, S.; Campillay, A.; Haislip, J. B.; LaClutze, A. P.; Moore, J. P.; Reichart, D. E.

    2014-01-01

    A comprehensive set of optical and near-infrared (NIR) photometry and spectroscopy is presented for the faint and fast 2008ha-like supernova (SN) 2010ae. Contingent on the adopted value of host extinction, SN 2010ae reached a peak brightness of -13.8 > MV > -15.3 mag, while modeling of the UVOIR light curve suggests it produced 0.003-0.007 M⊙ of 56Ni, ejected 0.30-0.60 M⊙ of material, and had an explosion energy of 0.04-0.30 × 1051 erg. The values of these explosion parameters are similar to the peculiar SN 2008ha -for which we also present previously unpublished early phase optical and NIR light curves - and places these two transients at the faint end of the 2002cx-like SN population. Detailed inspection of the post-maximum NIR spectroscopic sequence indicates the presence of a multitude of spectral features, which are identified through SYNAPPS modeling to be mainly attributed to Co ii. Comparison with a collection of published and unpublished NIR spectra of other 2002cx-like SNe, reveals that a Co ii footprint is ubiquitous to this subclass of transients, providing a link to Type Ia SNe. A visual-wavelength spectrum of SN 2010ae obtained at +252 days past maximum shows a striking resemblance to a similar epoch spectrum of SN 2002cx. However, subtle differences in the strength and ratio of calcium emission features, as well as diversity among similar epoch spectra of other 2002cx-like SNe indicates a range of physical conditions of the ejecta, highlighting the heterogeneous nature of thispeculiar class of transients. Based on observations collected at the European Organization for Astronomical Research in the Southern Hemisphere, Chile (ESO Programs 082.A-0526, 084.D-0719, 088.D-0222, 184.D-1140, and 386.D-0966); the Gemini Observatory, Cerro Pachon, Chile (Gemini Programs GS-2010A-Q-14 and GS-2010A-Q-38); the Magellan 6.5 m telescopes at Las Campanas Observatory; and the SOAR telescope.Tables 1-5 and Appendix A are available in electronic form at http

  20. SN 2008in-BRIDGING THE GAP BETWEEN NORMAL AND FAINT SUPERNOVAE OF TYPE IIP

    SciTech Connect

    Roy, Rupak; Kumar, Brijesh; Kumar, Brajesh; Pandey, S. B.; Benetti, Stefano; Bufano, Filomena; Pastorello, Andrea; Yuan, Fang; Akerlof, Carl W.; Brown, Peter J.; Immler, Stefan; Maund, Justyn; Wheeler, J. Craig; Quimby, Rorbert M.; Misra, Kuntal; Elias-Rosa, Nancy; Roming, Peter W. A. E-mail: rupakroy1980@gmail.com

    2011-08-01

    We present optical photometric and low-resolution spectroscopic observations of the Type II plateau supernova (SN) 2008in, which occurred in the outskirts of the nearly face-on spiral galaxy M61. Photometric data in the X-ray, ultraviolet, and near-infrared bands have been used to characterize this event. The SN field was imaged with the ROTSE-IIIb optical telescope about seven days before the explosion. This allowed us to constrain the epoch of the shock breakout to JD = 2454825.6. The duration of the plateau phase, as derived from the photometric monitoring, was {approx}98 days. The spectra of SN 2008in show a striking resemblance to those of the archetypal low-luminosity IIP SNe 1997D and 1999br. A comparison of ejecta kinematics of SN 2008in with the hydrodynamical simulations of Type IIP SNe by Dessart et al. indicates that it is a less energetic event ({approx}5 x 10{sup 50} erg). However, the light curve indicates that the production of radioactive {sup 56}Ni is significantly higher than that in the low-luminosity SNe. Adopting an interstellar absorption along the SN direction of A{sub V} {approx} 0.3 mag and a distance of 13.2 Mpc, we estimated a synthesized {sup 56}Ni mass of {approx}0.015 M{sub sun}. Employing semi-analytical formulae derived by Litvinova and Nadezhin, we derived a pre-SN radius of {approx}126 R{sub sun}, an explosion energy of {approx}5.4 x 10{sup 50} erg, and a total ejected mass of {approx}16.7 M{sub sun}. The latter indicates that the zero-age main-sequence mass of the progenitor did not exceed 20 M{sub sun}. Considering the above properties of SN 2008in and its occurrence in a region of sub-solar metallicity ([O/H] {approx} 8.44 dex), it is unlikely that fall-back of the ejecta onto a newly formed black hole occurred in SN 2008in. We therefore favor a low-energy explosion scenario of a relatively compact, moderate-mass progenitor star that generates a neutron star.

  1. DISCOVERY OF CARBON RADIO RECOMBINATION LINES IN M82

    SciTech Connect

    Morabito, Leah K.; Oonk, J. B. R.; Salgado, Francisco; Röttgering, H. J. A.; Tielens, A. G. G. M.; Haverkorn, Marijke; Toribio, M. Carmen; Heald, George; Beck, Rainer; Adebahr, Björn; Best, Philip; Beswick, Robert; Bonafede, Annalisa; Brüggen, Marcus; Brunetti, Gianfranco; Chyży, Krzysztof T.; Conway, J. E.; Horellou, Cathy; Van Driel, Wim; Gregson, Jonathan; and others

    2014-11-10

    Carbon radio recombination lines (RRLs) at low frequencies (≲ 500 MHz) trace the cold, diffuse phase of the interstellar medium, which is otherwise difficult to observe. We present the detection of carbon RRLs in absorption in M82 with the Low Frequency Array in the frequency range of 48-64 MHz. This is the first extragalactic detection of RRLs from a species other than hydrogen, and below 1 GHz. Since the carbon RRLs are not detected individually, we cross-correlated the observed spectrum with a template spectrum of carbon RRLs to determine a radial velocity of 219 km s{sup –1}. Using this radial velocity, we stack 22 carbon-α transitions from quantum levels n = 468-508 to achieve an 8.5σ detection. The absorption line profile exhibits a narrow feature with peak optical depth of 3 × 10{sup –3} and FWHM of 31 km s{sup –1}. Closer inspection suggests that the narrow feature is superimposed on a broad, shallow component. The total line profile appears to be correlated with the 21 cm H I line profile reconstructed from H I absorption in the direction of supernova remnants in the nucleus. The narrow width and centroid velocity of the feature suggests that it is associated with the nuclear starburst region. It is therefore likely that the carbon RRLs are associated with cold atomic gas in the direction of the nucleus of M82.

  2. Discovery of Carbon Radio Recombination Lines in M82

    NASA Astrophysics Data System (ADS)

    Morabito, Leah K.; Oonk, J. B. R.; Salgado, Francisco; Toribio, M. Carmen; Röttgering, H. J. A.; Tielens, A. G. G. M.; Beck, Rainer; Adebahr, Björn; Best, Philip; Beswick, Robert; Bonafede, Annalisa; Brunetti, Gianfranco; Brüggen, Marcus; Chyży, Krzysztof T.; Conway, J. E.; van Driel, Wim; Gregson, Jonathan; Haverkorn, Marijke; Heald, George; Horellou, Cathy; Horneffer, Andreas; Iacobelli, Marco; Jarvis, Matt J.; Marti-Vidal, Ivan; Miley, George; Mulcahy, D. D.; Orrú, Emanuela; Pizzo, Roberto; Scaife, A. M. M.; Varenius, Eskil; van Weeren, Reinout J.; White, Glenn J.; Wise, Michael W.

    2014-11-01

    Carbon radio recombination lines (RRLs) at low frequencies (lsim 500 MHz) trace the cold, diffuse phase of the interstellar medium, which is otherwise difficult to observe. We present the detection of carbon RRLs in absorption in M82 with the Low Frequency Array in the frequency range of 48-64 MHz. This is the first extragalactic detection of RRLs from a species other than hydrogen, and below 1 GHz. Since the carbon RRLs are not detected individually, we cross-correlated the observed spectrum with a template spectrum of carbon RRLs to determine a radial velocity of 219 km s-1. Using this radial velocity, we stack 22 carbon-α transitions from quantum levels n = 468-508 to achieve an 8.5σ detection. The absorption line profile exhibits a narrow feature with peak optical depth of 3 × 10-3 and FWHM of 31 km s-1. Closer inspection suggests that the narrow feature is superimposed on a broad, shallow component. The total line profile appears to be correlated with the 21 cm H I line profile reconstructed from H I absorption in the direction of supernova remnants in the nucleus. The narrow width and centroid velocity of the feature suggests that it is associated with the nuclear starburst region. It is therefore likely that the carbon RRLs are associated with cold atomic gas in the direction of the nucleus of M82.

  3. Locations of strabursts in M82

    NASA Astrophysics Data System (ADS)

    Shen, Jianjun; Lo, K. Y.

    1995-06-01

    Observations with 2.5 sec (38 pc) resolution of the CO (1-0) emission from the starburst nucleus of M82, obtained with the Berkeley-Illinois-Maryland Association (BIMA) six-element millimeter-wave array, have revealed unresolved (less than 30 pc) structure in the CO emission with very high brightness temperature (up to 34 K). The new observations have also resolved the previously identified double lobe and central peak in the integrated CO intensity into many peaks that are all due to 'velocity crowding' of several velocity components. Most of the CO emitting gas could be located in molecular spiral arms at 125 pc and 390 pc from the nucleus. Outflow motion approximately 230 km/s of part of the molecular gas normal to the plane is also indicated. The new observations suggest that the starbursts took place within molecular spiral arms at some distance from the nucleus. The starbursts may in fact have propagated inward. Given the substantial amount of dense molecular gas still present in the M82 starburst region, it is not clear why the starburst activity appears to have subsided.

  4. The Dense Gas in M82

    NASA Astrophysics Data System (ADS)

    Salas, P.; Galaz, G.; Salter, D.; Bolatto, A.; Herrera-Camus, R.

    2014-10-01

    Galactic winds are responsible of carrying energy and matter from the inner regions of galaxies to the outer regions, even reaching the intergalactic medium. This process removes gas from the inner regions, the available material to form stars. How and in which amount these winds remove gas from galaxies plays an important role in galaxy evolution. To study this effect we have obtained 3 mm maps of dense gas (n_{{crit}}>10^{4} cm^{-3}) in the central region of the starburst galaxy M82. We detect line emission from the dense molecular gas tracers HCN, HCO^{+}, HNC, CS, HC_{3}N and C_{6}H. Our maps reveal a considerable amount of HCO^{+} emission extending above and bellow the central star-forming disk, indicating that the dense gas is entangled in the outflow. The mass of molecular Hydrogen outside the central starburst is M_{{out}}≍ 3 ± 1× 10^{6} M_{odot}, while in the central starburst is M_{{disk}}≍ 8 ± 2× 10^{6} M_{odot}. These maps also show variations of the amount of dense gas over the starburst disk, revealing that the gas is more concentrated towards the center of the starburst and less towards the edges. It is the average amount of dense gas what drives the observed star formation law between dense gas and star formation rate on galactic scales.

  5. COMPTEL upper limits for Al-26 and Fe-60 from M82

    NASA Technical Reports Server (NTRS)

    Georgii, R.; Diehl, R.; Lichti, G.; Knoedlseder, J.; Oberlack, U.; Ryan, J.; vanSant, T.; Schoenfelder, V.

    1997-01-01

    Gamma ray lines from radioactive isotopes produced in supernova explosions provide information concerning the nucleosynthesis processes in stars before and during the explosion. Regions with high star formation rate are good candidates for such gamma ray lines. Starburst galaxies are examples of such regions with an explosive formation of massive stars. The emission of the most prominent starburst galaxy M 82 is analyzed. Two methods for the determination of the upper limits of fluxes are used to derive 2sigma upper limits for the fluxes of Al-26 and Fe-60 from Compton Gamma Ray Observatory data. These are found to be above the estimated fluxes originating from a supernova rate of 0.1 per year in M 82. An estimation of the necessary observation time for the detection of these fluxes with the Ge spectrometer onboard the International Gamma Ray Astrophysics Laboratory is given.

  6. Gamma-ray observations of NGC 253 and M82 with OSSE

    NASA Technical Reports Server (NTRS)

    Bhattacharya, D.; The, L. -S.; Kurfess, J. D.; Clayton, D. D.; Gehrels, N.; Leising, M. D.; Grabelsky, D. A.; Johnson, W. N.; Jung, G. V.; Kinzer, R. L.

    1994-01-01

    Gamma-ray observations of the nearby starburst galaxies NGC 253 and M82 over the energy range (0.05-10) MeV have been obtained with the Oriented Scintillation Spectrometer Experiment (OSSE) spectrometer on the Compton Gamma-Ray Observatory (CGRO). The priority of these galaxies as OSSE targets had been established on the grounds that the average supernova rate may be high in starbursts as indicated by infrared and radio observations, and at distances of approximately 3 Mpc a significant chance of supernova gamm-ray line detection exists. NGC 253 was detected in continuum emission up to 165 keV with a total significance of 4.4 sigma and an estimated luminosity of 3 x 10(exp 40) ergs/s. The spectrum is best fit by a power law of photon index approximately 2.5. We consider the possible contribution of different emission mechanisms, including inverse Compton scattering, bremsstrahlung, discrete sources, and Type Ia/Ib supernova continuum to the measured flux. No significant continuum flux was observed from M82. A search for the gamma-ray line from the decay of the most abundant radioactive element produced in supernovae (Ni-56 yields Co-56 yields Fe-56) yielded no significant detection: the 3 sigma upper limits to the line fluxes at 0.158, 0.812, 0.847, and 1.238 MeV for both galaxies are obtained.

  7. Selecting superluminous supernovae in faint galaxies from the first year of the Pan-STARRS1 Medium Deep Survey

    NASA Astrophysics Data System (ADS)

    McCrum, M.; Smartt, S. J.; Rest, A.; Smith, K.; Kotak, R.; Rodney, S. A.; Young, D. R.; Chornock, R.; Berger, E.; Foley, R. J.; Fraser, M.; Wright, D.; Scolnic, D.; Tonry, J. L.; Urata, Y.; Huang, K.; Pastorello, A.; Botticella, M. T.; Valenti, S.; Mattila, S.; Kankare, E.; Farrow, D. J.; Huber, M. E.; Stubbs, C. W.; Kirshner, R. P.; Bresolin, F.; Burgett, W. S.; Chambers, K. C.; Draper, P. W.; Flewelling, H.; Jedicke, R.; Kaiser, N.; Magnier, E. A.; Metcalfe, N.; Morgan, J. S.; Price, P. A.; Sweeney, W.; Wainscoat, R. J.; Waters, C.

    2015-04-01

    The Pan-STARRS1 (PS1) survey has obtained imaging in five bands (griz yP1) over 10 Medium Deep Survey (MDS) fields covering a total of 70 square degrees. This paper describes the search for apparently hostless supernovae (SNe) within the first year of PS1 MDS data with an aim of discovering superluminous supernovae (SLSNe). A total of 249 hostless transients were discovered down to a limiting magnitude of MAB ˜ 23.5, of which 76 were classified as Type Ia supernovae (SNe Ia). There were 57 SNe with complete light curves that are likely core-collapse SNe (CCSNe) or type Ic SLSNe and 12 of these have had spectra taken. Of these 12 hostless, non-Type Ia SNe, 7 were SLSNe of type Ic at redshifts between 0.5 and 1.4. This illustrates that the discovery rate of type Ic SLSNe can be maximized by concentrating on hostless transients and removing normal SNe Ia. We present data for two possible SLSNe; PS1-10pm (z = 1.206) and PS1-10ahf (z = 1.1), and estimate the rate of type Ic SLSNe to be between 3^{+3}_{-2}× 10^{-5} and 8^{+2}_{-1}× 10^{-5} that of the CCSN rate within 0.3 ≤ z ≤ 1.4 by applying a Monte Carlo technique. The rate of slowly evolving, type Ic SLSNe (such as SN2007bi) is estimated as a factor of 10 lower than this range.

  8. The Green Bank Telescope Maps the Dense Molecular Gas in the Starburst Galaxy M82

    NASA Astrophysics Data System (ADS)

    Kepley, Amanda A.; Leroy, A. K.; Frayer, D. T.; Usero, A.; Marvil, J.; Walter, F.

    2014-01-01

    In both the Milky Way and nearby galaxies, the presence of dense molecular gas is correlated with recent star formation, suggesting that the formation of this gas may represent a key regulating step in the star formation process. Testing this idea requires wide-area, high-resolution maps of dense molecular gas in galaxies to explore how local physical conditions drive dense gas formation. Until now, these observations have been limited by the faintness of dense gas tracers like HCN and HCO+, but new instruments like the 4mm receiver on Robert C. Byrd Green Bank Telescope (GBT) -- the largest single-dish millimeter telescope -- are poised to change this picture. We present GBT maps of the dense gas tracers HCN and HCO+ in the prototypical nearby starburst galaxy M82. The HCN and HCO+ in the disk of M82 correlates both with recent star formation and the diffuse molecular gas and shows kinematics consistent with a rotating torus. HCO+ emission is also associated with the outflow of molecular gas previously identified in CO. These observations mark the first time that dense molecular gas like HCO+ has been associated with an outflow in a nearby galaxy and suggests that the outflow of dense molecular gas from the center of galaxies like M82 may regulate the star formation globally. Finally, the CO-to-HCN and CO-to-HCO+ line ratios reveal that there is more dense gas at the center of M82, pointing to the starburst as a key driver of this relationship. These results establish that the GBT can efficiently map the dense molecular gas at 90 GHz in nearby galaxies; this capability will increase further with the 16-element feed array currently being built for the GBT.

  9. Enhanced Turbulence in M82 and M51 from Observations of Interstellar CH+

    NASA Astrophysics Data System (ADS)

    Ritchey, Adam M.; Welty, Daniel E.; Wallerstein, George

    2015-01-01

    Recent observations of diffuse molecular gas in M82 toward SN 2014J and in M51 toward its companion galaxy NGC 5195 have led to the discovery of high CH+ abundances in these extragalactic lines of sight. The column densities of CH+ are much higher in these directions (relative to the CH column densities) than would be expected based on other properties of the material. The equivalent widths of the λ5780.5 and λ5797.1 diffuse interstellar bands, for example, are suggestive of weak ambient radiation fields and/or significantly shielded environments, where the CH+ abundance would normally be expected to be rather low. We interpret these findings within the framework of recent models of turbulent dissipation regions, which find that the CH+ abundance is directly proportional to the average turbulent dissipation rate and inversely proportional to the square of the gas density. The high CH+ abundances toward SN 2014J and NGC 5195 then suggest that the average turbulent dissipation rates could be significantly enhanced in M82 and M51 (relative to typical values characterizing the local Galactic interstellar medium). As both M82 and M51 are interacting with neighboring galaxies, such enhanced interstellar turbulence could be due to those interactions, either directly (i.e., as a result of the gravitational encounter) or indirectly (e.g., through increased star formation and supernova rates).

  10. ON THE HEATING EFFICIENCY DERIVED FROM OBSERVATIONS OF YOUNG SUPER STAR CLUSTERS IN M82

    SciTech Connect

    Silich, Sergiy; Tenorio-Tagle, Guillermo; Torres-Campos, Ana; Munoz-Tunon, Casiana; Monreal-Ibero, Ana; Melo, Veronica E-mail: cmt@ll.iac.es

    2009-08-01

    Here, we discuss the mechanical feedback that massive stellar clusters provide to the interstellar medium of their host galaxy. We apply an analytic theory developed in a previous study for M82-A1 to a sample of 10 clusters located in the central zone of the starburst galaxy M82, all surrounded by compact and dense H II regions. We claim that the only way that such H II regions can survive around the selected clusters, is if they are embedded into a high-pressure ISM and if the majority of their mechanical energy is lost within the star cluster volume via strong radiative cooling. The latter implies that these clusters have a low heating efficiency, {eta}, and evolve in the bimodal hydrodynamic regime. In this regime, the shock-heated plasma in the central zones of a cluster becomes thermally unstable, loses its pressure and is accumulated there, whereas the matter injected by supernovae and stellar winds outside this volume forms a high-velocity outflow-the star cluster wind. We calculated the heating efficiency for each of the selected clusters and found that in all cases it does not exceed 10%. Such low heating efficiency values imply a low mechanical energy output and the impact that the selected clusters provide to the ISM of M82 is thus much smaller than what one would expect using stellar cluster synthetic models.

  11. A connection between star formation activity and cosmic rays in the starburst galaxy M82.

    PubMed

    2009-12-10

    Although Galactic cosmic rays (protons and nuclei) are widely believed to be mainly accelerated by the winds and supernovae of massive stars, definitive evidence of this origin remains elusive nearly a century after their discovery. The active regions of starburst galaxies have exceptionally high rates of star formation, and their large size-more than 50 times the diameter of similar Galactic regions-uniquely enables reliable calorimetric measurements of their potentially high cosmic-ray density. The cosmic rays produced in the formation, life and death of massive stars in these regions are expected to produce diffuse gamma-ray emission through interactions with interstellar gas and radiation. M82, the prototype small starburst galaxy, is predicted to be the brightest starburst galaxy in terms of gamma-ray emission. Here we report the detection of >700-GeV gamma-rays from M82. From these data we determine a cosmic-ray density of 250 eV cm(-3) in the starburst core, which is about 500 times the average Galactic density. This links cosmic-ray acceleration to star formation activity, and suggests that supernovae and massive-star winds are the dominant accelerators.

  12. Evidence for sub-Chandrasekhar-mass progenitors of Type Ia supernovae at the faint end of the width-luminosity relation

    NASA Astrophysics Data System (ADS)

    Blondin, Stéphane; Dessart, Luc; Hillier, D. John; Khokhlov, Alexei M.

    2017-09-01

    The faster light-curve evolution of low-luminosity Type Ia supernovae (SNe Ia) suggests that they could result from the explosion of white dwarf (WD) progenitors below the Chandrasekhar mass (MCh). Here we present 1D non-local thermodynamic equilibrium time-dependent radiative transfer simulations of pure central detonations of carbon-oxygen WDs with a mass (Mtot) between 0.88 and 1.15 M⊙ and a 56Ni yield between 0.08 and 0.84 M⊙. Their lower ejecta density compared to MCh models results in a more rapid increase of the luminosity at early times and an enhanced γ-ray escape fraction past maximum light. Consequently, their bolometric light curves display shorter rise times and larger post-maximum decline rates. Moreover, the higher M(56Ni)/Mtot ratio at a given 56Ni mass enhances the temperature and ionization level in the spectrum-formation region for the less luminous models, giving rise to bluer colours at maximum light and a faster post-maximum evolution of the B - V colour. For sub-MCh models fainter than MB ≈ -18.5 mag at peak, the greater bolometric decline and faster colour evolution lead to a larger B-band post-maximum decline rate, ΔM15(B). In particular, all of our previously published MCh models (standard and pulsational delayed detonations) are confined to ΔM15(B) < 1.4 mag, while the sub-MCh models with Mtot ≲ 1 M⊙ extend beyond this limit to ΔM15(B) ≈ 1.65 mag for a peak MB ≈ -17 mag, in better agreement with the observed width-luminosity relation (WLR). Regardless of the precise ignition mechanism, these simulations suggest that fast-declining SNe Ia at the faint end of the WLR could result from the explosion of WDs whose mass is significantly below the Chandrasekhar limit.

  13. Widespread HCO Emission in the Nuclear Starburst of M82

    NASA Astrophysics Data System (ADS)

    García-Burillo, S.; Martín-Pintado, J.; Fuente, A.; Usero, A.; Neri, R.

    2002-08-01

    We present a high-resolution (~5") image of the nucleus of M82 showing the presence of widespread emission of the formyl radical (HCO). The HCO map, the first obtained in an external galaxy, reveals the existence of a structured disk of ~650 pc full diameter. The HCO distribution in the plane mimics the ring morphology displayed by other molecular/ionized gas tracers in M82. More precisely, rings traced by HCO, CO, and H II regions are nested, with the HCO ring lying in the outer edge of the molecular torus. Observations of HCO in Galactic clouds indicate that the abundance of HCO is strongly enhanced in the interfaces between the ionized and molecular gas. The surprisingly high overall abundance of HCO measured in M82 [X(HCO)~4×10-10] indicates that its nuclear disk can be viewed as a giant photon-dominated region (PDR) of ~650 pc size. The existence of various nested gas rings, with the highest HCO abundance occurring at the outer ring [X(HCO)~0.8×10-9], suggests that PDR chemistry is propagating in the disk. We discuss the inferred large abundances of HCO in M82 in the context of a starburst evolutionary scenario, picturing the M82 nucleus as an evolved starburst. Based on observations carried out with the Institut de Radioastronomie Millimétrique (IRAM) Plateau de Bure Interferometer. IRAM is supported by the Institut National des Sciences de l'Univers/Centre National de la Recherche Scientifique (France), the Max-Planck-Gesellschaft (Germany), and the Instituto Geográfico Nacional (Spain).

  14. Diffuse Atomic and Molecular Gas in the Interstellar Medium of M82 toward SN 2014J

    NASA Astrophysics Data System (ADS)

    Ritchey, Adam M.; Welty, Daniel E.; Dahlstrom, Julie A.; York, Donald G.

    2015-02-01

    We present a comprehensive analysis of interstellar absorption lines seen in moderately high resolution, high signal-to-noise ratio optical spectra of SN 2014J in M82. Our observations were acquired over the course of six nights, covering the period from ~6 days before to ~30 days after the supernova reached its maximum B-band brightness. We examine complex absorption from Na I, Ca II, K I, Ca I, CH+, CH, and CN, arising primarily from diffuse gas in the interstellar medium (ISM) of M82. We detect Li I absorption over a range in velocity consistent with that exhibited by the strongest Na I and K I components associated with M82; this is the first detection of interstellar Li in a galaxy outside of the Local Group. There are no significant temporal variations in the absorption-line profiles over the 37 days sampled by our observations. The relative abundances of the various interstellar species detected reveal that the ISM of M82 probed by SN 2014J consists of a mixture of diffuse atomic and molecular clouds characterized by a wide range of physical/environmental conditions. Decreasing N(Na I)/N(Ca II) ratios and increasing N(Ca I)/N(K I) ratios with increasing velocity are indicative of reduced depletion in the higher-velocity material. Significant component-to-component scatter in the N(Na I)/N(Ca II) and N(Ca I)/N(Ca II) ratios may be due to variations in the local ionization conditions. An apparent anti-correlation between the N(CH+)/N(CH) and N(Ca I)/N(Ca II) ratios can be understood in terms of an opposite dependence on gas density and radiation field strength, while the overall high CH+ abundance may be indicative of enhanced turbulence in the ISM of M82. The Li abundance also seems to be enhanced in M82, which supports the conclusions of recent gamma-ray emission studies that the cosmic-ray acceleration processes are greatly enhanced in this starburst galaxy.

  15. Extragalactic Chemistry of Starbursts: the Case of M82

    NASA Astrophysics Data System (ADS)

    Usero, A.; García-Burillo, S.

    2003-09-01

    The study of Chemistry in External Galaxies has been made possible since the advent of last generation millimeter telescopes/interferometers. Going beyond CO maps is key to study the evolutionary path of massive star formation episodes in galaxies. We present here the results obtained from a high-resolution (~5'') study made in the nucleus of the starburst galaxy M82, based on observations of the silicon monoxide (SiO) and the formyl radical (HCO) species. Observations have been carried out with the IRAM Plateau de Bure interferometer. SiO and HCO are privileged tracers of shock chemistry and photon-dominated regions (PDR) environments, respectively. These maps show a sharp picture of the heavy influence of the star formation episode on the properties of the interstellar medium in M82.

  16. Super star clusters in the starburst core of M82

    NASA Astrophysics Data System (ADS)

    Westmoquette, Mark

    2009-07-01

    M82 is the archetype starburst galaxy and the nearest {3.6 Mpc} analogue to the star-forming galaxies identified at high-z. No other galaxy affords the opportunity to study an active starburst at such high spatial resolution, and with such a wealth of complimentary data available in the literature. In our cycle 10 STIS programme, we carried out the first spectroscopic study of a cluster in the core of the M82 starburst. Intriguingly, we found this young {6.5 Myr} cluster to be surrounded by a compact {4.5 pc}, high-pressure HII region, whose evolution appears to have been significantly affected by the high ambient pressures found in this region of the starburst. We therefore propose to obtain spatially resolved STIS spectroscopy of a sample of star clusters within the starburst core, distributed over a range of ambient conditions. Together with measuring accurate ages, masses, sizes, and extinctions of the star clusters, we will also measure the properties of their immediate environments {gas dynamics, pressures/densities, excitations}. Only with the spatial resolution of STIS can we isolate individual clusters in the crowded starburst core of M82, where the background is also bright and highly variable.The data from this proposal will uniquely chart relationships between SSCs and the ISM in their immediate vicinities. By so doing, they will provide the first systematic measurements of how SSCs transmit their power to their surroundings, and ultimately to the starburst-powered galactic wind.

  17. The Rise of SN 2014J in the Nearby Galaxy M 82

    NASA Technical Reports Server (NTRS)

    A.Goobar; Johansson, J.; Amanullah, R.; Cao, Y.; Perley, D.A.; Kasliwal, M. M.; Ferreti, R.; Nugent, P. E.; Harris, C.; Cenko, S. B.

    2014-01-01

    We report on the discovery of SN 2014J in the nearby galaxy M 82. Given its proximity, it offers the best opportunity to date to study a thermonuclear supernova over a wide range of the electromagnetic spectrum. Optical, near-IR and mid-IR observations on the rising lightcurve, orchestrated by the intermediate Palomar Transient Factory (iPTF), show that SN 2014J is a spectroscopically normal Type Ia supernova, albeit exhibiting high-velocity features in its spectrum and heavily reddened by dust in the host galaxy. Our earliest detections start just hours after the fitted time of explosion. We use high-resolution optical spectroscopy to analyze the dense intervening material and do not detect any evolution in the resolved absorption features during the lightcurve rise. Similarly to other highly reddened Type Ia supernovae, a low value of total-to-selective extinction, R (sub V) less than or approximately equal to 2, provides the best match to our observations. We also study pre-explosion optical and near-IR images from HST with special emphasis on the sources nearest to the SN location.

  18. New HI Clouds In The M81/M82 Group

    NASA Astrophysics Data System (ADS)

    Chynoweth, Katie M.; Langston, G.

    2007-12-01

    We present 5 newly discovered neutral hydrogen clouds in the M81/M82 group of galaxies, detected using the Robert C. Byrd Green Bank Telescope (GBT). All of the objects have properties similar to those of clouds previously found in our galaxy and other nearby galaxies. Based on the small angular distance of the clouds to group members, and the small velocity difference between group members and clouds, we conclude that the clouds are most likely stabilized relics of ongoing interactions between galaxies in the group. Our results are inconsistent with models of primordial HI clouds falling into the cluster. Previous studies of HI clouds have focused on the Milky Way and M31. Both galaxies are in a fairly relaxed state, and not currently interacting strongly with other galaxies. The M81/M82 group, in contrast, is highly unrelaxed and obviously interacting. Therefore, the study of HI clouds and other structures in the group is important in order to understand the full lifetime of these structures in relation to galaxy interactions. At 3.63 Mpc, the M81/M82 group is one of the closest groups, and because of its high declination and galactic latitude is an ideal location to search for analogs to local HVCs. We have searched the group in a 2° x 2° area, with a velocity range of greater than ± 500 km/s from any group galaxy, with a velocity resolution of 5.2 km/s. With a 7-sigma detection threshold of 8.4 x 10^5 M_Sun, we detect 5 HI clouds associated with the group, as well as associated filamentary HI structures. The clouds have masses between 10^6 and 10^7 M_Sun. The clouds are found only within small velocity differences from group members, and only at small angular separations. This work was supported by the NRAO Graduate Summer Student Research Assistantship Program.

  19. EVOLVING STARBURST MODELING OF FAR-INFRARED/SUBMILLIMETER/MILLIMETER LINE EMISSION. II. APPLICATION TO M 82

    SciTech Connect

    Yao Lihong

    2009-11-01

    We present starburst models for far-infrared/sub-millimeter/millimeter line emission of molecular and atomic gas in an evolving starburst region, which is treated as an ensemble of noninteracting hot bubbles that drive spherical shells of swept-up gas into a surrounding uniform gas medium. These bubbles and shells are driven by stellar winds and supernovae within massive star clusters formed during an instantaneous starburst. The underlying stellar radiation from the evolving clusters affects the properties and structure of photodissociation regions (PDRs) in the shells, and hence the spectral energy distributions (SEDs) of the molecular and atomic line emission from these swept-up shells and the associated parent giant molecular clouds contain a signature of the stage of evolution of the starburst. The physical and chemical properties of the shells and their structure are computed using a simple, well-known similarity solution for the shell expansion, a stellar population synthesis code, and a time-dependent PDR chemistry model. The SEDs for several molecular and atomic lines ({sup 12}CO and its isotope {sup 13}CO, HCN, HCO{sup +}, C, O, and C{sup +}) are computed using a nonlocal thermodynamic equilibrium line radiative transfer model. By comparing our models with the available observed data of nearby infrared bright galaxies, especially M 82, we constrain the models and in the case of M 82, we provide estimates for the ages (5-6 Myr, 10 Myr) of recent starburst activity. We also derive a total H{sub 2} gas mass of approx(2-3.4) x 10{sup 8} M {sub sun} for the observed regions of the central 1 kpc starburst disk of M 82.

  20. BIMA CO Observations of the Starburst Nucleus of M82

    NASA Astrophysics Data System (ADS)

    Shen, Jianjun; Lo, K. Y.

    1995-04-01

    Observations with 2.5" (38 pc) resolution of the CO (J=1-0) emission from the starburst nucleus of M82, obtained with the Berkeley-Illinois-Maryland Association (BIMA) 6-element millimeter-wave array, have revealed unresolved (< 30 pc) structure in the CO emission with very high brightness temperature (up to 34 K). The new observations have also resolved the previously identified double lobe and central peak in the integrated CO intensity into many peaks that are all due to ``velocity crowding" of several velocity components. Most of the CO emitting gas could be located in molecular spiral arms at 125 pc and 390 pc from the nucleus. Outflow motion (approximately 230 km/s) of part of the molecular gas normal to the plane is also indicated. The new observations suggest that the starbursts took place within molecular spiral arms at some distance from the nucleus. The starbursts may in fact have propagated inwards. Given the substantial amount of dense molecular gas still present in the M82 starburst region, it is not clear why the starburst activity appears to have subsided.

  1. Supernova VLBI

    NASA Astrophysics Data System (ADS)

    Bartel, N.

    2009-08-01

    We review VLBI observations of supernovae over the last quarter century and discuss the prospect of imaging future supernovae with space VLBI in the context of VSOP-2. From thousands of discovered supernovae, most of them at cosmological distances, ˜50 have been detected at radio wavelengths, most of them in relatively nearby galaxies. All of the radio supernovae are Type II or Ib/c, which originate from the explosion of massive progenitor stars. Of these, 12 were observed with VLBI and four of them, SN 1979C, SN 1986J, SN 1993J, and SN 1987A, could be imaged in detail, the former three with VLBI. In addition, supernovae or young supernova remnants were discovered at radio wavelengths in highly dust-obscured galaxies, such as M82, Arp 299, and Arp 220, and some of them could also be imaged in detail. Four of the supernovae so far observed were sufficiently bright to be detectable with VSOP-2. With VSOP-2 the expansion of supernovae can be monitored and investigated with unsurpassed angular resolution, starting as early as the time of the supernova's transition from its opaque to transparent stage. Such studies can reveal, in a movie, the aftermath of a supernova explosion shortly after shock break out.

  2. Supernovae

    NASA Astrophysics Data System (ADS)

    March, Marisa

    2014-03-01

    We live in a Universe that is getting bigger faster. This astonishing discovery of Universal acceleration was made in the late 1990s by two teams who made observations of a special type of exploded star known as a `Supernova Type Ia'. (SNeIa) Since the discovery of the accelerating Universe, one of the biggest questions in modern cosmology has been to determine the cause of that acceleration - the answer to this question will have far reaching implications for our theories of cosmology and fundamental physics more broadly. The two main competing explanations for this apparent late time acceleration of the Universe are modified gravity and dark energy. The Dark Energy Survey (DES) has been designed and commissioned to find to find answers to these questions about the nature of dark energy and modified gravity. The new 570 megapixel Dark Energy Camera is currently operating with the Cerro-Tololo Inter American Observatory's 4m Blanco teleccope, carrying out a systematic search for SNeIa, and mapping out the large scale structure of the Universe by making observations of galaxies. The DES science program program which saw first light in September 2013 will run for five years in total. DES SNeIa data in combination with the other DES observations of large scale structure will enable us to put increasingly accurate constraints on the expansion history of the Universe and will help us distinguish between competing theories of dark energy and modified gravity. As we draw to the close of the first observing season of DES in March 2014, we will report on the current status of the DES supernova survey, presenting first year supernovae data, preliminary results, survey strategy, discovery pipeline, spectroscopic target selection and data quality. This talk will give the first glimpse of the DES SN first year data and initial results as we begin our five year survey in search of dark energy. On behalf of the Dark Energy Survey collaboration.

  3. Probing the Mass Distribution and Stellar Populations of M82

    NASA Astrophysics Data System (ADS)

    Greco, Johnny; Martini, P.; Thompson, T. A.

    2012-01-01

    M82 is often considered the archetypical starburst galaxy because of its spectacular starbust-driven superwind. Its close proximity of 3.6 Mpc and nearly edge-on geometry make it a unique laboratory for studying the physics of rapid star formation and violent galactic winds. In addition, there is evidence that it has been tidally-truncated by its interaction with M81 and therefore has essentially no dark matter halo. The mass distribution of this galaxy is needed to estimate the power of its superwind, as well as determine if a dark matter halo is still present. Numerous studies have used stellar and gas dynamics to estimate the mass distribution, yet the substantial dust attenuation has been a significant challenge. We have measured the stellar kinematics in the near-infrared K-band with the LUCI-1 spectrograph at the Large Binocular Telescope. We used the '2CO stellar absorption bandhead at 2.29µm to measure the stellar rotation curve out to ˜4kpc, and our results confirm that the dark matter halo is still present. This is in stark contrast with the nearly Keplerian gas dynamics measured with HI and CO emission from the interstellar medium. We estimate M82's dynamical mass to be ˜1010 M⊙. We have also measured the equivalent width of the 12CO bandhead to provide new constraints on the spatial extent of the red supergiant population. The variation in the CO equivalent width with radius clearly shows that supergiants dominate the light within 0.5kpc radius. The superwind is likely launched from this region, where we estimate the enclosed mass is 2×109 M⊙.

  4. OBSERVATIONS OF THE M82 SN 2014J WITH THE KILODEGREE EXTREMELY LITTLE TELESCOPE

    SciTech Connect

    Siverd, Robert J.; Stassun, Keivan G.; Pepper, Joshua; Goobar, Ariel

    2015-01-20

    We report observations of the bright M82 supernova 2014J serendipitously obtained with the Kilodegree Extremely Little Telescope (KELT). The supernova (SN) was observed at high cadence for over 100 days, from pre-explosion, to early rise and peak times, through the secondary bump. The high cadence KELT data with high signal-to-noise ratio is completely unique for SN 2014J and for any other SNIa, with the exception of the (yet) unpublished Kepler data. Here, we report determinations of the SN explosion time and peak time. We also report measures of the ''smoothness'' of the light curve on timescales of minutes/hours never before probed, and we use this to place limits on energy produced from short-lived isotopes or inhomogeneities in the explosion or the circumstellar medium. From the non-observation of significant perturbations of the light curves, we derive a 3σ upper limit corresponding to 8.7 × 10{sup 36} erg  s{sup –1} for any such extra sources of luminosity at optical wavelengths.

  5. THE RISE OF SN 2014J IN THE NEARBY GALAXY M82

    SciTech Connect

    Goobar, A.; Johansson, J.; Amanullah, R.; Ferretti, R.; Cao, Y.; Perley, D. A.; Tendulkar, S. P.; Kasliwal, M. M.; Nugent, P. E.; Harris, C.; Gal-Yam, A.; Ofek, E. O.; Dennefeld, M.; Valenti, S.; Arcavi, I.; Banerjee, D. P. K.; Venkataraman, V.; Joshi, V.; Ashok, N. M.; Cenko, S. B.; and others

    2014-03-20

    We report on the discovery of SN 2014J in the nearby galaxy M82. Given its proximity, it offers the best opportunity to date to study a thermonuclear supernova (SN) over a wide range of the electromagnetic spectrum. Optical, near-IR, and mid-IR observations on the rising light curve, orchestrated by the intermediate Palomar Transient Factory, show that SN 2014J is a spectroscopically normal Type Ia supernova (SN Ia), albeit exhibiting high-velocity features in its spectrum and heavily reddened by dust in the host galaxy. Our earliest detections start just hours after the fitted time of explosion. We use high-resolution optical spectroscopy to analyze the dense intervening material and do not detect any evolution in the resolved absorption features during the light curve rise. Similar to other highly reddened SNe Ia, a low value of total-to-selective extinction, R{sub V} ≲ 2, provides the best match to our observations. We also study pre-explosion optical and near-IR images from Hubble Space Telescope with special emphasis on the sources nearest to the SN location.

  6. Mid-IR FORCAST/SOFIA Observations of M82

    NASA Astrophysics Data System (ADS)

    Nikola, T.; Herter, T. L.; Vacca, W. D.; Adams, J. D.; De Buizer, J. M.; Gull, G. E.; Henderson, C. P.; Keller, L. D.; Morris, M. R.; Schoenwald, J.; Stacey, G.; Tielens, A.

    2012-04-01

    We present 75'' × 75'' size maps of M82 at 6.4 μm, 6.6 μm, 7.7 μm, 31.5 μm, and 37.1 μm with a resolution of ~4'' that we have obtained with the mid-IR camera FORCAST on SOFIA. We find strong emission from the inner 60'' (~1 kpc) along the major axis, with the main peak 5'' west-southwest of the nucleus and a secondary peak 4'' east-northeast of the nucleus. The detailed morphology of the emission differs among the bands, which is likely due to different dust components dominating the continuum emission at short mid-IR wavelengths and long mid-IR wavelengths. We include Spitzer-IRS and Herschel/PACS 70 μm data to fit spectral energy distribution templates at both emission peaks. The best-fitting templates have extinctions of AV = 18 and AV = 9 toward the main and secondary emission peak and we estimated a color temperature of 68 K at both peaks from the 31 μm and 37 μm measurement. At the emission peaks the estimated dust masses are on the order of 104 M ⊙.

  7. Fainting (Syncope)

    MedlinePlus

    ... Adults Making Your Wishes Known Home & Community Home › Aging & Health A to Z › Fainting (Syncope) Font size A A A Print Share Glossary Basic Facts & Information Causes & Symptoms Diagnosis & Tests Care & Treatment Lifestyle & Management Other Resources Caregiving How ...

  8. A CENSUS OF THE HIGH-DENSITY MOLECULAR GAS IN M82

    SciTech Connect

    Naylor, B. J.; Bradford, C. M.; Bock, J. J.; Nguyen, H. T.; Zmuidzinas, J.; Aguirre, J. E.; Earle, L.; Glenn, J.; Kamenetzky, J.; Maloney, P. R.; Inami, H.; Matsuhara, H.

    2010-10-10

    We present a three-pointing study of the molecular gas in the starburst nucleus of M82 based on 190-307 GHz spectra obtained with Z-Spec at the Caltech Submillimeter Observatory. We present intensity measurements, detections, and upper limits, for 20 transitions, including several new detections of CS, HNC, C{sub 2}H, H{sub 2}CO, and CH{sub 3}CCH lines. We combine our measurements with previously published measurements at other frequencies for HCN, HNC, CS, C{sup 34}S, and HCO{sup +} in a multi-species likelihood analysis constraining gas mass, density and temperature, and the species' relative abundances. We find some (1.7-2.7) x 10{sup 8} M{sub sun} of gas with n{sub H{sub 2}} between (1-6) x 10{sup 4} cm{sup -3} and T > 50 K. While the mass and temperature are comparable to values inferred from mid-J CO transitions, the thermal pressure is a factor of 10-20 greater. The molecular interstellar medium is largely fragmented and is subject to ultraviolet irradiation from the star clusters. It is also likely subject to cosmic rays and mechanical energy input from the supernovae, and is warmer on average than the molecular gas in the massive star formation (SF) regions in the Milky Way. The typical conditions in the dense gas in M82's central kiloparsec appear unfavorable for further SF; if any appreciable stellar populations are currently forming, they are likely biased against low-mass stars, producing a top-heavy initial mass function.

  9. A LIKELY MICRO-QUASAR IN THE SHADOW OF M82 X-1

    SciTech Connect

    Xu, Xiao-jie; Liu, Jifeng; Liu, Jiren E-mail: jfliu@nao.cas.cn

    2015-02-01

    The ultra-luminous X-ray source M82 X-1 is one of the most promising intermediate mass black hole candidates in the local universe based on its high X-ray luminosities (10{sup 40}–10{sup 41} erg s{sup −1}) and quasi-periodic oscillations, and is possibly associated with a radio flare source. In this work, applying the sub-pixel technique to the 120 ks Chandra observation (ID: 10543) of M82 X-1, we split M82 X-1 into two sources separated by 1.″1. The secondary source is not detected in other M82 observations. The radio flare source is not found to associate with M82 X-1, but is instead associated with the nearby transient source S1 with an outburst luminosity of ∼10{sup 39} erg s{sup −1}. With X-ray outburst and radio flare activities analogous to the recently discovered micro-quasar in M31, S1 is likely to be a micro-quasar hidden in the shadow of M82 X-1.

  10. Intergalactic Stellar Distributions in the Interacting M81/M82 Galaxy Group

    NASA Astrophysics Data System (ADS)

    Sun, W.-H.; Zhou, Xu; Chen, W.-P.; Burstein, D.; Windhorst, R. A.; Ma, J.; Byun, Y.-I.; Jiang, Z.-J.; Chen, J.-S.

    2005-12-01

    Previous HI observations of the M81/M82/NGC3077 system clearly show widespread HI distribution within this galaxy group. While the gas is vulnerable to tidal disruption of a galaxy encounter, are there also stars imbedded in this HI distribution? Our deep exposures of the M81+M82 group in 10 optical bands using the Beijing-Arizona-Taipei-Connecticut (BATC) filter set clearly reveal, for the first time, widespread stellar distributions that coincide with the atomic hydrogen clouds - considered to be the relics of the merging process of the galaxies - splayed over the region. The spectral energy distributions of the stellar groups to the east and west of M81 (including the "Arp" Loop) are similar to that measured at the southeast edge of the optical disk of M82. This similarity in stellar radiation, combined with the observed peculiar rotational velocity of M82, suggests that the diffuse stellar population in the intergalactic space around M81 is mainly the relic of the tidally-disrupted disk of M82 during the last close encounter. Recent measurements of distances to and CBR radial velocities of M81 (3.63 Mpc and 48 km/s) and M82 (3.9 Mpc and 296 km/s) lend further support to the notion of a close passage between these two galaxies several hundred million years ago.

  11. Diffuse Interstellar Bands versus Known Atomic and Molecular Species in the Interstellar Medium of M82 toward SN 2014J

    NASA Astrophysics Data System (ADS)

    Welty, Daniel E.; Ritchey, Adam M.; Dahlstrom, Julie A.; York, Donald G.

    2014-09-01

    We discuss the absorption due to various constituents of the interstellar medium (ISM) of M82 seen in moderately high-resolution, high signal-to-noise ratio optical spectra of SN 2014J. Complex absorption from M82 is seen, at velocities 45 <~ v LSR <~ 260 km s-1, for Na I, K I, Ca I, Ca II, CH, CH+, and CN; many of the diffuse interstellar bands (DIBs) are also detected. Comparisons of the column densities of the atomic and molecular species and the equivalent widths of the DIBs reveal both similarities and differences in relative abundances, compared to trends seen in the ISM of our Galaxy and the Magellanic Clouds. Of the 10 relatively strong DIBs considered here, 6 (including λ5780.5) have strengths within ±20% of the mean values seen in the local Galactic ISM, for comparable N(K I); 2 are weaker by 20%-45% and 2 (including λ5797.1) are stronger by 25%-40%. Weaker than "expected" DIBs (relative to N(K I), N(Na I), and E(B - V)) in some Galactic sight lines and toward several other extragalactic supernovae appear to be associated with strong CN absorption and/or significant molecular fractions. While the N(CH)/N(K I) and N(CN)/N(CH) ratios seen toward SN 2014J are similar to those found in the local Galactic ISM, the combination of high N(CH+)/N(CH) and high W(5797.1)/W(5780.5) ratios has not been seen elsewhere. The centroids of many of the M82 DIBs are shifted relative to the envelope of the K I profile—likely due to component-to-component variations in W(DIB)/N(K I) that may reflect the molecular content of the individual components. We compare estimates for the host galaxy reddening E(B - V) and visual extinction A V derived from the various interstellar species with the values estimated from optical and near-IR photometry of SN 2014J.

  12. Diffuse interstellar bands versus known atomic and molecular species in the interstellar medium of M82 toward SN 2014J

    SciTech Connect

    Welty, Daniel E.; York, Donald G.; Ritchey, Adam M.; Dahlstrom, Julie A.

    2014-09-10

    We discuss the absorption due to various constituents of the interstellar medium (ISM) of M82 seen in moderately high-resolution, high signal-to-noise ratio optical spectra of SN 2014J. Complex absorption from M82 is seen, at velocities 45 ≲ v {sub LSR} ≲ 260 km s{sup –1}, for Na I, K I, Ca I, Ca II, CH, CH{sup +}, and CN; many of the diffuse interstellar bands (DIBs) are also detected. Comparisons of the column densities of the atomic and molecular species and the equivalent widths of the DIBs reveal both similarities and differences in relative abundances, compared to trends seen in the ISM of our Galaxy and the Magellanic Clouds. Of the 10 relatively strong DIBs considered here, 6 (including λ5780.5) have strengths within ±20% of the mean values seen in the local Galactic ISM, for comparable N(K I); 2 are weaker by 20%-45% and 2 (including λ5797.1) are stronger by 25%-40%. Weaker than 'expected' DIBs (relative to N(K I), N(Na I), and E(B – V)) in some Galactic sight lines and toward several other extragalactic supernovae appear to be associated with strong CN absorption and/or significant molecular fractions. While the N(CH)/N(K I) and N(CN)/N(CH) ratios seen toward SN 2014J are similar to those found in the local Galactic ISM, the combination of high N(CH{sup +})/N(CH) and high W(5797.1)/W(5780.5) ratios has not been seen elsewhere. The centroids of many of the M82 DIBs are shifted relative to the envelope of the K I profile—likely due to component-to-component variations in W(DIB)/N(K I) that may reflect the molecular content of the individual components. We compare estimates for the host galaxy reddening E(B – V) and visual extinction A {sub V} derived from the various interstellar species with the values estimated from optical and near-IR photometry of SN 2014J.

  13. The Green Bank Telescope Maps the Dense, Star-forming Gas in the Nearby Starburst Galaxy M82

    NASA Astrophysics Data System (ADS)

    Kepley, Amanda A.; Leroy, Adam K.; Frayer, David; Usero, Antonio; Marvil, Josh; Walter, Fabian

    2014-01-01

    Observations of the Milky Way and nearby galaxies show that dense molecular gas correlates with recent star formation, suggesting that the formation of this gas phase may help regulate star formation. A key test of this idea requires wide-area, high-resolution maps of dense molecular gas in galaxies to explore how local physical conditions drive dense gas formation, but these observations have been limited because of the faintness of dense gas tracers like HCN and HCO+. Here we demonstrate the power of the Robert C. Byrd Green Bank Telescope (GBT)—the largest single-dish millimeter radio telescope—for mapping dense gas in galaxies by presenting the most sensitive maps yet of HCN and HCO+ in the starburst galaxy M82. The HCN and HCO+ in the disk of this galaxy correlates with both recent star formation and more diffuse molecular gas and shows kinematics consistent with a rotating torus. The HCO+ emission extending to the north and south of the disk is coincident with the outflow previously identified in CO and traces the eastern edge of the hot outflowing gas. The central starburst region has a higher ratio of star formation to dense gas than the outer regions, pointing to the starburst as a key driver of this relationship. These results establish that the GBT can efficiently map the dense molecular gas at 90 GHz in nearby galaxies, a capability that will increase further with the 16 element feed array under construction.

  14. TWO CANDIDATE OPTICAL COUNTERPARTS OF M82 X-1 FROM HST OBSERVATIONS

    SciTech Connect

    Wang, Song; Liu, Jifeng; Bai, Yu; Guo, Jincheng E-mail: songw@bao.ac.cn

    2015-10-20

    Optical counterparts can provide significant constraints on the physical nature of ultraluminous X-ray sources (ULXs). In this Letter, we identify six point sources in the error circle of a ULX in M82, namely M82 X-1, by registering Chandra positions onto Hubble Space Telescope images. Two objects are considered as optical counterpart candidates of M82 X-1, which show F658N flux excess compared to the optical continuum that may suggest the existence of an accretion disk. The spectral energy distributions of the two candidates match well with the spectra for supergiants, with stellar types as F5-G0 and B5-G0, respectively. Deep spatially resolved spectroscopic follow-up and detailed studies are needed to identify the true companion and confirm the properties of this BH system.

  15. Intergalactic Stellar Distributions in the Interacting M81/M82 Galaxy Group

    NASA Astrophysics Data System (ADS)

    Sun, W.-H.; Zhou, X.; Chen, W.-P.; Burstein, D.; Windhorst, R. A.; Ma, J.; Byun, Y.-I.; Jiang, Z.-J.; Chen, J.-S.

    2005-09-01

    Previous H I observations of the M81/M82/NGC 3077 galaxy group clearly show a widespread H I distribution within this galaxy group. While the gas is vulnerable to tidal disruption from a galaxy encounter, are there also stars embedded in this H I distribution? Our deep, 1 deg2 exposures of the M81/M82 group in 10 optical bands using the Beijing-Arizona-Taipei-Connecticut (BATC) filter set clearly reveal widespread stellar distributions that coincide with the atomic hydrogen clouds-considered to be the relics of the merging process of the galaxies-splayed over the region. The spectral energy distributions of the stellar groups to the east and west of M81 (including the ``Arp Loop'') are similar to that measured at the southeast edge of the optical disk of M82. This similarity in stellar radiation, combined with the observed peculiar rotational velocity of M82, suggests that the diffuse stellar population in the intergalactic space around M81 is possibly a relic of the tidally disrupted disk of M82 during the last close encounter. Alternately, the stars could have formed in situ in the H I as it was drawn out of the galaxies. Recent measurements of distances to and radial velocities of M81 (3.63 Mpc and 48 km s-1, respectively) and M82 (3.9 Mpc and 296 km s-1) lend further support to the notion of a close passage between these two galaxies several hundred million years ago.

  16. M 82 - A radio continuum and polarisation study. I. Data reduction and cosmic ray propagation

    NASA Astrophysics Data System (ADS)

    Adebahr, B.; Krause, M.; Klein, U.; Weżgowiec, M.; Bomans, D. J.; Dettmar, R.-J.

    2013-07-01

    Context. The potential role of magnetic fields and cosmic ray propagation for feedback processes in the early Universe can be probed by studies of local starburst counterparts with an equivalent star-formation rate. Aims: In order to study the cosmic ray propagation and determine the magnetic field strength and dominant loss processes in the nearby prototypical starbursting galaxy M 82, a multi-frequency analysis at four radio wavelengths is presented. Methods: Archival data from the Westerbork Synthesis Radio Telescope (WSRT) was reduced and a new calibration technique introduced to reach the high dynamic ranges needed for the complex source morphology. These data were combined with archival Very Large Array (VLA) data, yielding total power maps at λ3 cm, λ6 cm, λ22 cm, and λ92 cm. Results: The data show a confinement of the emission at wavelengths of λ3/λ6 cm to the core region and a largely extended halo reaching up to 4 kpc away from the galaxy midplane at wavelengths of λ22/λ92 cm up to a sensitivity limit of 90 μJy and 1.8 mJy respectively indicating different physical processes in the core and halo regions. The results are used to calculate the magnetic field strength to 98 μG in the core region and to 24 μG in the halo regions. From the observation of ionisation losses, the filling factor of the ionised medium could be estimated to 2%. This leads to a revised view of the magnetic field distribution in the core region and the propagation processes from the core into the halo regions. Conclusions: We find that the radio emission from the core region is dominated by very dense H ii-regions and supernova remnants, while the surrounding medium is filled with hot X-ray and neutral gas. Cosmic rays radiating at frequencies higher than 1.4 GHz suffer from high synchrotron and inverse Compton losses in the core region and are not able to reach the halo. Even the cosmic rays radiating at longer wavelengths are only able to build up the observed kpc

  17. The N (II) 205 micron line in M82: The warm ionized medium

    NASA Technical Reports Server (NTRS)

    Petuchowski, S. J.; Bennett, C. L.; Haas, Michael R.; Erickson, Edwin F.; Lord, Steven D.; Rubin, Robert H.; Colgan, Sean W. J.; Hollenbach, D. J.

    1994-01-01

    Detection of the 205 micrometer fine structure line of N II in the nearby starburst galaxy M82 is reported. The intensity wihin a 54 sec Full width at Half Maximum (FWHM) beam is (7.1 +/- 1.2) x 10(exp -19) W cm(exp -2). The ratio of the intensity of the recently detected 122 micrometer line to that of the 2.5 micrometer lines is = (4.2) (sup =1.6) (sub -1.2), significantly larger than the corresponding Galactic value of 1.6 +/- 0.3, reflecting higher electron densities within the central 850 pc of M82 in comparison to the Cosmic Background Explorer (COBE) Galactic average. The 2.5 micrometer line profile is consistent with other far-infrared fine-structure line profiles observed in M82. The observations are interpreted in the context of a two-component model of the ionized medium in M82. We find that a component of density as low as approximately 50 cm(exp -3) can comprise up to 70% of the total mass of warm ionized gas within the beam. The balance of the ionized mass is comprised of a component of density approximately greater than 100 cm(exp -3). A model is explored in which the dneser ionized medium constitute the boundaries of neutral surfaces which border the expanding hot plasma from the nuclear region.

  18. THE GREEN BANK TELESCOPE MAPS THE DENSE, STAR-FORMING GAS IN THE NEARBY STARBURST GALAXY M82

    SciTech Connect

    Kepley, Amanda A.; Frayer, David; Leroy, Adam K.; Usero, Antonio; Walter, Fabian

    2014-01-01

    Observations of the Milky Way and nearby galaxies show that dense molecular gas correlates with recent star formation, suggesting that the formation of this gas phase may help regulate star formation. A key test of this idea requires wide-area, high-resolution maps of dense molecular gas in galaxies to explore how local physical conditions drive dense gas formation, but these observations have been limited because of the faintness of dense gas tracers like HCN and HCO{sup +}. Here we demonstrate the power of the Robert C. Byrd Green Bank Telescope (GBT)—the largest single-dish millimeter radio telescope—for mapping dense gas in galaxies by presenting the most sensitive maps yet of HCN and HCO{sup +} in the starburst galaxy M82. The HCN and HCO{sup +} in the disk of this galaxy correlates with both recent star formation and more diffuse molecular gas and shows kinematics consistent with a rotating torus. The HCO{sup +} emission extending to the north and south of the disk is coincident with the outflow previously identified in CO and traces the eastern edge of the hot outflowing gas. The central starburst region has a higher ratio of star formation to dense gas than the outer regions, pointing to the starburst as a key driver of this relationship. These results establish that the GBT can efficiently map the dense molecular gas at 90 GHz in nearby galaxies, a capability that will increase further with the 16 element feed array under construction.

  19. Optical depth of molecular gas in starburst galaxies - Is M82 the prototype?

    NASA Technical Reports Server (NTRS)

    Verter, F.; Rickard, L. J.

    1989-01-01

    An attempt is made to survey the CO(2-1) emission toward the centers of 17 IR-luminous galaxies which have previously been detected in CO(1-0). These galaxies span a wide range of size and L(FIR)/L(B) ratio, many have multiple-wavelength studies establishing them as starbursts, and some bear a morphological resemblance to M 82. Nine galaxies are detected and useful upper limits are placed on the remaining eight. Using the CO(2-1)/CO(1-0) ratio of antenna temperature as a diagnostic of optical depth, it is found that all of the galaxies contain predominantly optically thick molecular gas. This implies that the phase of starburst during which the molecular gas is optically thin, currently witnessed in M 82, is either uncommon or short-lived.

  20. Dust scattering and the radiation pressure force in the M82 superwind

    SciTech Connect

    Coker, Carl T.; Thompson, Todd A.; Martini, Paul E-mail: thompson@astronomy.ohio-state.edu

    2013-11-20

    Radiation pressure on dust grains may be an important physical mechanism driving galaxy-wide superwinds in rapidly star-forming galaxies. We calculate the combined dust and gas Eddington ratio (Γ) for the archetypal superwind of M82. By combining archival Galaxy Evolution Explorer data, a standard dust model, Monte Carlo dust scattering calculations, and the Herschel map of the dust surface density distribution, the observed far-UV/near-UV surface brightness in the outflow constrains both the total UV luminosity escaping from the starburst along its minor axis (L {sub *,UV}) and the flux-mean opacity, thus allowing a calculation of Γ. We find that L {sub *,UV} ≈ (1-6) × 10{sup 42} erg s{sup –1}, ∼2-12 times greater than the UV luminosity observed from our line of sight. On a scale of 1-3 kpc above the plane of M82, we find that Γ ∼ 0.01-0.06. On smaller scales (∼0.25-0.5 kpc), where the enclosed mass decreases, our calculation of L {sub *,UV} implies that Γ ∼ 0.1 with factor of few uncertainties. Within the starburst itself, we estimate the single-scattering Eddington ratio to be of order unity. Thus, although radiation pressure is weak compared to gravity on kpc scales above the plane of M82, it may yet be important in launching the observed outflow. We discuss the primary uncertainties in our calculation, the sensitivity of Γ to the dust grain size distribution, and the time evolution of the wind following M82's recent starburst episodes.

  1. A 400-solar-mass black hole in the galaxy M82.

    PubMed

    Pasham, Dheeraj R; Strohmayer, Tod E; Mushotzky, Richard F

    2014-09-04

    M82 X-1, the brightest X-ray source in the galaxy M82, has been thought to be an intermediate-mass black hole (100 to 10,000 solar masses) because of its extremely high luminosity and variability characteristics, although some models suggest that its mass may be only about 20 solar masses. The previous mass estimates were based on scaling relations that use low-frequency characteristic timescales which have large intrinsic uncertainties. For stellar-mass black holes, we know that the high-frequency quasi-periodic oscillations (100-450 hertz) in the X-ray emission that occur in a 3:2 frequency ratio are stable and scale in frequency inversely with black hole mass with a reasonably small dispersion. The discovery of such stable oscillations thus potentially offers an alternative and less ambiguous means of mass determination for intermediate-mass black holes, but has hitherto not been realized. Here we report stable, twin-peak (3:2 frequency ratio) X-ray quasi-periodic oscillations from M82 X-1 at frequencies of 3.32 ± 0.06 hertz and 5.07 ± 0.06 hertz. Assuming that we can extrapolate the inverse-mass scaling that holds for stellar-mass black holes, we estimate the black hole mass of M82 X-1 to be 428 ± 105 solar masses. In addition, we can estimate the mass using the relativistic precession model, from which we get a value of 415 ± 63 solar masses.

  2. Constraining the dipolar magnetic field of M82 X-2 by the accretion model

    NASA Astrophysics Data System (ADS)

    Chen, Wen-Cong

    2017-02-01

    Recently, ultraluminous X-ray source (ULX) M82 X-2 has been identified to be an accreting neutron star, which has a P = 1.37 s spin period, and is spinning up at a rate dot{P}=-2.0× 10^{-10} s s^{-1}. Interestingly, its isotropic X-ray luminosity Liso = 1.8 × 1040 erg s- 1 during outbursts is 100 times the Eddington limit for a 1.4 M⊙ neutron star. In this Letter, based on the standard accretion model we attempt to constrain the dipolar magnetic field of the pulsar in ULX M82 X-2. Our calculations indicate that the accretion rate at the magnetospheric radius must be super-Eddington during outbursts. To support such a super-Eddington accretion, a relatively high multipole field ( ≳ 1013 G) near the surface of the accretor is invoked to produce an accreting gas column. However, our constraint shows that the surface dipolar magnetic field of the pulsar should be in the range of 1.0-3.5 × 1012 G. Therefore, our model supports that the neutron star in ULX M82 X-2 could be a low-magnetic-field magnetar (proposed by Tong) with a normal dipolar field (˜1012 G) and relatively strong multipole field. For the large luminosity variations of this source, our scenario can also present a self-consistency interpretation.

  3. Preview of a Forthcoming Supernova

    NASA Image and Video Library

    2017-09-28

    Supernova Supernovae can occur one of two ways. The first occurs when a white dwarf—the vestigial ember of a dead star—passes so close to a living star that its matter leaks into the white dwarf. This causes a catastrophic explosion. However most people understand supernovae as the death of a massive star. When the star runs out of fuel toward the end of its life, the gravity at its heart sucks the surrounding mass into its center. At temperatures rocketing above 100 billion degrees Fahrenheit, all the layers of the star abruptly explode outward. The explosions produced by supernovae are so brilliant that astronomers use their luminosity to measure the distance between galaxies, the scale of the universe and the effects of dark energy. For a short period of time, one dying star can appear to shine as brightly as an entire galaxy. Supernovae are relatively common events, one occurring in our own galaxy once every 100 years. In 2014, a person could see the supernova M82 with a pair of binoculars. The cosmologist Tycho Brahe’s observation of a supernova in 1572 allowed him to disprove Aristotle’s theory that the heavens never changed. After a supernova, material expelled in the explosion can form a nebula—an interstellar pile of gas and dust. Over millions of years, gravity pulls the nebula’s materials into a dense orb called a protostar, which will become a new star. Within a few million years, this new star could go supernova as well. ------------------------------ Original Caption: NASA image release Feb. 24, 2012 At the turn of the 19th century, the binary star system Eta Carinae was faint and undistinguished. In the first decades of the century, it became brighter and brighter, until, by April 1843, it was the second brightest star in the sky, outshone only by Sirius (which is almost a thousand times closer to Earth). In the years that followed, it gradually dimmed again and by the 20th century was totally invisible to the naked eye. The star has

  4. Local dark energy: HST evidence from the vicinity of the M81/M82 galaxy group

    NASA Astrophysics Data System (ADS)

    Chernin, A. D.; Karachentsev, I. D.; Kashibadze, O. G.; Makarov, D. I.; Teerikorpi, P.; Valtonen, M. J.; Dolgachev, V. P.; Domozhilova, L. M.

    2007-10-01

    The Hubble Space Telescope observations of the nearby galaxy group M81/M82 and its vicinity indicate that the dynamics of the expansion outflow around the group is dominated by the antigravity of the dark energy background. The local density of dark energy in the area is estimated to be near the global dark energy density or perhaps exactly equal to it. This conclusion agrees well with our previous results for the Local Group vicinity and the vicinity of the Cen A/M83 group.

  5. Dizziness and Fainting Spells

    MedlinePlus

    ... or Animals Genitals and Urinary Tract Glands & Growth Head Neck & Nervous System Heart Infections Learning Disabilities Obesity Orthopedic ... Vaccine Preventable Diseases Healthy Children > Health Issues > Conditions > Head Neck & Nervous System > Dizziness and Fainting Spells Health Issues ...

  6. Fainting: First Aid

    MedlinePlus

    ... brain is momentarily inadequate, causing you to lose consciousness. This loss of consciousness is usually brief. Fainting can have no medical ... be a serious disorder. Therefore, treat loss of consciousness as a medical emergency until the signs and ...

  7. Mapping the Extent of M82's outlfows with VIRUS-P

    NASA Astrophysics Data System (ADS)

    Indahl, Briana; Hill, Gary J.; Drory, Niv; McLinden, Emily

    2017-06-01

    Starburst-driven outflows (SBDOs) and other feedback processes play a critical role in the evolution of galaxies through the regulation and disruption of star formation. However, our ability to observe and quantify feedback from SBDOs directly has been limited by the inability to obtain the spectroscopy needed for physical diagnostics over the large areas of local SBDOs. We present integral field spectroscopy taken with the George and Cynthia Mitchell Spectrograph (VIRUS-P) on the 2.7 meter Harlan J. Smith Telescope at McDonald Observatory mapping the full extent of M82’s northern outflow out to ~12kpc covering ~139 square arcminutes. We measured line ratios ([OIII]/Hβ, [OI]/Hα, [NII]/Hα), [SII]/Hα) for each spaxel in our fields. Using Ionization Diagnostic Diagrams (IDDs) we spatially map shock dominated regions which we show trace the biconical structure of the outflow. M82 is a local galaxy (z~0.000677) and the classical example of a starburst galaxy with vigorous outflows. As a result it has been comprehensively studied for nearly 50 years. However, we present the most sensitive and extensive map of the warm ionized gas to date from the disk to the Hα cap at ~12kpc.

  8. High-resolution X-ray imaging of the Starburst Galaxy M82

    NASA Technical Reports Server (NTRS)

    Bregman, Joel N.; Schulman, Eric; Tomisaka, Kohji

    1995-01-01

    Starburst galaxies are predicted to drive hot flows of gas from their central star-forming regions, and to test this expectation, a deep X-ray image was obtained of the nearby starburst galaxy M82 with the High-Resolution Imager (HRI) on the X-ray telescope ROSAT. Aside from three nuclear point sources, the flux is dominated by diffuse emission that we decompose into components along the disk and along the minor axis. The X-ray surface brightness of the disk component decreases exponentially with a scale length of 0.27 kpc, as does the optical line emission from warm ionized gas. This is not due to steady outflow of gas along the plane, but may indicate a rapid decrease in the star formation and energy input rate beyond the nuclear region. The X-ray emission along the minor axis is consistent with the outflow of gas in a jet that is partially confined within 1.6 kpc of the nucleus and expands freely at larger radii; this emission is detected to a distance of 6 kpc. In the center of M82, the hot gas density is 0.2-0.5/cu cm and the central gas pressure is P/k approximately = 0.3-3 x 10(exp 7) K/cu cm, which is similar to estimates of the pressure in the optical emission-line material and molecular gas.

  9. On the Magnetic Field of the Ultraluminous X-Ray Pulsar M82 X-2

    NASA Astrophysics Data System (ADS)

    Xu, Kun; Li, Xiang-Dong

    2017-04-01

    The discovery of the ultraluminous X-ray pulsar M82 X-2 has stimulated lively discussion on the nature of the accreting neutron star. In most of the previous studies the magnetic field of the neutron star was derived from the observed spin-up/down rates based on the standard thin, magnetized accretion disk model. However, under super-Eddington accretion the inner part of the accretion disk becomes geometrically thick. In this work we consider both radiation feedback from the neutron star and the sub-Keplerian rotation in a thick disk and calculate the magnetic moment–mass accretion rate relations for the measured rates of spin change. We find that the derived neutron star's dipole magnetic field depends on the maximum accretion rate adopted, but is likely ≲1013 G. The predicted accretion rate change can be used to test the proposed models by comparison with observations.

  10. Spectral modeling of the charge-exchange X-ray emission from M82

    SciTech Connect

    Zhang, Shuinai; Ji, Li; Zhou, Xin; Wang, Q. Daniel; Smith, Randall K.; Foster, Adam R.

    2014-10-10

    It has been proposed that the charge-exchange (CX) process at the interface between hot and cool interstellar gases could contribute significantly to the observed soft X-ray emission in star-forming galaxies. We analyze the XMM-Newton/reflection grating spectrometer (RGS) spectrum of M82 using a newly developed CX model combined with a single-temperature thermal plasma to characterize the volume-filling hot gas. The CX process is largely responsible for not only the strongly enhanced forbidden lines of the Kα triplets of various He-like ions but also good fractions of the Lyα transitions of C VI (∼87%), O VIII, and N VII (≳50%) as well. In total about a quarter of the X-ray flux in the RGS 6-30 Å band originates in the CX. We infer an ion incident rate of 3 × 10{sup 51} s{sup –1} undergoing CX at the hot and cool gas interface and an effective area of the interface of ∼2 × 10{sup 45} cm{sup 2} that is one order of magnitude larger than the cross section of the global biconic outflow. With the CX contribution accounted for, the best-fit temperature of the hot gas is 0.6 keV, and the metal abundances are approximately solar. We further show that the same CX/thermal plasma model also gives an excellent description of the EPIC-pn spectrum of the outflow Cap, projected at 11.6 kpc away from the galactic disk of M82. This analysis demonstrates that the CX is potentially an important contributor to the X-ray emission from starburst galaxies and also an invaluable tool to probe the interface astrophysics.

  11. EXTENDED HCN AND HCO{sup +} EMISSION IN THE STARBURST GALAXY M82

    SciTech Connect

    Salas, P.; Galaz, G.; Salter, D.; Herrera-Camus, R.; Bolatto, A. D.; Kepley, A.

    2014-12-20

    We mapped 3 mm continuum and line emission from the starburst galaxy M82 using the Combined Array for Research in Millimeter-wave Astronomy. We targeted the HCN, HCO{sup +}, HNC, CS, and HC{sub 3}N lines, but here we focus on the HCN and HCO{sup +} emission. The map covers a field of 1.'2 with an ≈5'' resolution. The HCN and HCO{sup +} observations are short spacings corrected. The molecular gas in M82 had been previously found to be distributed in a molecular disk, coincident with the central starburst, and a galactic scale outflow which originates in the central starburst. With the new short spacings-corrected maps we derive some of the properties of the dense molecular gas in the base of the outflow. From the HCN and HCO{sup +} J = (1-0) line emission, and under the assumptions of the gas being optically thin and in local thermodynamic equilibrium, we place lower limits on the amount of dense molecular gas in the base of the outflow. The lower limits are 7 × 10{sup 6} M {sub ☉} and 21 × 10{sup 6} M {sub ☉}, or ≳ 2% of the total molecular mass in the outflow. The kinematics and spatial distribution of the dense gas outside the central starburst suggests that it is being expelled through chimneys. Assuming a constant outflow velocity, the derived outflow rate of dense molecular gas is ≥0.3 M {sub ☉} yr{sup –1}, which would lower the starburst lifetime by ≥5%. The energy required to expel this mass of dense gas is (1-10) × 10{sup 52} erg.

  12. Extended HCN and HCO+ Emission in the Starburst Galaxy M82

    NASA Astrophysics Data System (ADS)

    Salas, P.; Galaz, G.; Salter, D.; Herrera-Camus, R.; Bolatto, A. D.; Kepley, A.

    2014-12-01

    We mapped 3 mm continuum and line emission from the starburst galaxy M82 using the Combined Array for Research in Millimeter-wave Astronomy. We targeted the HCN, HCO+, HNC, CS, and HC3N lines, but here we focus on the HCN and HCO+ emission. The map covers a field of 1.'2 with an ≈5'' resolution. The HCN and HCO+ observations are short spacings corrected. The molecular gas in M82 had been previously found to be distributed in a molecular disk, coincident with the central starburst, and a galactic scale outflow which originates in the central starburst. With the new short spacings-corrected maps we derive some of the properties of the dense molecular gas in the base of the outflow. From the HCN and HCO+ J = (1-0) line emission, and under the assumptions of the gas being optically thin and in local thermodynamic equilibrium, we place lower limits on the amount of dense molecular gas in the base of the outflow. The lower limits are 7 × 106 M ⊙ and 21 × 106 M ⊙, or >~ 2% of the total molecular mass in the outflow. The kinematics and spatial distribution of the dense gas outside the central starburst suggests that it is being expelled through chimneys. Assuming a constant outflow velocity, the derived outflow rate of dense molecular gas is >=0.3 M ⊙ yr-1, which would lower the starburst lifetime by >=5%. The energy required to expel this mass of dense gas is (1-10) × 1052 erg.

  13. The Contribution of Charge Exchange to the X-ray Spectrum of M82

    NASA Astrophysics Data System (ADS)

    Miller, Ansley; Stancil, Phillip C.; Shelton, Robin L.; Cumbee, Renata; Mullen, Patrick Dean; Zhang, Shuinai; Foster, Adam; Smith, Randall K.

    2017-06-01

    As the resolution of space-based X-ray detectors improve, deducing the mechanism(s) responsible for the observed emission has in many cases proved to be problematic. Emission from most galactic and extragalactic sources are typically attributed to hot thermal plasmas driven by electron impact excitation (EIE). Other sources may be due to radiative recombination (RR) from a photoionized plasma. Charge exchange (CX) is another process that has more recently been ascribed to observed emission, particularly when unexplained by EIE or RR. However, laboratory astrophysics data on CX needed to accurately model X-ray emission has not generally been available. As a consequence a number of approximate CX models have been developed to ascertain the relative importance of CX (e.g., the AtomDB Charge eXchange model, ACX, Smith et al. 2012). Recently, Zhang et al. (2014) combined ACX with a thermal plasma model to study the X-ray emission from starburst galaxy M82, obtained with the XMM-Newton/reflection grating spectrometer (RGS). They deduced that for some emission lines the CX contribution could be a much as 87%. Here we revisit their M82 model,but replace ACX with explicitly computed and benchmarked CX cross sections from the Kronos database (Cumbee et al. 2017, Mullen et al. 2017).Cumbee R. S. et al. 2017, ApJ, submittedMullen, P. D. et al. 2017, ApJ, submittedSmith, R. K. et al. 2012, AN, 333, 301Zhang, S. et al. 2014, ApJ, 794, 61This work was partially supported by NASA grants NNX09AC46G and NNG09WF24I.

  14. Deep HST/ACS Photometry of an Arc of Young Stars in the Southern Halo of M82

    NASA Astrophysics Data System (ADS)

    Suwannajak, Chutipong

    2016-01-01

    We present deep HST/ACS photometry of an arclike, overdense region of stars in the southern halo of M82, located approximately 5 kpc from its disk. This arc feature was originally identified about a decade ago. The early ground-based studies suggested that it contains young stars with ages and metallicities similar to those that formed in the tidal tails between M81, M82, and NGC3077 during their interactions. The arc is clearly presented in the spatial distribution of stars in our field with significantly higher stellar density than the background M82 halo stars. The location of the tip of the red giant branch (RGB) reveals the arc to have a similar distance to M81 and M82, therefore confirming that it belongs to this interacting system. Combining our data with those from the ACS Nearby Galaxy Survey Treasury (ANGST), we construct a color-magnitude diagram (CMD) for the arc. A sequence of young stars is clearly presented on its CMD. This young main sequence is not seen in other parts of the M82 halo. Single-metallicity isochrones are used to derive the age of the young stars in the arc. We confirm that these stars exhibit ages consistent with young stars found in the HI bridges between M81, M82 and NGC3077. Furthermore, the mean metallicity of the RGB stars is also derived from their metallicity distribution function and found to be similar to that found in the HI bridges.

  15. Large-Field CO(J = 1→0) Observations of the Starburst Galaxy M 82

    NASA Astrophysics Data System (ADS)

    Salak, Dragan; Nakai, Naomasa; Miyamoto, Yusuke; Yamauchi, Aya; Tsuru, Takeshi G.

    2013-06-01

    We present large-field (15.7 × 16.9 arcmin2) CO(J = 1→0) observations of the starburst galaxy M 82, at an angular resolution of 22" with the NRO 45-m telescope. The CO emission was detected in the galactic disk, outflow (driven by the galactic wind) up to ˜2 kpc above the galactic plane in the halo, and in tidal streams. The kinematics of the outflow (including CO line splitting) suggests that it has the shape of a cylinder that is diverging outwards. The mass and kinetic energy of the molecular gas outflow are estimated to be (0.26-1.0) × 109 M⊙ and (1-4) × 1056 erg. A clump of CO gas was discovered 3.5 kpc above the galactic plane; it coincides with a dark lane previously found in X-ray observations, and a peak in H I emission. A comparison with H I, hot molecular hydrogen and dust suggests that the molecular gas shows signatures of warm and cool components in the outflow and tidal streams, respectively.

  16. High angular resolution mm- and submm-observations of dense molecular gas in M82

    NASA Technical Reports Server (NTRS)

    Wild, W.; Eckart, Andreas; Genzel, Reinhard; Harris, Andrew I.; Jackson, James M.; Jaffe, D. T.; Lugten, J. B.; Stutzki, J.

    1990-01-01

    Researchers observed CO(7-6), CO(3-2), HCN(3-2) and HCO+(3-2) line emission toward the starburst nucleus of M82 and have obtained an upper limit to H13CN(3-2). These are the first observations of the CO(7-6), HCN(3-2) and HCO+(3-2) lines in any extragalactic source. Researchers took the CO(7-6) spectrum in January 1988 at the Infrared Telescope Facility (IRTF) with the Max Planck Institute for Extraterrestrial Physics/Univ. of California, Berkeley 800 GHz Heterodyne Receiver. In March 1989 researchers used the Institute for Radio Astronomy in the Millimeter range (IRAM) 30 m telescope to observe the CO(3-2) line with the new MPE 350 GHz Superconductor Insulator Superconductor (SIS) receiver and the HCN(3-2) and HCO+(3-2) lines with the (IRAM) 230 GHz SIS receiver (beam 12" FWHM, Blundell et al. 1988). The observational parameters are summarized.

  17. High angular resolution mm- and submm-observations of dense molecular gas in M82

    NASA Astrophysics Data System (ADS)

    Wild, W.; Eckart, Andreas; Genzel, Reinhard; Harris, Andrew I.; Jackson, James M.; Jaffe, D. T.; Lugten, J. B.; Stutzki, J.

    1990-07-01

    Researchers observed CO(7-6), CO(3-2), HCN(3-2) and HCO+(3-2) line emission toward the starburst nucleus of M82 and have obtained an upper limit to H13CN(3-2). These are the first observations of the CO(7-6), HCN(3-2) and HCO+(3-2) lines in any extragalactic source. Researchers took the CO(7-6) spectrum in January 1988 at the Infrared Telescope Facility (IRTF) with the Max Planck Institute for Extraterrestrial Physics/Univ. of California, Berkeley 800 GHz Heterodyne Receiver. In March 1989 researchers used the Institute for Radio Astronomy in the Millimeter range (IRAM) 30 m telescope to observe the CO(3-2) line with the new MPE 350 GHz Superconductor Insulator Superconductor (SIS) receiver and the HCN(3-2) and HCO+(3-2) lines with the (IRAM) 230 GHz SIS receiver (beam 12" FWHM, Blundell et al. 1988). The observational parameters are summarized.

  18. Ne X X-ray emission due to charge exchange in M82

    NASA Astrophysics Data System (ADS)

    Cumbee, R. S.; Liu, L.; Lyons, D.; Schultz, D. R.; Stancil, P. C.; Wang, J. G.; Ali, R.

    2016-06-01

    Recent X-ray observations of star-forming galaxies such as M82 have shown the Ly β/Ly α line ratio of Ne X to be in excess of predictions for thermal electron impact excitation. Here, we demonstrate that the observed line ratio may be due to charge exchange and can be used to constrain the ion kinetic energy to be ≲ 500 eV/u. This is accomplished by computing spectra and line ratios via a range of theoretical methods and comparing these to experiments with He over astrophysically relevant collision energies. The charge exchange emission spectra calculations were performed for Ne10++ H and Ne10++ He using widely applied approaches including the atomic orbital close coupling, classical trajectory Monte Carlo, and multichannel Landau-Zener (MCLZ) methods. A comparison of the results from these methods indicates that for the considered energy range and neutrals (H, He) the so-called low-energy ℓ-distribution MCLZ method provides the most likely reliable predictions.

  19. Diversity in hapten recognition: structural study of an anti-cocaine antibody M82G2.

    PubMed

    Pozharski, Edwin; Moulin, Aaron; Hewagama, Anura; Shanafelt, Armen B; Petsko, Gregory A; Ringe, Dagmar

    2005-06-10

    Antibodies against cocaine and other drugs of abuse are the basis for diagnostic tests for the presence of those drugs in human serum. The 1.7A resolution crystal structure of the anti-cocaine monoclonal antibody M82G2 in complex with cocaine is presented. This structure determination was undertaken to establish the stereochemical features in the antibody binding site that confer specificity for cocaine, and as part of an ongoing project to understand the rules that govern molecular recognition. The cocaine-binding site can be characterized topologically as a narrow groove on the protein surface. The antibody utilizes water-mediated hydrogen bonding, and cation-pi and stacking (pi-pi) interactions to provide specificity. Comparison with the previously published structure of the anti-cocaine antibody GNC92H2 shows that binding of a small ligand can be achieved in diverse ways, both in terms of a binding site structure/topology and protein-ligand interactions.

  20. Matching Supernovae to Galaxies

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-12-01

    One of the major challenges for modern supernova surveys is identifying the galaxy that hosted each explosion. Is there an accurate and efficient way to do this that avoids investing significant human resources?Why Identify Hosts?One problem in host galaxy identification. Here, the supernova lies between two galaxies but though the centroid of the galaxy on the right is closer in angular separation, this may be a distant background galaxy that is not actually near the supernova. [Gupta et al. 2016]Supernovae are a critical tool for making cosmological predictions that help us to understand our universe. But supernova cosmology relies on accurately identifying the properties of the supernovae including their redshifts. Since spectroscopic followup of supernova detections often isnt possible, we rely on observations of the supernova host galaxies to obtain redshifts.But how do we identify which galaxy hosted a supernova? This seems like a simple problem, but there are many complicating factors a seemingly nearby galaxy could be a distant background galaxy, for instance, or a supernovas host could be too faint to spot.The authors algorithm takes into account confusion, a measure of how likely the supernova is to be mismatched. In these illustrations of low (left) and high (right) confusion, the supernova is represented by a blue star, and the green circles represent possible host galaxies. [Gupta et al. 2016]Turning to AutomationBefore the era of large supernovae surveys, searching for host galaxies was done primarily by visual inspection. But current projects like the Dark Energy Surveys Supernova Program is finding supernovae by the thousands, and the upcoming Large Synoptic Survey Telescope will likely discover hundreds of thousands. Visual inspection will not be possible in the face of this volume of data so an accurate and efficient automated method is clearly needed!To this end, a team of scientists led by Ravi Gupta (Argonne National Laboratory) has recently

  1. Spatially resolved Spitzer-IRS spectral maps of the superwind in M82

    NASA Astrophysics Data System (ADS)

    Beirão, P.; Armus, L.; Lehnert, M. D.; Guillard, P.; Heckman, T.; Draine, B.; Hollenbach, D.; Walter, F.; Sheth, K.; Smith, J. D.; Shopbell, P.; Boulanger, F.; Surace, J.; Hoopes, C.; Engelbracht, C.

    2015-08-01

    We have mapped the superwind/halo region of the nearby starburst galaxy M82 in the mid-infrared with Spitzer - IRS. The spectral regions covered include the H2 S(1)-S(3), [Ne II], [Ne III] emission lines and polycyclic aromatic hydrocarbon (PAH) features. We estimate the total warm H2 mass and the kinetic energy of the outflowing warm molecular gas to be between Mwarm ˜ 5 and 17 × 106 M⊙ and EK ˜ 6 and 20 × 1053 erg. Using the ratios of the 6.2, 7.7 and 11.3 μm PAH features in the IRS spectra, we are able to estimate the average size and ionization state of the small grains in the superwind. There are large variations in the PAH flux ratios throughout the outflow. The 11.3/7.7 and the 6.2/7.7 PAH ratios both vary by more than a factor of 5 across the wind region. The northern part of the wind has a significant population of PAH's with smaller 6.2/7.7 ratios than either the starburst disc or the southern wind, indicating that on average, PAH emitters are larger and more ionized. The warm molecular gas to PAH flux ratios (H2/PAH) are enhanced in the outflow by factors of 10-100 as compared to the starburst disc. This enhancement in the H2/PAH ratio does not seem to follow the ionization of the atomic gas (as measured with the [Ne III]/[Ne II] line flux ratio) in the outflow. This suggests that much of the warm H2 in the outflow is excited by shocks. The observed H2 line intensities can be reproduced with low-velocity shocks (v < 40 km s-1) driven into moderately dense molecular gas (102 < nH < 104 cm-3) entrained in the outflow.

  2. HERSCHEL-SPIRE IMAGING SPECTROSCOPY OF MOLECULAR GAS IN M82

    SciTech Connect

    Kamenetzky, J.; Glenn, J.; Rangwala, N.; Maloney, P.; Bradford, M.; Wilson, C. D.; Schirm, M. R. P.; Bendo, G. J.; Baes, M.; Boselli, A.; Cooray, A.; Isaak, K. G.; Lebouteiller, V.; Madden, S.; Panuzzo, P.; Wu, R.

    2012-07-01

    We present new Herschel-SPIRE imaging spectroscopy (194-671 {mu}m) of the bright starburst galaxy M82. Covering the CO ladder from J = 4 {yields} 3 to J = 13 {yields} 12, spectra were obtained at multiple positions for a fully sampled {approx}3 Multiplication-Sign 3 arcmin map, including a longer exposure at the central position. We present measurements of {sup 12}CO, {sup 13}CO, [C I], [N II], HCN, and HCO{sup +} in emission, along with OH{sup +}, H{sub 2}O{sup +}, and HF in absorption and H{sub 2}O in both emission and absorption, with discussion. We use a radiative transfer code and Bayesian likelihood analysis to model the temperature, density, column density, and filling factor of multiple components of molecular gas traced by {sup 12}CO and {sup 13}CO, adding further evidence to the high-J lines tracing a much warmer ({approx}500 K), less massive component than the low-J lines. The addition of {sup 13}CO (and [C I]) is new and indicates that [C I] may be tracing different gas than {sup 12}CO. No temperature/density gradients can be inferred from the map, indicating that the single-pointing spectrum is descriptive of the bulk properties of the galaxy. At such a high temperature, cooling is dominated by molecular hydrogen. Photon-dominated region (PDR) models require higher densities than those indicated by our Bayesian likelihood analysis in order to explain the high-J CO line ratios, though cosmic-ray-enhanced PDR models can do a better job reproducing the emission at lower densities. Shocks and turbulent heating are likely required to explain the bright high-J emission.

  3. ISOCAM view of the starburst galaxies M 82, NGC 253 and NGC 1808

    NASA Astrophysics Data System (ADS)

    Förster Schreiber, N. M.; Sauvage, M.; Charmandaris, V.; Laurent, O.; Gallais, P.; Mirabel, I. F.; Vigroux, L.

    2003-03-01

    We present results of mid-infrared lambda = 5.0-16.5 μm spectrophotometric imaging of the starburst galaxies M 82, NGC 253, and NGC 1808 from the ISOCAM instrument on board the Infrared Space Observatory. The mid-infrared spectra of the three galaxies are very similar in terms of features present. The lambda >~ 11 μm continuum attributed to very small dust grains (VSGs) exhibits a large spread in intensity relative to the short-wavelength emission. We find that the 15 mu m dust continuum flux density correlates well with the fine-structure [Ar Ii] 6.99 mu m line flux and thus provides a good quantitative indicator of the level of star formation activity. By contrast, the lambda = 5-11 μm region dominated by emission from polycyclic aromatic hydrocarbons (PAHs) has a nearly invariant shape. Variations in the relative intensities of the PAH features are nevertheless observed, at the 20%-100% level. We illustrate extinction effects on the shape of the mid-infrared spectrum of obscured starbursts, emphasizing the differences depending on the applicable extinction law and the consequences for the interpretation of PAH ratios and extinction estimates. The relative spatial distributions of the PAH, VSG, and [Ar Ii] 6.99 mu m emission between the three galaxies exhibit remarkable differences. The la 1 kpc size of the mid-infrared source is much smaller than the optical extent of our sample galaxies and 70%-100% of the IRAS 12 mu m flux is recovered within the ISOCAM <= 1.5 arcmin2 field of view, indicating that the nuclear starburst dominates the total mid-infrared emission while diffuse light from quiescent disk star formation contributes little. Based on observations with ISO, an ESA project with instruments funded by ESA member states (especially the PI countries: France, Germany, The Netherlands, and the UK), and with participation of ISAS and NASA.

  4. A possible 55-d X-ray period of the ultraluminous accreting pulsar M82 X-2

    NASA Astrophysics Data System (ADS)

    Kong, Albert K. H.; Hu, Chin-Ping; Lin, Lupin Chun-Che; Li, K. L.; Jin, Ruolan; Liu, C. Y.; Yen, David Chien-Chang

    2016-10-01

    We report on the possible detection of a 55-d X-ray modulation for the ultraluminous accreting pulsar M82 X-2 from archival Chandra observations. Because M82 X-2 is known to have a 2.5-d orbital period, if the 55-d period is real, then it will be the superorbital period of the system. We also investigated variabilities of three other nearby ultraluminous X-ray sources in the central region of M82 with the Chandra data, and we did not find any evidence of periodicities. Furthermore, we re-examined the previously reported 62-d periodicity near the central region of M82 by performing a systematic timing study with all the archival Rossi X-Ray Timing Explorer and Swift data. Using various dynamic timing analysis methods, we have confirmed that the 62-d period is not stable, suggesting that it is not the orbital period of M82 X-1; this is in agreement with previous work.

  5. VLBI observations of galactic nuclei at 18 centimeters - NGC 1052, NGC 4278, M82, and M104

    NASA Technical Reports Server (NTRS)

    Shaffer, D. B.; Marscher, A. P.

    1979-01-01

    Compact radio sources about a light year in size have been detected in the nuclei of the galaxies NGC 1052, NGC 3034 (M82), NGC 4278, and NGC 4594 (M104) at a wavelength of 18 cm. The compact nucleus detected in M81 at 6 cm was not seen at 18 cm. The compact source in M82 is unique among extragalactic sources in its size-spectrum relationship. It is either broadened by scattering within M82 or it lies behind, and is absorbed by, an H II region. In these galaxies, the size of the nuclear radio source at 18 cm is larger than it is at higher frequencies. The nucleus of the giant radio galaxy DA 240 was not detected.

  6. CONFIRMATION OF FAINT DWARF GALAXIES IN THE M81 GROUP

    SciTech Connect

    Chiboucas, Kristin; Jacobs, Bradley A.; Tully, R. Brent; Karachentsev, Igor D. E-mail: bjacobs@ifa.hawaii.edu E-mail: ikar@luna.sao.ru

    2013-11-01

    We have followed up on the results of a 65 deg{sup 2} CFHT/MegaCam imaging survey of the nearby M81 Group searching for faint and ultra-faint dwarf galaxies. The original survey turned up 22 faint candidate dwarf members. Based on two-color HST ACS/WFC and WFPC2 photometry, we now confirm 14 of these as dwarf galaxy members of the group. Distances and stellar population characteristics are discussed for each. To a completeness limit of M{sub r{sup '}}= -10, we find a galaxy luminosity function slope of –1.27 ± 0.04 for the M81 Group. In this region, there are now 36 M81 Group members known, including 4 blue compact dwarfs; 8 other late types including the interacting giants M81, NGC 3077, and M82; 19 early type dwarfs; and at least 5 potential tidal dwarf galaxies. We find that the dSph galaxies in M81 appear to lie in a flattened distribution, similar to that found for the Milky Way and M31. One of the newly discovered dSph galaxies has properties similar to the ultra-faint dwarfs being found in the Local Group with a size R{sub e} ∼ 100 pc and total magnitude estimates M{sub r{sup '}}= -6.8 and M{sub I} ∼ –9.1.

  7. Early Observations and Analysis of the Type Ia SN 2014J in M82

    NASA Astrophysics Data System (ADS)

    Marion, G. H.; Sand, D. J.; Hsiao, E. Y.; Banerjee, D. P. K.; Valenti, S.; Stritzinger, M. D.; Vinkó, J.; Joshi, V.; Venkataraman, V.; Ashok, N. M.; Amanullah, R.; Binzel, R. P.; Bochanski, J. J.; Bryngelson, G. L.; Burns, C. R.; Drozdov, D.; Fieber-Beyer, S. K.; Graham, M. L.; Howell, D. A.; Johansson, J.; Kirshner, R. P.; Milne, P. A.; Parrent, J.; Silverman, J. M.; Vervack, R. J., Jr.; Wheeler, J. C.

    2015-01-01

    We present optical and near infrared (NIR) observations of the nearby Type Ia SN 2014J. Seventeen optical and 23 NIR spectra were obtained from 10 days before (-10d) to 10 days after (+10d) the time of maximum B-band brightness. The relative strengths of absorption features and their patterns of development can be compared at one day intervals throughout most of this period. Carbon is not detected in the optical spectra, but we identify C I λ1.0693 in the NIR spectra. Mg II lines with high oscillator strengths have higher initial velocities than other Mg II lines. We show that the velocity differences can be explained by differences in optical depths due to oscillator strengths. The spectra of SN 2014J show that it is a normal SN Ia, but many parameters are near the boundaries between normal and high-velocity subclasses. The velocities for O I, Mg II, Si II, S II, Ca II, and Fe II suggest that SN 2014J has a layered structure with little or no mixing. That result is consistent with the delayed detonation explosion models. We also report photometric observations, obtained from -10d to +29d, in the UBVRIJH and Ks bands. The template fitting package SNooPy is used to interpret the light curves and to derive photometric parameters. Using RV = 1.46, which is consistent with previous studies, SNooPy finds that AV = 1.80 for E(B - V)host = 1.23 ± 0.06 mag. The maximum B-band brightness of -19.19 ± 0.10 mag was reached on February 1.74 UT ± 0.13 days and the supernova has a decline parameter, Δm 15, of 1.12 ± 0.02 mag.

  8. EARLY OBSERVATIONS AND ANALYSIS OF THE TYPE Ia SN 2014J IN M82

    SciTech Connect

    Marion, G. H.; Vinkó, J.; Sand, D. J.; Hsiao, E. Y.; Banerjee, D. P. K.; Joshi, V.; Venkataraman, V.; Ashok, N. M.; Valenti, S.; Howell, D. A.; Stritzinger, M. D.; Amanullah, R.; Johansson, J.; Binzel, R. P.; Bochanski, J. J.; Bryngelson, G. L.; Burns, C. R.; Drozdov, D.; Fieber-Beyer, S. K.; Graham, M. L.; and others

    2015-01-01

    We present optical and near infrared (NIR) observations of the nearby Type Ia SN 2014J. Seventeen optical and 23 NIR spectra were obtained from 10 days before (–10d) to 10 days after (+10d) the time of maximum B-band brightness. The relative strengths of absorption features and their patterns of development can be compared at one day intervals throughout most of this period. Carbon is not detected in the optical spectra, but we identify C I λ1.0693 in the NIR spectra. Mg II lines with high oscillator strengths have higher initial velocities than other Mg II lines. We show that the velocity differences can be explained by differences in optical depths due to oscillator strengths. The spectra of SN 2014J show that it is a normal SN Ia, but many parameters are near the boundaries between normal and high-velocity subclasses. The velocities for O I, Mg II, Si II, S II, Ca II, and Fe II suggest that SN 2014J has a layered structure with little or no mixing. That result is consistent with the delayed detonation explosion models. We also report photometric observations, obtained from –10d to +29d, in the UBVRIJH and K{sub s} bands. The template fitting package SNooPy is used to interpret the light curves and to derive photometric parameters. Using R{sub V} = 1.46, which is consistent with previous studies, SNooPy finds that A{sub V} = 1.80 for E(B – V){sub host} = 1.23 ± 0.06 mag. The maximum B-band brightness of –19.19 ± 0.10 mag was reached on February 1.74 UT ± 0.13 days and the supernova has a decline parameter, Δm {sub 15}, of 1.12 ± 0.02 mag.

  9. A Stellar-mass Black Hole in the Ultra-luminous X-ray Source M82 X-1

    NASA Technical Reports Server (NTRS)

    Okajima, Takashi; Ebisawa, Ken; Kawaguchi, Toshihiro

    2007-01-01

    We have analyzed the archival XMM-Newton data of the archetypal Ultra-Luminous X-ray Source (ULX) M82 X-1 with an LO5 ksec exposure when the source was in the steady state. Thanks to the high photon statistics from the large effective area and long exposure, we were able to discriminate different X-ray continuum spectral models. Neither the standard accretion disk model (where the radial dependency of the disk effective temperature is T(r) proportional to r(sup -3/4)) nor a power-law model gives a satisfactory fit. In fact, observed curvature of the M82 X-1 spectrum was just between those of the two models. When the exponent of the radial dependence (p in T(r) proportional to r(sup -P)) of the disk temperature is allowed to be free, we obtained p = 0.61 (sup +0.03)(sub -0.02). Such a reduction of p from the standard value 3/4 under extremely high mass accretion rates is predicted from the accretion disk theory as a consequence of the radial energy advection. Thus, the accretion disk in M82 X-1 is considered to be in the Slim disk state, where an optically thick Advection Dominant Accretion Flow (ADAF) is taking place. We have applied a theoretical slim disk spectral model to M82 X-1, and estimated the black hole mass approximately equal to 19 - 32 solar mass. We conclude that M82 X-1 is a stellar black hole which has been produced through evolution of an extremely massive star, shining at a several times the super-Eddington luminosity.

  10. A more direct measure of supernova rates in starburst galaxies

    NASA Technical Reports Server (NTRS)

    Van Buren, Dave; Greenhouse, Matthew A.

    1994-01-01

    We determine ages for young supernova remnants in the starburst galaxies M82 and NGC 253 by applying Chevalier's model for radio emission from supernova blast waves expanding into the ejecta of their precursor stars. Absolute ages are determined by calibrating the model with radio observations of Cas A. We derive supernova rates of 0.10 and 0.08/yr for M82 and NGC 253, respectively. Assuming L (sub FIR) to be proportional to the supernova rate, we find r(sub SN) approximately equal 2 x 10(exp -12) x L(sub FIR), solar yr(exp -1) for these archetypal starburst galaxies. This approach is unique in that the supernova rate is derived from direct observation of supernova remnants rather than from star formation rates and an assumed initial mass function (IMF). We suggest that the approach presented here can be used to derive star-formation rates that are more directly related to observable quantities than those derived by other methods. We find that the supernova rate, far infrared (FIR) luminosity, and dynamical mass of the M82 starburst place few constraints on the initial mass function (IMF) slope and mass limits.

  11. How Faint Can You Go?

    NASA Astrophysics Data System (ADS)

    Henden, Arne

    2017-06-01

    For many scientific projects, knowledge of the faint limit of your exposure can be extremely important. In addition, it can be just plain fun to know how faint your equipment can go under varying circumstances. This paper describes the concept and gives some guidance as to how to increase the scientific value of your reports.

  12. Constraints on the Progenitor System of the Type Ia Supernova 2014J from Pre-Explosion Hubble Space Telescope Imaging

    NASA Technical Reports Server (NTRS)

    Kelly, Patrick L.; Fox, Ori D.; Filippenko, Alexei V.; Cenko, S. Bradley; Prato, Lisa; Schaefer, Gail; Shen, Ken J.; Zheng, WeiKang; Graham, Melissa L.; Tucker, Brad E.

    2014-01-01

    We constrain the properties of the progenitor system of the highly reddened Type Ia supernova (SN Ia) 2014J in Messier 82 (M82; d (is) approx. 3.5 Mpc). We determine the supernova (SN) location using Keck-II K-band adaptive optics images, and we find no evidence for flux from a progenitor system in pre-explosion near-ultraviolet through near-infrared Hubble Space Telescope (HST) images. Our upper limits exclude systems having a bright red giant companion, including symbiotic novae with luminosities comparable to that of RS Ophiuchi. While the flux constraints are also inconsistent with predictions for comparatively cool He-donor systems (T (is) approximately 35,000 K), we cannot preclude a system similar to V445 Puppis. The progenitor constraints are robust across a wide range of RV and AV values, but significantly greater values than those inferred from the SN light curve and spectrum would yield proportionally brighter luminosity limits. The comparatively faint flux expected from a binary progenitor system consisting of white dwarf stars would not have been detected in the pre-explosion HST imaging. Infrared HST exposures yield more stringent constraints on the luminosities of very cool (T (is) less than 3000 K) companion stars than was possible in the case of SN Ia 2011fe.

  13. Constraints on the progenitor system of the type Ia supernova 2014J from pre-explosion Hubble space telescope imaging

    SciTech Connect

    Kelly, Patrick L.; Fox, Ori D.; Filippenko, Alexei V.; Shen, Ken J.; Zheng, WeiKang; Graham, Melissa L.; Tucker, Brad E.; Cenko, S. Bradley; Schaefer, Gail

    2014-07-20

    We constrain the properties of the progenitor system of the highly reddened Type Ia supernova (SN Ia) 2014J in Messier 82 (M82; d ≈ 3.5 Mpc). We determine the supernova (SN) location using Keck-II K-band adaptive optics images, and we find no evidence for flux from a progenitor system in pre-explosion near-ultraviolet through near-infrared Hubble Space Telescope (HST) images. Our upper limits exclude systems having a bright red giant companion, including symbiotic novae with luminosities comparable to that of RS Ophiuchi. While the flux constraints are also inconsistent with predictions for comparatively cool He-donor systems (T ≲ 35,000 K), we cannot preclude a system similar to V445 Puppis. The progenitor constraints are robust across a wide range of R{sub V} and A{sub V} values, but significantly greater values than those inferred from the SN light curve and spectrum would yield proportionally brighter luminosity limits. The comparatively faint flux expected from a binary progenitor system consisting of white dwarf stars would not have been detected in the pre-explosion HST imaging. Infrared HST exposures yield more stringent constraints on the luminosities of very cool (T < 3000 K) companion stars than was possible in the case of SN Ia 2011fe.

  14. Is M82 X-1 Really an Intermediate-Mass Black Hole? X-Ray Spectral and Timing Evidence

    NASA Technical Reports Server (NTRS)

    Fiorito, Ralph; Titarchuk, Lev

    2004-01-01

    Ultraluminous X-ray sources (ULXs) with apparent luminosities up to hundreds of times the Eddington luminosity for a neutron star have been discovered in external galaxies. The existence of intermediate-mass black holes has been proposed to explain these sources. We present evidence for an intermediate-mass black hole in the ULX M82 X-1 based on the spectral features and timing (quasi-periodic oscillation [QPO]) properties of the X-radiation from this source. We revisited XMM-Newton and Rossi X-Ray Timing Explorer (RXTE) data for M82 X-1 obtained in 2001 and 1997 for XMM and RXTE, respectively. We show for these observations that the source is either in transition or in a high/soft state with photon spectral indices 2.1 and 2.7, respectively. We confirm the early determination of the QPO frequency nu approx. = 55 mHz in this source by Strohmayer & Mushotzky and identify this as the low-frequency QPO for the source. We apply a new method to determine the black hole mass of M82 X-1. The method uses the index-QPO low-frequency correlation that has been recently established in Galactic black hole candidates GRS 1915+105, XTE JI550-564, 4U 1630-47, and others. Using scaling arguments and the correlation derived from the consideration of Galactic black holes, we conclude that M82 X-1 is an intermediate black hole with a mass of the order of 1000 solar mass,.

  15. Is M82 X-1 Really an Intermediate-Mass Black Hole? X-Ray Spectral and Timing Evidence

    NASA Technical Reports Server (NTRS)

    Fiorito, Ralph; Titarchuk, Lev

    2004-01-01

    Ultraluminous X-ray sources (ULXs) with apparent luminosities up to hundreds of times the Eddington luminosity for a neutron star have been discovered in external galaxies. The existence of intermediate-mass black holes has been proposed to explain these sources. We present evidence for an intermediate-mass black hole in the ULX M82 X-1 based on the spectral features and timing (quasi-periodic oscillation [QPO]) properties of the X-radiation from this source. We revisited XMM-Newton and Rossi X-Ray Timing Explorer (RXTE) data for M82 X-1 obtained in 2001 and 1997 for XMM and RXTE, respectively. We show for these observations that the source is either in transition or in a high/soft state with photon spectral indices 2.1 and 2.7, respectively. We confirm the early determination of the QPO frequency nu approx. = 55 mHz in this source by Strohmayer & Mushotzky and identify this as the low-frequency QPO for the source. We apply a new method to determine the black hole mass of M82 X-1. The method uses the index-QPO low-frequency correlation that has been recently established in Galactic black hole candidates GRS 1915+105, XTE JI550-564, 4U 1630-47, and others. Using scaling arguments and the correlation derived from the consideration of Galactic black holes, we conclude that M82 X-1 is an intermediate black hole with a mass of the order of 1000 solar mass,.

  16. A solar-type star polluted by calcium-rich supernova ejecta inside the supernova remnant RCW 86

    NASA Astrophysics Data System (ADS)

    Gvaramadze, Vasilii V.; Langer, Norbert; Fossati, Luca; Bock, Douglas C.-J.; Castro, Norberto; Georgiev, Iskren Y.; Greiner, Jochen; Johnston, Simon; Rau, Arne; Tauris, Thomas M.

    2017-06-01

    When a massive star in a binary system explodes as a supernova, its companion star may be polluted with heavy elements from the supernova ejecta. Such pollution has been detected in a handful of post-supernova binaries 1 , but none of them is associated with a supernova remnant. We report the discovery of a binary G star strongly polluted with calcium and other elements at the position of the candidate neutron star [GV2003] N within the young galactic supernova remnant RCW 86. Our discovery suggests that the progenitor of the supernova that produced RCW 86 could have been a moving star, which exploded near the edge of its wind bubble and lost most of its initial mass because of common-envelope evolution shortly before core collapse, and that the supernova explosion might belong to the class of calcium-rich supernovaefaint and fast transients 2,3 , the origin of which is strongly debated 4-6 .

  17. A single prolific r-process event preserved in an ultra-faint dwarf galaxy

    NASA Astrophysics Data System (ADS)

    Ji, Alexander; Frebel, Anna; Chiti, Anirudh; Simon, Joshua

    2016-03-01

    The heaviest elements in the periodic table are synthesized through the r-process, but the astrophysical site for r-process nucleosynthesis is still unknown. Ultra-faint dwarf galaxies contain a simple fossil record of early chemical enrichment that may determine this site. Previous measurements found very low levels of neutron-capture elements in ultra-faint dwarfs, preferring supernovae as the r-process site. I present high-resolution chemical abundances of nine stars in the recently discovered ultra-faint dwarf Reticulum II, which display extremely enhanced r-process abundances 2-3 orders of magnitude higher than the other ultra-faint dwarfs. Stars with such extreme r-process enhancements are only rarely found in the Milky Way halo. The r-process abundances imply that the neutron-capture material in Reticulum II was synthesized in a single prolific event that is incompatible with r-process yields from ordinary core-collapse supernovae. Reticulum II provides an opportunity to discriminate whether the source of this pure r-process signature is a neutron star merger or magnetorotationally driven supernova. The single event is also a uniquely stringent constraint on the metal mixing and star formation history of this ultra-faint dwarf galaxy.

  18. Supernova Flashback

    NASA Image and Video Library

    2008-10-01

    The Cassiopeia A supernova first flash of radiation makes six clumps of dust circled in annotated version unusually hot. The supernova remnant is the large white ball in the center. This infrared picture was taken by NASA Spitzer Space Telescope.

  19. A new observational and numerical study of tidal interactions in M81-M82-NGC3077 system

    NASA Technical Reports Server (NTRS)

    Yun, M. S.; Ho, P. T. P.; Brouillet, N.; Lo, K. Y.

    1993-01-01

    A nearby system of interacting galaxies M81-M82-NGC3077 triplet (D = 3.3 Mpc; Freeman & Madore 1988) has been studied using multi-wavelength observations and numerical simulations to obtain a comprehensive understanding on the dynamics and the consequences of tidal interactions in a group environment. The VLA 12-field Mosaic H I observations of 2 x 1.5 deg. region have revealed a vast array of H I filaments which suggests that the severity and extent of tidal disruptions far exceed the previous estimates. A tidal remnant of the former H I disk of M82 extending up to 30 kpc (in projection) is identified for the first time, and the pervasive effects of the tidal disruption are traced into the inner disk by optical and CO observations, including a kinematic trace of a large scale bar potential (Yun, Ho, & Lo 1992). The H I disk of M81 is traced out to 40 kpc in radius, and a large scale (l approx. 20 kpc) velocity anomaly ('High Velocity Trough'), which may be a remnant of a gaseous collision, is found within the disk of M81. The large H I bridge between M81 and NGC 3077 (van der Hulst 1979) is also found to extend approx. greater than 50 kpc further, bending around NGC 3077, toward M82. The total H I detected in this experiment, 5.6 x 10(exp 9) solar mass, represents the majority of the single-dish flux (Appleton, Davies, & Stephenson 1981) and suggests that the bulk of H I found in the region belongs to the three galaxies and the tidal filaments. The impact and details of the tidal interactions have been further examined through the use of numerical techniques. The 'restricted 3-body' approach was used to simulate the observed distribution of tidal H I streamers connecting the three galaxies, and the success of the simulation is further strengthened by the accurate predictions on the gas kinematics.

  20. THE MULTI-PHASE COLD FOUNTAIN IN M82 REVEALED BY A WIDE, SENSITIVE MAP OF THE MOLECULAR INTERSTELLAR MEDIUM

    SciTech Connect

    Leroy, Adam K.; Martini, Paul; Walter, Fabian; Roussel, Hélène; Sandstrom, Karin; Ott, Jürgen; Weiss, Axel; Bolatto, Alberto D.; Schuster, Karl; Dessauges-Zavadsky, Miroslava

    2015-12-01

    We present a wide area (≈8 × 8 kpc), sensitive map of CO (2–1) emission around the nearby starburst galaxy M82. Molecular gas extends far beyond the stellar disk, including emission associated with the well-known outflow as far as 3 kpc from M82's midplane. Kinematic signatures of the outflow are visible in both the CO and H i emission: both tracers show a minor axis velocity gradient and together they show double peaked profiles, consistent with a hot outflow bounded by a cone made of a mix of atomic and molecular gas. Combining our CO and H i data with observations of the dust continuum, we study the changing properties of the cold outflow as it leaves the disk. While H{sub 2} dominates the ISM near the disk, the dominant phase of the cool medium changes as it leaves the galaxy and becomes mostly atomic after about a kpc. Several arguments suggest that regardless of phase, the mass in the cold outflow does not make it far from the disk; the mass flux through surfaces above the disk appears to decline with a projected scale length of ≈1–2 kpc. The cool material must also end up distributed over a much wider angle than the hot outflow based on the nearly circular isophotes of dust and CO at low intensity and the declining rotation velocities as a function of height from the plane. The minor axis of M82 appears so striking at many wavelengths because the interface between the hot wind cavity and the cool gas produces Hα, hot dust, polycyclic aromatic hydrocarbon emission, and scattered UV light. We also show the level at which a face-on version of M82 would be detectable as an outflow based on unresolved spectroscopy. Finally, we consider multiple constraints on the CO-to-H{sub 2} conversion factor, which must change across the galaxy but appears to be only a factor of ≈2 lower than the Galactic value in the outflow.

  1. The Multi-phase Cold Fountain in M82 Revealed by a Wide, Sensitive Map of the Molecular Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Leroy, Adam K.; Walter, Fabian; Martini, Paul; Roussel, Hélène; Sandstrom, Karin; Ott, Jürgen; Weiss, Axel; Bolatto, Alberto D.; Schuster, Karl; Dessauges-Zavadsky, Miroslava

    2015-12-01

    We present a wide area (≈8 × 8 kpc), sensitive map of CO (2-1) emission around the nearby starburst galaxy M82. Molecular gas extends far beyond the stellar disk, including emission associated with the well-known outflow as far as 3 kpc from M82's midplane. Kinematic signatures of the outflow are visible in both the CO and H i emission: both tracers show a minor axis velocity gradient and together they show double peaked profiles, consistent with a hot outflow bounded by a cone made of a mix of atomic and molecular gas. Combining our CO and H i data with observations of the dust continuum, we study the changing properties of the cold outflow as it leaves the disk. While H2 dominates the ISM near the disk, the dominant phase of the cool medium changes as it leaves the galaxy and becomes mostly atomic after about a kpc. Several arguments suggest that regardless of phase, the mass in the cold outflow does not make it far from the disk; the mass flux through surfaces above the disk appears to decline with a projected scale length of ≈1-2 kpc. The cool material must also end up distributed over a much wider angle than the hot outflow based on the nearly circular isophotes of dust and CO at low intensity and the declining rotation velocities as a function of height from the plane. The minor axis of M82 appears so striking at many wavelengths because the interface between the hot wind cavity and the cool gas produces Hα, hot dust, polycyclic aromatic hydrocarbon emission, and scattered UV light. We also show the level at which a face-on version of M82 would be detectable as an outflow based on unresolved spectroscopy. Finally, we consider multiple constraints on the CO-to-H2 conversion factor, which must change across the galaxy but appears to be only a factor of ≈2 lower than the Galactic value in the outflow.

  2. Imaging stellar faint companions

    NASA Astrophysics Data System (ADS)

    Cagigal, Manuel P.; Canales, Vidal F.

    . The conclusion is that the use of the Dark Speckle technique in a compensated nulling interferometer could be a promising way to detect faint objects, although the application of the technique in the infrared range requires the development of appropriate detectors.

  3. IDENTIFICATION OF THE X-RAY THERMAL DOMINANT STATE IN AN ULTRALUMINOUS X-RAY SOURCE IN M82

    SciTech Connect

    Feng Hua; Kaaret, Philip

    2010-04-01

    The thermal dominant state in black hole binaries (BHBs) is well understood but rarely seen in ultraluminous X-ray sources (ULXs). Using simultaneous observations of M82 with Chandra and XMM-Newton, we report the first likely identification of the thermal dominant state in a ULX based on the disappearance of X-ray oscillations, low timing noise, and a spectrum dominated by multicolor disk emission with luminosity varying to the fourth power of the disk temperature. This indicates that ULXs are similar to Galactic BHBs. The brightest X-ray spectrum can be fitted with a relativistic disk model with either a highly super-Eddington (L {sub disk}/L {sub Edd} = 160) non-rotating black hole (BH) or a close to Eddington (L {sub disk}/L {sub Edd} {approx} 2) rapidly rotating BH. The latter interpretation is preferred, due to the absence of such highly super-Eddington states in Galactic BHs and active galactic nuclei, and suggests that the ULX in M82 contains a BH of 200-800 solar masses with nearly maximal spin. On long timescales, the source normally stays at a relatively low flux level with a regular 62-day orbital modulation and occasionally exhibits irregular flaring activity. These thermal dominant states are observed during outbursts.

  4. THE OPTICAL STRUCTURE OF THE STARBURST GALAXY M82. I. DYNAMICS OF THE DISK AND INNER-WIND

    SciTech Connect

    Westmoquette, M. S.; Smith, L. J.; Konstantopoulos, I. S.; Gallagher, J. S.; Trancho, G.

    2009-05-01

    We present Gemini-North GMOS-IFU observations of the central starburst clumps and inner wind of M82, together with WIYN DensePak IFU observations of the inner 2 x 0.9 kpc of the disk. These cover the emission lines of H{alpha}, [N II], [S II], and [S III] at a spectral resolution of 45-80 km s{sup -1}. The high signal-to-noise of the data is sufficient to accurately decompose the emission line profiles into multiple narrow components (FWHM {approx} 30-130 km s{sup -1}) superimposed on a broad (FWHM {approx} 150-350 km s{sup -1}) feature. This paper is the first of a series examining the optical structure of M82's disk and inner wind; here we focus on the ionized gaseous and stellar dynamics and present maps of the relevant emission line properties. Our observations show that ionized gas in the starburst core of M82 is dynamically complex with many overlapping expanding structures located at different radii. Localised line splitting of up to 100 km s{sup -1} in the narrow component is associated with expanding shells of compressed, cool, photoionized gas at the roots of the superwind outflow. We have been able to associate some of this inner-wind gas with a distinct outflow channel characterised by its dynamics and gas density patterns, and we discuss the consequences of this discovery in terms of the developing wind outflow. The broad optical emission line component is observed to become increasingly important moving outward along the outflow channel, and in general with increasing height above/below the plane. Following our recent work on the origins of this component, we associate it with turbulent gas in wind-clump interface layers and hence sites of mass loading, meaning that the turbulent mixing of cooler gas into the outflowing hot gas must become increasingly important with height, and provides powerful direct evidence for the existence of mass-loading over a large, spatially extended area reaching far into the inner wind. We discuss the consequences and

  5. Echoes from Ancient supernovae in the Large Magellanic Cloud

    SciTech Connect

    Rest, A; Suntzeff, N B; Olsen, K; Prieto, J L; Smith, R C; Welch, D L; Becker, A; Bergmann, M; Clocchiatti, A; Cook, K; Garg, A; Huber, M; Miknaitis, G; Minniti, D; Nikolaev, S; Stubbs, C

    2005-06-15

    In principle, historical supernovae could still be visible as scattered-light echoes even centuries later [1, 2]. Searches for surface brightness variations using photographic plates have not recovered any echoes in the regions of historical Galactic supernovae [3]. Using differenced images, our SuperMACHO collaboration has discovered three faint new variable surface brightness complexes with high apparent proper motion pointing back to well-defined positions in the Large Magellanic Cloud (LMC). These correspond to three of the six smallest (and likely youngest) supernova remnants believed to be due to thermonuclear (Type Ia) supernovae [4]. A lower limit to the age of these remnants and echoes is 200 years given the lack of any reported LMC supernovae until 1987. The discovery of historical supernova echoes in the LMC suggests that similar echoes for Galactic supernovae such as Tycho, Kepler, Cas A, or SN1006 could be visible using standard image differencing techniques.

  6. Light echoes from ancient supernovae in the Large Magellanic Cloud.

    PubMed

    Rest, Armin; Suntzeff, Nicholas B; Olsen, Knut; Prieto, Jose Luis; Smith, R Chris; Welch, Douglas L; Becker, Andrew; Bergmann, Marcel; Clocchiatti, Alejandro; Cook, Kem; Garg, Arti; Huber, Mark; Miknaitis, Gajus; Minniti, Dante; Nikolaev, Sergei; Stubbs, Christopher

    2005-12-22

    The light from historical supernovae could in principle still be visible as scattered-light echoes centuries after the explosion. The detection of light echoes could allow us to pinpoint the supernova event both in position and age and, most importantly, permit the acquisition of spectra to determine the 'type' of the supernova centuries after the direct light from the explosion first reached Earth. Although echoes have been discovered around some nearby extragalactic supernovae, targeted searches have not found any echoes in the regions of historical Galactic supernovae. Here we report three faint variable-surface-brightness complexes with high apparent proper motions pointing back to three of the six smallest (and probably youngest) previously catalogued supernova remnants in the Large Magellanic Cloud, which are believed to have been thermonuclear (type Ia) supernovae. Using the distance and apparent proper motions of these echo arcs, we estimate ages of 610 and 410 years for two of them.

  7. THE OPTICAL STRUCTURE OF THE STARBURST GALAXY M82. II. NEBULAR PROPERTIES OF THE DISK AND INNER WIND

    SciTech Connect

    Westmoquette, M. S.; Smith, L. J.; Konstantopoulos, I. S.; Gallagher, J. S.; Trancho, G.

    2009-12-01

    In this second paper of the series, we present the results from optical Gemini-North GMOS-IFU and WIYN DensePak IFU spectroscopic observations of the starburst and inner wind zones of M82, with a focus on the state of the T approx 10{sup 4} K ionized interstellar medium. Our electron density maps show peaks of a few 1000 cm{sup -3} (implying very high thermal pressures), local small spatial-scale variations, and a falloff in the minor axis direction. We discuss the implications of these results with regards to the conditions/locations that may favor the escape of individual cluster winds that ultimately power the large-scale superwind. Our findings, when combined with the body of literature built up over the last decade on the state of the interstellar medium (ISM) in M82, imply that the starburst environment is highly fragmented into a range of clouds from small/dense clumps with low-filling factors (<1 pc, n {sub e} approx> 10{sup 4} cm{sup -3}) to larger filling factor, less dense gas. The most compact clouds seem to be found in the cores of the star cluster complexes, whereas the cloud sizes in the inter-complex region are larger. These dense clouds are bathed with an intense radiation field and embedded in an extensive high temperature (T approx> 10{sup 6} K), X-ray-emitting ISM that is a product of the high star formation rates in the starburst zones of M82. The near-constant state of the ionization state of the approx10{sup 4} K gas throughout the M82 starburst zone can be explained as a consequence of the small cloud sizes, which allow the gas conditions to respond quickly to any changes. In Paper I, we found that the observed emission lines are composed of multiple components, including a broad (FWHM approx 150-350 km s{sup -1}) feature that we associate with emission from turbulent mixing layers on the surfaces of the gas clouds, resulting from the interaction of the fast wind outflows from the synchrotron self-Comptons. The large number of compact clouds

  8. Aspherical supernovae

    SciTech Connect

    Kasen, Daniel Nathan

    2004-01-01

    Although we know that many supernovae are aspherical, the exact nature of their geometry is undetermined. Because all the supernovae we observe are too distant to be resolved, the ejecta structure can't be directly imaged, and asymmetry must be inferred from signatures in the spectral features and polarization of the supernova light. The empirical interpretation of this data, however, is rather limited--to learn more about the detailed supernova geometry, theoretical modeling must been undertaken. One expects the geometry to be closely tied to the explosion mechanism and the progenitor star system, both of which are still under debate. Studying the 3-dimensional structure of supernovae should therefore provide new break throughs in our understanding. The goal of this thesis is to advance new techniques for calculating radiative transfer in 3-dimensional expanding atmospheres, and use them to study the flux and polarization signatures of aspherical supernovae. We develop a 3-D Monte Carlo transfer code and use it to directly fit recent spectropolarimetric observations, as well as calculate the observable properties of detailed multi-dimensional hydrodynamical explosion simulations. While previous theoretical efforts have been restricted to ellipsoidal models, we study several more complicated configurations that are tied to specific physical scenarios. We explore clumpy and toroidal geometries in fitting the spectropolarimetry of the Type Ia supernova SN 2001el. We then calculate the observable consequences of a supernova that has been rendered asymmetric by crashing into a nearby companion star. Finally, we fit the spectrum of a peculiar and extraordinarily luminous Type Ic supernova. The results are brought to bear on three broader astrophysical questions: (1) What are the progenitors and the explosion processes of Type Ia supernovae? (2) What effect does asymmetry have on the observational diversity of Type Ia supernovae, and hence their use in cosmology? (3) And

  9. Hubble Space Telescope Space Telescope Imaging Spectrograph Spectroscopy of the Environment in the Starburst Core of M82

    NASA Astrophysics Data System (ADS)

    Westmoquette, M. S.; Smith, L. J.; Gallagher, J. S., III; O'Connell, R. W.; Rosario, D. J.; de Grijs, R.

    2007-12-01

    We present optical HST STIS observations made with two slits crossing four of the optically brightest starburst clumps near the nucleus of M82. These provide Hα kinematics, extinction, electron density, and emission measures. From the radial velocity curves derived from both slits we confirm the presence of a stellar bar. We derive a new model for the orientation of the bar and disk with respect to the main starburst clumps and the cluster M82-A1. We propose that clump A has formed within the bar region as a result of gas interactions between the bar orbits, whereas region C lies at the edge of the bar and regions D and E are located farther out from the nucleus but heavily obscured. We derive extremely high interstellar densities of 500-900 cm-3, corresponding to ISM pressures of P/k~(0.5-1.0)×107 cm-3 K, and discuss the implications of the measured gas properties on the production and evolution of the galactic wind. Despite varying pressures, the ionization parameter is uniform down to parsec scales, and we discuss why this might be so. Where the signal-to-noise ratios of our spectra are high enough, we identify multiple emission-line components. Through detailed Gaussian line fitting, we identify a ubiquitous broad (200-300 km s-1) underlying component to the bright Hα line and discuss the physical mechanism(s) that could be responsible for such widths. We conclude that evaporation and/or ablation of material from interstellar gas clouds caused by the impact of high-energy photons and fast flowing cluster winds produce a highly turbulent layer on the surface of the clouds from which the emission arises. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555. These observations are associated with program 9117.

  10. An optical-near-IR study of a triplet of super star clusters in the starburst core of M82

    SciTech Connect

    Westmoquette, M. S.; Bastian, N.; Smith, L. J.; Seth, A. C.; Gallagher III, J. S.; Ryon, J. E.; O'Connell, R. W.; Silich, S.; Mayya, Y. D.; González, D. Rosa; Muñoz-Tuñón, C.

    2014-07-10

    We present HST/STIS optical and Gemini/NIFS near-IR IFU spectroscopy and archival Hubble Space Telescope (HST) imaging of the triplet of super star clusters (A1, A2, and A3) in the core of the M82 starburst. Using model fits to the Space Telescope Imaging Spectrograph (STIS) spectra and the weakness of red supergiant CO absorption features (appearing at ∼6 Myr) in the NIFS H-band spectra, the ages of A2 and A3 are 4.5 ± 1.0 Myr. A1 has strong CO bands, consistent with our previously determined age of 6.4 ± 0.5 Myr. The photometric masses of the three clusters are 4-7 × 10{sup 5} M{sub ☉}, and their sizes are R{sub eff} = 159, 104, 59 mas (∼2.8, 1.8, 1.0 pc) for A1, A2, and A3. The STIS spectra yielded radial velocities of 320 ± 2, 330 ± 6, and 336 ± 5 km s{sup –1} for A1, A2, and A3, placing them at the eastern end of the x{sub 2} orbits of M82's bar. Clusters A2 and A3 are in high-density (800-1000 cm{sup –3}) environments, and like A1, are surrounded by compact H II regions. We suggest the winds from A2 and A3 have stalled, as in A1, due to the high ISM ambient pressure. We propose that the three clusters were formed in situ on the outer x{sub 2} orbits in regions of dense molecular gas subsequently ionized by the rapidly evolving starburst. The similar radial velocities of the three clusters and their small projected separation of ∼25 pc suggest that they may merge in the near future unless this is prevented by velocity shearing.

  11. SPATIALLY RESOLVED STAR FORMATION HISTORY ALONG THE DISK OF M82 USING MULTI-BAND PHOTOMETRIC DATA

    SciTech Connect

    Rodriguez-Merino, L. H.; Rosa-Gonzalez, D.; Mayya, Y. D.

    2011-01-01

    We present results on the star formation history and extinction in the disk of M82 over spatial scales of 10'' ({approx}180 pc). Multi-band photometric data covering the far-ultraviolet to the near-infrared bands were fitted to a grid of synthetic spectral energy distributions. We obtained distribution functions of age and extinction for each of the 117 apertures analyzed, taking into account observational errors through Monte Carlo simulations. These distribution functions were fitted with Gaussian functions to obtain the mean ages and extinctions together with their errors. The zones analyzed include the high surface brightness complexes defined by O'Connell and Mangano. We found that these complexes share the same star formation history and extinction as the field stellar populations in the disk. There is an indication that the stellar populations are marginally older at the outer disk (450 Myr at {approx}3 kpc) as compared to the inner disk (100 Myr at 0.5 kpc). For the nuclear region (radius less than 500 pc), we obtained an age of less than 10 Myr. The results obtained in this work are consistent with the idea that the 0.5-3 kpc part of the disk of M82 formed around 90% of the stellar mass in a star-forming episode that started around 450 Myr ago and lasted for about 350 Myr. We found that field stars are the major contributors to the flux over the spatial scales analyzed in this study, with the stellar cluster contribution being 7% in the nucleus and 0.7% in the disk.

  12. An active ac/ds transposon system for activation tagging in tomato cultivar m82 using clonal propagation.

    PubMed

    Carter, Jared D; Pereira, Andy; Dickerman, Allan W; Veilleux, Richard E

    2013-05-01

    Tomato (Solanum lycopersicum) is a model organism for Solanaceae in both molecular and agronomic research. This project utilized Agrobacterium tumefaciens transformation and the transposon-tagging construct Activator (Ac)/Dissociator (Ds)-ATag-Bar_gosGFP to produce activation-tagged and knockout mutants in the processing tomato cultivar M82. The construct carried hygromycin resistance (hyg), green fluorescent protein (GFP), and the transposase (TPase) of maize (Zea mays) Activator major transcript X054214.1 on the stable Ac element, along with a 35S enhancer tetramer and glufosinate herbicide resistance (BAR) on the mobile Ds-ATag element. An in vitro propagation strategy was used to produce a population of 25 T0 plants from a single transformed plant regenerated in tissue culture. A T1 population of 11,000 selfed and cv M82 backcrossed progeny was produced from the functional T0 line. This population was screened using glufosinate herbicide, hygromycin leaf painting, and multiplex polymerase chain reaction (PCR). Insertion sites of transposed Ds-ATag elements were identified through thermal asymmetric interlaced PCR, and resulting product sequences were aligned to the recently published tomato genome. A population of 509 independent, Ds-only transposant lines spanning all 12 tomato chromosomes has been developed. Insertion site analysis demonstrated that more than 80% of these lines harbored Ds insertions conducive to activation tagging. The capacity of the Ds-ATag element to alter transcription was verified by quantitative real-time reverse transcription-PCR in two mutant lines. The transposon-tagged lines have been immortalized in seed stocks and can be accessed through an online database, providing a unique resource for tomato breeding and analysis of gene function in the background of a commercial tomato cultivar.

  13. Mapping MgII Emission in the M82 Superwind: A Rosetta Stone for Understanding Feedback in the Distant Universe

    NASA Astrophysics Data System (ADS)

    Rubin, Kate

    2013-10-01

    Galactic-scale outflows driven by star formation are a pervasive feature of galaxy formation models, and are required to prevent the overproduction of low-mass galaxies by regulating their cool gas supply. Winds from star-forming galaxies are commonly observed in the local Universe and out to z~6; however, empirical constraints on the spatial extent and energetics of winds in distant systems have been very challenging to obtain. Our group has pioneered the study of outflows in emission using resonantly-scattered MgII 2796, 2803 photons, a method which has the potential to map the spatial extent and morphology of galactic winds out to z~2. To take full advantage of this technique, we request 15 orbits for WFC3/UVIS narrow-band imaging of the prototypical starburst M82 to map its superwind in MgII emission. This map will trace photons resonantly scattered from cool, photoionized gas flowing from this galaxy for the first time. Unlike optical nebular lines, scattered MgII emission is an unbiased probe of T<10^4 K material, and will thus reveal a heretofore hidden component of the M82 outflow. This pilot program will focus on a single WFC3/UVIS pointing, and will leverage an extensive suite of archival WFC3/UVIS and ACS observations including H-alpha, H-beta, [OII], [OIII] and [SII] narrow-band imaging. This HST coverage, along with existing soft X-ray and CO emission maps, will yield the most detailed constraints on the physical state of gas in a galactic superwind to date, providing a crucial link between local and high-redshift studies of this phenomenon. Such constraints are fundamental to understanding the impact of feedback processes on galaxy evolution.

  14. Supernova Neutrinos

    SciTech Connect

    Beacom, John

    2009-11-14

    Supernovae in our Galaxy probably occur about 3 times per century, though 90% of them are invisible optically because of obscuration by dust. However, present solar neutrino detectors are sensitive to core-collapse supernovae anywhere in our Galaxy, and would detect of order 10,000 events from a supernova at a distance of 10 kpc (roughly the distance to the Galactic center). I will describe how this data can be used to understand the supernova itself, as well as to test the properties of neutrinos.

  15. Hot Young Solution to Faint Sun Paradox

    NASA Astrophysics Data System (ADS)

    Riofrio, L.

    2006-12-01

    the present value. The "paradox" leads to an extraordinary confirmation of Theory. The solar constant may indeed be constant, allowing life to have evolved on Earth for billions of years. Prediction of a changing c can be more precisely corroborated using observations of Type Ia supernovae. Earth's temperature provides additional data points to supplement supernova data from a more distant past. This corroborating data distinguishes Theory from "accelerating universe" ideas. Theory also may help determine whether CO2 warmed Earth's temperature in the past. In conclusion, the "Faint Young Sun" is not a problem but a window from the Earth sciences to astrophysics and cosmology. Geology and the fossil record can help verify "fossil" values of fundamental measurements, determining whether those values are indeed constant.

  16. Kinematics of faint white dwarfs.

    PubMed

    Luyten, W J

    1978-10-01

    An analysis has been made for solar motion for 128 very faint white dwarfs of color class b or a. While about 40% of these stars may be high-velocity objects, it seems definitely indicated that the luminosity of all of them is considerably lower than that for the "normal" white dwarf of the same color.

  17. X-ray QPOs from the Ultra-luminous X-ray Source in M82: Evidence Against Beaming

    NASA Technical Reports Server (NTRS)

    Strohmayer, Tod E.; Mushotzky, Richard F.

    2003-01-01

    We report the discovery with the European Photon Imaging Camera (EPIC) CCD cameras onboard XMM-Newton of a 54 mHz quasiperiodic oscillation (QPO) in the greater than 2 keV X-ray flux from the ultra-luminous X-ray source (ULX) X41.4+60 in the starburst galaxy M82. This is the first detection of a QPO in the X-ray flux from an extra-Galactic ULX, and confirms that the source is a compact object. The QPO is detected in the combined PN and MOS data at the approx. 6sigma level, and separately at lower significances in both the PN and MOS instruments. It had a centroid frequency of 54.3 +/- 0.9 mHz, a coherence Q is identical with nu(sub 0)/Delta nu(sub fwhm) is approx. 5, and an amplitude (rms) in the 2 - 10 keV band of 8.5%. Below about 0.2 Hz the power spectrum can be described by a power-law with index approx. 1, and integrated amplitude (rms) of 13.5%. The X-ray spectrum requires a curving continuum, with a disk-blackbody (diskbb) at T = 3.1 keV providing an acceptable, but not unique, fit. A broad Fe line centered at 6.55 keV is required in all fits, but the equivalent width (EW) of the line is sensitive to the choice of continuum model. There is no evidence of a reflection component. The implied bolometric luminosity is approx. 4 - 5 x 10(exp 40) ergs/s. Data from several archival Rossi X-ray Timing Explorer (RXTE) pointings at M82 also show evidence for QPOs in the 50 - 100 mHz frequency range. Several Galactic black hole candidates (BHCs), including GRS 1915+105, GRO J1655-40, and XTE 1550-564, show QPOs in the same frequency range as the 50 - 100 mHz QPOs in X41.4+60, which at first glance suggests a possible connection with such objects. However, strong, narrow QPOs provide solid evidence for disk emission, and thus present enormous theoretical difficulties for models which rely on either geometrically or relativistically beamed emission to account for the high X-ray luminosities. We discuss the implications of our findings for models of the ULX sources.

  18. An Optical-Near-IR Study of a Triplet of Super Star Clusters in the Starburst Core of M82

    NASA Astrophysics Data System (ADS)

    Westmoquette, M. S.; Bastian, N.; Smith, L. J.; Seth, A. C.; Gallagher, J. S., III; O'Connell, R. W.; Ryon, J. E.; Silich, S.; Mayya, Y. D.; Muñoz-Tuñón, C.; Rosa González, D.

    2014-07-01

    We present HST/STIS optical and Gemini/NIFS near-IR IFU spectroscopy and archival Hubble Space Telescope (HST) imaging of the triplet of super star clusters (A1, A2, and A3) in the core of the M82 starburst. Using model fits to the Space Telescope Imaging Spectrograph (STIS) spectra and the weakness of red supergiant CO absorption features (appearing at ~6 Myr) in the NIFS H-band spectra, the ages of A2 and A3 are 4.5 ± 1.0 Myr. A1 has strong CO bands, consistent with our previously determined age of 6.4 ± 0.5 Myr. The photometric masses of the three clusters are 4-7 × 105 M ⊙, and their sizes are R eff = 159, 104, 59 mas (~2.8, 1.8, 1.0 pc) for A1, A2, and A3. The STIS spectra yielded radial velocities of 320 ± 2, 330 ± 6, and 336 ± 5 km s-1 for A1, A2, and A3, placing them at the eastern end of the x 2 orbits of M82's bar. Clusters A2 and A3 are in high-density (800-1000 cm-3) environments, and like A1, are surrounded by compact H II regions. We suggest the winds from A2 and A3 have stalled, as in A1, due to the high ISM ambient pressure. We propose that the three clusters were formed in situ on the outer x 2 orbits in regions of dense molecular gas subsequently ionized by the rapidly evolving starburst. The similar radial velocities of the three clusters and their small projected separation of ~25 pc suggest that they may merge in the near future unless this is prevented by velocity shearing. Based on observations with the NASA/ESA Hubble Space Telescope under program 11641 and the Gemini-North telescope under program GN-2010B-Q-4.

  19. supernovae: Photometric classification of supernovae

    NASA Astrophysics Data System (ADS)

    Charnock, Tom; Moss, Adam

    2017-05-01

    Supernovae classifies supernovae using their light curves directly as inputs to a deep recurrent neural network, which learns information from the sequence of observations. Observational time and filter fluxes are used as inputs; since the inputs are agnostic, additional data such as host galaxy information can also be included.

  20. TRANSITION TO THE DISK DOMINANT STATE OF A NEW ULTRALUMINOUS X-RAY SOURCE IN M82

    SciTech Connect

    Jin Jing; Feng Hua; Kaaret, Philip

    2010-06-10

    We report on the identification of a third, new ultraluminous X-ray source in the starburst galaxy M82. Previously, the source was observed at fluxes consistent with the high state of Galactic black hole binaries (BHBs). We observe fluxes up to (6.5 {+-} 0.3) x 10{sup 39} erg s{sup -1} in the ultraluminous regime. When the source is not in the low/hard state, spectral fitting using a multicolor disk model shows that the disk luminosity varies as the disk inner temperature raised to the power 4.8 {+-} 0.9, consistent with the behavior of Galactic BHBs in the thermal dominant state. Fitting the spectrum with a multicolor disk model with general relativistic corrections suggests that the source harbors a rapidly spinning black hole with a mass less than 100 solar masses. A soft excess was found in the source spectrum that could be blackbody emission from a photosphere created by a massive outflow. The source also showed soft dips during a flare.

  1. DISCOVERY OF MILLIHERTZ X-RAY OSCILLATIONS IN A TRANSIENT ULTRALUMINOUS X-RAY SOURCE IN M82

    SciTech Connect

    Feng Hua; Rao Fengyun; Kaaret, Philip

    2010-02-20

    We report on the discovery of X-ray quasi-periodic oscillations (QPOs) at frequencies of 3-4 mHz from a transient ultraluminous X-ray source X42.3+59 in M82. The QPOs are strong and broad and appear with weak or absent red noise, and are detected only in Chandra observations when the source is brighter than 10{sup 40} erg s{sup -1}. The QPO behavior is similar to the type A-I QPOs found in XTE J1550 - 564, which is a subclass of low-frequency QPOs with properties in between types A and B. Therefore, we identify the QPOs in X42.3+59 as of type A or B and rule out the possibility of type C. With this identification, the mass of the black hole in X42.3+59 can be inferred as in the range of 12,000-43,000 solar masses by scaling the QPO frequency to that of the type A/B QPOs in stellar mass black holes. Cool disk emission is detected in one Chandra observation, and the disk inner radius suggests a similar black hole mass range. Black holes of such a high mass are able to produce an energy output in a manner similar to X42.3+59 by accreting from the interstellar medium directly.

  2. Charge-exchange X-ray emission of M82: Kα triplets of O VII, Ne IX and Mg XI

    NASA Astrophysics Data System (ADS)

    Liu, Jiren; Mao, Shude; Wang, Q. Daniel

    2011-07-01

    Starburst galaxies are primary feedback sources of mechanical energy and metals, which are generally measured from associated X-ray emission lines, assuming that they are from the thermal emission of the outflowing hot gas. Such line emission, however, can also arise from the charge-exchange X-ray emission (CXE) between highly ionized ions and neutral species. To understand the feedback of energy and metals, it is crucial to determine the origin of the X-ray emission lines and to distinguish the contributions from the CXE and the thermal emission. The origin of the lines can be diagnosed by the Kα triplets of He-like ions, because the CXE favours the intercombination and forbidden lines, while the thermal emission favours the resonance line. We analyse the triplets of O VII, Ne IX and Mg XI observed in the XMM-Newton reflection grating spectra of the starburst galaxy M82. The flux contribution of the CXE is 90, 50 and 30 per cent to the O VII, Ne IX and Mg XI triplets, respectively. Averaged over all the three triplets, the contribution of the CXE is ˜50 per cent of the total observed triplet flux. To correctly understand the hot outflow of starburst galaxies, it is necessary to include the CXE. Based on the measured CXE fluxes of the O VII, Ne IX and Mg XI triplets, we estimate the relative abundances of O, Ne and Mg of the outflow and find they are similar to the solar ratios.

  3. Supernova models

    SciTech Connect

    Woosley, S.E.; Weaver, T.A.

    1980-01-01

    Recent progress in understanding the observed properties of Type I supernovae as a consequence of the thermonuclear detonation of white dwarf stars and the ensuing decay of the /sup 56/Ni produced therein is reviewed. Within the context of this model for Type I explosions and the 1978 model for Type II explosions, the expected nucleosynthesis and gamma-line spectra from both kinds of supernovae are presented. Finally, a qualitatively new approach to the problem of massive star death and Type II supernovae based upon a combination of rotation and thermonuclear burning is discussed.

  4. Chandra Observations of Faint LMXB's

    NASA Technical Reports Server (NTRS)

    Wilson, Colleen A.; Patel, S. K.; Kouveliotou, C.; vanderKlis, M.; Belloni, T.; Lewin, W. H. G.; Six, N. Frank (Technical Monitor)

    2002-01-01

    There exists a group of persistently faint galactic X-ray sources that based on their location in the galaxy, high Lx/Lopt, association with X-ray bursts, and absence of X-ray pulsations are thought to be low-mass X-ray binaries (LMXBs). We present results from Chandra observations for 7 of these systems: 1708-409, 1711-339, 1735-269, 1736-297, 1746-331, 1746.7-3224, and 1812-12. Improved locations for all sources, excluding 1736-297 and 1746-331 (which were not detected) are presented. Our observations are consistent with previously reported transient behavior of 1736-297, 1746-331, and 1711-339 (which we detect in one of two observations). Energy and power spectra are presented for 1735-269, 1711-339, and 1746.7-3224. The energy spectra are hard, consistent with typical faint LMXB spectra. Further, we present a newly discovered source, a very faint, soft, source, separated by 2.7' from 1746.7-3224.

  5. Kinematic Masses of Super-Star Clusters in M82 from High-Resolution Near-Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    McCrady, Nate; Gilbert, Andrea M.; Graham, James R.

    2003-10-01

    Using high-resolution (R~22,000) near-infrared (1.51-1.75 μm) spectra from Keck Observatory, we measure the kinematic masses of two super-star clusters in M82. Cross-correlation of the spectra with template spectra of cool evolved stars gives stellar velocity dispersions of σr=15.9+/-0.8 km s-1 for J0955505+694045 (MGG-9) and σr=11.4+/-0.8 km s-1 for J0955502+694045 (MGG-11). The cluster spectra are dominated by the light of red supergiants and correlate most closely with template supergiants of spectral types M0 and M4.5. King model fits to the observed profiles of the clusters in archival Hubble Space Telescope/Near-Infrared Camera and Multi-Object Spectometer images give half-light radii of rhp=2.6+/-0.4 pc for MGG-9 and rhp=1.2+/-0.17 pc for MGG-11. Applying the virial theorem, we determine masses of 1.5+/-0.3×106 Msolar for MGG-9 and 3.5+/-0.7×105 Msolar for MGG-11 (where the quoted errors include σr, rhp, and the distance). Population synthesis modeling suggests that MGG-9 is consistent with a standard initial mass function (IMF), whereas MGG-11 appears to be deficient in low-mass stars relative to a standard IMF. There is, however, evidence of mass segregation in the clusters, in which case the virial mass estimates would represent lower limits. Based on observations made at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  6. Supernova Neutrinos

    SciTech Connect

    Cardall, Christian Y

    2007-01-01

    A nascent neutron star resulting from stellar collapse is a prodigious source of neutrinos of all flavors. While the most basic features of this neutrino emission can be estimated from simple considerations, the detailed simulation of the neutrinos' decoupling from the hot neutron star is not yet computationally tractable in its full glory, being a time-dependent six-dimensional transport problem. Nevertheless, supernova neutrino fluxes are of great interest in connection with the core-collapse supernova explosion mechanism and supernova nucleosynthesis, and as a potential probe of the supernova environment and of some of the neutrino mixing parameters that remain unknown; hence, a variety of approximate transport schemes have been used to obtain results with reduced dimensionality. However, none of these approximate schemes have addressed a recent challenge to the conventional wisdom that neutrino flavor mixing cannot impact the explosion mechanism or r-process nucleosynthesis.

  7. Fainting

    MedlinePlus

    ... usually because changes in the nervous system and circulatory system cause a temporary drop in the amount of ... a lot of changes, including changes in the circulatory system. This leads to low blood pressure that may ...

  8. Fainting

    MedlinePlus

    ... usually because changes in the nervous system and circulatory_system cause a temporary drop in the amount of ... a lot of changes, including changes in the circulatory system. This leads to low blood pressure that may ...

  9. Faintness

    MedlinePlus

    ... yourself? About Stephen J. Schueler, M.D News Advertising How It Works FAQ for Consumers FAQ for Physicians Testimonials Site Map Terms of Use Contact Us FreeMD is provided for information purposes only and should not be used as a ...

  10. A low-energy core-collapse supernova without a hydrogen envelope.

    PubMed

    Valenti, S; Pastorello, A; Cappellaro, E; Benetti, S; Mazzali, P A; Manteca, J; Taubenberger, S; Elias-Rosa, N; Ferrando, R; Harutyunyan, A; Hentunen, V P; Nissinen, M; Pian, E; Turatto, M; Zampieri, L; Smartt, S J

    2009-06-04

    The final fate of massive stars depends on many factors. Theory suggests that some with initial masses greater than 25 to 30 solar masses end up as Wolf-Rayet stars, which are deficient in hydrogen in their outer layers because of mass loss through strong stellar winds. The most massive of these stars have cores which may form a black hole and theory predicts that the resulting explosion of some of them produces ejecta of low kinetic energy, a faint optical luminosity and a small mass fraction of radioactive nickel. An alternative origin for low-energy supernovae is the collapse of the oxygen-neon core of a star of 7-9 solar masses. No weak, hydrogen-deficient, core-collapse supernovae have hitherto been seen. Here we report that SN 2008ha is a faint hydrogen-poor supernova. We propose that other similar events have been observed but have been misclassified as peculiar thermonuclear supernovae (sometimes labelled SN 2002cx-like events). This discovery could link these faint supernovae to some long-duration gamma-ray bursts, because extremely faint, hydrogen-stripped core-collapse supernovae have been proposed to produce such long gamma-ray bursts, the afterglows of which do not show evidence of associated supernovae.

  11. The faint quasar luminosity function

    NASA Technical Reports Server (NTRS)

    Kron, Richard G.; Bershady, Matthew A.; Munn, Jeffrey A.; Smetanka, John J.; Majewski, Steven; Koo, David C.

    1991-01-01

    Preliminary results of an expanded program to determine the faint-quasar luminosity function are described. Quasars have been selected in four fields totaling 1.2 sq deg from four-band photometry. Out of a total of 130 quasars with good spectroscopy, 37 have J greater than 21.5 and 46 have F greater than 21.0. The spectroscopic sample is representative of all of the color-selected candidates. An estimate of the luminosity function as a function of redshift is derived.

  12. First results from the Faint Object Camera - SN 1987A

    NASA Technical Reports Server (NTRS)

    Jakobsen, P.; Albrecht, R.; Barbieri, C.; Blades, J. C.; Boksenberg, A.

    1991-01-01

    The first images of SN 1987A taken on day 1278 after outburst with the Faint Object Camera on board the Hubble Space Telescope are presented. The supernova is well detected and resolved spatially in three broadband ultraviolet exposures spanning the 1500-3800 A range and in a narrow-band image centered on the forbidden O III 5007 line. Simple uniform disk fits to the profiles of SN 1987A yield an average angular diameter of 170 + or - 30 mas, corresponding to an average expansion velocity of 6000 km/s. The derived broadband ultraviolet fluxes, when corrected for interstellar absorption, indicate a blue ultraviolet spectrum corresponding to a color temperature near 13,000 K.

  13. First results from the Faint Object Camera - SN 1987A

    SciTech Connect

    Jakobsen, P.; Albrecht, R.; Barbieri, C.; Blades, J.C.; Boksenberg, A. Space Telescope European Coordinating Facility, Garching Padova, Osservatorio Astronomico, Padua Space Telescope Science Institute, Baltimore, MD Royal Greenwich Observatory, Cambridge )

    1991-03-01

    The first images of SN 1987A taken on day 1278 after outburst with the Faint Object Camera on board the Hubble Space Telescope are presented. The supernova is well detected and resolved spatially in three broadband ultraviolet exposures spanning the 1500-3800 A range and in a narrow-band image centered on the forbidden O III 5007 line. Simple uniform disk fits to the profiles of SN 1987A yield an average angular diameter of 170 + or - 30 mas, corresponding to an average expansion velocity of 6000 km/s. The derived broadband ultraviolet fluxes, when corrected for interstellar absorption, indicate a blue ultraviolet spectrum corresponding to a color temperature near 13,000 K. 24 refs.

  14. SN 2009E: a faint clone of SN 1987A

    NASA Astrophysics Data System (ADS)

    Pastorello, A.; Pumo, M. L.; Navasardyan, H.; Zampieri, L.; Turatto, M.; Sollerman, J.; Taddia, F.; Kankare, E.; Mattila, S.; Nicolas, J.; Prosperi, E.; San Segundo Delgado, A.; Taubenberger, S.; Boles, T.; Bachini, M.; Benetti, S.; Bufano, F.; Cappellaro, E.; Cason, A. D.; Cetrulo, G.; Ergon, M.; Germany, L.; Harutyunyan, A.; Howerton, S.; Hurst, G. M.; Patat, F.; Stritzinger, M.; Strolger, L.-G.; Wells, W.

    2012-01-01

    H, Na I, [Ca II] and [O I], with the [O I] feature being relatively strong compared to the [Ca II] doublet. The overall spectroscopic evolution is reminiscent of that of the faint 56Ni-poor type II-plateau supernovae. This suggests that SN 2009E belongs to the low-luminosity, low 56Ni mass, low-energy tail in the distribution of the 1987A-like objects in the same manner as SN 1997D and similar events represent the faint tail in the distribution of physical properties for normal type II-plateau supernovae. Appendices A and B are available in electronic form at http://www.aanda.orgFull Table 2 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/537/A141

  15. The Faint Young Sun and Faint Young Stars Paradox

    NASA Astrophysics Data System (ADS)

    Martens, Petrus C.

    2017-10-01

    The purpose of this paper is to explore a resolution for the Faint Young Sun Paradox that has been mostly rejected by the community, namely the possibility of a somewhat more massive young Sun with a large mass loss rate sustained for two to three billion years. This would make the young Sun bright enough to keep both the terrestrial and Martian oceans from freezing, and thus resolve the paradox. It is found that a large and sustained mass loss is consistent with the well observed spin-down rate of Sun-like stars, and indeed may be required for it. It is concluded that a more massive young Sun must be considered a plausible hypothesis.

  16. MID-IR SPECTRA OF TYPE Ia SN 2014J IN M82 SPANNING THE FIRST 4 MONTHS

    SciTech Connect

    Telesco, Charles M.; Li, Dan; Barnes, Peter J.; Mariñas, Naibí; Zhang, Han; Höflich, Peter; Álvarez, Carlos; Fernández, Sergio; Rebolo, Rafael; Hough, James H.; Levenson, N. A.; Pantin, Eric; Roche, Patrick E-mail: phoeflich77@gmail.com

    2015-01-10

    We present a time series of 8-13 μm spectra and photometry for SN 2014J obtained 57, 81, 108, and 137 days after the explosion using CanariCam on the Gran Telescopio Canarias. This is the first mid-IR time series ever obtained for a Type Ia supernova (SN Ia). These observations can be understood within the framework of the delayed detonation model and the production of ∼0.6 M {sub ☉} of {sup 56}Ni, consistent with the observed brightness, the brightness decline relation, and the γ-ray fluxes. The [Co III] line at 11.888 μm is particularly useful for evaluating the time evolution of the photosphere and measuring the amount of {sup 56}Ni and thus the mass of the ejecta. Late-time line profiles of SN 2014J are rather symmetric and not shifted in the rest frame. We see argon emission, which provides a unique probe of mixing in the transition layer between incomplete burning and nuclear statistical equilibrium. We may see [Fe III] and [Ni IV] emission, both of which are observed to be substantially stronger than indicated by our models. If the latter identification is correct, then we are likely observing stable Ni, which might imply central mixing. In addition, electron capture, also required for stable Ni, requires densities larger than ∼1 × 10{sup 9} g cm{sup –3}, which are expected to be present only in white dwarfs close to the Chandrasekhar limit. This study demonstrates that mid-IR studies of SNe Ia are feasible from the ground and provide unique information, but it also indicates the need for better atomic data.

  17. Luminous supernovae.

    PubMed

    Gal-Yam, Avishay

    2012-08-24

    Supernovae, the luminous explosions of stars, have been observed since antiquity. However, various examples of superluminous supernovae (SLSNe; luminosities >7 × 10(43) ergs per second) have only recently been documented. From the accumulated evidence, SLSNe can be classified as radioactively powered (SLSN-R), hydrogen-rich (SLSN-II), and hydrogen-poor (SLSN-I, the most luminous class). The SLSN-II and SLSN-I classes are more common, whereas the SLSN-R class is better understood. The physical origins of the extreme luminosity emitted by SLSNe are a focus of current research.

  18. Interacting supernovae and supernova impostors: Evidence of incoming supernova explosions?

    SciTech Connect

    Tartaglia, L.

    2015-02-24

    Violent eruptions, and consequently major mass loss, are a common feature of the so–called Luminous Blue Variable (LBV) stars. During major eruptive episodes LBVs mimic the behavior of real type IIn supernovae (SNe), showing comparable radiated energy and similar spectroscopic properties. For this reason these events are frequently labelled as SN impostors. Type IIn SN spectra are characterized by the presence of prominent narrow Balmer lines in emission. In most cases, SNe IIn arise from massive stars (M>8{sub ⊙}) exploding in a dense H–rich circumstellar medium (CSM), produced by progenitor’s mass loss prior to the SN explosion. Although the mechanisms triggering these eruptions are still unknown, recently we had direct proofs of the connection between very massive stars, their eruptions and ejecta-CSM interacting SNe. SNe 2006jc, 2010mc, 2011ht and the controversial SN 2009ip are famous cases in which we observed the explosion of the star months to years after major outbursts. In this context, the case of a recent transient event, LSQ13zm, is extremely interesting since we observed an outburst just ∼3 weeks before the terminal SN explosion. All of this may suggest that SN impostors occasionally herald true SN explosions. Nonetheless, there are several cases where major eruptions are followed by a quiescent phase in the LBV life. The impostor SN 2007sv is one of these cases, since it showed a single outburst event. Its photometric (a relatively faint absolute magnitude at the maximum) and spectroscopic properties (low velocity and temperature of the ejecta, and the absence of the typical elements produced in the explosive nucleosynthesis) strongly suggest that SN 2007sv was the giant eruption of an LBV, which has then returned in a quiescent stage.

  19. Interacting supernovae and supernova impostors: Evidence of incoming supernova explosions?

    NASA Astrophysics Data System (ADS)

    Tartaglia, L.

    2015-02-01

    Violent eruptions, and consequently major mass loss, are a common feature of the so-called Luminous Blue Variable (LBV) stars. During major eruptive episodes LBVs mimic the behavior of real type IIn supernovae (SNe), showing comparable radiated energy and similar spectroscopic properties. For this reason these events are frequently labelled as SN impostors. Type IIn SN spectra are characterized by the presence of prominent narrow Balmer lines in emission. In most cases, SNe IIn arise from massive stars (M>8⊙) exploding in a dense H-rich circumstellar medium (CSM), produced by progenitor's mass loss prior to the SN explosion. Although the mechanisms triggering these eruptions are still unknown, recently we had direct proofs of the connection between very massive stars, their eruptions and ejecta-CSM interacting SNe. SNe 2006jc, 2010mc, 2011ht and the controversial SN 2009ip are famous cases in which we observed the explosion of the star months to years after major outbursts. In this context, the case of a recent transient event, LSQ13zm, is extremely interesting since we observed an outburst just ˜3 weeks before the terminal SN explosion. All of this may suggest that SN impostors occasionally herald true SN explosions. Nonetheless, there are several cases where major eruptions are followed by a quiescent phase in the LBV life. The impostor SN 2007sv is one of these cases, since it showed a single outburst event. Its photometric (a relatively faint absolute magnitude at the maximum) and spectroscopic properties (low velocity and temperature of the ejecta, and the absence of the typical elements produced in the explosive nucleosynthesis) strongly suggest that SN 2007sv was the giant eruption of an LBV, which has then returned in a quiescent stage.

  20. Faint dwarfs in nearby groups

    SciTech Connect

    Speller, Ryan; Taylor, James E. E-mail: taylor@uwaterloo.ca

    2014-06-20

    The number and distribution of dwarf satellite galaxies remain a critical test of cold dark matter-dominated structure formation on small scales. Until recently, observational information about galaxy formation on these scales has been limited mainly to the Local Group. We have searched for faint analogues of Local Group dwarfs around nearby bright galaxies, using a spatial clustering analysis of the photometric catalog of the Sloan Digital Sky Survey (SDSS) Data Release 8. Several other recent searches of SDSS have detected clustered satellite populations down to Δm{sub r} ≡ (m{sub r,} {sub sat} – m{sub r,} {sub main}) ∼ 6-8, using photometric redshifts to reduce background contamination. SDSS photometric redshifts are relatively imprecise, however, for faint and nearby galaxies. Instead, we use angular size to select potential nearby dwarfs and consider only the nearest isolated bright galaxies as primaries. As a result, we are able to detect an excess clustering signal from companions down to Δm{sub r} = 12, 4 mag fainter than most recent studies. We detect an overdensity of objects at separations <400 kpc, corresponding to about 4.6 ± 0.5 satellites per central galaxy, consistent with the satellite abundance expected from the Local Group, given our selection function. Although the sample of satellites detected is incomplete by construction, since it excludes the least and most compact dwarfs, this detection provides a lower bound on the average satellite luminosity function, down to luminosities corresponding to the faintest ''classical'' dwarfs of the Local Group.

  1. Globular Clusters for Faint Galaxies

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2017-07-01

    The origin of ultra-diffuse galaxies (UDGs) has posed a long-standing mystery for astronomers. New observations of several of these faint giants with the Hubble Space Telescope are now lending support to one theory.Faint-Galaxy MysteryHubble images of Dragonfly 44 (top) and DFX1 (bottom). The right panels show the data with greater contrast and extended objects masked. [van Dokkum et al. 2017]UDGs large, extremely faint spheroidal objects were first discovered in the Virgo galaxy cluster roughly three decades ago. Modern telescope capabilities have resulted in many more discoveries of similar faint galaxies in recent years, suggesting that they are a much more common phenomenon than we originally thought.Despite the many observations, UDGs still pose a number of unanswered questions. Chief among them: what are UDGs? Why are these objects the size of normal galaxies, yet so dim? There are two primary models that explain UDGs:UDGs were originally small galaxies, hence their low luminosity. Tidal interactions then puffed them up to the large size we observe today.UDGs are effectively failed galaxies. They formed the same way as normal galaxies of their large size, but something truncated their star formation early, preventing them from gaining the brightness that we would expect for galaxies of their size.Now a team of scientists led by Pieter van Dokkum (Yale University) has made some intriguing observations with Hubble that lend weight to one of these models.Globulars observed in 16 Coma-cluster UDGs by Hubble. The top right panel shows the galaxy identifications. The top left panel shows the derived number of globular clusters in each galaxy. [van Dokkum et al. 2017]Globulars GaloreVan Dokkum and collaborators imaged two UDGs with Hubble: Dragonfly 44 and DFX1, both located in the Coma galaxy cluster. These faint galaxies are both smooth and elongated, with no obvious irregular features, spiral arms, star-forming regions, or other indications of tidal interactions

  2. Simulating Supernova Light Curves

    SciTech Connect

    Even, Wesley Paul; Dolence, Joshua C.

    2016-05-05

    This report discusses supernova light simulations. A brief review of supernovae, basics of supernova light curves, simulation tools used at LANL, and supernova results are included. Further, it happens that many of the same methods used to generate simulated supernova light curves can also be used to model the emission from fireballs generated by explosions in the earth’s atmosphere.

  3. Astronomical Resources: Supernovae.

    ERIC Educational Resources Information Center

    Fraknoi, Andrew

    1987-01-01

    Contains a partially annotated, nontechnical bibliography of recent materials about supernovae, including some about the discovery of a supernova in the Large Magellanic Cloud. Includes citations of general books and articles about supernovae, articles about Supernova 1987A, and a few science fiction stories using supernovae. (TW)

  4. Electron-capture supernovae exploding within their progenitor wind

    NASA Astrophysics Data System (ADS)

    Moriya, Takashi J.; Tominaga, Nozomu; Langer, Norbert; Nomoto, Ken'ichi; Blinnikov, Sergei I.; Sorokina, Elena I.

    2014-09-01

    The most massive stars on the asymptotic giant branch (AGB), or the so-called super-AGB stars, are thought to produce supernovae triggered by electron captures in their degenerate O+Ne+Mg cores. Super-AGB stars are expected to have slow winds with high mass-loss rates, so their circumstellar density is high. The explosions of super-AGB stars are therefore presumed to occur in this dense circumstellar environment. We provide the first synthetic light curves for such events by exploding realistic electron-capture supernova progenitors within their super-AGB winds. We find that the early light curve - that is, before the recombination wave reaches the bottom of the hydrogen-rich envelope of supernova ejecta (the plateau phase) - is not affected by the dense wind. However, after the luminosity drop following the plateau phase, the luminosity remains much higher when the super-AGB wind is taken into account. We compare our results to the historical light curve of SN 1054, the progenitor of the Crab Nebula, and show that the explosion of an electron-capture supernova within an ordinary super-AGB wind can explain the observed light curve features. We conclude that SN 1054 could have been a Type IIn supernova without any extra extreme mass loss, which was previously suggested to be necessary to account for its early high luminosity. We also show that our light curves match Type IIn supernovae with an early plateau phase or the so-called Type IIn-P supernovae, and suggest that they are electron-capture supernovae within super-AGB winds. Although some electron-capture supernovae can be bright in the optical spectral range due to the large progenitor radius, their X-ray luminosity from the interaction does not necessarily get as bright as other Type IIn supernovae whose optical luminosities are also powered by the interaction. Thus, we suggest that optically bright X-ray-faint Type IIn supernovae can emerge from electron-capture supernovae. Optically faint Type IIn supernovae

  5. Interpretation of colors of faint galaxies

    SciTech Connect

    Kron, R.G.

    1980-10-01

    We present new calculations for evolving light in galaxies which allow the color distribution expected for faint field galaxies to be computed. We normalize the expected counts to data in catalogs of bright galaxies, and find that an excellent fit to Kron's faint photometry can be achieved with a Friedmann model and no other special assumptions.

  6. On the Nature of the mHz X-Ray QPOs from ULX M82 X-1: Evidence for Timing-Spectral (anti) Correlation

    NASA Technical Reports Server (NTRS)

    Pasham, Dheeraj R.; Strohmayer, Tod E.

    2013-01-01

    Using all the archival XMM-Newton X-ray (3-10 keV) observations of the ultraluminous X-ray source (ULX) M82 X-1 we searched for a correlation between its variable mHz quasi-periodic oscillation (QPO) frequency and its energy spectral power-law index. These quantities are known to correlate in stellar mass black holes (StMBHs) exhibiting Type-C QPOs (approx 0.2-15 Hz). The detection of such a correlation would strengthen the identification of its mHz QPOs as Type-C and enable a more reliable mass estimate by scaling its QPO frequencies to those of Type-C QPOs in StMBHs of known mass. We resolved the count rates of M82 X-1 and a nearby bright ULX (source 5/X42.3+59) through surface brightness modeling and identify observations in which M82 X-1 was at least as bright as source 5. Using only those observations, we detect QPOs in the frequency range of 36-210 mHz during which the energy spectral power-law index varied from 1.7-2.2. Interestingly, we find evidence for an anti-correlation (Pearsons correlation coefficient = -0.95) between the power-law index and the QPO centroid frequency. While such an anti-correlation is observed in StMBHs at high Type-C QPO frequencies (approx 5-15 Hz), the frequency range over which it holds in StMBHs is significantly smaller (factor of approx 1.5-3) than the QPO range reported here from M82 X-1 (factor of 6). However, it remains possible that contamination from source 5 can bias our result. Joint Chandra/XMM-Newton observations in the future can resolve this problem and confirm the timing-spectral anti-correlation reported here.

  7. Supernova Forensics

    NASA Astrophysics Data System (ADS)

    Soderberg, Alicia M.

    2014-01-01

    For decades, the study of stellar explosions -- supernovae -- have focused almost exclusively on the strong optical emission that dominates the bolometric luminosity in the days following the ultimate demise of the star. Yet many of the leading breakthroughs in our understanding of stellar death have been enabled by obtaining data at other wavelengths. For example, I have shown that 1% of all supernovae give rise to powerful relativistic jets, representing the biggest bangs in the Universe since the Big Bang. My recent serendipitous X-ray discovery of a supernova in the act of exploding (“in flagrante delicto”) revealed a novel technique to discover new events and provide clues on the shock physics at the heart of the explosion. With the advent of sensitive new radio telescopes, my research group combines clues from across the electromagnetic spectrum (radio to gamma-ray), leading us to a holistic study of stellar death, the physics of the explosions, and their role in fertilizing the Universe with new elements, by providing the community with cosmic autopsy reports.

  8. Happy birthday, supernova. [1987A

    SciTech Connect

    Schorn, R.A.

    1988-02-01

    The advances in understanding that have been made concerning SN 1987A in the year since it appeared are reviewed. The rapidity of the initial rise in brightness and the relatively faint absolute magnitude during the first few weeks have been found to be due to the progenitor star's being a blue giant, relatively small compared to a red giant. The nitrogen lines in the spectrum are evidence that the star was once a red giant whose stellar wind was so strong that the resulting loss of material converted the star into a blue giant. The variations in the light curve of the supernova are explained in terms of the radioactive decay of Ni-56 and Co-56 and the interaction of the resulting gamma rays with the debris cloud. Some of the remaining unanswered questions are summarized.

  9. Supernovae and the Accelerating Universe

    NASA Technical Reports Server (NTRS)

    Wood, H. John

    2003-01-01

    Orbiting high above the turbulence of the earth's atmosphere, the Hubble Space Telescope (HST) has provided breathtaking views of astronomical objects never before seen in such detail. The steady diffraction-limited images allow this medium-size telescope to reach faint galaxies of 30th stellar magnitude. Some of these galaxies are seen as early as 2 billion years after the Big Bang in a 15 billion year old universe. Up until recently, astronomers assumed that all of the laws of physics and astronomy applied back then as they do today. Now, using the discovery that certain supernovae are standard candles, astronomers have found that the universe is expanding faster today than it was back then: the universe is accelerating in its expansion.

  10. Supernovae and the Accelerating Universe

    NASA Technical Reports Server (NTRS)

    Wood, H. John

    2003-01-01

    Orbiting high above the turbulence of the earth's atmosphere, the Hubble Space Telescope (HST) has provided breathtaking views of astronomical objects never before seen in such detail. The steady diffraction-limited images allow this medium-size telescope to reach faint galaxies of 30th stellar magnitude. Some of these galaxies are seen as early as 2 billion years after the Big Bang in a 15 billion year old universe. Up until recently, astronomers assumed that all of the laws of physics and astronomy applied back then as they do today. Now, using the discovery that certain supernovae are standard candles, astronomers have found that the universe is expanding faster today than it was back then: the universe is accelerating in its expansion.

  11. Food for the photometrists - Faint galaxies revealed

    NASA Astrophysics Data System (ADS)

    Malin, D. F.

    The advantages of photographic plates over CCD detectors for some types of astronomical photometry (uniformity over large areas and information-storage capacity) are discussed, and illustrated using images of faint galaxies and faint galactic structures. It is pointed out that the photographic amplification technique (Malin, 1978), although at present only qualitative, is much more time-efficient than digital scanning. Consideration is also given to the production of full-color images by superimposition of B, V, and R plates.

  12. Supernova Relic Neutrinos and the Supernova Rate Problem: Analysis of Uncertainties and Detectability of ONeMg and Failed Supernovae

    NASA Astrophysics Data System (ADS)

    Mathews, Grant J.; Hidaka, Jun; Kajino, Toshitaka; Suzuki, Jyutaro

    2014-08-01

    Direct measurements of the core collapse supernova rate (R SN) in the redshift range 0 <= z <= 1 appear to be about a factor of two smaller than the rate inferred from the measured cosmic massive star formation rate (SFR). This discrepancy would imply that about one-half of the massive stars that have been born in the local observed comoving volume did not explode as luminous supernovae. In this work, we explore the possibility that one could clarify the source of this "supernova rate problem" by detecting the energy spectrum of supernova relic neutrinos with a next generation 106 ton water Čerenkov detector like Hyper-Kamiokande. First, we re-examine the supernova rate problem. We make a conservative alternative compilation of the measured SFR data over the redshift range 0 <=z <= 7. We show that by only including published SFR data for which the dust obscuration has been directly determined, the ratio of the observed massive SFR to the observed supernova rate R SN has large uncertainties {\\sim }1.8^{+1.6}_{-0.6} and is statistically consistent with no supernova rate problem. If we further consider that a significant fraction of massive stars will end their lives as faint ONeMg SNe or as failed SNe leading to a black hole remnant, then the ratio reduces to {\\sim }1.1^{+1.0}_{-0.4} and the rate problem is essentially solved. We next examine the prospects for detecting this solution to the supernova rate problem. We first study the sources of uncertainty involved in the theoretical estimates of the neutrino detection rate and analyze whether the spectrum of relic neutrinos can be used to independently identify the existence of a supernova rate problem and its source. We consider an ensemble of published and unpublished core collapse supernova simulation models to estimate the uncertainties in the anticipated neutrino luminosities and temperatures. We illustrate how the spectrum of detector events might be used to establish the average neutrino temperature and

  13. Supernova relic neutrinos and the supernova rate problem: Analysis of uncertainties and detectability of ONeMg and failed supernovae

    SciTech Connect

    Mathews, Grant J.; Hidaka, Jun; Kajino, Toshitaka; Suzuki, Jyutaro

    2014-08-01

    Direct measurements of the core collapse supernova rate (R{sub SN}) in the redshift range 0 ≤ z ≤ 1 appear to be about a factor of two smaller than the rate inferred from the measured cosmic massive star formation rate (SFR). This discrepancy would imply that about one-half of the massive stars that have been born in the local observed comoving volume did not explode as luminous supernovae. In this work, we explore the possibility that one could clarify the source of this 'supernova rate problem' by detecting the energy spectrum of supernova relic neutrinos with a next generation 10{sup 6} ton water Čerenkov detector like Hyper-Kamiokande. First, we re-examine the supernova rate problem. We make a conservative alternative compilation of the measured SFR data over the redshift range 0 ≤z ≤ 7. We show that by only including published SFR data for which the dust obscuration has been directly determined, the ratio of the observed massive SFR to the observed supernova rate R{sub SN} has large uncertainties ∼1.8{sub −0.6}{sup +1.6} and is statistically consistent with no supernova rate problem. If we further consider that a significant fraction of massive stars will end their lives as faint ONeMg SNe or as failed SNe leading to a black hole remnant, then the ratio reduces to ∼1.1{sub −0.4}{sup +1.0} and the rate problem is essentially solved. We next examine the prospects for detecting this solution to the supernova rate problem. We first study the sources of uncertainty involved in the theoretical estimates of the neutrino detection rate and analyze whether the spectrum of relic neutrinos can be used to independently identify the existence of a supernova rate problem and its source. We consider an ensemble of published and unpublished core collapse supernova simulation models to estimate the uncertainties in the anticipated neutrino luminosities and temperatures. We illustrate how the spectrum of detector events might be used to establish the average

  14. HUBBLE SPIES MOST DISTANT SUPERNOVA EVER SEEN

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Using NASA's Hubble Space Telescope, astronomers pinpointed a blaze of light from the farthest supernova ever seen, a dying star that exploded 10 billion years ago. The detection and analysis of this supernova, called 1997ff, is greatly bolstering the case for the existence of a mysterious form of dark energy pervading the cosmos, making galaxies hurl ever faster away from each other. The supernova also offers the first glimpse of the universe slowing down soon after the Big Bang, before it began speeding up. This panel of images, taken with the Wide Field and Planetary Camera 2, shows the supernova's cosmic neighborhood; its home galaxy; and the dying star itself. Astronomers found this supernova in 1997 during a second look at the northern Hubble Deep Field [top panel], a tiny region of sky first explored by the Hubble telescope in 1995. The image shows the myriad of galaxies Hubble spied when it peered across more than 10 billion years of time and space. The white box marks the area where the supernova dwells. The photo at bottom left is a close-up view of that region. The white arrow points to the exploding star's home galaxy, a faint elliptical. Its redness is due to the billions of old stars residing there. The picture at bottom right shows the supernova itself, distinguished by the white dot in the center. Although this stellar explosion is among the brightest beacons in the universe, it could not be seen directly in the Hubble images. The stellar blast is so distant from Earth that its light is buried in the glow of its host galaxy. To find the supernova, astronomers compared two pictures of the 'deep field' taken two years apart. One image was of the original Hubble Deep Field; the other, the follow-up deep-field picture taken in 1997. Using special computer software, astronomers then measured the light from the galaxies in both images. Noting any changes in light output between the two pictures, the computer identified a blob of light in the 1997 picture

  15. HUBBLE SPIES MOST DISTANT SUPERNOVA EVER SEEN

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Using NASA's Hubble Space Telescope, astronomers pinpointed a blaze of light from the farthest supernova ever seen, a dying star that exploded 10 billion years ago. The detection and analysis of this supernova, called 1997ff, is greatly bolstering the case for the existence of a mysterious form of dark energy pervading the cosmos, making galaxies hurl ever faster away from each other. The supernova also offers the first glimpse of the universe slowing down soon after the Big Bang, before it began speeding up. This panel of images, taken with the Wide Field and Planetary Camera 2, shows the supernova's cosmic neighborhood; its home galaxy; and the dying star itself. Astronomers found this supernova in 1997 during a second look at the northern Hubble Deep Field [top panel], a tiny region of sky first explored by the Hubble telescope in 1995. The image shows the myriad of galaxies Hubble spied when it peered across more than 10 billion years of time and space. The white box marks the area where the supernova dwells. The photo at bottom left is a close-up view of that region. The white arrow points to the exploding star's home galaxy, a faint elliptical. Its redness is due to the billions of old stars residing there. The picture at bottom right shows the supernova itself, distinguished by the white dot in the center. Although this stellar explosion is among the brightest beacons in the universe, it could not be seen directly in the Hubble images. The stellar blast is so distant from Earth that its light is buried in the glow of its host galaxy. To find the supernova, astronomers compared two pictures of the 'deep field' taken two years apart. One image was of the original Hubble Deep Field; the other, the follow-up deep-field picture taken in 1997. Using special computer software, astronomers then measured the light from the galaxies in both images. Noting any changes in light output between the two pictures, the computer identified a blob of light in the 1997 picture

  16. Direct Measurement of the Supernova Rate in Starburst Galaxies

    NASA Technical Reports Server (NTRS)

    Bregman, Jesse D.; Temi, Pasquale; Rank, David; DeVincenzi, Donald L. (Technical Monitor)

    1999-01-01

    Supernovae play a key role in the dynamics, structure, and chemical evolution of galaxies. The massive stars that end their lives as supernovae live for short times. Many are still associated with dusty star formation regions when they explode, making them difficult to observe at visible wavelengths. In active star forming regions (galactic nuclei and starburst regions), dust extintion is especially severe. Thus, determining the supernova rate in the active star forming regions of galaxies, where the supernova rate can be one or two orders of magnitude higher than the average, has proven to be difficult. From observations of SN1987A, we know that the [NiII] 6.63 micron emission line was the strongest line in the infrared spectrum for a period of a year and a half after the explosion. Since dust extintion is much less at 6.63 pm than at visible wavelengths (A(sub 6.63)/A(sub V) = 0.025), the NiII line can be used as a sensitive probe for the detection of recent supernovae. We have observed a sample of starburst galaxies at 6.63 micron using ISOCAM to search for the NiII emission line characteristic of recent supernovae. We did not detect any NiII line emission brighter than a 5sigma limit of 5 mJy. We can set upper limits to the supernova rate in our sample, scaled to the rate in M82, of less than 0.3 per year at the 90% confidence level using Bayesian methods. Assuming that a supernova would have a NiII with the same luminosity as observed in SN1987A, we find less than 0.09 and 0.15 per year at the 50% and 67% confidence levels. These rates are somewhat less if a more normal type II supernovae has a NiII line luminosity greater than the line in SN1987A.

  17. Direct Measurement of the Supernova Rate in Starburst Galaxies

    NASA Technical Reports Server (NTRS)

    Bregman, J. D.; Temi, P.; Rank, D.

    2000-01-01

    Supernovae play a key role in the dynamics, structure, and chemical evolution of galaxies. The massive stars that end their lives as supernovae live for short enough times that many are still associated with dusty star formation regions when they explode, making them difficult to observe at visible wavelengths. In active star forming regions (galactic nuclei and starburst regions), dust extinction is especially severe. Thus, determining the supernova rate in active star forming regions of galaxies, where the supernova rate can be one or two orders of magnitude higher than the average, has proven to be difficult. From observations of SN1987A, we know that the [NiII] 6.63 micrometer emission line was the strongest line in the infrared spectrum for a period of a year and half after th explosion. Since dust extinction is much less at 6.63 micrometers than at visible wavelengths (A(sub 6.63)/A(sub V) = 0.025), the [NiII] line can be used as a sensitive probe for the detection of recent supernovae. We have observed a sample of starburst galaxies at 6.63 micrometers using ISOCAM to search for the [NiII] emission line characteristic of recent supernovae. We did not detect any [NiII] line emission brighter than a 5-sigma limit of 5 mJy. We can set upper limits to the supernova rate in our sample, scaled ot the rate in M82, of less than 0.3 per year at the 90% confidence level using Bayesian methods. Assuming that a supernova would have a [NiII] line with the same luminosity as observed in SN1987A, we find less than 0.09 and 0.15 per year at the 50% and 67% confidence levels. These rates are somewhat less if a more normal type II supernovae has a [NiII] line luminosity greater than the line in SN1987A.

  18. The Phylogeography of Y-Chromosome Haplogroup H1a1a-M82 Reveals the Likely Indian Origin of the European Romani Populations

    PubMed Central

    Pathak, Ajai Kumar; Singh, Vipin Kumar; Karmin, Monika; Singh, Manvendra; Rani, Deepa Selvi; Anugula, Sharath; Yadav, Brijesh Kumar; Singh, Ashish; Srinivasagan, Ramkumar; Yadav, Anita; Kashyap, Manju; Narvariya, Sapna; Reddy, Alla G.; Underhill, Peter A.; Villems, Richard; Kivisild, Toomas; Singh, Lalji; Thangaraj, Kumarasamy

    2012-01-01

    Linguistic and genetic studies on Roma populations inhabited in Europe have unequivocally traced these populations to the Indian subcontinent. However, the exact parental population group and time of the out-of-India dispersal have remained disputed. In the absence of archaeological records and with only scanty historical documentation of the Roma, comparative linguistic studies were the first to identify their Indian origin. Recently, molecular studies on the basis of disease-causing mutations and haploid DNA markers (i.e. mtDNA and Y-chromosome) supported the linguistic view. The presence of Indian-specific Y-chromosome haplogroup H1a1a-M82 and mtDNA haplogroups M5a1, M18 and M35b among Roma has corroborated that their South Asian origins and later admixture with Near Eastern and European populations. However, previous studies have left unanswered questions about the exact parental population groups in South Asia. Here we present a detailed phylogeographical study of Y-chromosomal haplogroup H1a1a-M82 in a data set of more than 10,000 global samples to discern a more precise ancestral source of European Romani populations. The phylogeographical patterns and diversity estimates indicate an early origin of this haplogroup in the Indian subcontinent and its further expansion to other regions. Tellingly, the short tandem repeat (STR) based network of H1a1a-M82 lineages displayed the closest connection of Romani haplotypes with the traditional scheduled caste and scheduled tribe population groups of northwestern India. PMID:23209554

  19. Supernova neutrinos

    SciTech Connect

    John Beacom

    2003-01-23

    We propose that neutrino-proton elastic scattering, {nu} + p {yields} {nu} + p, can be used for the detection of supernova neutrinos. Though the proton recoil kinetic energy spectrum is soft, with T{sub p} {approx_equal} 2E{sub {nu}}{sup 2}/M{sub p}, and the scintillation light output from slow, heavily ionizing protons is quenched, the yield above a realistic threshold is nearly as large as that from {bar {nu}}{sub e} + p {yields} e{sup +} + n. In addition, the measured proton spectrum is related to the incident neutrino spectrum, which solves a long-standing problem of how to separately measure the total energy release and temperature of {nu}{sub {mu}}, {nu}{sub {tau}}, {bar {nu}}{sub {mu}}, and {bar {nu}}{sub {tau}}. The ability to detect this signal would give detectors like KamLAND and Borexino a crucial and unique role in the quest to detect supernova neutrinos.

  20. A thick-disc origin for Tycho Brahe's 1572 supernova?

    NASA Astrophysics Data System (ADS)

    Fuhrmann, Klaus

    2005-05-01

    The very recent suggestion for the identification of a faint G-type subgiant, dubbed `Tycho G', as the binary progenitor of Tycho Brahe's 1572 Type Ia supernova by Ruiz-Lapuente et al. is essentially based on the peculiar space velocity of the star. Here we demonstrate that the kinematics of Tycho G are likewise in keeping with the stars of the Milky Way's thick-disc population. Hence we may well be seeing an object that is only coincidentally passing in the vicinity of the supernova remnant, or Tycho Brahe and his contemporaries may indeed have witnessed the late explosion of one of the first stars in the Galaxy.

  1. Autopsy of the Supernova Remnant Cassiopeia A

    NASA Astrophysics Data System (ADS)

    Milisavljevic, Dan; Fesen, Robert A.

    2014-01-01

    Three-dimensional kinematic reconstructions of optically emitting ejecta in the young Galactic supernova remnant Cassiopeia A (Cas A) are discussed. The reconstructions encompass the remnant's faint outlying ejecta knots, including the exceptionally high-velocity NE and SW streams of debris often referred to as `jets'. The bulk of Cas A's ejecta are arranged in several circular rings with diameters between approximately 30'' (0.5 pc) and 2' (2 pc). We suggest that similar large-scale ejecta rings may be a common phenomenon of young core-collapse remnants and may explain lumpy emission line profile substructure sometimes observed in spectra of extragalactic core-collapse supernovae years after explosion. A likely origin for these large ejecta rings is post-explosion input of energy from plumes of radioactive 56Ni-rich ejecta that rise, expand, and compress non-radioactive material to form bubble-like structures.

  2. Superluminous Extragalactic Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Chen, C. H. R.; Chu, Y.-H.

    1998-12-01

    Extragalactic supernova remnants (SNRs) are conventionally surveyed by optical emission-line images, using the [S II]/Hα line ratio to diagnose SNRs. The majority of the optically identified extragalactic SNRs are too faint to be confirmed at X-ray or radio wavelengths. Conversely, extragalactic SNRs that are initially identified by X-ray or radio observations are all superluminous, e.g., the X-ray SNR in NGC 6946 (Blair & Fesen 1994, ApJ, 424, L103) and the radio SNR in NGC 5471 (Skillman 1985, ApJ, 290, 449). NGC 5471 is a giant H II region in M101. Optical echelle observations of the SNR in NGC 5471 have detected high-velocity gas with a FWZI of at least 350 km/s. Decomposing the narrow H II component and the broad SNR component in the Hα velocity profile, Chu & Kennicutt (1986) derived a total mass of 6500+/-3000 M_sun and a kinetic energy of a few *E(50) ergs. Using archival ROSAT X-ray observations, Williams & Chu (1995) measured an X-ray luminosity of ~ 1 x 10(38) ergs/s for NGC 5471. Apparently, the SNR in NGC 5471 is superluminous at all wavelengths. To determine the physical conditions and nature of the superluminous SNR in NGC 5471, we have obtained HST WFPC2 images of NGC 5471 in the Hα and [S II] lines and two continuum bands. These high-resolution images reveal a [S II]-enhanced shell with a diameter of ~ 60 pc. A recent 180-ks ROSAT High Resolution Imager image of M101 shows that the X-ray emission from NGC 5471 peaks at this SNR shell. We are thus confident in the identification of the superluminous SNR in NGC 5471. Are superluminous SNRs produced by particularly powerful supernova explosions? Are they associated with gamma-ray bursters? Are their luminosities caused by dense interstellar environment? We will report the detailed physical properties of the SNR in NGC 5471, compare it to the other superluminous SNRs, and address these questions.

  3. Cygnus Loop Supernova Blast Wave

    NASA Technical Reports Server (NTRS)

    1993-01-01

    This is an image of a small portion of the Cygnus Loop supernova remnant, which marks the edge of a bubble-like, expanding blast wave from a colossal stellar explosion, occurring about 15,000 years ago. The HST image shows the structure behind the shock waves, allowing astronomers for the first time to directly compare the actual structure of the shock with theoretical model calculations. Besides supernova remnants, these shock models are important in understanding a wide range of astrophysical phenomena, from winds in newly-formed stars to cataclysmic stellar outbursts. The supernova blast is slamming into tenuous clouds of insterstellar gas. This collision heats and compresses the gas, causing it to glow. The shock thus acts as a searchlight revealing the structure of the interstellar medium. The detailed HST image shows the blast wave overrunning dense clumps of gas, which despite HST's high resolution, cannot be resolved. This means that the clumps of gas must be small enough to fit inside our solar system, making them relatively small structures by interstellar standards. A bluish ribbon of light stretching left to right across the picture might be a knot of gas ejected by the supernova; this interstellar 'bullet' traveling over three million miles per hour (5 million kilometres) is just catching up with the shock front, which has slowed down by ploughing into interstellar material. The Cygnus Loop appears as a faint ring of glowing gases about three degrees across (six times the diameter of the full Moon), located in the northern constellation, Cygnus the Swan. The supernova remnant is within the plane of our Milky Way galaxy and is 2,600 light-years away. The photo is a combination of separate images taken in three colors, oxygen atoms (blue) emit light at temperatures of 30,000 to 60,000 degrees Celsius (50,000 to 100,000 degrees Farenheit). Hydrogen atoms (green) arise throughout the region of shocked gas. Sulfur atoms (red) form when the gas cools to

  4. CAN THE 62 DAY X-RAY PERIOD OF ULX M82 X-1 BE DUE TO A PRECESSING ACCRETION DISK?

    SciTech Connect

    Pasham, Dheeraj R.; Strohmayer, Tod E. E-mail: tod.strohmayer@nasa.gov

    2013-09-10

    We have analyzed all archival Rossi X-Ray Timing Explorer/Proportional Counter Array monitoring observations of the ultraluminous X-ray source M82 X-1 in order to study the properties of its 62 day X-ray period, which was found by Kaaret and Feng in 2007. Based on its high coherence, it has been argued that the observed period is the orbital period of the binary. Utilizing a much longer data set than in previous studies, we find the following. (1) The phase-resolved X-ray (3-15 keV) spectra-modeled with a thermal accretion disk and a power law-suggest that the accretion disk's contribution to the total flux is strongly modulated with phase. (2) Suggestive evidence for a sudden phase shift of approximately 0.4 in phase (25 days) between the first and the second halves of the light curve separated by roughly 1000 days. If confirmed, the implied timescale to change the period is {approx}10 yr, which is exceptionally fast for an orbital phenomenon. These two independent pieces of evidence are consistent with the periodicity being due to a precessing accretion disk, similar to the super-orbital periods observed in systems like Her X-1, LMC X-4, and SS433. However, the timing evidence for a change in the period needs to be confirmed with additional observations. This should be possible with further monitoring of M82 with instruments such as the Swift X-Ray Telescope.

  5. Mass fainting in garment factories in Cambodia.

    PubMed

    Eisenbruch, Maurice

    2017-04-01

    This paper reports an ethnographic study of mass fainting among garment factory workers in Cambodia. Research was undertaken in 2010-2015 in 48 factories in Phnom Penh and 8 provinces. Data were collected in Khmer using nonprobability sampling. In participant observation with monks, factory managers, health workers, and affected women, cultural understandings were explored. One or more episodes of mass fainting occurred at 34 factories, of which 9 were triggered by spirit possession. Informants viewed the causes in the domains of ill-health/toxins and supernatural activities. These included "haunting" ghosts at factory sites in the wake of Khmer Rouge atrocities or recent fatal accidents and retaliating guardian spirits at sites violated by foreign owners. Prefigurative dreams, industrial accidents, or possession of a coworker heralded the episodes. Workers witnessing a coworker fainting felt afraid and fainted. When taken to clinics, some showed signs of continued spirit influence. Afterwards, monks performed ritual ceremonies to appease spirits, extinguish bonds with ghosts, and prevent recurrence. Decoded through its cultural motifs of fear and protest, contagion, forebodings, the bloody Khmer Rouge legacy, and trespass, mass fainting in Cambodia becomes less enigmatic.

  6. On the clustering of faint red galaxies

    NASA Astrophysics Data System (ADS)

    Xu, Haojie; Zheng, Zheng; Guo, Hong; Zhu, Ju; Zehavi, Idit

    2016-08-01

    Faint red galaxies in the Sloan Digital Sky Survey show a puzzling clustering pattern in previous measurements. In the two-point correlation function (2PCF), they appear to be strongly clustered on small scales, indicating a tendency to reside in massive haloes as satellite galaxies. However, their weak clustering on large scales suggests that they are more likely to be found in low-mass haloes. The interpretation of the clustering pattern suffers from the large sample variance in the 2PCF measurements, given the small volume of the volume-limited sample of such faint galaxies. We present improved clustering measurements of faint galaxies by making a full use of a flux-limited sample to obtain volume-limited measurements with an increased effective volume. In the improved 2PCF measurements, the fractional uncertainties on large scales drop by more than 40 per cent, and the strong contrast between small-scale and large-scale clustering amplitudes seen in previous work is no longer prominent. From halo occupation distribution modelling of the measurements, we find that a considerable fraction of faint red galaxies to be satellites in massive haloes, a scenario supported by the strong covariance of small-scale 2PCF measurements and the relative spatial distribution of faint red galaxies and luminous galaxies. However, the satellite fraction is found to be degenerate with the slope of the distribution profile of satellites in inner haloes. We compare the modelling results with semi-analytic model predictions and discuss the implications.

  7. M-82 Primer Flow Study

    DTIC Science & Technology

    1978-06-01

    indicate the location of the pressure transducers (Reference 9) • • • • 31 2. The development of the flow at the vent hole. (a) t = 0, 52.9 [vis]; (b...x 10Ŗ [m]. Photographs courtesy of Dr. K. J. White, Propulsion Division, BRL 32 3. Comparison of calculated and experimentally observed pressure ...function of time in [s] 36 6- Vent hole temperature in degrees [K] as a function of time expressed in [s] 37 7. Vent hole pressure in units

  8. First stars, hypernovae, and superluminous supernovae

    NASA Astrophysics Data System (ADS)

    Nomoto, Ken'Ichi

    2016-07-01

    After the big bang, production of heavy elements in the early universe takes place starting from the formation of the first (Pop III) stars, their evolution, and explosion. The Pop III supernova (SN) explosions have strong dynamical, thermal, and chemical feedback on the formation of subsequent stars and evolution of galaxies. However, the nature of Pop III stars/supernovae (SNe) have not been well-understood. The signature of nucleosynthesis yields of the first SN can be seen in the elemental abundance patterns observed in extremely metal-poor (EMP) stars. We show that the abundance patterns of EMP stars, e.g. the excess of C, Co, Zn relative to Fe, are in better agreement with the yields of hyper-energetic explosions (Hypernovae, (HNe)) rather than normal supernovae. We note the large variation of the abundance patterns of EMP stars propose that such a variation is related to the diversity of the GRB-SNe and posssibly superluminous supernovae (SLSNe). For example, the carbon-enhanced metal-poor (CEMP) stars may be related to the faint SNe (or dark HNe), which could be the explosions induced by relativistic jets. Finally, we examine the various mechanisms of SLSNe.

  9. The Nature of the mHz X-ray QPOs from the Ultraluminous X-ray Source M82 X-1: Timing-Spectral (anti)-correlation?

    NASA Astrophysics Data System (ADS)

    Ranga Reddy Pasham, Dheeraj; Strohmayer, T. E.

    2013-04-01

    We have analyzed all archival XMM-Newton observations of the ultraluminous X-ray source (ULX) M82 X-1 in order to search for a correlation between its mHz quasiperiodic oscillation (QPO) frequency and energy spectral power-law index. These quantities are known to correlate in stellar mass black holes (StMBHs) exhibiting so-called Type-C QPOs. The detection of a similar relation in M82 X-1 would strengthen the identification of its mHz QPOs as Type-C and thus enable more reliable mass estimates by scaling of the QPO frequencies in X-1 to those of Type-C QPOs in StMBHs of known mass. We used surface brightness modeling to estimate the count rates produced by X-1 and a nearby (5'') bright source that can contribute substantial flux in XMM-Newton's 15'' (HPD) beam. We thus identify the observations in which M82 X-1 is at least as bright as the nearby source. In these observations we detect mHz QPOs with centroid frequencies spanning the range from 36 mHz to 210 mHz (the lowest and the highest yet reported from X-1). We model the 3-10 keV spectrum and find that the power-law index changes significantly from 1.7 - 2.2 during these observations. With all observations included we find evidence for an anti-correlation between the centroid frequency of the mHz QPOs and the power-law index. The value of the Pearson's correlation coefficient is -0.95. While such an anti-correlation is observed in StMBHs at high Type-C QPO frequencies (5-15 Hz), the frequency range over which it holds in StMBHs is significantly smaller (factor of 1-3) than the QPO range now reported here for X-1, which varies over a factor of 5.8 (36-210 mHz). However, we note that the correlation hinges on the observation with the lowest inferred energy spectral index and for which the fitted count rate ratio of X-1 to the nearby source is 1.1. So the implied anti-correlation needs to be confirmed with either less ``contaminated" observations or higher angular resolution spectral measurements made in tandem

  10. Detection of gamma-ray emission from the Starburst Galaxies M82 and NGC 253 with the Large Area Telescope on Fermi

    DOE PAGES

    Abdo, A. A.

    2010-01-14

    Here, we report the detection of high-energy γ-ray emission from two starburst galaxies using data obtained with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. Furthermore, we detected a steady point-like emission above 200 MeV at significance levels of 6.8σ and 4.8σ, respectively, from sources positionally coincident with locations of the starburst galaxies M82 and NGC 253. The total fluxes of the sources are consistent with γ-ray emission originating from the interaction of cosmic rays with local interstellar gas and radiation fields and constitute evidence for a link between massive star formation and γ-ray emission in star-formingmore » galaxies.« less

  11. Detection of gamma-ray emission from the Starburst Galaxies M82 and NGC 253 with the Large Area Telescope on Fermi

    SciTech Connect

    Abdo, A. A.

    2010-01-14

    Here, we report the detection of high-energy γ-ray emission from two starburst galaxies using data obtained with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. Furthermore, we detected a steady point-like emission above 200 MeV at significance levels of 6.8σ and 4.8σ, respectively, from sources positionally coincident with locations of the starburst galaxies M82 and NGC 253. The total fluxes of the sources are consistent with γ-ray emission originating from the interaction of cosmic rays with local interstellar gas and radiation fields and constitute evidence for a link between massive star formation and γ-ray emission in star-forming galaxies.

  12. Can the 62 Day X-ray Period of ULX M82 X-1 Be Due to a Precessing Accretion Disk?

    NASA Technical Reports Server (NTRS)

    Pasham, Dheeraj R.; Strohmayer, Tod E.

    2013-01-01

    We have analyzed all the archival RXTE/PCA monitoring observations of the ultraluminous X-ray source (ULX) M82 X-1 in order to study the properties of its previously discovered 62 day X-ray period (Kaaret & Feng 2007). Based on the high coherence of the modulation it has been argued that the observed period is the orbital period of the binary. Utilizing a much longer data set than in previous studies we find: (1) The phase-resolved X-ray (3-15 keV) energy spectra - modeled with a thermal accretion disk and a power-law corona - suggest that the accretion disk's contribution to the total flux is responsible for the overall periodic modulation while the power-law flux remains approximately constant with phase. (2) Suggestive evidence for a sudden phase shift-of approximately 0.3 in phase (20 days)-between the first and the second halves of the light curve separated by roughly 1000 days. If confirmed, the implied timescale to change the period is approx. = 10 yrs, which is exceptionally fast for an orbital phenomenon. These independent pieces of evidence are consistent with the 62 day period being due to a precessing accretion disk, similar to the so-called super-orbital periods observed in systems like Her X-1, LMC X-4, and SS433. However, the timing evidence for a change in the period needs to be confirmed with additional observations. This should be possible with further monitoring of M82 with instruments such as the X-ray telescope (XRT) on board Swift.

  13. An Active Ac/Ds Transposon System for Activation Tagging in Tomato Cultivar M82 Using Clonal Propagation1[W][OA

    PubMed Central

    Carter, Jared D.; Pereira, Andy; Dickerman, Allan W.; Veilleux, Richard E.

    2013-01-01

    Tomato (Solanum lycopersicum) is a model organism for Solanaceae in both molecular and agronomic research. This project utilized Agrobacterium tumefaciens transformation and the transposon-tagging construct Activator (Ac)/Dissociator (Ds)-ATag-Bar_gosGFP to produce activation-tagged and knockout mutants in the processing tomato cultivar M82. The construct carried hygromycin resistance (hyg), green fluorescent protein (GFP), and the transposase (TPase) of maize (Zea mays) Activator major transcript X054214.1 on the stable Ac element, along with a 35S enhancer tetramer and glufosinate herbicide resistance (BAR) on the mobile Ds-ATag element. An in vitro propagation strategy was used to produce a population of 25 T0 plants from a single transformed plant regenerated in tissue culture. A T1 population of 11,000 selfed and cv M82 backcrossed progeny was produced from the functional T0 line. This population was screened using glufosinate herbicide, hygromycin leaf painting, and multiplex polymerase chain reaction (PCR). Insertion sites of transposed Ds-ATag elements were identified through thermal asymmetric interlaced PCR, and resulting product sequences were aligned to the recently published tomato genome. A population of 509 independent, Ds-only transposant lines spanning all 12 tomato chromosomes has been developed. Insertion site analysis demonstrated that more than 80% of these lines harbored Ds insertions conducive to activation tagging. The capacity of the Ds-ATag element to alter transcription was verified by quantitative real-time reverse transcription-PCR in two mutant lines. The transposon-tagged lines have been immortalized in seed stocks and can be accessed through an online database, providing a unique resource for tomato breeding and analysis of gene function in the background of a commercial tomato cultivar. PMID:23569107

  14. Supernova frequency estimates

    SciTech Connect

    Tsvetkov, D.Y.

    1983-01-01

    Estimates of the frequency of type I and II supernovae occurring in galaxies of different types are derived from observational material acquired by the supernova patrol of the Shternberg Astronomical Institute.

  15. Supernova neutrino detection

    SciTech Connect

    Scholberg, K.

    2015-07-15

    In this presentation I summarize the main detection channels for neutrinos from core-collapse supernovae, and describe current status of and future prospects for supernova-neutrino-sensitive detectors worldwide.

  16. DISCOVERY OF A NEW PHOTOMETRIC SUB-CLASS OF FAINT AND FAST CLASSICAL NOVAE

    SciTech Connect

    Kasliwal, M. M.; Kulkarni, S. R.; Ofek, E. O.; Quimby, R.; Cenko, S. B.; Rau, A.

    2011-07-10

    We present photometric and spectroscopic follow-up of a sample of extragalactic novae discovered by the Palomar 60 inch telescope during a search for 'Fast Transients In Nearest Galaxies' (P60-FasTING). Designed as a fast cadence (1 day) and deep (g < 21 mag) survey, P60-FasTING was particularly sensitive to short-lived and faint optical transients. The P60-FasTING nova sample includes 10 novae in M 31, 6 in M 81, 3 in M 82, 1 in NGC 2403, and 1 in NGC 891. This significantly expands the known sample of extragalactic novae beyond the Local Group, including the first discoveries in a starburst environment. Surprisingly, our photometry shows that this sample is quite inconsistent with the canonical maximum-magnitude-rate-of-decline (MMRD) relation for classical novae. Furthermore, the spectra of the P60-FasTING sample are indistinguishable from classical novae. We suggest that we have uncovered a sub-class of faint and fast classical novae in a new phase space in luminosity-timescale of optical transients. Thus, novae span two orders of magnitude in both luminosity and time. Perhaps the MMRD, which is characterized only by the white dwarf mass, was an oversimplification. Nova physics appears to be characterized by a relatively rich four-dimensional parameter space in white dwarf mass, temperature, composition, and accretion rate.

  17. Discovery of a New Photometric Sub-class of Faint and Fast Classical Novae

    NASA Astrophysics Data System (ADS)

    Kasliwal, M. M.; Cenko, S. B.; Kulkarni, S. R.; Ofek, E. O.; Quimby, R.; Rau, A.

    2011-07-01

    We present photometric and spectroscopic follow-up of a sample of extragalactic novae discovered by the Palomar 60 inch telescope during a search for "Fast Transients In Nearest Galaxies" (P60-FasTING). Designed as a fast cadence (1 day) and deep (g < 21 mag) survey, P60-FasTING was particularly sensitive to short-lived and faint optical transients. The P60-FasTING nova sample includes 10 novae in M 31, 6 in M 81, 3 in M 82, 1 in NGC 2403, and 1 in NGC 891. This significantly expands the known sample of extragalactic novae beyond the Local Group, including the first discoveries in a starburst environment. Surprisingly, our photometry shows that this sample is quite inconsistent with the canonical maximum-magnitude-rate-of-decline (MMRD) relation for classical novae. Furthermore, the spectra of the P60-FasTING sample are indistinguishable from classical novae. We suggest that we have uncovered a sub-class of faint and fast classical novae in a new phase space in luminosity-timescale of optical transients. Thus, novae span two orders of magnitude in both luminosity and time. Perhaps the MMRD, which is characterized only by the white dwarf mass, was an oversimplification. Nova physics appears to be characterized by a relatively rich four-dimensional parameter space in white dwarf mass, temperature, composition, and accretion rate.

  18. Faint detection of exoplanets in microlensing surveys

    SciTech Connect

    Brown, Robert A.

    2014-06-20

    We propose a new approach to discovering faint microlensing signals below traditional thresholds, and for estimating the binary-lens mass ratio and the apparent separation from such signals. The events found will be helpful in accurately estimating the true distribution of planetary semimajor axes, which is an important goal of space microlensing surveys.

  19. An enigmatic long-lasting gamma-ray burst not accompanied by a bright supernova.

    PubMed

    Della Valle, M; Chincarini, G; Panagia, N; Tagliaferri, G; Malesani, D; Testa, V; Fugazza, D; Campana, S; Covino, S; Mangano, V; Antonelli, L A; D'Avanzo, P; Hurley, K; Mirabel, I F; Pellizza, L J; Piranomonte, S; Stella, L

    2006-12-21

    Gamma-ray bursts (GRBs) are short, intense flashes of soft gamma-rays coming from the distant Universe. Long-duration GRBs (those lasting more than approximately 2 s) are believed to originate from the deaths of massive stars, mainly on the basis of a handful of solid associations between GRBs and supernovae. GRB 060614, one of the closest GRBs discovered, consisted of a 5-s hard spike followed by softer, brighter emission that lasted for approximately 100 s (refs 8, 9). Here we report deep optical observations of GRB 060614 showing no emerging supernova with absolute visual magnitude brighter than M(V) = -13.7. Any supernova associated with GRB 060614 was therefore at least 100 times fainter, at optical wavelengths, than the other supernovae associated with GRBs. This demonstrates that some long-lasting GRBs can either be associated with a very faint supernova or produced by different phenomena.

  20. Electron-capture supernovae of super-asymptotic giant branch stars and the Crab supernova 1054

    SciTech Connect

    Nomoto, Ken'ichi; Tominaga, Nozomu; Blinnikov, Sergei I.

    2014-05-02

    An electron-capture supernova (ECSN) is a core-collapse supernova explosion of a super-asymptotic giant branch (SAGB) star with a main-sequence mass M{sub Ms} ∼ 7 - 9.5M{sub ⊙}. The explosion takes place in accordance with core bounce and subsequent neutrino heating and is a unique example successfully produced by first-principle simulations. This allows us to derive a first self-consistent multicolor light curves of a core-collapse supernova. Adopting the explosion properties derived by the first-principle simulation, i.e., the low explosion energy of 1.5 × 10{sup 50} erg and the small {sup 56}Ni mass of 2.5 × 10{sup −3} M{sub ⊙}, we perform a multigroup radiation hydrodynamics calculation of ECSNe and present multicolor light curves of ECSNe of SAGB stars with various envelope mass and hydrogen abundance. We demonstrate that a shock breakout has peak luminosity of L ∼ 2 × 10{sup 44} erg s{sup −1} and can evaporate circumstellar dust up to R ∼ 10{sup 17} cm for a case of carbon dust, that plateau luminosity and plateau duration of ECSNe are L ∼ 10{sup 42} erg s{sup −1} and {sup t} ∼ 60 - 100 days, respectively, and that a plateau is followed by a tail with a luminosity drop by ∼ 4 mag. The ECSN shows a bright and short plateau that is as bright as typical Type II plateau supernovae, and a faint tail that might be influenced by spin-down luminosity of a newborn pulsar. Furthermore, the theoretical models are compared with ECSN candidates: SN 1054 and SN 2008S. We find that SN 1054 shares the characteristics of the ECSNe. For SN 2008S, we find that its faint plateau requires a ECSN model with a significantly low explosion energy of E ∼ 10{sup 48} erg.

  1. Electron-capture supernovae of super-asymptotic giant branch stars and the Crab supernova 1054

    NASA Astrophysics Data System (ADS)

    Nomoto, Ken'ichi; Tominaga, Nozomu; Blinnikov, Sergei I.

    2014-05-01

    An electron-capture supernova (ECSN) is a core-collapse supernova explosion of a super-asymptotic giant branch (SAGB) star with a main-sequence mass MMs ˜ 7 - 9.5M⊙. The explosion takes place in accordance with core bounce and subsequent neutrino heating and is a unique example successfully produced by first-principle simulations. This allows us to derive a first self-consistent multicolor light curves of a core-collapse supernova. Adopting the explosion properties derived by the first-principle simulation, i.e., the low explosion energy of 1.5 × 1050 erg and the small 56Ni mass of 2.5 × 10-3 M⊙, we perform a multigroup radiation hydrodynamics calculation of ECSNe and present multicolor light curves of ECSNe of SAGB stars with various envelope mass and hydrogen abundance. We demonstrate that a shock breakout has peak luminosity of L ˜ 2 × 1044 erg s-1 and can evaporate circumstellar dust up to R ˜ 1017 cm for a case of carbon dust, that plateau luminosity and plateau duration of ECSNe are L ˜ 1042 erg s-1 and t ˜ 60 - 100 days, respectively, and that a plateau is followed by a tail with a luminosity drop by ˜ 4 mag. The ECSN shows a bright and short plateau that is as bright as typical Type II plateau supernovae, and a faint tail that might be influenced by spin-down luminosity of a newborn pulsar. Furthermore, the theoretical models are compared with ECSN candidates: SN 1054 and SN 2008S. We find that SN 1054 shares the characteristics of the ECSNe. For SN 2008S, we find that its faint plateau requires a ECSN model with a significantly low explosion energy of E ˜ 1048 erg.

  2. The Global Supernova Project

    NASA Astrophysics Data System (ADS)

    Howell, Dale Andrew; Global Supernova Project

    2017-06-01

    The Global Supernova Project is worldwide collaboration to study 600 supernovae of all types between May 2017 and July 2020. It is a Key Project at Las Cumbres Observatory, whose global robotic telescope network will provide lightcurves and spectra. Follow-up observations will be obtained on many other facilities, including Swift, VLA, K2, the NTT, IRTF, Keck, and Gemini. Observations are managed by the Supernova Exchange, a combination observatin database and telescope control system run by LCO. Here we report on results from the previous Supernova Key Project, and first results from the Global Supernova Project.

  3. Short-Lived Circumstellar Interaction in a Low-Luminosity Type IIP Supernova

    NASA Astrophysics Data System (ADS)

    Hosseinzadeh, Griffin; Valenti, Stefano; Arcavi, Iair; McCully, Curtis; Howell, Dale Andrew

    2017-01-01

    While interaction with circumstellar material is known to play an important role in Type IIn supernovae, analyses of the more common Type IIP and IIL supernovae have not traditionally included interaction as a significant power source. However, recent campaigns to observe supernovae within days of explosion have revealed narrow emission lines of high-ionization species in the earliest spectra of luminous Type II supernovae of all subclasses. These "flash spectroscopy" features indicate the presence of a confined shell of material around the progenitor star. Here we present the first low-luminosity supernova to show flash spectroscopy features, SN 2016bkv. This supernova peaked at MV = -16 mag and has expansion velocities around maximum light of < 2000 km s-1, placing it at the faint/slow end of the distribution of Type IIP supernovae (similar to SN 2005cs). The detection of flash spectroscopy features in this event demonstrates that circumstellar interaction plays a role even in a low-luminosity Type IIP supernovae. Conversely, it implies that the range of luminosities of Type II supernovae is not solely driven by the presence of circumstellar material.

  4. Extreme Faint Flux Imaging with an EMCCD

    NASA Astrophysics Data System (ADS)

    Daigle, Olivier; Carignan, Claude; Gach, Jean-Luc; Guillaume, Christian; Lessard, Simon; Fortin, Charles-Anthony; Blais-Ouellette, Sébastien

    2009-08-01

    An EMCCD camera, designed from the ground up for extreme faint flux imaging, is presented. CCCP, the CCD Controller for Counting Photons, has been integrated with a CCD97 EMCCD from e2v technologies into a scientific camera at the Laboratoire d’Astrophysique Expérimentale (LAE), Université de Montréal. This new camera achieves subelectron readout noise and very low clock-induced charge (CIC) levels, which are mandatory for extreme faint flux imaging. It has been characterized in laboratory and used on the Observatoire du Mont Mégantic 1.6 m telescope. The performance of the camera is discussed and experimental data with the first scientific data are presented.

  5. Faint-object spectrograph for Space Telescope

    NASA Technical Reports Server (NTRS)

    Harms, r. J.; Beaver, E.; Burbidge, E. M.; Angel, R.; Bartko, F.; Bloomquist, W.; Flemming, J. C.; Bohlin, R.; Davidsen, A. F.; Ford, H.

    1979-01-01

    The paper presents the Faint Object Spectrograph (FOS) for the Space Telescope to provide a digitized spectra of faint astronomical objects over the 115 to 700 nm wavelength range at resolving powers of 1000 and 100. A variety of concave gratings and prisms is employed to form nearly stigmatic spectra on one of the two Digicon photon counting detectors which are optimized for two different but overlapping ranges. The scientific goals associated with quasars, active galaxies, and objects within our solar system are discussed, and the FOS optical design features, including detectors, electronics, signal processing, power supplies, and data handling are examined. The FOS structural system, mechanism, and controls are described, along with the predicted performance capabilities in the spectral and spectropolarimetry modes. Finally, system performance parameters, including spatial resolution, time resolution, noise, and efficiency are discussed.

  6. Does faint galaxy clustering contradict gravitational instability?

    NASA Technical Reports Server (NTRS)

    Melott, Adrian L.

    1992-01-01

    It has been argued, based on the weakness of clustering of faint galaxies, that these objects cannot be the precursors of present galaxies in a simple Einstein-de Sitter model universe with clustering driven by gravitational instability. It is shown that the assumptions made about the growth of clustering were too restrictive. In such a universe, the growth of clustering can easily be fast enough to match the data.

  7. DIFFERENCE IN THE SPATIAL DISTRIBUTION BETWEEN H{sub 2}O AND CO{sub 2} ICES IN M 82 FOUND WITH AKARI

    SciTech Connect

    Yamagishi, Mitsuyoshi; Kaneda, Hidehiro; Ishihara, Daisuke; Oyabu, Shinki; Onaka, Takashi; Shimonishi, Takashi; Suzuki, Toyoaki; Minh, Young Chol

    2013-08-20

    With AKARI, we obtain the spatially resolved near-infrared (NIR) (2.5-5.0 {mu}m) spectra for the nearby starburst galaxy M 82. These spectra clearly show absorption features due to interstellar ices. Based on the spectra, we created the column density maps of H{sub 2}O and CO{sub 2} ices. As a result, we find that the spatial distribution of H{sub 2}O ice is significantly different from that of CO{sub 2} ice; H{sub 2}O ice is widely distributed, while CO{sub 2} ice is concentrated near the galactic center. Our result reveals for the first time variations in CO{sub 2}/H{sub 2}O ice abundance ratio on a galactic scale, suggesting that an ice-forming interstellar environment changes within a galaxy. We discuss the cause of the spatial variations in the ice abundance ratio, utilizing spectral information on the hydrogen recombination Br{alpha} and Br{beta} lines and the polycyclic aromatic hydrocarbon 3.3 {mu}m emission appearing in the AKARI NIR spectra.

  8. Faint Submillimeter Galaxies Behind Lensing Clusters

    NASA Astrophysics Data System (ADS)

    Hsu, Li-Yen; Lauchlan Cowie, Lennox; Barger, Amy J.; Desai, Vandana; Murphy, Eric J.

    2017-01-01

    Faint submillimeter galaxies are the major contributors to the submillimeter extragalactic background light and hence the dominant star-forming population in the dusty universe. Determining how much these galaxies overlap the optically selected samples is critical to fully account for the cosmic star formation history. Observations of massive cluster fields are the best way to explore this faint submillimeter population, thanks to gravitational lensing effects. We have been undertaking a lensing cluster survey with the SCUBA-2 camera on the James Clerk Maxwell Telescope to map nine galaxy clusters, including the northern five clusters in the HST Frontier Fields program. We have also been using the Submillimeter Array and the Very Large Array to determine the accurate positions of our detected sources. Our observations have discovered high-redshift dusty galaxies with far-infrared luminosities similar to that of the Milky Way or luminous infrared galaxies. Some of these galaxies are still undetected in deep optical and near-infrared images. These results suggest that a substantial amount of star formation in even the faint submillimeter population may be hidden from rest-frame optical surveys.

  9. Supernovae and mass extinctions

    NASA Technical Reports Server (NTRS)

    Vandenbergh, S.

    1994-01-01

    Shklovsky and others have suggested that some of the major extinctions in the geological record might have been triggered by explosions of nearby supernovae. The frequency of such extinction events will depend on the galactic supernova frequency and on the distance up to which a supernova explosion will produce lethal effects upon terrestrial life. In the present note it will be assumed that a killer supernova has to occur so close to Earth that it will be embedded in a young, active, supernova remnant. Such young remnants typically have radii approximately less than 3 pc (1 x 10(exp 19) cm). Larger (more pessimistic?) killer radii have been adopted by Ruderman, Romig, and by Ellis and Schramm. From observations of historical supernovae, van den Bergh finds that core-collapse (types Ib and II) supernovae occur within 4 kpc of the Sun at a rate of 0.2 plus or minus 0.1 per century. Adopting a layer thickness of 0.3 kpc for the galacitc disk, this corresponds to a rate of approximately 1.3 x 10(exp -4) supernovae pc(exp -3) g.y.(exp -1). Including supernovae of type Ia will increase the total supernovae rate to approximately 1.5 x 10(exp -4) supernovae pc(exp -3) g.y.(exp -1). For a lethal radius of R pc the rate of killer events will therefore be 1.7 (R/3)(exp 3) x 10(exp -2) supernovae per g.y. However, a frequency of a few extinctions per g.y. is required to account for the extinctions observed during the phanerozoic. With R (extinction) approximately 3 pc, the galactic supernova frequency is therefore too low by 2 orders of magnitude to account for the major extinctions in the geological record.

  10. Supernovae neutrino pasta interaction

    NASA Astrophysics Data System (ADS)

    Lin, Zidu; Horowitz, Charles; Caplan, Matthew; Berry, Donald; Roberts, Luke

    2017-01-01

    In core-collapse supernovae, the neutron rich matter is believed to have complex structures, such as spherical, slablike, and rodlike shapes. They are collectively called ``nuclear pasta''. Supernovae neutrinos may scatter coherently on the ``nuclear pasta'' since the wavelength of the supernovae neutrinos are comparable to the nuclear pasta scale. Consequently, the neutrino pasta scattering is important to understand the neutrino opacity in the supernovae. In this work we simulated the ``nuclear pasta'' at different temperatures and densities using our semi-classical molecular dynamics and calculated the corresponding static structure factor that describes ν-pasta scattering. We found the neutrino opacities are greatly modified when the ``pasta'' exist and may have influence on the supernovae neutrino flux and average energy. Our neutrino-pasta scattering effect can finally be involved in the current supernovae simulations and we present preliminary proto neutron star cooling simulations including our pasta opacities.

  11. Sequence-Based SSR Marker Development and Their Application in Defining the Introgressions of LA0716 (Solanum pennellii) in the Background of cv. M82 (Solanum lycopersicum)

    PubMed Central

    Long, Wenbo; Li, Ye; Zhou, Wenjuan; Ling, Hong-Qing; Zheng, Shusong

    2013-01-01

    The introgression lines (ILs) from cv. M82 (Solanum lycopersicum) × LA0716 (S. pennellii) have been proven to be exceptionally useful for genetic analysis and gene cloning. The introgressions were originally defined by RFLP markers at their development. The objectives of this study are to develop polymorphic SSR markers, and to re-define the DNA introgression from LA0716 in the ILs. Tomato sequence data was scanned by software to generate SSR markers. In total, 829 SSRs, which could be robustly amplified by PCR, were developed. Among them, 658 SSRs were dinucleotide repeats, 162 were trinucleotide repeats, and nine were tetranucleotide repeats. The 829 SSRs together with 96 published RFLPs were integrated into the physical linkage map of S. lycopersicum. Introgressions of DNA fragments from LA0716 were re-defined among the 75 ILs using the newly developed SSRs. A specific introgression of DNA fragment from LA0716 was identified in 72 ILs as described previously by RFLP, whereas the specific DNA introgression described previously were not detected in the ILs LA4035, LA4059 and LA4091. The physical location of each investigated DNA introgression was finely determined by SSR mapping. Among the 72 ILs, eight ILs showed a shorter and three ILs (IL3-2, IL12-3 and IL12-3-1) revealed a longer DNA introgression than that framed by RFLPs. Furthermore, 54 previously undefined segments were found in 21 ILs, ranging from 1 to 11 DNA introgressions per IL. Generally, the newly developed SSRs provide additional markers for genetic studies of tomatoes, and the fine definition of DNA introgressions from LA0716 would facilitate the use of the ILs for genetic analysis and gene cloning. PMID:24339899

  12. Sequence-based SSR marker development and their application in defining the Introgressions of LA0716 (Solanum pennellii) in the background of cv. M82 (Solanum lycopersicum).

    PubMed

    Long, Wenbo; Li, Ye; Zhou, Wenjuan; Ling, Hong-Qing; Zheng, Shusong

    2013-01-01

    The introgression lines (ILs) from cv. M82 (Solanum lycopersicum) × LA0716 (S. pennellii) have been proven to be exceptionally useful for genetic analysis and gene cloning. The introgressions were originally defined by RFLP markers at their development. The objectives of this study are to develop polymorphic SSR markers, and to re-define the DNA introgression from LA0716 in the ILs. Tomato sequence data was scanned by software to generate SSR markers. In total, 829 SSRs, which could be robustly amplified by PCR, were developed. Among them, 658 SSRs were dinucleotide repeats, 162 were trinucleotide repeats, and nine were tetranucleotide repeats. The 829 SSRs together with 96 published RFLPs were integrated into the physical linkage map of S. lycopersicum. Introgressions of DNA fragments from LA0716 were re-defined among the 75 ILs using the newly developed SSRs. A specific introgression of DNA fragment from LA0716 was identified in 72 ILs as described previously by RFLP, whereas the specific DNA introgression described previously were not detected in the ILs LA4035, LA4059 and LA4091. The physical location of each investigated DNA introgression was finely determined by SSR mapping. Among the 72 ILs, eight ILs showed a shorter and three ILs (IL3-2, IL12-3 and IL12-3-1) revealed a longer DNA introgression than that framed by RFLPs. Furthermore, 54 previously undefined segments were found in 21 ILs, ranging from 1 to 11 DNA introgressions per IL. Generally, the newly developed SSRs provide additional markers for genetic studies of tomatoes, and the fine definition of DNA introgressions from LA0716 would facilitate the use of the ILs for genetic analysis and gene cloning.

  13. The Supernova Key Project

    NASA Astrophysics Data System (ADS)

    Howell, Dale Andrew

    2017-01-01

    Las Cumbres Observatory is a global network of robotic telescopes specializing in time domain astronomy. It currently has nine 1m telescopes, two 2m telescopes, and seven 0.4m telescopes. The Supernova Key Project is a 3 year program to obtain light curves and spectra of 500 supernovae with Las Cumbres Observatory. Here we show recent results, detail plans for the next Supernova Key Project, and explain how the US community can get involved.

  14. An Optically Faint Quasar Survey at z ∼ 5 in the CFHTLS Wide Field: Estimates of the Black Hole Masses and Eddington Ratios

    NASA Astrophysics Data System (ADS)

    Ikeda, H.; Nagao, T.; Matsuoka, K.; Kawakatu, N.; Kajisawa, M.; Akiyama, M.; Miyaji, T.; Morokuma, T.

    2017-09-01

    We present the result of our spectroscopic follow-up observation for faint quasar candidates at z ∼ 5 in part of the Canada–France–Hawaii Telescope Legacy Survey wide field. We select nine photometric candidates and identify three z ∼ 5 faint quasars, one z ∼ 4 faint quasar, and a late-type star. Since two faint quasar spectra show the C iv emission line without suffering from a heavy atmospheric absorption, we estimate their black hole masses ({M}{BH}) and Eddington ratios (L/{L}{Edd}). The inferred {log}{M}{BH} are 9.04 ± 0.14 and 8.53 ± 0.20, respectively. In addition, the inferred {log}(L/{L}{Edd}) are ‑1.00 ± 0.15 and ‑0.42 ± 0.22, respectively. If we adopt that L/{L}{Edd}={constant} {or}\\propto {(1+z)}2, the seed black hole masses ({M}{seed}) of our z ∼ 5 faint quasars are expected to be > {10}5 {M}ȯ in most cases. We also compare the observational results with a mass accretion model, where angular momentum is lost due to supernova explosions. Accordingly, {M}{BH} of the z ∼ 5 faint quasars in our sample can be explained even if {M}{seed} is ∼ {10}3 {M}ȯ . Since z ∼ 6 luminous qusars and our z ∼ 5 faint quasars are not on the same evolutionary track, z ∼ 6 luminous quasars and our z ∼ 5 quasars are not the same populations but different populations, due to the difference of a period of the mass supply from host galaxies. Furthermore, we confirm that one can explain {M}{BH} of z ∼ 6 luminous quasars and our z ∼ 5 faint quasars even if their seed black holes are formed at z ∼ 7.

  15. SOUSA Supernova Surprises

    NASA Astrophysics Data System (ADS)

    Brown, Peter J.

    2017-01-01

    The Swift Optical/Ultraviolet Supernova Archive is an effort to make public the Swift UVOT images and final photometry of as many supernovae as possible. These include many of the nearest, brightest, and most exciting supernovae of the last decade. Hiding within the archive, however, are supernovae you have never heard of, which never the less show extremes in color or luminosity or interesting light curve behavior in the ultraviolet. I will highlight some of the extreme objects of different subtypes and puzzling objects which warrant further study.

  16. Surviving Companions of Supernovae

    NASA Astrophysics Data System (ADS)

    Kerzendorf, W.

    2016-06-01

    Most supernovae should occur in binaries. Massive stars, the progenitors of core collapse supernovae (SN II/Ib/c), have a very high binarity fraction of 80 percent (on average, they have 1.5 companions). Binary systems are also required to produce thermonuclear supernovae (SN Ia). Understanding the role that binarity plays in pre-supernova evolution is one of the great mysteries in supernova research. Finding and studying surviving companions of supernovae has the power to shed light on some of these mysteries. Searching Galactic and nearby supernova remnants for surviving companions is a particularly powerful technique. This might allow to study the surviving companion in great detail possibly enabling a relatively detailed reconstruction of the pre-supernova evolution. In this talk, I will summarize the multitude of theoretical studies that have simulated the impact of the shockwave on the companion star and the subsequent evolution of the survivor. I will then give an overview of the searches that used these theoretical findings to identify surviving companions in nearby supernova remnants as well as their results. Finally, I will give an outlook of new opportunities in the relatively young field.

  17. Atomic and molecular supernovae

    NASA Technical Reports Server (NTRS)

    Liu, Weihong

    1997-01-01

    Atomic and molecular physics of supernovae is discussed with an emphasis on the importance of detailed treatments of the critical atomic and molecular processes with the best available atomic and molecular data. The observations of molecules in SN 1987A are interpreted through a combination of spectral and chemical modelings, leading to strong constraints on the mixing and nucleosynthesis of the supernova. The non-equilibrium chemistry is used to argue that carbon dust can form in the oxygen-rich clumps where the efficient molecular cooling makes the nucleation of dust grains possible. For Type Ia supernovae, the analyses of their nebular spectra lead to strong constraints on the supernova explosion models.

  18. The Population of Optically Faint GEO Debris

    NASA Technical Reports Server (NTRS)

    Seitzer, Patrick; Barker, Ed; Buckalew, Brent; Burkhardt, Andrew; Cowardin, Heather; Frith, James; Gomez, Juan; Kaleida, Catherine; Lederer, Susan M.; Lee, Chris H.

    2016-01-01

    The 6.5-m Magellan telescope 'Walter Baade' at the Las Campanas Observatory in Chile has been used for spot surveys of the GEO orbital regime to study the population of optically faint GEO debris. The goal is to estimate the size of the population of GEO debris at sizes much smaller than can be studied with 1-meter class telescopes. Despite the small size of the field of view of the Magellan instrument (diameter 0.5-degree), a significant population of objects fainter than R = 19th magnitude have been found with angular rates consistent with circular orbits at GEO. We compare the size of this population with the numbers of GEO objects found at brighter magnitudes by smaller telescopes. The observed detections have a wide range in characteristics starting with those appearing as short uniform streaks. But there are a substantial number of detections with variations in brightness, flashers, during the 5-second exposure. The duration of each of these flashes can be extremely brief: sometimes less than half a second. This is characteristic of a rapidly tumbling object with a quite variable projected size times albedo. If the albedo is of the order of 0.2, then the largest projected size of these objects is around 10-cm. The data in this paper was collected over the last several years using Magellan's IMACS camera in f/2 mode. The analysis shows the brightness bins for the observed GEO population as well as the periodicity of the flashers. All objects presented are correlated with the catalog: the focus of the paper will be on the uncorrelated, optically faint, objects. The goal of this project is to better characterize the faint debris population in GEO that access to a 6.5-m optical telescope in a superb site can provide.

  19. The formation of Jupiter's faint rings

    PubMed

    Burns; Showalter; Hamilton; Nicholson; de Pater I; Ockert-Bell; Thomas

    1999-05-14

    Observations by the Galileo spacecraft and the Keck telescope showed that Jupiter's outermost (gossamer) ring is actually two rings circumscribed by the orbits of the small satellites Amalthea and Thebe. The gossamer rings' unique morphology-especially the rectangular end profiles at the satellite's orbit and the enhanced intensities along the top and bottom edges of the rings-can be explained by collisional ejecta lost from the inclined satellites. The ejecta evolves inward under Poynting-Robertson drag. This mechanism may also explain the origin of Jupiter's main ring and suggests that faint rings may accompany all small inner satellites of the other jovian planets.

  20. Faint variable stars observed with Kepler

    NASA Astrophysics Data System (ADS)

    Lovekin, Catherine; Tompkins, Jasmin

    2017-09-01

    We present preliminary analysis of approximately 10 variable stars observed with Kepler. The sample stars are faint, and have temperatures greater than 8000 K. The stars were observed for up to three quarters (Q14-Q16) in long cadence mode. Frequencies were extracted with Period04, and 1-21 frequencies were detected in each quarter, with an average of 8 frequencies per quarter. Some variability is detected from quarter to quarter, while the dominant frequencies remain unchanged. We fit the frequencies using MESA models between 1.5 and 3 solar masses, and varied the core overshoot. Best fitting properties of each of these stars will be discussed.

  1. DISCOVERY OF THE EXTREMELY ENERGETIC SUPERNOVA 2008fz

    SciTech Connect

    Drake, A. J.; Djorgovski, S. G.; Mahabal, A.; Williams, R.; Graham, M. J.; Prieto, J. L.; Balam, D.; Catelan, M.; Beshore, E.; Larson, S.

    2010-08-01

    We report on the discovery and initial observations of the energetic type IIn supernova 2008fz. This object was discovered at redshift z = 0.133 and reached an apparent magnitude of V {approx} 17. After correcting for Galactic extinction and redshift, we determine the peak absolute magnitude of the event to be M{sub V} = -22.3, placing it among the most luminous supernovae discovered. The optical energy emitted by SN 2008fz (based on the light curve over an 88 day period) is possibly the most ever observed for a supernova (>1.4 x 10{sup 51} erg). The event was more luminous than the type IIn SN 2006gy, but exhibited the same smooth, slowly evolving light curve. As is characteristic of type IIn supernova, the early spectra of SN 2008fz initially exhibited narrow Balmer lines which were replaced by a broader component at later times. The spectra also show a blue continuum with no signs of Ca or Na absorption, suggesting that there is little extinction due to dust in the host or circumstellar material. No host galaxy is identified in prior co-added images reaching R {approx} 22. From the supernova's redshift, we place an upper limit on the brightness of the host of M{sub R} {approx} -17 (similar to the brightness of the Small Magellanic Cloud). The presence of the supernova within such a faint galaxy follows the majority of recently discovered highly luminous supernovae. A possible reason for this is the combination of a high star formation rate in low-mass galaxies with a low-metallicity environment.

  2. Discovery of the Extremely Energetic Supernova 2008fz

    NASA Astrophysics Data System (ADS)

    Drake, A. J.; Djorgovski, S. G.; Prieto, J. L.; Mahabal, A.; Balam, D.; Williams, R.; Graham, M. J.; Catelan, M.; Beshore, E.; Larson, S.

    2010-08-01

    We report on the discovery and initial observations of the energetic type IIn supernova 2008fz. This object was discovered at redshift z = 0.133 and reached an apparent magnitude of V ~ 17. After correcting for Galactic extinction and redshift, we determine the peak absolute magnitude of the event to be MV = -22.3, placing it among the most luminous supernovae discovered. The optical energy emitted by SN 2008fz (based on the light curve over an 88 day period) is possibly the most ever observed for a supernova (>1.4 × 1051 erg). The event was more luminous than the type IIn SN 2006gy, but exhibited the same smooth, slowly evolving light curve. As is characteristic of type IIn supernova, the early spectra of SN 2008fz initially exhibited narrow Balmer lines which were replaced by a broader component at later times. The spectra also show a blue continuum with no signs of Ca or Na absorption, suggesting that there is little extinction due to dust in the host or circumstellar material. No host galaxy is identified in prior co-added images reaching R ~ 22. From the supernova's redshift, we place an upper limit on the brightness of the host of MR ~ -17 (similar to the brightness of the Small Magellanic Cloud). The presence of the supernova within such a faint galaxy follows the majority of recently discovered highly luminous supernovae. A possible reason for this is the combination of a high star formation rate in low-mass galaxies with a low-metallicity environment.

  3. Cold H I in faint dwarf galaxies

    NASA Astrophysics Data System (ADS)

    Patra, Narendra Nath; Chengalur, Jayaram N.; Karachentsev, Igor D.; Kaisin, Serafim S.; Begum, Ayesha

    2016-03-01

    We present the results of a study of the amount and distribution of cold atomic gas, as well its correlation with recent star formation in a sample of extremely faint dwarf irregular galaxies. Our sample is drawn from the Faint Irregular Galaxy GMRT Survey (FIGGS) and its extension, FIGGS2. We use two different methods to identify cold atomic gas. In the first method, line-of-sight H I spectra were decomposed into multiple Gaussian components and narrow Gaussian components were identified as cold H I. In the second method, the brightness temperature (TB ) is used as a tracer of cold H I. We find that the amount of cold gas identified using the TB method is significantly larger than the amount of gas identified using Gaussian decomposition. We also find that a large fraction of the cold gas identified using the TB method is spatially coincident with regions of recent star formation, although the converse is not true. That is only a small fraction of the regions with recent star formation are also covered by cold gas. For regions where the star formation and the cold gas overlap, we study the relationship between the star formation rate density and the cold H I column density. We find that the star formation rate density has a power-law dependence on the H I column density, but that the slope of this power law is significantly flatter than that of the canonical Kennicutt-Schmidt relation.

  4. Probing the Supernova Fraction out to the Virial Radius of A3112

    NASA Astrophysics Data System (ADS)

    Bulbul, Esra; Bautz, Mark W.; Miller, Eric D.; Ezer, Cemile; Ercan, Nihal; Smith, Randall K.; Loewenstein, Michael; McDonald, Michael

    2017-08-01

    Owing to their deep potential wells, clusters of galaxies retain all metals synthesized by supernova explosions. The low particle background of Suzaku detectors has allowed the measurements of the chemical enrichment in faint cluster outskirts. I will present our recent Suzaku measurements of the type Ia to core collapse supernova fraction out to the viral radius of a nearby cluster A3112. The observed uniform distribution at a level of 12-16% is consistent with the supernova fraction in our Galaxy. The non-varying supernova fraction indicates that the intra-cluster medium in cluster outskirts was enriched by metals at an early star formation stage at redshifts of 2-3.

  5. CHEMICAL ENRICHMENT IN THE CARBON-ENHANCED DAMPED Ly{alpha} SYSTEM BY POPULATION III SUPERNOVAE

    SciTech Connect

    Kobayashi, Chiaki; Tominaga, Nozomu; Nomoto, Ken'ichi

    2011-04-01

    We show that the recently observed elemental abundance pattern of the carbon-rich metal-poor damped Ly{alpha} (DLA) system is in excellent agreement with the nucleosynthesis yields of faint core-collapse supernovae of primordial stars. The observed abundance pattern is not consistent with the nucleosynthesis yields of pair-instability supernovae. The DLA abundance pattern is very similar to that of carbon-rich extremely metal-poor (EMP) stars, and the contributions from low-mass stars and/or binary effects should be very small in DLAs. This suggests that chemical enrichment by the first stars in the first galaxies is driven by core-collapse supernovae from {approx}20 to 50 M{sub sun} stars and also supports the supernova scenario as the enrichment source of EMP stars in the Milky Way Galaxy.

  6. THE EXTENDED HUBBLE SPACE TELESCOPE SUPERNOVA SURVEY: THE RATE OF CORE COLLAPSE SUPERNOVAE TO z {approx} 1

    SciTech Connect

    Dahlen, Tomas; Riess, Adam G.; Strolger, Louis-Gregory; Mattila, Seppo; Kankare, Erkki; Mobasher, Bahram

    2012-09-20

    We use a sample of 45 core collapse supernovae detected with the Advanced Camera for Surveys on board the Hubble Space Telescope to derive the core collapse supernova rate in the redshift range 0.1 < z < 1.3. In redshift bins centered on (z) = 0.39, (z) = 0.73, and (z) = 1.11, we find rates of 3.00{sup +1.28}{sub -0.94} {sup +1.04}{sub -0.57}, 7.39{sup +1.86}{sub -1.52} {sup +3.20}{sub -1.60}, and 9.57{sup +3.76}{sub -2.80} {sup +4.96}{sub -2.80}, respectively, given in units of yr{sup -1} Mpc{sup -3} 10{sup -4} h {sup 3}{sub 70}. The rates have been corrected for host galaxy extinction, including supernovae missed in highly dust-enshrouded environments in infrared bright galaxies. The first errors are statistical while the second ones are the estimated systematic errors. We perform a detailed discussion of possible sources of systematic errors and note that these start to dominate over statistical errors at z > 0.5, emphasizing the need to better control the systematic effects. For example, a better understanding of the amount of dust extinction in the host galaxies and knowledge of the supernova luminosity function, in particular the fraction of faint M {approx}> -15 supernovae, is needed to better constrain the rates. When comparing our results with the core collapse supernova rate based on the star formation rate, we find a good agreement, consistent with the supernova rate following the star formation rate, as expected.

  7. Chemical Diversity in the Ultra-faint Dwarf Galaxy Tucana II

    NASA Astrophysics Data System (ADS)

    Ji, Alexander P.; Frebel, Anna; Ezzeddine, Rana; Casey, Andrew R.

    2016-11-01

    We present the first detailed chemical abundance study of the ultra-faint dwarf galaxy Tucana II, based on high-resolution Magellan/MIKE spectra of four red giant stars. The metallicities of these stars range from [Fe/H] = -3.2 to -2.6, and all stars are low in neutron-capture abundances ([Sr/Fe] and [Ba/Fe] < -1). However, a number of anomalous chemical signatures are present. One star is relatively metal-rich ([Fe/H] = -2.6) and shows [Na, α, Sc/Fe] < 0, suggesting an extended star formation history with contributions from AGB stars and SNe Ia. Two stars with [Fe/H] < -3 are mildly carbon-enhanced ([C/Fe] ˜ 0.7) and may be consistent with enrichment by faint supernovae, if such supernovae can produce neutron-capture elements. A fourth star with [Fe/H] = -3 is carbon-normal, and exhibits distinct light element abundance ratios from the carbon-enhanced stars. This carbon-normal star implies that at least two distinct nucleosynthesis sources, both possibly associated with Population III stars, contributed to the early chemical enrichment of this galaxy. Despite its very low luminosity, Tucana II shows a diversity of chemical signatures that preclude it from being a simple “one-shot” first galaxy yet still provide a window into star and galaxy formation in the early universe. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

  8. A Search for Optically Faint GEO Debris

    NASA Technical Reports Server (NTRS)

    Seitzer, Patrick; Lederer, Susan M.; Barker, Edwin S.; Cowardin, Heather; Abercromby, Kira J.; ilha, Jiri

    2011-01-01

    Existing optical surveys for debris at geosynchronous orbit (GEO) have been conducted with meter class telescopes, which have detection limits in the range of 18th-19th magnitude. We report on a new search for optically faint debris at GEO using the 6.5-m Magellan 1 telescope Walter Baade at Las Campanas Observatory in Chile. Our goal is to go as faint as possible and characterize the brightness distribution of debris fainter than R = 20th magnitude, corresponding to a size smaller than 10 cm assuming an albedo of 0.175. We wish to compare the inferred size distribution for GEO debris with that for LEO debris. We describe results obtained during 9.4 hours of observing time during 25-27 March 2011. We used the IMACS f/2 instrument, which has a mosaic of 8 CCDs, and a field of view of 30 arc-minutes in diameter. This is the widest field of view of any instrument on either Magellan telescope. All observations were obtained through a Sloan r filter. The limiting magnitude for 5 second exposures is estimated to be fainter than 22. With this small field of view and the limited observing time, our objective was to search for optically faint objects from the Titan 3C Transtage (1968-081) fragmentation in 1992. Eight debris pieces and the parent rocket body are in the Space Surveillance Network public catalog. We successfully tracked two cataloged pieces of Titan debris (SSN # 25001 and 33519) with the 6.5-m telescope, followed by a survey for objects on similar orbits but with a spread in mean anomaly. To detect bright objects over a wider field of view (1.6x1.6 degrees), we observed the same field centers at the same time through a similar filter with the 0.6-m MODEST (Michigan Orbital DEbris Survey Telescope), located 100 km to the south of Magellan at Cerro Tololo Inter-American Observatory, Chile. We will describe our experiences using Magellan, a telescope never used previously for orbital debris research, and our initial results.

  9. A Search For Optically Faint GEO Debris

    NASA Astrophysics Data System (ADS)

    Seitzer, P.; Lederer, S.; Barker, E.; Cowardin, H.; Abercromby, K.; Silha, J.; Burkhardt, A.

    2011-09-01

    Existing optical surveys for debris at geosynchronous orbit (GEO) have been conducted with meter class telescopes, which have detection limits in the range of 18th-19th magnitude. We report on a new search for optically faint debris at GEO using the 6.5-m Magellan telescope ‘Walter Baade’ at Las Campanas Observatory in Chile. Our goal is to go as faint as possible and characterize the brightness distribution of debris fainter than R = 20th magnitude, corresponding to a size smaller than 10 cm assuming an albedo of 0.175. We wish to compare the inferred size distribution for GEO debris with that for LEO debris. We describe preliminary results obtained during 9.4 hours of observing time during 25-27 March 2011. We used the IMACS f/2 instrument, which has a mosaic of 8 CCDs, and a field of view of 30 arc-minutes in diameter. This is the widest field of view of any instrument on either Magellan telescope. All observations were obtained through a Sloan r’ filter. The limiting magnitude for 5 second exposures is measured to be fainter tan R = 21. With this small field of view and the limited observing time, our objective was to search for optically faint objects from the Titan 3C Transtage (1968-081) fragmentation in 1992. Eight debris pieces and the parent rocket body are in the Space Surveillance Network public catalog. We successfully tracked two cataloged pieces of Titan debris (SSN # 25001 and 33519) with the 6.5-m telescope, followed by a survey for objects on similar orbits but with a spread in mean anomaly. To detect bright objects over a wider field of view (1.6x1.6 degrees), we observed the same field centers at the same time through a similar filter with the 0.6-m MODEST (Michigan Orbital DEbris Survey Telescope), located 100 km to the south of Magellan at Cerro Tololo Inter-American Observatory, Chile. We will describe our experiences using Magellan, a telescope never used previously for orbital debris research, and our initial results.

  10. HUBBLE PINPOINTS DISTANT SUPERNOVAE

    NASA Technical Reports Server (NTRS)

    2002-01-01

    These Hubble Space Telescope images pinpoint three distant supernovae, which exploded and died billions of years ago. Scientists are using these faraway light sources to estimate if the universe was expanding at a faster rate long ago and is now slowing down. Images of SN 1997cj are in the left hand column; SN 1997ce, in the middle; and SN 1997ck, on the right. All images were taken by the Hubble telescope's Wide Field and Planetary Camera 2. The top row of images are wider views of the supernovae. The supernovae were discovered in April 1997 in a ground-based survey at the Canada-France-Hawaii Telescope on Mauna Kea, Hawaii. Once the supernovae were discovered, the Hubble telescope was used to distinguish the supernovae from the light of their host galaxies. A series of Hubble telescope images were taken in May and June 1997 as the supernovae faded. Six Hubble telescope observations spanning five weeks were taken for each supernova. This time series enabled scientists to measure the brightness and create a light curve. Scientists then used the light curve to make an accurate estimate of the distances to the supernovae. Scientists combined the estimated distance with the measured velocity of the supernova's host galaxy to determine the expansion rate of the universe in the past (5 to 7 billion years ago) and compare it with the current rate. These supernovae belong to a class called Type Ia, which are considered reliable distance indicators. Looking at great distances also means looking back in time because of the finite velocity of light. SN 1997ck exploded when the universe was half its present age. It is the most distant supernova ever discovered (at a redshift of 0.97), erupting 7.7 billion years ago. The two other supernovae exploded about 5 billion years ago. SN 1997ce has a redshift of 0.44; SN 1997cj, 0.50. SN 1997ck is in the constellation Hercules, SN 1997ce is in Lynx, just north of Gemini; and SN 1997cj is in Ursa Major, near the Hubble Deep Field

  11. HUBBLE PINPOINTS DISTANT SUPERNOVAE

    NASA Technical Reports Server (NTRS)

    2002-01-01

    These Hubble Space Telescope images pinpoint three distant supernovae, which exploded and died billions of years ago. Scientists are using these faraway light sources to estimate if the universe was expanding at a faster rate long ago and is now slowing down. Images of SN 1997cj are in the left hand column; SN 1997ce, in the middle; and SN 1997ck, on the right. All images were taken by the Hubble telescope's Wide Field and Planetary Camera 2. The top row of images are wider views of the supernovae. The supernovae were discovered in April 1997 in a ground-based survey at the Canada-France-Hawaii Telescope on Mauna Kea, Hawaii. Once the supernovae were discovered, the Hubble telescope was used to distinguish the supernovae from the light of their host galaxies. A series of Hubble telescope images were taken in May and June 1997 as the supernovae faded. Six Hubble telescope observations spanning five weeks were taken for each supernova. This time series enabled scientists to measure the brightness and create a light curve. Scientists then used the light curve to make an accurate estimate of the distances to the supernovae. Scientists combined the estimated distance with the measured velocity of the supernova's host galaxy to determine the expansion rate of the universe in the past (5 to 7 billion years ago) and compare it with the current rate. These supernovae belong to a class called Type Ia, which are considered reliable distance indicators. Looking at great distances also means looking back in time because of the finite velocity of light. SN 1997ck exploded when the universe was half its present age. It is the most distant supernova ever discovered (at a redshift of 0.97), erupting 7.7 billion years ago. The two other supernovae exploded about 5 billion years ago. SN 1997ce has a redshift of 0.44; SN 1997cj, 0.50. SN 1997ck is in the constellation Hercules, SN 1997ce is in Lynx, just north of Gemini; and SN 1997cj is in Ursa Major, near the Hubble Deep Field

  12. Faint radio sources and gravitational lensing

    SciTech Connect

    Langston, G.I.; Conner, S.R.; Heflin, M.B.; Lehar, J.; Burke, B.F. MIT, Cambridge, MA )

    1990-04-01

    Measurements of the surface density of radio sources resulting from a deep VLA integration at 5 GHz and the MIT-Green Bank (MG) II 5 GHz survey are summarized. The faint source counts are combined with previous observations and fitted to a power-law function of surface density vs. limiting flux density. The surface density of radio sources brighter than 1 mJy is k = 0.019 + or - 0.004/arcmin. The power-law exponent is best fit by -0.93 + or - 0.14. Between 15 and 100 mJy, the surface density of radio sources varies nearly as predicted by Euclidian models of the universe. Estimates are given for the number of chance alignments of radio sources in the VLA snapshot observations of the MIT-Princeton-Caltech gravitational lens search. The probability of lens candidate configurations occurring by chance alignment is calculated. 28 refs.

  13. Spectroscopy of faint asteroids, satellites, and comets

    NASA Technical Reports Server (NTRS)

    Degewij, J.

    1980-01-01

    Nineteen asteroids with orbital elements comparable to those of short-period comets and the outer Jovian satellites J6 Himalia and J7 Elara have been observed with the 228-cm telescope and image-tube spectrograph of Steward Observatory. No activity indicating cometary outgassing was detected. If comets are being perturbed into asteroidal orbits, then this lack of activity can be explained by an apparently short transition time between active and extinct phase. In addition, spectra of the faint comets Sanguin 1977p, Chernykh 1977l, Arend-Rigaux 1950 VII, West 1978a, and van Biesbroeck 1954 IV were obtained, showing CN(0,0) and in some cases C2(1,0) and C3 emission. Comet Arend-Rigaux was active again in the fall of 1977 and Comet West showed on May 31, 1978 a weak tail at a distance from the sun of 6.0 AU.

  14. Faint Infrared-Excess Field Galaxies: FROGs

    NASA Astrophysics Data System (ADS)

    Moustakas, L. A.; Davis, M.; Zepf, S. E.; Bunker, A. J.

    Deep near-infrared and optical imaging surveys in the field reveal a curious population of galaxies that are infrared-bright (I-K>4), yet with relatively blue optical colors (V-I<2). Their surface density, several per square arcminute at K>20, is high enough that if placed at z>1 as our models suggest, their space densities are about one-tenth of phi-*. The colors of these ``faint red outlier galaxies'' (fROGs) may derive from exceedingly old underlying stellar populations, a dust-embedded starburst or AGN, or a combination thereof. Determining the nature of these fROGs, and their relation with the I-K>6 ``extremely red objects,'' has implications for our understanding of the processes that give rise to infrared-excess galaxies in general. We report on an ongoing study of several targets with HST & Keck imaging and Keck/LRIS multislit spectroscopy.

  15. Searching for Optically Faint GEO Debris

    NASA Technical Reports Server (NTRS)

    Seitzer, Patrick; Lederer, Susan M.; Abercromby, Kira J.; Barker, Edwin S.; Burkhardt, Andrew; Cowardin, Heather; Krisko, Paula; Silha, Jiri

    2012-01-01

    We report on results from a search for optically faint debris (defined as R > 20th magnitude, or smaller than 10 cm assuming an albedo of 0.175)) at geosynchronous orbit (GEO) using the 6.5-m Magellan telescope "Walter Baade" at Las Campanas Observatory in Chile. Our goal is to characterize the brightness distribution of debris to the faintest limiting magnitude possible. Our data was obtained during 6 hours of observing time during the photometric nights of 26 and 27 March 2011 with the IMACS f/2 instrument, which has a field of view (fov) of 0.5 degrees in diameter. All observations were obtained through a Sloan r filter, and calibrated by observations of Landolt standard stars. Our primary objective was to search for optically faint objects from one of the few known fragmentations at GEO: the Titan 3C Transtage (1968-081) fragmentation in 1992. Eight debris pieces and the parent rocket body are in the Space Surveillance Network public catalog. We successfully tracked two cataloged pieces of Titan debris with the 6.5-m telescope, followed by a survey for unknown objects on similar orbits but with different mean anomalies. To establish the bright end of the debris population, calibrated observations were acquired on the same field centers, telescope rates, and time period with a similar filter on the 0.6-m MODEST (Michigan Orbital DEbris Survey Telescope), located 100 km to the south of Magellan at Cerro Tololo Inter-American Observatory, Chile. We will show the calibrated brightness distributions from both telescopes, and compare the observed brightness distributions with that predicted for various population models of debris of different sizes.

  16. On the Nature of the mHz X-ray Quasi-Periodic Oscillations from Ultraluminous X-ray source M82 X-1: Search for Timing-Spectral Correlations

    NASA Technical Reports Server (NTRS)

    Pasham, Dheeraj R.; Strohmayer, Tod E.

    2013-01-01

    Using all the archival XMM-Newton X-ray (3-10 keV) observations of the ultraluminous X-ray source (ULX) M82 X-1, we searched for a correlation between its variable mHz quasi-periodic oscillation (QPO) frequency and its hardness ratio (5-10 keV/3-5 keV), an indicator of the energy spectral power-law index. When stellar-mass black holes (StMBHs) exhibit type-C low-frequency QPOs (0.2-15 Hz), the centroid frequency of the QPO is known to correlate with the energy spectral index. The detection of such a correlation would strengthen the identification of M82 X-1's mHz QPOs as type-C and enable a more reliable mass estimate by scaling its QPO frequencies to those of type-C QPOs in StMBHs of known mass.We resolved the count rates and the hardness ratios of M82 X-1 and a nearby bright ULX (source 5/X42.3+59) through surface brightness modeling.We detected QPOs in the frequency range of 36-210 mHz during which M82 X-1's hardness ratio varied from 0.42 to 0.47. Our primary results are (1) that we do not detect any correlation between the mHz QPO frequency and the hardness ratio (a substitute for the energy spectral power-law index) and (2) similar to some accreting X-ray binaries, we find that M82 X-1's mHz QPO frequency increases with its X-ray count rate (Pearson's correlation coefficient = +0.97). The apparent lack of a correlation between the QPO centroid frequency and the hardness ratio poses a challenge to the earlier claims that the mHz QPOs of M82 X-1 are the analogs of the type-C low-frequency QPOs of StMBHs. On the other hand, it is possible that the observed relation between the hardness ratio and the QPO frequency represents the saturated portion of the correlation seen in type-C QPOs of StMBHs-in which case M82 X-1's mHz QPOs can still be analogous to type-C QPOs.

  17. ON THE NATURE OF THE mHz X-RAY QUASI-PERIODIC OSCILLATIONS FROM ULTRALUMINOUS X-RAY SOURCE M82 X-1: SEARCH FOR TIMING-SPECTRAL CORRELATIONS

    SciTech Connect

    Pasham, Dheeraj R.; Strohmayer, Tod E. E-mail: tod.strohmayer@nasa.gov

    2013-07-10

    Using all the archival XMM-Newton X-ray (3-10 keV) observations of the ultraluminous X-ray source (ULX) M82 X-1, we searched for a correlation between its variable mHz quasi-periodic oscillation (QPO) frequency and its hardness ratio (5-10 keV/3-5 keV), an indicator of the energy spectral power-law index. When stellar-mass black holes (StMBHs) exhibit type-C low-frequency QPOs ({approx}0.2-15 Hz), the centroid frequency of the QPO is known to correlate with the energy spectral index. The detection of such a correlation would strengthen the identification of M82 X-1's mHz QPOs as type-C and enable a more reliable mass estimate by scaling its QPO frequencies to those of type-C QPOs in StMBHs of known mass. We resolved the count rates and the hardness ratios of M82 X-1 and a nearby bright ULX (source 5/X42.3+59) through surface brightness modeling. We detected QPOs in the frequency range of 36-210 mHz during which M82 X-1's hardness ratio varied from 0.42 to 0.47. Our primary results are (1) that we do not detect any correlation between the mHz QPO frequency and the hardness ratio (a substitute for the energy spectral power-law index) and (2) similar to some accreting X-ray binaries, we find that M82 X-1's mHz QPO frequency increases with its X-ray count rate (Pearson's correlation coefficient = +0.97). The apparent lack of a correlation between the QPO centroid frequency and the hardness ratio poses a challenge to the earlier claims that the mHz QPOs of M82 X-1 are the analogs of the type-C low-frequency QPOs of StMBHs. On the other hand, it is possible that the observed relation between the hardness ratio and the QPO frequency represents the saturated portion of the correlation seen in type-C QPOs of StMBHs-in which case M82 X-1's mHz QPOs can still be analogous to type-C QPOs.

  18. On the Nature of the mHz X-Ray Quasi-periodic Oscillations from Ultraluminous X-Ray Source M82 X-1: Search for Timing-Spectral Correlations

    NASA Astrophysics Data System (ADS)

    Pasham, Dheeraj R.; Strohmayer, Tod E.

    2013-07-01

    Using all the archival XMM-Newton X-ray (3-10 keV) observations of the ultraluminous X-ray source (ULX) M82 X-1, we searched for a correlation between its variable mHz quasi-periodic oscillation (QPO) frequency and its hardness ratio (5-10 keV/3-5 keV), an indicator of the energy spectral power-law index. When stellar-mass black holes (StMBHs) exhibit type-C low-frequency QPOs (~0.2-15 Hz), the centroid frequency of the QPO is known to correlate with the energy spectral index. The detection of such a correlation would strengthen the identification of M82 X-1's mHz QPOs as type-C and enable a more reliable mass estimate by scaling its QPO frequencies to those of type-C QPOs in StMBHs of known mass. We resolved the count rates and the hardness ratios of M82 X-1 and a nearby bright ULX (source 5/X42.3+59) through surface brightness modeling. We detected QPOs in the frequency range of 36-210 mHz during which M82 X-1's hardness ratio varied from 0.42 to 0.47. Our primary results are (1) that we do not detect any correlation between the mHz QPO frequency and the hardness ratio (a substitute for the energy spectral power-law index) and (2) similar to some accreting X-ray binaries, we find that M82 X-1's mHz QPO frequency increases with its X-ray count rate (Pearson's correlation coefficient = +0.97). The apparent lack of a correlation between the QPO centroid frequency and the hardness ratio poses a challenge to the earlier claims that the mHz QPOs of M82 X-1 are the analogs of the type-C low-frequency QPOs of StMBHs. On the other hand, it is possible that the observed relation between the hardness ratio and the QPO frequency represents the saturated portion of the correlation seen in type-C QPOs of StMBHs—in which case M82 X-1's mHz QPOs can still be analogous to type-C QPOs.

  19. Galaxy Zoo Supernovae

    NASA Astrophysics Data System (ADS)

    Smith, A. M.; Lynn, S.; Sullivan, M.; Lintott, C. J.; Nugent, P. E.; Botyanszki, J.; Kasliwal, M.; Quimby, R.; Bamford, S. P.; Fortson, L. F.; Schawinski, K.; Hook, I.; Blake, S.; Podsiadlowski, P.; Jönsson, J.; Gal-Yam, A.; Arcavi, I.; Howell, D. A.; Bloom, J. S.; Jacobsen, J.; Kulkarni, S. R.; Law, N. M.; Ofek, E. O.; Walters, R.

    2011-04-01

    This paper presents the first results from a new citizen science project: Galaxy Zoo Supernovae. This proof-of-concept project uses members of the public to identify supernova candidates from the latest generation of wide-field imaging transient surveys. We describe the Galaxy Zoo Supernovae operations and scoring model, and demonstrate the effectiveness of this novel method using imaging data and transients from the Palomar Transient Factory (PTF). We examine the results collected over the period 2010 April-July, during which nearly 14 000 supernova candidates from the PTF were classified by more than 2500 individuals within a few hours of data collection. We compare the transients selected by the citizen scientists to those identified by experienced PTF scanners and find the agreement to be remarkable - Galaxy Zoo Supernovae performs comparably to the PTF scanners and identified as transients 93 per cent of the ˜130 spectroscopically confirmed supernovae (SNe) that the PTF located during the trial period (with no false positive identifications). Further analysis shows that only a small fraction of the lowest signal-to-noise ratio detections (r > 19.5) are given low scores: Galaxy Zoo Supernovae correctly identifies all SNe with ≥8σ detections in the PTF imaging data. The Galaxy Zoo Supernovae project has direct applicability to future transient searches, such as the Large Synoptic Survey Telescope, by both rapidly identifying candidate transient events and via the training and improvement of existing machine classifier algorithms. This publication has been made possible by the participation of more than 10 000 volunteers in the Galaxy Zoo Supernovae project ().

  20. Neutrino Nucleosynthesis in Supernovae

    SciTech Connect

    Yoshida, Takashi; Suzuki, Toshio; Chiba, Satoshi; Kajino, Toshitaka; Yokomakura, Hidekazu; Kimura, Keiichi; Takamura, Akira; Hartmann, Dieter H.

    2009-05-04

    Neutrino nucleosynthesis is an important synthesis process for light elements in supernovae. One important physics input of neutrino nucleosynthesis is cross sections of neutrino-nucleus reactions. The cross sections of neutrino-{sup 12}C and {sup 4}He reactions are derived using new shell model Hamiltonians. With the new cross sections, light element synthesis of a supernova is investigated. The appropriate range of the neutrino temperature for supernovae is constrained to be between 4.3 MeV and 6.5 MeV from the {sup 11}B abundance in Galactic chemical evolution. Effects by neutrino oscillations are also discussed.

  1. Neutrinos and Supernovae

    SciTech Connect

    Meyer, Bradley S.

    2008-05-12

    Core-collapse supernovae are one of the few astrophysical environments in which neutrinos play a dominant role. Neutrinos emission is the means by which a newly-born neutron star formed in a core-collapse event cools. Neutrinos may play a significant role in causing the supernova explosion. Finally neutrinos may significantly affect the nucleosynthesis occurring in the layers of the exploding star that are eventually ejected into interstellar space. This paper reviews some interesting neutrino-nucleus processes that may occur in the cores of exploding massive stars and then discusses some effects neutrinos may have on explosive nucleosynthesis in supernovae.

  2. Polarizer mechanism for the space telescope faint object spectrograph

    NASA Technical Reports Server (NTRS)

    Thulson, M. D.

    1983-01-01

    The polarizer mechanism for the Space Telescope Faint Object Spectrograph is described. This device will allow spectropolarimetric measurements of faint astronomical objects. The mechanism employs a unique arrangement to meet functional requirements in a compact package and with only one actuator. Detailed tolerance analysis and a variety of tests indicate that the polarizer is capable of accurate and reliable performance.

  3. First Results from the ISO-IRAS Faint Galaxy Survey

    NASA Technical Reports Server (NTRS)

    Wolstencroft, R. D.; Wehrle, A. E.; Levine, D. A.

    1997-01-01

    We present the first result from the ISO-IRAS Faint Galaxy Survey (IIFGS), a program designed to obtain ISO observations of the most distant and luminous galaxies in the IRAS Faint Source Survey by filling short gaps in the ISO observing schedule with pairs of 12um ISOCAM AND 90um ISOPHOT observation.

  4. First Results from the ISO-IRAS Faint Galaxy Survey

    NASA Technical Reports Server (NTRS)

    Wolstencroft, R. D.; Wehrle, A. E.; Levine, D. A.

    1997-01-01

    We present the first result from the ISO-IRAS Faint Galaxy Survey (IIFGS), a program designed to obtain ISO observations of the most distant and luminous galaxies in the IRAS Faint Source Survey by filling short gaps in the ISO observing schedule with pairs of 12um ISOCAM AND 90um ISOPHOT observation.

  5. Fingerprinting Hydrogen in Core-Collapse Supernovae

    NASA Astrophysics Data System (ADS)

    Nance, Sarafina; Parrent, Jerod; Soderberg, Alicia Margarita

    2016-01-01

    This is a preliminary report on the mass of remaining hydrogen envelopes for stars massive enough to explode under core collapse. Using the stellar evolution code, MESA, our initial findings suggest that a significant fraction of massive stars with M_ZAMS = 20-60 Msun lose all but 10^-3 Msun -10^-1 Msun as they near eventual core collapse. This result is dependent on the mass-loss prescription, degree of rotation, metallicity, rates of nuclear burning in the core, and the final stellar configuration. Nevertheless, each of our test cases include a few stars that retain trace amounts of surface hydrogen, which would then be detected as faint H in type IIb/Ib/Ic supernova spectra. We also compare our findings to the progenitor candidate identified for iPTF13bvn using the most recent photometric corrections. We agree with the previous conclusion found by Groh et al. (2013) that the progenitor had an initial mass of 32 Msun, but now with an additional condition of 0.06 Msun of hydrogen on its surface just prior to the explosion. We demonstrate through our study that not all Type Ib supernovae are fully devoid of hydrogen at the time of explosion, which has implications for the nature of the progenitor star and thus provides impetus for a revised classification scheme for 'stripped envelope' supernovae. This work was supported in part by the NSF REU and DoD ASSURE programs under NSF grant no. 1262851 and by the Smithsonian Institution.

  6. Automated search for supernovae

    SciTech Connect

    Kare, J.T.

    1984-11-15

    This thesis describes the design, development, and testing of a search system for supernovae, based on the use of current computer and detector technology. This search uses a computer-controlled telescope and charge coupled device (CCD) detector to collect images of hundreds of galaxies per night of observation, and a dedicated minicomputer to process these images in real time. The system is now collecting test images of up to several hundred fields per night, with a sensitivity corresponding to a limiting magnitude (visual) of 17. At full speed and sensitivity, the search will examine some 6000 galaxies every three nights, with a limiting magnitude of 18 or fainter, yielding roughly two supernovae per week (assuming one supernova per galaxy per 50 years) at 5 to 50 percent of maximum light. An additional 500 nearby galaxies will be searched every night, to locate about 10 supernovae per year at one or two percent of maximum light, within hours of the initial explosion.

  7. Evolution of a Supernova

    NASA Image and Video Library

    2014-02-19

    A massive star left, which has created elements as heavy as iron in its interior, blows up in a tremendous explosion middle, scattering its outer layers in a structure called a supernova remnant right.

  8. Supernovae, neutrinos, and nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Fröhlich, Carla

    2014-04-01

    Core-collapse supernovae are the violent explosions at the end of the life of massive stars (≳ 8 - 10 M⊙). In these explosions a wide range of elements are synthesized and ejected: low-mass elements (O and Mg) from the hydrostatic evolution, intermediate-mass elements and Fe-group elements from explosive nucleosynthesis, and elements heavier than iron from the νp-process and potentially an r-process. However, supernova nucleosynthesis predictions are hampered by the not yet fully understood supernova explosion mechanism. In addition, recent progress in observational astronomy paints a fascinating picture for the origin of heavy elements, which is more complicated than the traditional s-, r-, and γ-processes. In this paper, we summarize the status of core-collapse supernova nucleosynthesis.

  9. Nucleosynthesis in Thermonuclear Supernovae

    SciTech Connect

    Claudia, Travaglio; Hix, William Raphael

    2013-01-01

    We review our understanding of the nucleosynthesis that occurs in thermonuclear supernovae and their contribution to Galactic Chemical evolution. We discuss the prospects to improve the modeling of the nucleosynthesis within simulations of these events.

  10. Infrared supernovae in starbursts

    SciTech Connect

    Van Buren, D.; Norman, C.A.

    1989-01-01

    The problem of uniquely confirming that the luminosity source of starburst galaxies is a young population of massive stars is considered. Unambiguous detection of the supernova explosion associated with a massive stellar population would provide proof of the starburst hypothesis. High spatial resolution narrow-band infrared imaging of starburst galaxies directly detects the cobalt synthesized in Type II supernova explosions. Coupled with observations of other infrared lines and continuum, progenitor masses can be at least roughly estimated. A statistically large sample of starburst supernovae will lead to an average starburst initial mass function. Standard candles can also be constructed, based on both individual and populations of supernovae. With current and planned instruments, K-band can be found out to cosmological distances. 27 references.

  11. Berkeley automated supernova search

    SciTech Connect

    Kare, J.T.; Pennypacker, C.R.; Muller, R.A.; Mast, T.S.; Crawford, F.S.; Burns, M.S.

    1981-01-01

    The Berkeley automated supernova search employs a computer controlled 36-inch telescope and charge coupled device (CCD) detector to image 2500 galaxies per night. A dedicated minicomputer compares each galaxy image with stored reference data to identify supernovae in real time. The threshold for detection is m/sub v/ = 18.8. We plan to monitor roughly 500 galaxies in Virgo and closer every night, and an additional 6000 galaxies out to 70 Mpc on a three night cycle. This should yield very early detection of several supernovae per year for detailed study, and reliable premaximum detection of roughly 100 supernovae per year for statistical studies. The search should be operational in mid-1982.

  12. VizieR Online Data Catalog: Superluminous supernovae in faint galaxies (McCrum+, 2015)

    NASA Astrophysics Data System (ADS)

    McCrum, M.; Smartt, S. J.; Rest, A.; Smith, K.; Kotak, R.; Rodney, S. A.; Young, D. R.; Chornock, R.; Berger, E.; Foley, R. J.; Fraser, M.; Wright, D.; Scolnic, D.; Tonry, J. L.; Urata, Y.; Huang, K.; Pastorello, A.; Botticella, M. T.; Valenti, S.; Mattila, S.; Kankare, E.; Farrow, D. J.; Huber, M. E.; Stubbs, C. W.; Kirshner, R. P.; Bresolin, F.; Burgett, W. S.; Chambers, K. C.; Draper, P. W.; Flewelling, H.; Jedicke, R.; Kaiser, N.; Magnier, E. A.; Metcalfe, N.; Morgan, J. S.; Price, P. A.; Sweeney, W.; Wainscoat, R. J.; Waters, C.

    2015-09-01

    From the period starting February 25th 2010 and ending July 9th 2011, 249 hostless transients or "orphans" were discovered in the PS1 Medium Deep fields. AN orphan is defined as an object that is >3.4" away from the centre of a catalogued galaxy or point source brighter than approximately 23.5m (in any of the gP1 rP1 iP1 filters that the transient was detected in). The PS1 observations are obtained through a set of five broadband filters, which we have designated as gP1, rP1, iP1, zP1, and yP1. Although the filter system for PS1 has much in common with that used in previous surveys, such as SDSS (Abazajian et al., 2009ApJS..182..543A), there are important differences. The gP1 filter extends 20nm redward of gSDSS, paying the price of 5577Å emission for greater sensitivity and lower systematics for photometric redshifts, and the zP1 filter is cut off at 930nm, giving it a different response than the detector response which defined zSDSS. SDSS has no corresponding yP1 filter. Further information on the passband shapes is described in Stubbs et al. (2010ApJS..191..376S). The PS1 photometric system and its response is covered in detailed in Tonry et al. (2012ApJ...750...99T, Cat. J/ApJ/750/99). Photometry is in the "natural" PS1 system, m=-2.5log(flux)+m', with a single zeropoint adjustment m' made in each band to conform to the AB magnitude scale. (8 data files).

  13. Supernova 1987A

    NASA Astrophysics Data System (ADS)

    McCray, R.; Murdin, P.

    2002-10-01

    Supernova 1987A (SN1987A) in the LARGE MAGELLANIC CLOUD (LMC) is the brightest supernova to be observed since SN1604 (Kepler), the first to be observed in every band of the ELECTROMAGNETIC SPECTRUM and the first to be detected through its initial burst of NEUTRINOS. Although the bolometric luminosity of SN1987A today is ≈10-6 of its value at maximum light (Lmax≈2.5×108L⊙), it ...

  14. Handbook of Supernovae

    NASA Astrophysics Data System (ADS)

    Athem Alsabti, Abdul

    2015-08-01

    Since the discovery of pulsars in 1967, few celestial phenomena have fascinated amateur and professional astronomers, and the public, more than supernovae - dying stars that explode spectacularly and, in so doing, may outshine a whole galaxy. Thousands of research papers, reviews, monographs and books have been published on this subject. These publications are often written either for a highly specific level of expertise or education, or with respect to a particular aspect of supernovae research. However, the study of supernovae is a very broad topic involving many integral yet connected aspects, including physics, mathematics, computation, history, theoretical studies and observation. More specifically, areas of study include historical supernovae, the different types and light curves, nucleosynthesis, explosion mechanisms, formation of black holes, neutron stars, cosmic rays, neutrinos and gravitational waves. Related questions include how supernovae remnants interact with interstellar matter nearby and how do these events affect the formation of new stars or planetary systems? Could they affect existing planetary systems? Closer to home, did any supernovae affect life on earth in the past or could they do so in the future? And on the larger scale, how did supernovae observations help measure the size and expansion of the universe? All these topics, and more, are to be covered in a new reference work, consisting of more than 100 articles and more than 1700 pages. It is intended to cover all the main facets of current supernovae research. It will be pitched at or above the level of a new postgraduate student, who will have successfully studied physics (or a similar scientific subject) to Bachelor degree level. It will be available in both print and electronic (updatable) formats, with the exception of the first section, which will consist of a review of all the topics of the handbook at a level that allows anyone with basic scientific knowledge to grasp the

  15. Physics of supernovae

    SciTech Connect

    Woosley, S.E.; Weaver, T.A.

    1985-12-13

    Presupernova models of massive stars are presented and their explosion by ''delayed neutrino transport'' examined. A new form of long duration Type II supernova model is also explored based upon repeated encounter with the electron-positron pair instability in stars heavier than about 60 Msub solar. Carbon deflagration in white dwarfs is discussed as the probable explanation of Type I supernovae and special attention is paid to the physical processes whereby a nuclear flame propagates through degenerate carbon. 89 refs., 12 figs.

  16. Hubble Finds Supernova Companion Star after Two Decades of Searching

    NASA Image and Video Library

    2017-09-27

    This is an artist's impression of supernova 1993J, an exploding star in the galaxy M81 whose light reached us 21 years ago. The supernova originated in a double-star system where one member was a massive star that exploded after siphoning most of its hydrogen envelope to its companion star. After two decades, astronomers have at last identified the blue helium-burning companion star, seen at the center of the expanding nebula of debris from the supernova. The Hubble Space Telescope identified the ultraviolet glow of the surviving companion embedded in the fading glow of the supernova. More info: Using NASA’s Hubble Space Telescope, astronomers have discovered a companion star to a rare type of supernova. The discovery confirms a long-held theory that the supernova, dubbed SN 1993J, occurred inside what is called a binary system, where two interacting stars caused a cosmic explosion. "This is like a crime scene, and we finally identified the robber," said Alex Filippenko, professor of astronomy at University of California (UC) at Berkeley. "The companion star stole a bunch of hydrogen before the primary star exploded." SN 1993J is an example of a Type IIb supernova, unusual stellar explosions that contains much less hydrogen than found in a typical supernova. Astronomers believe the companion star took most of the hydrogen surrounding the exploding main star and continued to burn as a super-hot helium star. “A binary system is likely required to lose the majority of the primary star’s hydrogen envelope prior to the explosion. The problem is that, to date, direct observations of the predicted binary companion star have been difficult to obtain since it is so faint relative to the supernova itself,” said lead researcher Ori Fox of UC Berkeley. Read more: 1.usa.gov/1Az5Qb9 Credit: NASA, ESA, G. Bacon (STScI) NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar

  17. Dust in supernova remnants

    NASA Astrophysics Data System (ADS)

    Gomez, H.

    In this Review, I will discuss our changing view on supernovae as interstellar dust sources. In particular I will focus on infrared and submillimetre studies of the historical supernova remnants Cassiopeia A, the Crab Nebula, SN 1987A, Tycho and Kepler. In the last decade (and particularly in recent years), SCUBA, Herschel and ALMA have now demonstrated that core-collapse supernovae are prolific dust factories, with evidence of 0.1 - 0.7 M⊙ of dust formed in the ejecta, though there is little evidence (as yet) for significant dust production in Type Ia supernova ejecta. There is no longer any question that dust (and molecule) formation is efficient after some supernova events, though it is not clear how much of this will survive over longer timescales. Current and future instruments will allow us to investigate the spatial distribution of dust within corecollapse ejecta, and whether this component contributes a significant amount to the dust content of the Universe or if supernovae ultimately provide a net loss once dust destruction by shocks is taken into account.

  18. Neutrinos from supernovae.

    NASA Astrophysics Data System (ADS)

    Burrows, A. S.

    First, the author presents a short history of supernova neutrino theory. Then, the theory of core collapse supernovae is reviewed. Because of the profound opacity to light of the dense core that experiences collapse, we "see" this core directly only through its neutrino signature. Every bump and wiggle echoes the internal convulsions of the event and can provide clues about both the supernova mechanism and the neutron star that remains. The author discusses the only neutrino observations of a supernova so far, SN 1987A. While the agreement with calculations has been gratifying, there remain, of course, plenty of outstanding issues in supernova theory to be tested. These are high-lighted throughout the text. Since neutrinos give us the only real access to the physics inside the collapse, it is important that observation of these particles continue. In an appendix the author describes some of the available or contemplated neutrino detectors capable of good time resolution and therefore of shedding light on supernova mechanisms.

  19. Is the faint young Sun paradox solved?

    NASA Astrophysics Data System (ADS)

    Wolf, E. T.; Toon, O. B.

    2013-12-01

    How did the early Earth remain warm despite weak solar luminosity? The faint young Sun paradox has stubbornly resisted a self-consistent solution since it was first introduced by Sagan and Mullen [1] over four decades ago. However, recent revisions to expected paleo-ocean temperatures [2, 3] along with new results from three-dimensional climate models [4] may allow this long standing problem to be finally put to rest. Here we use a modified version of the Community Atmosphere Model version 3 from the National Center for Atmospheric Research to study early climate. We find that resolving the faint young Sun paradox becomes less problematic when viewing a full representation of the climate system. For the late Archean climate (80% solar constant), relatively modest amounts of CO2 (≤0.02 bar) and CH4 (0.001 bar) yield surface temperatures equal to the present day with no other alterations to climate. Cooler climates with large ice caps but with temperate tropical regions can be supported with considerably smaller greenhouse gas burdens. The incorporation of systematic climate system elements expected for the Archean such as fewer cloud condensation nuclei (CCN) [5], reduced land albedos [5], and an increased atmospheric inventory of N2 [6], can provide a combined 10 to 20 K of additional surface warming given reasonable assumptions. With the inclusion of 0.001 bar of CH4, 2 PAL of N2, reduced land albedos, and reduced CCN, present day mean surface temperatures can be maintained for the earliest Archean (75% solar constant) with only ~0.01 bar of CO2. However, lower requirements for atmospheric CO2 may imply that photochemical hazes were frequent during the Archean. [1] Sagan, C., & Mullen, G. Science 177, 52 (1972) [2] Hren, M.T., Tice, M.M., & Chamberlin, C.P. Nature 462, 205 (2009) [3] Blake. R.E., Chang, S.J., & Lepland, A. Nature 464, 1029 (2010) [4] Wolf, E.T., & Toon, O.B. Astrobiology 13(7), 1 (2013) [5] Rosing, M.T., Bird, D.K., Sleep, N.H., & Bjerrum, C

  20. Faint high-latitude carbon stars

    NASA Astrophysics Data System (ADS)

    Green, Paul Jonathan

    We have undertaken a wide area survey to search for faint high latitude carbon (FHLC) stars. Carbon giants are ideal for study of the structure and kinematics of the outer galactic halo. We use two color photometric selection with large format charge-coupled devices (CCD's) to cover 52 deg2 of sky to a depth of about V = 18. Below this limit, we find good (approximately less than 20 percent) agreement between our object counts as a function of magnitude and the galactic models of Bahcall and Soneira at a variety of latitudes and longitudes. Our spectroscopic followup began with low-resolution spectra of 19 unconfirmed C star candidates from the Case objective-prism photographic survey of Sanduleak and Pesch. Four of these we find to be M stars. The 15 C stars we classify on the two-parameter Keenan-Morgan system as warm (color class less than 3). Of 94 faint C star candidates from our own CCD survey, one highly ranked V = 17 candidate was found to have strong carbon and CN bands. We estimate that to a depth of V = 18, the surface density FHLC stars is 0.019+0.044-.016 deg-2. We identify two FHLC stars with previously catalogued high proper motion objects. These objects are thus inferred to be dwarf carbon (dC) stars, supplementing the one previously known case, G77-61. Not all dC stars will have detectable proper motions, so other luminosity/distance indicators are needed: we find that C dwarfs all have similar JHK colors, and possibly an unusually strong lambda-6191 bandhead of carbon. By comparing positions in the HST Guide Star Catalog and the original Palomar Observatory Sky Survey, we detect proper motions in two additional FHLC stars. Our proper motion survey, spanning a 30 year baseline, thus identifies two new dC's, and provides proper motion upper limits for another 44 FHLC stars. Kinematic simulations suggest that virtually all Population 2 dC's will have detectable proper motions in a survey as sensitive as our own, and that to a limit of V approximately

  1. Faint High-Latitude Carbon Stars

    NASA Astrophysics Data System (ADS)

    Green, Paul J.

    1992-10-01

    Since carbon giants are ideal for study of the structure and kinematics of the outer galactic halo, we have undertaken a wide-area survey to search for faint high-latitude carbon (FHLC) stars. We use two-color photometric selection with large format CCDs to cover 52 deg^2 of sky to a depth of about V=18. Below this limit, we find good (< 20%) agreement between our object counts as a function of magnitude and the galactic models of Bahcall and Coneira (1984) at a variety of latitudes and longitudes. Our spectroscopic followup began with low-resolution spectra of 19 unconfirmed C-star candidates from the Case objective-prism photographic survey of Sanduleak and Pesch (1988). Four of these we find to be M stars. The 15 C stars we classify on the two-parameter Keenan-Morgan (1941) system as warm (color class < 4), with moderate to weak carbon band strengths (C class < 3). Of 94 faint C-star candidates from our own CCD survey, one highly ranked V=17 candidate was found to have strong carbon and CN bands. We estimate that to a depth of V=18, the surface density of FHLC stars is 0.019^0.044_-0.016 deg^-2. We identify two FHLC stars with previously cataloged high-proper-motion objects. These objects are thus inferred to be dwarf carbon (dC) stars, supplementing the one previously known case, G 77-61. Not all dC stars will have detectable proper motions, so other luminosity/distance indicators are needed: we find that C dwarfs all have similar JHK colors, and possibly an unusually strong lambda-6191 bandhead of carbon. By comparing positions of the HST Guide Star Catalog and the original Palomar Observatory Sky Survey, we detect proper motions in two additional FHLC stars. Our proper-motion survey, spanning a 30-yr base line, thus identifies four new dC's, and provides proper-motion upper limits for another 44 FHLC stars. Kinematic simulations suggest that virtually all Population II dCs will have detectable proper motions in a survey as sensitive as our own, and that to a

  2. Faint Compact Galaxy in the Early Universe

    NASA Image and Video Library

    2015-12-03

    This is a Hubble Space Telescope view of a very massive cluster of galaxies, MACS J0416.1-2403, located roughly 4 billion light-years away and weighing as much as a million billion suns. The cluster's immense gravitational field magnifies the image of galaxies far behind it, in a phenomenon called gravitational lensing. The inset is an image of an extremely faint and distant galaxy that existed only 400 million years after the big bang. It was discovered by Hubble and NASA's Spitzer Space Telescope. The gravitational lens makes the galaxy appear 20 times brighter than normal. The galaxy is comparable in size to the Large Magellanic Cloud (LMC), a diminutive satellite galaxy of our Milky Way. It is rapidly making stars at a rate ten times faster than the LMC. This might be the growing core of what was to eventually evolve into a full-sized galaxy. The research team has nicknamed the object Tayna, which means "first-born" in Aymara, a language spoken in the Andes and Altiplano regions of South America. http://photojournal.jpl.nasa.gov/catalog/PIA20054

  3. Detection of Optically Faint GEO Debris

    NASA Technical Reports Server (NTRS)

    Seitzer, P.; Lederer, S.; Barker, E.; Cowardin, H.; Abercromby, K.; Silha, J.; Burkhardt, A.

    2014-01-01

    There have been extensive optical surveys for debris at geosynchronous orbit (GEO) conducted with meter-class telescopes, such as those conducted with MODEST (the Michigan Orbital DEbris Survey Telescope, a 0.6-m telescope located at Cerro Tololo in Chile), and the European Space Agency's 1.0-m space debris telescope (SDT) in the Canary Islands. These surveys have detection limits in the range of 18th or 19th magnitude, which corresponds to sizes larger than 10 cm assuming an albedo of 0.175. All of these surveys reveal a substantial population of objects fainter than R = 15th magnitude that are not in the public U.S. Satellite Catalog. To detect objects fainter than 20th magnitude (and presumably smaller than 10 cm) in the visible requires a larger telescope and excellent imaging conditions. This combination is available in Chile. NASA's Orbital Debris Program Office has begun collecting orbital debris observations with the 6.5-m (21.3-ft diameter) "Walter Baade" Magellan telescope at Las Campanas Observatory. The goal is to detect objects as faint as possible from a ground-based observatory and begin to understand the brightness distribution of GEO debris fainter than R = 20th magnitude.

  4. The Population of Optically Faint GEO Debris

    NASA Astrophysics Data System (ADS)

    Seitzer, P.; Barker, E.; Buckalew, B.; Burkhardt, A.; Cowardin, H.; Frith, J.; Kaleida, C.; Lederer, S.; Lee, C.

    2016-09-01

    The 6.5-m Magellan telescope, 'Walter Baade', at the Las Campanas Observatory in Chile has been used for spot surveys of the geosynchronous Earth orbit (GEO) regime to study the population of optically faint GEO debris. The goal is to estimate the population of GEO debris at sizes much smaller than can be studied with 1-meter class telescopes. Despite the small field of view of the Magellan instrument (diameter 0.5-degree), a significant population of objects fainter than R = 19th magnitude has been found with angular rates consistent with circular orbits at GEO. We compare the size of this population with the numbers of GEO objects found at brighter magnitudes by smaller telescopes. The detections have a wide range of characteristics starting with those appearing as short uniform streaks. But there are a substantial number of detections that vary in brightness ("flashers") during the 5-second exposure. The duration of each of these flashes can be extremely brief: sometimes less than half a second. This is characteristic of a rapidly tumbling object with a quite variable projected product of size * albedo. If the albedo is of the order of 0.2, then the largest projected size of these objects is around 10-cm.

  5. Optically faint radio sources: reborn AGN?

    NASA Astrophysics Data System (ADS)

    Filho, M. E.; Brinchmann, J.; Lobo, C.; Antón, S.

    2011-12-01

    We present our discovery of several relatively strong radio sources in the field-of-view of SDSS galaxy clusters that have no optical counterparts down to the magnitude limits of the SDSS. The optically faint radio sources appear as double-lobed or core-jet objects in the FIRST radio images and have projected angular sizes ranging from 0.5 to 1.0 arcmin. We followed-up these sources with near-infrared imaging using the wide-field imager HAWK-I on the VLT. We detected Ks-band emitting regions, about 1.5 arcsec in size and coincident with the centers of the radio structures, in all sources, with magnitudes in the range 17-20 mag. We used spectral modelling to characterize the sample sources. In general, the radio properties are similar to those observed in 3CRR sources but the optical-radio slopes are consistent with those of moderate to high redshift (z < 4) gigahertz-peaked spectrum sources. Our results suggest that these unusual objects are galaxies whose black hole has been recently re-ignited but that retain large-scale radio structures, which are signatures of previous AGN activity.

  6. Accurate shear measurement with faint sources

    SciTech Connect

    Zhang, Jun; Foucaud, Sebastien; Luo, Wentao E-mail: walt@shao.ac.cn

    2015-01-01

    For cosmic shear to become an accurate cosmological probe, systematic errors in the shear measurement method must be unambiguously identified and corrected for. Previous work of this series has demonstrated that cosmic shears can be measured accurately in Fourier space in the presence of background noise and finite pixel size, without assumptions on the morphologies of galaxy and PSF. The remaining major source of error is source Poisson noise, due to the finiteness of source photon number. This problem is particularly important for faint galaxies in space-based weak lensing measurements, and for ground-based images of short exposure times. In this work, we propose a simple and rigorous way of removing the shear bias from the source Poisson noise. Our noise treatment can be generalized for images made of multiple exposures through MultiDrizzle. This is demonstrated with the SDSS and COSMOS/ACS data. With a large ensemble of mock galaxy images of unrestricted morphologies, we show that our shear measurement method can achieve sub-percent level accuracy even for images of signal-to-noise ratio less than 5 in general, making it the most promising technique for cosmic shear measurement in the ongoing and upcoming large scale galaxy surveys.

  7. Spectral Indices of Faint Radio Sources

    NASA Astrophysics Data System (ADS)

    Gim, Hansung B.; Hales, Christopher A.; Momjian, Emmanuel; Yun, Min Su

    2015-01-01

    The significant improvement in bandwidth and the resultant sensitivity offered by the Karl G. Jansky Very Large Array (VLA) allows us to explore the faint radio source population. Through the study of the radio continuum we can explore the spectral indices of these radio sources. Robust radio spectral indices are needed for accurate k-corrections, for example in the study of the radio - far-infrared (FIR) correlation. We present an analysis of measuring spectral indices using two different approaches. In the first, we use the standard wideband imaging algorithm in the data reduction package CASA. In the second, we use a traditional approach of imaging narrower bandwidths to derive the spectral indices. For these, we simulated data to match the observing parameter space of the CHILES Con Pol survey (Hales et al. 2014). We investigate the accuracy and precision of spectral index measurements as a function of signal-to noise, and explore the requirements to reliably probe possible evolution of the radio-FIR correlation in CHILES Con Pol.

  8. PROGENITORS OF RECOMBINING SUPERNOVA REMNANTS

    SciTech Connect

    Moriya, Takashi J.

    2012-05-01

    Usual supernova remnants have either ionizing plasma or plasma in collisional ionization equilibrium, i.e., the ionization temperature is lower than or equal to the electron temperature. However, the existence of recombining supernova remnants, i.e., supernova remnants with ionization temperature higher than the electron temperature, has been recently confirmed. One suggested way to have recombining plasma in a supernova remnant is to have a dense circumstellar medium at the time of the supernova explosion. If the circumstellar medium is dense enough, collisional ionization equilibrium can be established in the early stage of the evolution of the supernova remnant and subsequent adiabatic cooling, which occurs after the shock wave gets out of the dense circumstellar medium, makes the electron temperature lower than the ionization temperature. We study the circumstellar medium around several supernova progenitors and show which supernova progenitors can have a circumstellar medium dense enough to establish collisional ionization equilibrium soon after the explosion. We find that the circumstellar medium around red supergiants (especially massive ones) and the circumstellar medium dense enough to make Type IIn supernovae can establish collisional ionization equilibrium soon after the explosion and can evolve to become recombining supernova remnants. Wolf-Rayet stars and white dwarfs have the possibility to be recombining supernova remnants but the fraction is expected to be very small. As the occurrence rate of the explosions of red supergiants is much higher than that of Type IIn supernovae, the major progenitors of recombining supernova remnants are likely to be red supergiants.

  9. Faint spatial object classifier construction based on data mining technology

    NASA Astrophysics Data System (ADS)

    Lou, Xin; Zhao, Yang; Liao, Yurong; Nie, Yong-ming

    2016-11-01

    Data mining can effectively obtain the faint spatial object's patterns and characteristics, the universal relations and other implicated data characteristics, the key of which is classifier construction. Faint spatial object classifier construction with spatial data mining technology for faint spatial target detection is proposed based on theoretical analysis of design procedures and guidelines in detail. For the one-sidedness weakness during dealing with the fuzziness and randomness using this method, cloud modal classifier is proposed. Simulating analyzing results indicate that this method can realize classification quickly through feature combination and effectively resolve the one-sidedness weakness problem.

  10. The Supernova Spectropolarimetry Project: Photometric Followup in the Optical and Near-Infrared by the Mount Laguna Supernova Survey

    NASA Astrophysics Data System (ADS)

    Khandrika, Harish G.; Leonard, Douglas C.; Horst, Chuck; Rachubo, Alisa; Duong, Nhieu; Williams, G. Grant; Smith, Paul S.; Smith, Nathan; Milne, Peter; Hoffman, Jennifer L.; Huk, Leah N.; Dessart, Luc

    2014-06-01

    The SuperNova SpectroPOLarimetry project (SNSPOL) is a recently formed collaboration between observers and theorists that focuses on decoding the complex, time-dependent spectropolarimetric behavior of supernovae (SNe) of all types. Photometric followup of targeted SNe is provided by the MOunt LAguna SUpernova Survey (MOLASUS), which is carried out using Mount Laguna Observatory's 1-meter telescope. Here we present optical and near-infrared (NIR) photometric observations of three recent SNe that were observed as part of this coordinated effort: SN 2013ej, SN 2013dy, and SN 2014J. We discuss the multi-band light curves of these three SNe, with a particular focus on the use of NIRIM (Meixner et al. 1999), our NIR camera used to obtain the J, H, and K' data. SN 2013ej is a Type II supernova in M74, discovered by the Lick Observatory Supernova Search (LOSS) on 2013 July 25.45 (UT; UT dates are used throughout). Our monitoring of this object began 2013 August 07.88 and continued until 2013 December 13.74. The data provide evidence for aphotospheric phase lasting roughly 70 days from our first observation, with SN 2013ej then declining by about 3 magnitudes in H-band over the following 50 days. SN 2013dy is a Type Ia supernova in NGC 7250 discovered by LOSS on 2013 July 10.45. We monitored SN 2013dy from July 19.89 until 2013 December 13.62. Our observations show a characteristic type Ia light curve that declines in brightness by about 3 magnitudes in H through the course of our monitoring. Lastly, SN 2014J is a Type Ia-HV [High Velocity] (Takaki et. al (2014) - ATEL 5791) in M82, discovered on 2014 January 21.81, and the closest Type Ia supernovae in over three decades. Our monitoring of SN 2014J began on 2014 January 30.67.We acknowledge support from NSF grants AST-1009571 and AST-1210311, under which part of this research was carried out.

  11. Modeling Core Collapse Supernovae

    NASA Astrophysics Data System (ADS)

    Mezzacappa, Anthony

    2017-01-01

    Core collapse supernovae, or the death throes of massive stars, are general relativistic, neutrino-magneto-hydrodynamic events. The core collapse supernova mechanism is still not in hand, though key components have been illuminated, and the potential for multiple mechanisms for different progenitors exists. Core collapse supernovae are the single most important source of elements in the Universe, and serve other critical roles in galactic chemical and thermal evolution, the birth of neutron stars, pulsars, and stellar mass black holes, the production of a subclass of gamma-ray bursts, and as potential cosmic laboratories for fundamental nuclear and particle physics. Given this, the so called ``supernova problem'' is one of the most important unsolved problems in astrophysics. It has been fifty years since the first numerical simulations of core collapse supernovae were performed. Progress in the past decade, and especially within the past five years, has been exponential, yet much work remains. Spherically symmetric simulations over nearly four decades laid the foundation for this progress. Two-dimensional modeling that assumes axial symmetry is maturing. And three-dimensional modeling, while in its infancy, has begun in earnest. I will present some of the recent work from the ``Oak Ridge'' group, and will discuss this work in the context of the broader work by other researchers in the field. I will then point to future requirements and challenges. Connections with other experimental, observational, and theoretical efforts will be discussed, as well.

  12. Faint CV Monitoring at CBA Pretoria

    NASA Astrophysics Data System (ADS)

    Monard, L. A. G. B.

    2006-05-01

    The regular monitoring of faint cataclysmic variables (CV) is one of five observing programs that are run at CBA Pretoria. It started off in 2002 with about 120 CVs and related objects in the program. The intention was to observe those targets as often as possible with unfiltered CCD. There were continuous additions of more CVs by digging deeper in the CV atlas, new finds, and reclassified stars while some were taken off the list. At the end of 2004 the number of CVs in the observing program exceeded 200. With only one telescope and one observer and so many other things to observe, the actual number of snapshot CV observations have been much less than hoped. Despite this, the program has shown to be very successful. Publications have been referring to reported findings from this program while even more publications resulted from observing campaigns (time resolved photometry) dedicated to CVs that were found in outburst by observations at CBA Pretoria. In most cases they were the first real-time outburst detection of that CV. The present paper will not deal with those published or alerted finds but will show observing results of other CVs from the list just to give an indication of the broader meaningfulness of such a program. A selection of fifteen light curves obtained after three years of monitoring will be shown and discussed. The choice of the 15 stars was based on their possible interest and the fact that they have been positively observed on most occasions, since they were mostly brighter than magnitude 18 CR (unfiltered with red zero-point).

  13. The ISO-IRAS Faint Galaxy Survey

    NASA Technical Reports Server (NTRS)

    Smith, Harding E.

    1999-01-01

    As part of the ISO-IRAS Faint Galaxy Survey ISO Satellite observations of over 600 IRAS sources have been obtained with the ISOCAM instrument. Because our survey strategy involved relatively short integrations, great care was required in developing analysis software including cosmic-ray and transient removal and calibration. These observations have now been through final pipeline processing at IPAC and ground-based follow-up is ongoing. The observations are for sources from two samples: a " Filler' sample selected to be at z greater than 0.1 and a fainter sample which selected for the highest redshift galaxies in the IRAS survey, with redshifts 0.2 less than z less than 1.0. I now have obtained ground-based follow-up spectrophotometry at Lick and Palomar observatories for 100 LFIRGs with 0.1 less than z less than 0.7. Our observations have confirmed that these systems are comparable to nearby LFIRGs such as Arp 220, with L (sub -)(fir) greater than 10(exp 11) L(sub -) sun and typically HII/Liner optical excitation. About 10% of the galaxies show true AGN (Sy2) excitation. Based on our work on a nearby complete sample of LFIRGS, we believe that the majority of these systems are luminous Starbursts, thus this project is tracing the luminous end of the galaxy star-forming luminosity function - the (infrared) star-formation history of the Universe to z approx. 1, a topic of some considerable recent interest. A by-product of these ISOCAM observations is approximately 1 square degree of deep 2 microns pointings outside the IRAS error boxes, allowing us an independent estimate of the mid-infrared log N - log S relation. Ground-based observations of this sample are continuing.

  14. Faint solar radio structures from decametric observations

    NASA Astrophysics Data System (ADS)

    Briand, C.; Zaslavsky, A.; Maksimovic, M.; Zarka, P.; Lecacheux, A.; Rucker, H. O.; Konovalenko, A. A.; Abranin, E. P.; Dorovsky, V. V.; Stanislavsky, A. A.; Melnik, V. N.

    2008-10-01

    Aims: Decameter radio observations of the solar corona reveal the presence of numerous faint frequency drifting emissions, similar to “solar S bursts” which are reported in the literature. We present a statistical analysis of the characteristics of these emissions and propose a mechanism to excite the Langmuir waves thought to be at the origin of these emissions. Methods: The observations were performed between 1998 and 2002 with the Digital Spectro Polarimeter (DSP) receivers operated at the UTR-2 and Nançay decameter radio telescopes in the frequency range 15-30 MHz. Our theoretical explanation is based on Vlasov-Ampère simulations. Results: Based on the frequency drift rate, three populations of structures can be identified. The largest population presents an average negative frequency drift of -0.9 MHz s-1 and a lifetime up to 11 s (median value of 2.72 s). A second population shows a very small frequency drift of -0.1 MHz s-1 and a short lifetime of about 1 s. The third population presents an average positive frequency drift of +0.95 MHz s-1 and a lifetime of up to 3 s. Also, the frequency drift as a function of frequency is consistent with the former results, which present results in higher frequency range. No specific relationship was found between the occurrence of these emissions and the solar cycle or presence of flares. Assuming that these emissions are produced by “electron clouds” propagating the solar corona, we deduce electron velocities of about 3-5 times the electron thermal velocity. As previously shown, a localized, time-dependent modulation of the electron distribution function (heating) leads to low velocity electron clouds (consistent with observations), which, in turn, can generate Langmuir waves and electromagnetic signals by nonlinear processes.

  15. The ISO-IRAS Faint Galaxy Survey

    NASA Technical Reports Server (NTRS)

    Smith, Harding E.

    1999-01-01

    As part of the ISO-IRAS Faint Galaxy Survey ISO Satellite observations of over 600 IRAS sources have been obtained with the ISOCAM instrument. Because our survey strategy involved relatively short integrations, great care was required in developing analysis software including cosmic-ray and transient removal and calibration. These observations have now been through final pipeline processing at IPAC and ground-based follow-up is ongoing. The observations are for sources from two samples: a " Filler' sample selected to be at z greater than 0.1 and a fainter sample which selected for the highest redshift galaxies in the IRAS survey, with redshifts 0.2 less than z less than 1.0. I now have obtained ground-based follow-up spectrophotometry at Lick and Palomar observatories for 100 LFIRGs with 0.1 less than z less than 0.7. Our observations have confirmed that these systems are comparable to nearby LFIRGs such as Arp 220, with L (sub -)(fir) greater than 10(exp 11) L(sub -) sun and typically HII/Liner optical excitation. About 10% of the galaxies show true AGN (Sy2) excitation. Based on our work on a nearby complete sample of LFIRGS, we believe that the majority of these systems are luminous Starbursts, thus this project is tracing the luminous end of the galaxy star-forming luminosity function - the (infrared) star-formation history of the Universe to z approx. 1, a topic of some considerable recent interest. A by-product of these ISOCAM observations is approximately 1 square degree of deep 2 microns pointings outside the IRAS error boxes, allowing us an independent estimate of the mid-infrared log N - log S relation. Ground-based observations of this sample are continuing.

  16. Three Great Eyes on Kepler's Supernova Remnant

    NASA Technical Reports Server (NTRS)

    2004-01-01

    supernova shock wave. The dust re-radiates the shock wave's energy as infrared light. The Spitzer data are brightest in the regions surrounding those seen in detail by the Hubble telescope.

    The Chandra X-ray data show regions of very hot gas, and extremely high-energy particles. The hottest gas (higher-energy X-rays, colored blue) is located primarily in the regions directly behind the shock front. These regions also show up in the Hubble observations, and also align with the faint rim of glowing material seen in the Spitzer data. The X-rays from the region on the lower left (colored blue) may be dominated by extremely high-energy electrons that were produced by the shock wave and are radiating at radio through X-ray wavelengths as they spiral in the intensified magnetic field behind the shock front. Cooler X-ray gas (lower-energy X-rays, colored green) resides in a thick interior shell and marks the location of heated material expelled from the exploded star.

    Kepler's supernova, the last such object seen to explode in our Milky Way galaxy, resides about 13,000 light-years away in the constellation Ophiuchus.

    The Chandra observations were taken in June 2000, the Hubble in August 2003; and the Spitzer in August 2004.

  17. Three Great Eyes on Kepler's Supernova Remnant

    NASA Technical Reports Server (NTRS)

    2004-01-01

    supernova shock wave. The dust re-radiates the shock wave's energy as infrared light. The Spitzer data are brightest in the regions surrounding those seen in detail by the Hubble telescope.

    The Chandra X-ray data show regions of very hot gas, and extremely high-energy particles. The hottest gas (higher-energy X-rays, colored blue) is located primarily in the regions directly behind the shock front. These regions also show up in the Hubble observations, and also align with the faint rim of glowing material seen in the Spitzer data. The X-rays from the region on the lower left (colored blue) may be dominated by extremely high-energy electrons that were produced by the shock wave and are radiating at radio through X-ray wavelengths as they spiral in the intensified magnetic field behind the shock front. Cooler X-ray gas (lower-energy X-rays, colored green) resides in a thick interior shell and marks the location of heated material expelled from the exploded star.

    Kepler's supernova, the last such object seen to explode in our Milky Way galaxy, resides about 13,000 light-years away in the constellation Ophiuchus.

    The Chandra observations were taken in June 2000, the Hubble in August 2003; and the Spitzer in August 2004.

  18. NASA Researches the 'FaINT' Side of Sonic Booms

    NASA Image and Video Library

    As the latest in a continuing progression of NASA supersonics research projects aimed at reducing or mitigating the effect of sonic booms, the Farfield Investigation of No Boom Threshold, or FaINT,...

  19. Supernovae by the Hundreds: the LCOGT Supernova Key Project

    NASA Astrophysics Data System (ADS)

    Howell, Dale Andrew; Arcavi, Iair; Hosseinzadeh, Griffin; McCully, Curtis; Valenti, Stefano; LCOGT Key Project

    2016-01-01

    The LCOGT Supernova Key Project is a three year project to obtain lightcurves and spectra of 600 supernovae. To do this, it has been awarded 2900 hours per year on the 9 one meter and 2 two meter robotic telescopes of the Las Cumbres Observatory Global Telescope network (LCOGT). At the midway point of the Key Project, it is on track to achieving its goals. I will discuss recent insights into supernova progenitors, exotic individual supernovae, and some of the large samples of supernovae studied by the project.

  20. Radio and optical studies of supernova 1961V in NGC 1058

    NASA Astrophysics Data System (ADS)

    Cowan, John J.; Henry, Richard B. C.; Branch, David

    1988-06-01

    Radio observations of the Sc galaxy NGC 1058 at 20 cm and 6 cm reveal two radio sources. One of the sources is coincident with supernova 1961V and has a spectral index of -0.4 + or - 0.3. This is the second (and probably the third) detection of radio emission from a supernova decades after optical maximum. The absolute luminosity of SN 1961V at 20 cm is comparable to Cas A. A second source, about 2.3 arcsec to the west, has a spectral index of -0.3 + or - 0.3 and is likely to be the remnant of a supernova that was not optically detected. Optical images of NGC 1058 show two faint H II regions associated with the radio sources. Filter photometry in several bands indicates that these two H II regions are normal with respect to the many optically brighter, albeit radio-quiet, H II regions in NGC 1058.

  1. Light-Echo Spectrum Reveals the Type of Tycho Brahe's 1572 Supernova

    NASA Astrophysics Data System (ADS)

    Usuda, T.; Krause, O.; Tanaka, M.; Hattori, T.; Goto, M.; Birkmann, S. M.; Nomoto, K.

    2013-01-01

    We successfully obtained the first optical spectra of the faint light echoes around Cassiopeia A and Tycho Brahe's supernova remnants (SNRs) with FOCAS and the Subaru Telescope. We conclude that Cas A and Tycho's SN 1572 belong to the Type IIb and normal Type Ia supernovae, respectively. Light echo spectra are important in order to obtain further insight into the supernova explosion mechanism of Tycho's SN 1572: how the Type Ia explosion actually proceeds, and whether accretion occurs from a companion or by the merging of two white dwarfs. The proximity of the SN 1572 remnant has allowed detailed studies, such as the possible identification of the binary companion, and provides a unique opportunity to test theories of the explosion mechanism and the nature of the progenitor. Future light-echo spectra, obtained in different spatial directions of SN 1572, will enable to construct a three-dimensional spectroscopic view of the explosion.

  2. An optical and near infrared search for a pulsar in Supernova 1987A

    SciTech Connect

    Sasseen, T.P.

    1990-12-01

    We describe a search for an optical pulsar in the remnant of Supernova 1987A. We have performed over one hundred separate observations of the supernova, covering wavelengths from 3500 angstroms to 1.8 microns, with sensitivity to pulsations as faint as magnitude 22.7. As of September 26, 1990, we have not seen evidence for pulsations due to a pulsar in the supernova. We discuss the implications of this result on predictions of pulsar optical luminosity. We have constructed for the search two photodiode detectors and a data system. We describe their design, calibration and performance. These detectors have allowed us to increase our sensitivity as much as a factor of 5 over standard photomultiplier tubes, and extend this search to near infrared wavelengths. 59 refs., 10 figs., 1 tab.

  3. Radio and optical studies of supernova 1961V in NGC 1058

    SciTech Connect

    Cowan, J.J.; Henry, R.B.C.; Branch, D.

    1988-06-01

    Radio observations of the Sc galaxy NGC 1058 at 20 cm and 6 cm reveal two radio sources. One of the sources is coincident with supernova 1961V and has a spectral index of -0.4 + or - 0.3. This is the second (and probably the third) detection of radio emission from a supernova decades after optical maximum. The absolute luminosity of SN 1961V at 20 cm is comparable to Cas A. A second source, about 2.3 arcsec to the west, has a spectral index of -0.3 + or - 0.3 and is likely to be the remnant of a supernova that was not optically detected. Optical images of NGC 1058 show two faint H II regions associated with the radio sources. Filter photometry in several bands indicates that these two H II regions are normal with respect to the many optically brighter, albeit radio-quiet, H II regions in NGC 1058. 33 references.

  4. Radio and optical studies of supernova 1961V in NGC 1058

    NASA Technical Reports Server (NTRS)

    Cowan, John J.; Henry, Richard B. C.; Branch, David

    1988-01-01

    Radio observations of the Sc galaxy NGC 1058 at 20 cm and 6 cm reveal two radio sources. One of the sources is coincident with supernova 1961V and has a spectral index of -0.4 + or - 0.3. This is the second (and probably the third) detection of radio emission from a supernova decades after optical maximum. The absolute luminosity of SN 1961V at 20 cm is comparable to Cas A. A second source, about 2.3 arcsec to the west, has a spectral index of -0.3 + or - 0.3 and is likely to be the remnant of a supernova that was not optically detected. Optical images of NGC 1058 show two faint H II regions associated with the radio sources. Filter photometry in several bands indicates that these two H II regions are normal with respect to the many optically brighter, albeit radio-quiet, H II regions in NGC 1058.

  5. X-Ray Illumination of the Ejecta of Supernova 1987A

    NASA Technical Reports Server (NTRS)

    Larsson, J.; Fransson, C.; Oestlin, G.; Groeningsson, P.; Jerkstrand, A.; Kozma, C.; Sollerman, J.; Challis, P.; Kirshner, R. P.; Chevalier, R. A.; hide

    2011-01-01

    When a massive star explodes as a supernova, substantial amounts of radioactive elements-primarily Ni-56, Ni-57 and Ti-44 are produced. After the initial from shock heating, the light emitted by the supernova is due to the decay of these elements. However, after decades, the energy powering a supernova remnant comes from the shock interaction between the ejecta and the surrounding medium. The transition to this phase has hitherto not been observed: supernovae occur too infrequently in the Milky Way to provide a young example, and extragalactic supernovae are generally too faint and too small. Here we report observations that show this transition in the supernova SN 1987A in the Large Magellan Cloud. From 1994 to 200l, the ejecta faded owing to radioactive decay of Ti-44 as predicted. Then the flux started to increase, more than doubling by the end of 2009. We show that this increase is the result of heat deposited by X-rays produced as the ejecta interacts with the surrounding material. In time, the X-rays will penetrate farther into the ejects, enabling us to analyse the structure and chemistry of the vanished star.

  6. X-ray illumination of the ejecta of supernova 1987A.

    PubMed

    Larsson, J; Fransson, C; Ostlin, G; Gröningsson, P; Jerkstrand, A; Kozma, C; Sollerman, J; Challis, P; Kirshner, R P; Chevalier, R A; Heng, K; McCray, R; Suntzeff, N B; Bouchet, P; Crotts, A; Danziger, J; Dwek, E; France, K; Garnavich, P M; Lawrence, S S; Leibundgut, B; Lundqvist, P; Panagia, N; Pun, C S J; Smith, N; Sonneborn, G; Wang, L; Wheeler, J C

    2011-06-08

    When a massive star explodes as a supernova, substantial amounts of radioactive elements--primarily (56)Ni, (57)Ni and (44)Ti--are produced. After the initial flash of light from shock heating, the fading light emitted by the supernova is due to the decay of these elements. However, after decades, the energy powering a supernova remnant comes from the shock interaction between the ejecta and the surrounding medium. The transition to this phase has hitherto not been observed: supernovae occur too infrequently in the Milky Way to provide a young example, and extragalactic supernovae are generally too faint and too small. Here we report observations that show this transition in the supernova SN 1987A in the Large Magellanic Cloud. From 1994 to 2001, the ejecta faded owing to radioactive decay of (44)Ti as predicted. Then the flux started to increase, more than doubling by the end of 2009. We show that this increase is the result of heat deposited by X-rays produced as the ejecta interacts with the surrounding material. In time, the X-rays will penetrate farther into the ejecta, enabling us to analyse the structure and chemistry of the vanished star.

  7. Bolometric Light Curves of Peculiar Type II-P Supernovae

    NASA Astrophysics Data System (ADS)

    Lusk, Jeremy A.; Baron, E.

    2017-04-01

    We examine the bolometric light curves of five Type II-P supernovae (SNe 1998A, 2000cb, 2006V, 2006au, and 2009E), which are thought to originate from blue supergiant progenitors like that of SN 1987A, using a new python package named SuperBoL. With this code, we calculate SNe light curves using three different common techniques common from the literature: the quasi-bolometric method, which integrates the observed photometry, the direct integration method, which additionally corrects for unobserved flux in the UV and IR, and the bolometric correction method, which uses correlations between observed colors and V-band bolometric corrections. We present here the light curves calculated by SuperBoL, along with previously published light curves, as well as peak luminosities and 56Ni yields. We find that the direct integration and bolometric correction light curves largely agree with previously published light curves, but with what we believe to be more robust error calculations, with 0.2≲ δ {L}{bol}/{L}{bol}≲ 0.5. Peak luminosities and 56Ni masses are similarly comparable to previous work. SN 2000cb remains an unusual member of this sub-group, owing to the faster rise and flatter plateau than the other supernovae in the sample. Initial comparisons with the NLTE atmosphere code PHOENIX show that the direct integration technique reproduces the luminosity of a model supernova spectrum to ∼5% when given synthetic photometry of the spectrum as input. Our code is publicly available. The ability to produce bolometric light curves from observed sets of broadband light curves should be helpful in the interpretation of other types of supernovae, particularly those that are not well characterized, such as extremely luminous supernovae and faint fast objects.

  8. Bolometric Lightcurves of Peculiar Type II-P Supernovae

    NASA Astrophysics Data System (ADS)

    Lusk, Jeremy A.; Baron, Edward A.

    2017-01-01

    We examine the bolometric lightcurves of five Type II-P supernovae (SNe 1998A, 2000cb, 2006V, 2006au and 2009E) which are thought to originate from blue supergiant progenitors using a new python package named SuperBoL. With this code, we calculate SNe lightcurves using three different techniques common in the literature: the quasi-bolometric method, which integrates the observed photometry, the direct integration method, which additionally corrects for unobserved flux in the UV and IR, and the bolometric correction method, which uses correlations between observed colors and V-band bolometric corrections. We present here the lightcurves calculated by SuperBoL along with previously published lightcurves, as well as peak luminosities and 56Ni yields. We find that the direct integration and bolometric correction lightcurves largely agree with previously published lightcurves, but with what we believe to be more robust error calculations, with 0.2 ≤ δL/L ≤ 0.5. Peak luminosities and 56Ni masses are similarly comparable to previous work. SN 2000cb remains an unusual member of this sub-group, owing to the faster rise and flatter plateau than the other supernovae in the sample. Initial comparisons with the NLTE atmosphere code PHOENIX show that the direct integration technique reproduces the luminosity of a model supernova spectrum to ˜5% when given synthetic photometry of the spectrum as input. Our code is publicly available. The ability to produce bolometric lightcurves from observed sets of broad-band light curves should be helpful in the interpretation of other types of supernovae, particularly those that are not well characterized, such as extremely luminous supernovae and faint fast objects.

  9. Supernova and cosmic rays

    NASA Technical Reports Server (NTRS)

    Wefel, J. P.

    1981-01-01

    A general overview of supernova astronomy is presented, followed by a discussion of the relationship between SN and galactic cosmic rays. Pre-supernova evolution is traced to core collapse, explosion, and mass ejection. The two types of SN light curves are discussed in terms of their causes, and the different nucleosynthetic processes inside SNs are reviewed. Physical events in SN remnants are discussed. The three main connections between cosmic rays and SNs, the energy requirement, the acceleration mechanism, and the detailed composition of CR, are detailed.

  10. What Shapes Supernova Remnants?

    NASA Astrophysics Data System (ADS)

    Lopez, Laura A.

    2014-01-01

    Evidence has mounted that Type Ia and core-collapse (CC) supernovae (SNe) can have substantial deviations from spherical symmetry; one such piece of evidence is the complex morphologies of supernova remnants (SNRs). However, the relative role of the explosion geometry and the environment in shaping SNRs remains an outstanding question. Recently, we have developed techniques to quantify the morphologies of SNRs, and we have applied these methods to the extensive X-ray and infrared archival images available of Milky Way and Magellanic Cloud SNRs. In this proceeding, we highlight some results from these studies, with particular emphasis on SNR asymmetries and whether they arise from ``nature'' or ``nurture''.

  11. Demonstrating Supernova Remnant Evolution

    NASA Astrophysics Data System (ADS)

    Leahy, Denis A.; Williams, Jacqueline

    2017-01-01

    We have created a software tool to calculate at display supernova remnant evolution which includes all stages from early ejecta dominated phase to late-time merging with the interstellar medium. The software was created using Python, and can be distributed as Python code, or as an executable file. The purpose of the software is to demonstrate the different phases and transitions that a supernova remnant undergoes, and will be used in upper level undergraduate astrophysics courses as a teaching tool. The usage of the software and its graphical user interface will be demonstrated.

  12. The WFIRST Supernova Survey

    NASA Astrophysics Data System (ADS)

    Foley, Ryan J.; Hounsell, Rebekah; Scolnic, Daniel; WFIRST Supernova Science Investigation Team

    2017-01-01

    WFRIST is expected to launch in the mid 2020s. As part of its main mission, it will conduct a survey to measure the Universe's cosmic expansion history with supernovae. I will present the first simulations of this survey. The simulations take into account our current knowledge of the hardware, realistic properties of the supernovae, and our understanding of the relevant systematic uncertainties. I will compare the ultimate dark enegery figures of merit derived from the simulations and discuss future plans. These data will be extremely useful for other science; other transient science and studies of the resulting deep static images will particularly benefit.

  13. Supernova remnant morphology

    NASA Astrophysics Data System (ADS)

    Manchester, R. N.

    1994-04-01

    The morphology of supernova remnants is principally determined by two components, a shell formed by interaction of the supernova ejecta with the surrounding medium, and a nebula which is powered directly by the associated pulsar. This nebula, often called a 'plerion', is usually located within the shell. These two components appear to evolve independently; in many cases there is no detectable plerion and in a few cases, the Crab Nebula being the most notable example, there is no detectable shell. A 'theoretician's supernova remnant' has spherical symmetry, but observers know that this is rarely the case. There are four main possible sources of non-sphericity, namely, the surrounding interstellar medium, the circumstellar medium, the surpernova explosion, and the associated pulsar. Supernovae often occured in active star formation regions and these regions often have complex networks of cavities blown by strong stellar winds. A supernova remnant expanding in this environment can consist of a several shell-like structure. IC443 is a good example (Braun and Strom, 1986, Astron. Astrophys., 1264, 193). The enhancement of Supernova remnant (SNR) shell brightness toward the Galactic plane (Caswell, 1977, Proc. Astron. Soc. Aust., 3, 130) is further evidence of the influence of the large-scale structure of the interstellar medium. One of the most common forms of non-sphericity is a bilateral symmetry attributed to a barrel-shaped enhancement of the shell (Kesteven and Caswell, 1987, Astron. Astrophys., 183, 118). There is good evidence that this and the associated bi-annular structure often obseved (Manchester, 1987, Astron. Astrophys., 171, 205) ar due to structure in the circumstellar material resulting from mass loss from the pre-supernova star (Storey et al., 1992, Astron. Astrophys., 265, 752). supernova remants (e.g., Tuohy, Clark and Burton, 1982, Astrophys. &J., 260, L65) are evidence that

  14. Supernova 1987A

    NASA Technical Reports Server (NTRS)

    Mccray, Richard; Li, Hong Wei

    1988-01-01

    Supernova 1987A (February 23, 1987) in the Large Magellanic Cloud is the brightest supernova to be observed since SN 1604 AD (Kepler). Detection of a burst of neutrinos indicates that a neutron star was formed. Radioactive decay of about 0.07 solar mass of Co-56 is responsible for the observed optical light as well as hard X-rays and gamma-ray lines. Ultraviolet, optical, and infrared 'light echoes' and soft X-rays provide information on the distribution of circumstellar matter and the evolution of the progenitor star.

  15. Supernova science with LCOGT

    NASA Astrophysics Data System (ADS)

    Howell, Dale A.; Valenti, S.; Sand, D. J.; Parrent, J. T.; Arcavi, I.; Graham, M. L.

    2014-01-01

    Las Cumbres Observatory Global Telescope Network (LCOGT.net) is a collection of nine robotic one meter telescopes with imagers spaced around the world in longitude, operated as a single network. There are also two robotic FLOYDS spectrographs on the two meter Faulkes telescopes in Siding Spring, Australia, and Haleakala, Hawaii. Here we describe recent supernova lightcurves and spectra with taken with LCOGT after being triggered from Pan-STARRS1, the La Silla-QUEST survey, the intermediate Palomar Transient Factory, and the IAU circulars. Since at least one telescope is always in the dark, and the facilities are robotic, LCOGT is uniquely suited to early-time supernova science.

  16. Supernova 1987A

    NASA Technical Reports Server (NTRS)

    Mccray, Richard; Li, Hong Wei

    1988-01-01

    Supernova 1987A (February 23, 1987) in the Large Magellanic Cloud is the brightest supernova to be observed since SN 1604 AD (Kepler). Detection of a burst of neutrinos indicates that a neutron star was formed. Radioactive decay of about 0.07 solar mass of Co-56 is responsible for the observed optical light as well as hard X-rays and gamma-ray lines. Ultraviolet, optical, and infrared 'light echoes' and soft X-rays provide information on the distribution of circumstellar matter and the evolution of the progenitor star.

  17. HST observations of faint Cold Classical KBOs

    NASA Astrophysics Data System (ADS)

    Penteado, Paulo F.; Trilling, David E.; Grundy, Will

    2016-10-01

    The size distribution of the known Kuiper Belt Objects has been described by a double power law, with a break at R magnitude 25. There are two leading interpretations to this break: 1) It is the result of the collisional evolution, with the objects smaller than the break being the population most affected by collisional erosion. 2) The size distribution break is primordial, set during the Kuiper Belt formation.The low inclination KBOs, the Cold Classical population, is thought to have been dynamically isolated since the formation of the Solar System, and thus only collisions between Cold Classicals would have affected their size distribution. If the distribution is collisional, it probes parameters of the Kuiper Belt history: strengths of the bodies, impact energies and frequency, and the the number of objects. If the distribution is primordial, it reveals parameters of the Kuiper Belt accretion, as well as limits on its subsequent collisional history.We obtained HST observations of 16 faint Cold Classicals, which we combine with archival HST observations of 20 others, to examine the distribution of two properties of the smallest KBOs: colors and binary fraction. These properties can differentiate between a primordial and a collisional origin of the size distribution break. If the smaller bodies have been through extensive collisional evolution, they will have exposed materials from their interiors, which has not been exposed to weathering, and thus should be bluer than the old surfaces of the larger bodies. Another constraint can be derived from the fraction of binary objects: the angular momentum of the observed binaries is typically too high to result from collisions, thus a collisionally-evolved population would have a lower binary fraction, due to the easier separation of binaries, compared to the disruption of similar-sized bodies, and the easier disruption of the binary components, due to the smaller size.We present the constraints to the color and binary

  18. The Intensity Distribution of Faint Gamma-Ray Bursts Detected with BATSE

    NASA Technical Reports Server (NTRS)

    Kommers, Jefferson M.; Lewin, Walter H. G.; Kouveliotou, Chryssa; vanParadus, Jan; Pendleton, Geoffrey N.; Meegan, Charles A.; Fishman, Gerald J.

    2000-01-01

    We have recently completed a search of six years of archival Burst and Transient Source Experiment (BATSE) data for gamma-ray bursts (GRBs) that were too faint to activate the real-time burst detection system running on board the spacecraft. These 'nontriggered' bursts can be combined with the 'triggered' bursts detected on board to produce a GRB intensity distribution that reaches peak fluxes a factor of approximately two lower than could be studied previously. The value of the statistic (in Euclidean space) for the bursts we detect is 0.177 +/- 0.006. This surprisingly low value is obtained because we detected very few bursts on the 4.096 s and 8.192 s timescales (where most bursts have their highest signal-to-noise ratio) that were not already detected on the 1.024 s timescale. If allowance is made for a power-law distribution of intrinsic peak luminosities, the extended peak flux distribution is consistent with models in which the redshift distribution of the gamma-ray burst rate approximately traces the star formation history of the universe. We argue that this class of models is preferred over those in which the burst rate is independent of redshift. We use the peak flux distribution to derive a limit of 10% (99% confidence) on the fraction of the total burst rate that could be contributed by a spatially homogeneous (in Euclidean space) subpopulation of burst sources, such as type Ib/c supernovae. These results lend support to the conclusions of previous studies predicting that relatively few faint 'classical' GRBs will be found below the BATSE onboard detection threshold.

  19. The Intensity Distribution of Faint Gamma-Ray Bursts Detected with BATSE

    NASA Technical Reports Server (NTRS)

    Kommers, Jefferson M.; Lewin, Walter H. G.; Kouveliotou, Chryssa; VanParadijs, Jan; Pendleton, Geoffrey N.; Meegan, Charles A.; Fishman, Gerald J.

    2000-01-01

    We have recently completed a search of 6 years of archival BATSE data for gamma-ray bursts (GRBS) that were too faint to activate the real-time burst detection system running on board the spacecraft. These "nontriggered" bursts can be combined with the "triggered" bursts detected on board to produce a GRB intensity distribution that reaches peak fluxes a factor of approximately 2 lower than could be studied previously. The value of the statistic (in Euclidean space) for the bursts we detect is 0.177 plus or minus 0.006. This surprisingly low value is obtained because we detected very few bursts on the 4.096 s and 8.192 s timescales (where most bursts have their highest signal-to-noise ratio) that were not already detected on the 1.024 s timescale. If allowance is made for a power-law distribution of intrinsic peak luminosities, the extended peak flux distribution is consistent with models in which the redshift distribution of the gamma-ray burst rate approximately traces the star formation history of the universe. We argue that this class of models is preferred over those in which the burst rate is independent of redshift. We use the peak flux distribution to derive a limit of 10% (99% confidence) on the fraction of the total burst rate that could be contributed by a spatially homogeneous (in Euclidean space) subpopulation of burst sources, such as type lb/c supernovae. These results lend support to the conclusions of previous studies predicting that relatively few faint "classical" GRBs will be found below the BATSE onboard detection threshold.

  20. Supernova Explosions of Super-asymptotic Giant Branch Stars: Multicolor Light Curves of Electron-capture Supernovae

    NASA Astrophysics Data System (ADS)

    Tominaga, Nozomu; Blinnikov, Sergei I.; Nomoto, Ken'ichi

    2013-07-01

    An electron-capture supernova (ECSN) is a core-collapse supernova (CCSN) explosion of a super-asymptotic giant branch (SAGB) star with a main-sequence mass M MS ~ 7-9.5 M ⊙. The explosion takes place in accordance with core bounce and subsequent neutrino heating and is a unique example successfully produced by first-principle simulations. This allows us to derive a first self-consistent multicolor light curve of a CCSN. Adopting the explosion properties derived by the first-principle simulation, i.e., the low explosion energy of 1.5 × 1050 erg and the small 56Ni mass of 2.5 × 10-3 M ⊙, we perform a multi-group radiation hydrodynamics calculation of ECSNe and present multicolor light curves of ECSNe of SAGB stars with various envelope masses and hydrogen abundances. We demonstrate that a shock breakout has a peak luminosity of L ~ 2 × 1044 erg s-1 and can evaporate circumstellar dust up to R ~ 1017 cm for the case of carbon dust, that the plateau luminosity and plateau duration of ECSNe are L ~ 1042 erg s-1 and t ~ 60-100 days, respectively, and that a plateau is followed by a tail with a luminosity drop by ~4 mag. The ECSN shows a bright and short plateau that is as bright as typical Type II plateau supernovae, and a faint tail that might be influenced by the spin-down luminosity of a newborn pulsar. Furthermore, the theoretical models are compared with ECSN candidates: SN 1054 and SN 2008S. We find that SN 1054 shares the characteristics of the ECSNe. For SN 2008S, we find that its faint plateau requires an ECSN model with a significantly low explosion energy of E ~ 1048 erg.

  1. Theoretical models for supernovae

    SciTech Connect

    Woosley, S.E.; Weaver, T.A.

    1981-09-21

    The results of recent numerical simulations of supernova explosions are presented and a variety of topics discussed. Particular emphasis is given to (i) the nucleosynthesis expected from intermediate mass (10sub solar less than or equal to M less than or equal to 100 Msub solar) Type II supernovae and detonating white dwarf models for Type I supernovae, (ii) a realistic estimate of the ..gamma..-line fluxes expected from this nucleosynthesis, (iii) the continued evolution, in one and two dimensions, of intermediate mass stars wherein iron core collapse does not lead to a strong, mass-ejecting shock wave, and (iv) the evolution and explosion of vary massive stars (M greater than or equal to 100 Msub solar of both Population I and III. In one dimension, nuclear burning following a failed core bounce does not appear likely to lead to a supernova explosion although, in two dimensions, a combination of rotation and nuclear burning may do so. Near solar proportions of elements from neon to calcium and very brilliant optical displays may be created by hypernovae, the explosions of stars in the mass range 100 M/sub solar/ to 300 M/sub solar/. Above approx. 300 M/sub solar/ a black hole is created by stellar collapse following carbon ignition. Still more massive stars may be copious producers of /sup 4/He and /sup 14/N prior to their collapse on the pair instability.

  2. Core-collapse Supernovae

    SciTech Connect

    Hix, William Raphael; Lentz, E. J.; Baird, Mark L; Chertkow, Merek A; Lee, Ching-Tsai; Blondin, J. M.; Bruenn, S. W.; Messer, Bronson; Mezzacappa, Anthony

    2013-01-01

    Marking the inevitable death of a massive star, and the birth of a neutron star or black hole, core-collapse supernovae bring together physics at a wide range in spatial scales, from kilometer-sized hydrodynamic motions (growing to gigameter scale) down to femtometer scale nuclear reactions. Carrying 10$^{51}$ ergs of kinetic energy and a rich-mix of newly synthesized atomic nuclei, core-collapse supernovae are the preeminent foundries of the nuclear species which make up ourselves and our solar system. We will discuss our emerging understanding of the convectively unstable, neutrino-driven explosion mechanism, based on increasingly realistic neutrino-radiation hydrodynamic simulations that include progressively better nuclear and particle physics. Recent multi-dimensional models with spectral neutrino transport from several research groups, which slowly develop successful explosions for a range of progenitors, have motivated changes in our understanding of the neutrino reheating mechanism. In a similar fashion, improvements in nuclear physics, most notably explorations of weak interactions on nuclei and the nuclear equation of state, continue to refine our understanding of how supernovae explode. Recent progress on both the macroscopic and microscopic effects that affect core-collapse supernovae are discussed.

  3. QCD and Supernovas

    NASA Astrophysics Data System (ADS)

    Barnes, T.

    2005-12-01

    In this contribution we briefly summarize aspects of the physics of QCD which are relevant to the supernova problem. The topic of greatest importance is the equation of state (EOS) of nuclear and strongly-interacting matter, which is required to describe the physics of the proto-neutron star (PNS) and the neutron star remnant (NSR) formed during a supernova event. Evaluation of the EOS in the regime of relevance for these systems, especially the NSR, requires detailed knowledge of the spectrum and strong interactions of hadrons of the accessible hadronic species, as well as other possible phases of strongly interacting matter, such as the quark-gluon plasma (QGP). The forces between pairs of baryons (both nonstrange and strange) are especially important in determining the EOS at NSR densities. Predictions for these forces are unfortunately rather model dependent where not constrained by data, and there are several suggestions for the QCD mechanism underlying these short-range hadronic interactions. The models most often employed for determining these strong interactions are broadly of two types, 1) meson exchange models (usually assumed in the existing neutron star and supernova literature), and 2) quark-gluon models (mainly encountered in the hadron, nuclear and heavy-ion literature). Here we will discuss the assumptions made in these models, and discuss how they are applied to the determination of hadronic forces that are relevant to the supernova problem.

  4. Supernova Photometric Lightcurve Classification

    NASA Astrophysics Data System (ADS)

    Zaidi, Tayeb; Narayan, Gautham

    2016-01-01

    This is a preliminary report on photometric supernova classification. We first explore the properties of supernova light curves, and attempt to restructure the unevenly sampled and sparse data from assorted datasets to allow for processing and classification. The data was primarily drawn from the Dark Energy Survey (DES) simulated data, created for the Supernova Photometric Classification Challenge. This poster shows a method for producing a non-parametric representation of the light curve data, and applying a Random Forest classifier algorithm to distinguish between supernovae types. We examine the impact of Principal Component Analysis to reduce the dimensionality of the dataset, for future classification work. The classification code will be used in a stage of the ANTARES pipeline, created for use on the Large Synoptic Survey Telescope alert data and other wide-field surveys. The final figure-of-merit for the DES data in the r band was 60% for binary classification (Type I vs II).Zaidi was supported by the NOAO/KPNO Research Experiences for Undergraduates (REU) Program which is funded by the National Science Foundation Research Experiences for Undergraduates Program (AST-1262829).

  5. Supernova Confetti in Meteorites

    NASA Astrophysics Data System (ADS)

    Taylor, G. J.

    2010-11-01

    Chromium has four isotopes, with atomic weights of 50, 52, 53, and 54. In terrestrial rocks the isotopes behave in predictable ways, with their variations in relative abundance governed by geochemical processes. In contrast, some meteorites have deviant abundances of the heaviest (hence the one with the most neutrons) Cr isotope, chromium-54. These anomalies in isotopic composition are almost certainly caused by nuclear reactions in stars that existed before our Sun was formed. However, the mineralogical carrier of the special chromium-54 was not known until Nicolas Dauphas (University of Chicago) and eight colleagues there and at the California Institute of Technology, the Museum National d'Histoire Naturelle in Paris, the Jet Propulsion Laboratory, and the Universite de Lille (France) made detailed analyses of chemical and physical separates from the Orgueil and Murchison carbonaceous chondrites. They found that the carrier of the isotopically-anomalous Cr is spinel, Cr-bearing oxide grains generally smaller than 100 nanometers. Only supernovae can produce the chromium-54 anomalies, although which specific type of supernova is not clear. An intriguing possibility is that the chromium-54-rich nano-oxide particles were produced in the same supernova that made two other short-lived isotopes, iron-60 and aluminum-26, which also existed in the Solar System when it formed. This suggests that formation of the Solar System was triggered by a supernova explosion.

  6. A Supernova Shockwaves

    NASA Image and Video Library

    2007-06-13

    Supernovae are the explosive deaths of the universe most massive stars. This false-color composite from NASA Spitzer Space Telescope and NASA Chandra X-ray Observatory shows the remnant of N132D, the wispy pink shell of gas at center.

  7. Three Great Eyes on Kepler Supernova Remnant

    NASA Image and Video Library

    2004-10-06

    blue) is locatedprimarily in the regions directly behind the shock front. These regions alsoshow up in the Hubble observations, and also align with the faint rim of glowingmaterial seen in the Spitzer data. The X-rays from the region on the lower left(colored blue) may be dominated by extremely high-energy electrons that wereproduced by the shock wave and are radiating at radio through X-ray wavelengthsas they spiral in the intensified magnetic field behind the shock front. CoolerX-ray gas (lower-energy X-rays, colored green) resides in a thick interior shelland marks the location of heated material expelled from the exploded star. Kepler's supernova, the last such object seen to explode in our Milky Waygalaxy, resides about 13,000 light-years away in the constellation Ophiuchus. The Chandra observations were taken in June 2000, the Hubble in August 2003;and the Spitzer in August 2004. http://photojournal.jpl.nasa.gov/catalog/PIA06907

  8. The Distribution of Alpha Elements in Ultra-faint Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Vargas, Luis C.; Geha, Marla; Kirby, Evan N.; Simon, Joshua D.

    2013-04-01

    The Milky Way ultra-faint dwarf (UFD) galaxies contain some of the oldest, most metal-poor stars in the universe. We present [Mg/Fe], [Si/Fe], [Ca/Fe], [Ti/Fe], and mean [α/Fe] abundance ratios for 61 individual red giant branch stars across eight UFDs. This is the largest sample of alpha abundances published to date in galaxies with absolute magnitudes MV > -8, including the first measurements for Segue 1, Canes Venatici II, Ursa Major I, and Leo T. Abundances were determined via medium-resolution Keck/DEIMOS spectroscopy and spectral synthesis. The sample spans the metallicity range -3.4 <[Fe/H] < -1.1. With the possible exception of Segue 1 and Ursa Major II, the individual UFDs show on average lower [α/Fe] at higher metallicities, consistent with enrichment from Type Ia supernovae. Thus, even the faintest galaxies have undergone at least a limited level of chemical self-enrichment. Together with recent photometric studies, this suggests that star formation in the UFDs was not a single burst, but instead lasted at least as much as the minimum time delay of the onset of Type Ia supernovae (~100 Myr) and less than ~2 Gyr. We further show that the combined population of UFDs has an [α/Fe] abundance pattern that is inconsistent with a flat, Galactic halo-like alpha abundance trend, and is also qualitatively different from that of the more luminous CVn I dSph, which does show a hint of a plateau at very low [Fe/H].

  9. THE DISTRIBUTION OF ALPHA ELEMENTS IN ULTRA-FAINT DWARF GALAXIES

    SciTech Connect

    Vargas, Luis C.; Geha, Marla; Kirby, Evan N.; Simon, Joshua D.

    2013-04-20

    The Milky Way ultra-faint dwarf (UFD) galaxies contain some of the oldest, most metal-poor stars in the universe. We present [Mg/Fe], [Si/Fe], [Ca/Fe], [Ti/Fe], and mean [{alpha}/Fe] abundance ratios for 61 individual red giant branch stars across eight UFDs. This is the largest sample of alpha abundances published to date in galaxies with absolute magnitudes M{sub V} > -8, including the first measurements for Segue 1, Canes Venatici II, Ursa Major I, and Leo T. Abundances were determined via medium-resolution Keck/DEIMOS spectroscopy and spectral synthesis. The sample spans the metallicity range -3.4 <[Fe/H] < -1.1. With the possible exception of Segue 1 and Ursa Major II, the individual UFDs show on average lower [{alpha}/Fe] at higher metallicities, consistent with enrichment from Type Ia supernovae. Thus, even the faintest galaxies have undergone at least a limited level of chemical self-enrichment. Together with recent photometric studies, this suggests that star formation in the UFDs was not a single burst, but instead lasted at least as much as the minimum time delay of the onset of Type Ia supernovae ({approx}100 Myr) and less than {approx}2 Gyr. We further show that the combined population of UFDs has an [{alpha}/Fe] abundance pattern that is inconsistent with a flat, Galactic halo-like alpha abundance trend, and is also qualitatively different from that of the more luminous CVn I dSph, which does show a hint of a plateau at very low [Fe/H].

  10. The faint galaxy contribution to the diffuse extragalactic background light

    NASA Technical Reports Server (NTRS)

    Cole, Shaun; Treyer, Marie-Agnes; Silk, Joseph

    1992-01-01

    Models of the faint galaxy contribution to the diffuse extragalactic background light are presented, which are consistent with current data on faint galaxy number counts and redshifts. The autocorrelation function of surface brightness fluctuations in the extragalactic diffuse light is predicted, and the way in which these predictions depend on the cosmological model and assumptions of biasing is determined. It is confirmed that the recent deep infrared number counts are most compatible with a high density universe (Omega-0 is approximately equal to 1) and that the steep blue counts then require an extra population of rapidly evolving blue galaxies. The faintest presently detectable galaxies produce an interesting contribution to the extragalactic diffuse light, and still fainter galaxies may also produce a significant contribution. These faint galaxies still only produce a small fraction of the total optical diffuse background light, but on scales of a few arcminutes to a few degrees, they produce a substantial fraction of the fluctuations in the diffuse light.

  11. Enhanced faint companion photometry and astrometry using wavelength diversity.

    PubMed

    Burke, Daniel; Devaney, Nicholas

    2010-11-01

    In this paper we examine approaches to faint companion detection and estimation in multi-spectral images. We will employ the Hotelling observer, which is the optimal linear algorithm for signal detection. We have shown how to use this observer to estimate faint object position and brightness in the presence of residual speckle, which usually limits astrometric and photometric techniques. These speckles can be reduced by differential imaging techniques such as Angular Differential Imaging and Spectral Differential Imaging. Here we present results based on simulations of adaptive-optics-corrected images from an Extremely Large Telescope (ELT) that contain quasi-static speckle noise. The simulation includes Angular Differential Imaging and Spectral Differential Imaging to reduce the residual speckle and subsequent multi-wavelength processing. We examine the feasibility of this approach on simulated ELT observations of faint companions.

  12. The nature of faint emission-line galaxies

    NASA Technical Reports Server (NTRS)

    Smetanka, John J.

    1993-01-01

    One of the results of faint galaxy redshift surveys is the increased fraction of galaxies which have strong emission-line spectra. These faint surveys find that roughly 50 percent of the galaxies have an equivalent width of (OII), W sub 3727, greater than 20 A while this fraction is less than 20 percent in the DARS survey. This has been interpreted as evidence for strong evolution in the galaxy population at redshifts less than 0.5. In order to further investigate the properties of the galaxies in faint redshift surveys, two important factors must be addressed. The first is the observed correlation between color, luminosity, and W sub 3727. There is a correlation between color and the strength of emission lines, bluer galaxies having stronger emission features, as evident for Markarian galaxies and for galaxies in Kennicutt's spectrophotometric atlas. This correlation also applies galaxies in faint redshift surveys. In addition, low luminosity galaxies have a larger average W sub 3727 (and bluer colors) than higher luminosity galaxies. This is illustrated for Kennicutt's low z late-type galaxies, for the Durham Faint Surveys, and for galaxies in SA68. The second factor which must be incorporated into any interpretation of the faint emission galaxies is the different luminosity functions for galaxies depending on color. This is usually modeled by varying M* for different color classes (or morphological types); however, the shape of the luminosity function is different for galaxies with different colors. Low luminosity, blue galaxies have a much larger number density than low luminosity, red galaxies. Furthermore, the low luminosity end of the blue galaxy luminosity function is not well fit by a Schechter function. These two factors have been included in a very simple, no-evolution, model for the galaxy population. This model uses the luminosity functions from Shanks (1990) and spectral energy distributions (SED's) from Bruzual (1988). W sub 3727 is predicted using

  13. Host Galaxy Identification for Supernova Surveys

    SciTech Connect

    Gupta, Ravi R.; Kuhlmann, Steve; Kovacs, Eve; Spinka, Harold; Kessler, Richard; Goldstein, Daniel A.; Liotine, Camille; Pomian, Katarzyna; D’Andrea, Chris B.; Sullivan, Mark; Carretero, Jorge; Castander, Francisco J.; Nichol, Robert C.; Finley, David A.; Fischer, John A.; Foley, Ryan J.; Kim, Alex G.; Papadopoulos, Andreas; Sako, Masao; Scolnic, Daniel M.; Smith, Mathew; Tucker, Brad E.; Uddin, Syed; Wolf, Rachel C.; Yuan, Fang; Abbott, Tim M. C.; Abdalla, Filipe B.; Benoit-Lévy, Aurélien; Bertin, Emmanuel; Brooks, David; Rosell, Aurelio Carnero; Kind, Matias Carrasco; Cunha, Carlos E.; Costa, Luiz N. da; Desai, Shantanu; Doel, Peter; Eifler, Tim F.; Evrard, August E.; Flaugher, Brenna; Fosalba, Pablo; Gaztañaga, Enrique; Gruen, Daniel; Gruendl, Robert; James, David J.; Kuehn, Kyler; Kuropatkin, Nikolay; Maia, Marcio A. G.; Marshall, Jennifer L.; Miquel, Ramon; Plazas, Andrés A.; Romer, A. Kathy; Sánchez, Eusebio; Schubnell, Michael; Sevilla-Noarbe, Ignacio; Sobreira, Flávia; Suchyta, Eric; Swanson, Molly E. C.; Tarle, Gregory; Walker, Alistair R.; Wester, William

    2016-11-08

    Host galaxy identification is a crucial step for modern supernova (SN) surveys such as the Dark Energy Survey (DES) and the Large Synoptic Survey Telescope (LSST), which will discover SNe by the thousands. Spectroscopic resources are limited, so in the absence of real-time SN spectra these surveys must rely on host galaxy spectra to obtain accurate redshifts for the Hubble diagram and to improve photometric classification of SNe. In addition, SN luminosities are known to correlate with host-galaxy properties. Therefore, reliable identification of host galaxies is essential for cosmology and SN science. We simulate SN events and their locations within their host galaxies to develop and test methods for matching SNe to their hosts. We use both real and simulated galaxy catalog data from the Advanced Camera for Surveys General Catalog and MICECATv2.0, respectively. We also incorporate "hostless" SNe residing in undetected faint hosts into our analysis, with an assumed hostless rate of 5%. Our fully automated algorithm is run on catalog data and matches SNe to their hosts with 91% accuracy. We find that including a machine learning component, run after the initial matching algorithm, improves the accuracy (purity) of the matching to 97% with a 2% cost in efficiency (true positive rate). Although the exact results are dependent on the details of the survey and the galaxy catalogs used, the method of identifying host galaxies we outline here can be applied to any transient survey.

  14. Host galaxy identification for supernova surveys

    SciTech Connect

    Gupta, Ravi R.; Kuhlmann, Steve; Kovacs, Eve; Spinka, Harold; Kessler, Richard; Goldstein, Daniel A.; Liotine, Camille; Pomian, Katarzyna; D’Andrea, Chris B.; Sullivan, Mark; Carretero, Jorge; Castander, Francisco J.; Nichol, Robert C.; Finley, David A.; Fischer, John A.; Foley, Ryan J.; Kim, Alex G.; Papadopoulos, Andreas; Sako, Masao; Scolnic, Daniel M.; Smith, Mathew; Tucker, Brad E.; Uddin, Syed; Wolf, Rachel C.; Yuan, Fang; Abbott, Tim M. C.; Abdalla, Filipe B.; Benoit-Lévy, Aurélien; Bertin, Emmanuel; Brooks, David; Rosell, Aurelio Carnero; Kind, Matias Carrasco; Cunha, Carlos E.; Costa, Luiz N. da; Desai, Shantanu; Doel, Peter; Eifler, Tim F.; Evrard, August E.; Flaugher, Brenna; Fosalba, Pablo; Gaztañaga, Enrique; Gruen, Daniel; Gruendl, Robert; James, David J.; Kuehn, Kyler; Kuropatkin, Nikolay; Maia, Marcio A. G.; Marshall, Jennifer L.; Miquel, Ramon; Plazas, Andrés A.; Romer, A. Kathy; Sánchez, Eusebio; Schubnell, Michael; Sevilla-Noarbe, Ignacio; Sobreira, Flávia; Suchyta, Eric; Swanson, Molly E. C.; Tarle, Gregory; Walker, Alistair R.; Wester, William

    2016-11-10

    Host galaxy identification is a crucial step for modern supernova (SN) surveys such as the Dark Energy Survey and the Large Synoptic Survey Telescope, which will discover SNe by the thousands. Spectroscopic resources are limited, and so in the absence of real-time SN spectra these surveys must rely on host galaxy spectra to obtain accurate redshifts for the Hubble diagram and to improve photometric classification of SNe. In addition, SN luminosities are known to correlate with host-galaxy properties. Therefore, reliable identification of host galaxies is essential for cosmology and SN science. We simulate SN events and their locations within their host galaxies to develop and test methods for matching SNe to their hosts. We use both real and simulated galaxy catalog data from the Advanced Camera for Surveys General Catalog and MICECATv2.0, respectively. We also incorporate "hostless" SNe residing in undetected faint hosts into our analysis, with an assumed hostless rate of 5%. Our fully automated algorithm is run on catalog data and matches SNe to their hosts with 91% accuracy. Here, we find that including a machine learning component, run after the initial matching algorithm, improves the accuracy (purity) of the matching to 97% with a 2% cost in efficiency (true positive rate). Although the exact results are dependent on the details of the survey and the galaxy catalogs used, the method of identifying host galaxies we outline here can be applied to any transient survey.

  15. Host galaxy identification for supernova surveys

    DOE PAGES

    Gupta, Ravi R.; Kuhlmann, Steve; Kovacs, Eve; ...

    2016-11-10

    Host galaxy identification is a crucial step for modern supernova (SN) surveys such as the Dark Energy Survey and the Large Synoptic Survey Telescope, which will discover SNe by the thousands. Spectroscopic resources are limited, and so in the absence of real-time SN spectra these surveys must rely on host galaxy spectra to obtain accurate redshifts for the Hubble diagram and to improve photometric classification of SNe. In addition, SN luminosities are known to correlate with host-galaxy properties. Therefore, reliable identification of host galaxies is essential for cosmology and SN science. We simulate SN events and their locations within theirmore » host galaxies to develop and test methods for matching SNe to their hosts. We use both real and simulated galaxy catalog data from the Advanced Camera for Surveys General Catalog and MICECATv2.0, respectively. We also incorporate "hostless" SNe residing in undetected faint hosts into our analysis, with an assumed hostless rate of 5%. Our fully automated algorithm is run on catalog data and matches SNe to their hosts with 91% accuracy. Here, we find that including a machine learning component, run after the initial matching algorithm, improves the accuracy (purity) of the matching to 97% with a 2% cost in efficiency (true positive rate). Although the exact results are dependent on the details of the survey and the galaxy catalogs used, the method of identifying host galaxies we outline here can be applied to any transient survey.« less

  16. Host Galaxy Identification for Supernova Surveys

    NASA Astrophysics Data System (ADS)

    Gupta, Ravi R.; Kuhlmann, Steve; Kovacs, Eve; Spinka, Harold; Kessler, Richard; Goldstein, Daniel A.; Liotine, Camille; Pomian, Katarzyna; D'Andrea, Chris B.; Sullivan, Mark; Carretero, Jorge; Castander, Francisco J.; Nichol, Robert C.; Finley, David A.; Fischer, John A.; Foley, Ryan J.; Kim, Alex G.; Papadopoulos, Andreas; Sako, Masao; Scolnic, Daniel M.; Smith, Mathew; Tucker, Brad E.; Uddin, Syed; Wolf, Rachel C.; Yuan, Fang; Abbott, Tim M. C.; Abdalla, Filipe B.; Benoit-Lévy, Aurélien; Bertin, Emmanuel; Brooks, David; Carnero Rosell, Aurelio; Carrasco Kind, Matias; Cunha, Carlos E.; da Costa, Luiz N.; Desai, Shantanu; Doel, Peter; Eifler, Tim F.; Evrard, August E.; Flaugher, Brenna; Fosalba, Pablo; Gaztañaga, Enrique; Gruen, Daniel; Gruendl, Robert; James, David J.; Kuehn, Kyler; Kuropatkin, Nikolay; Maia, Marcio A. G.; Marshall, Jennifer L.; Miquel, Ramon; Plazas, Andrés A.; Romer, A. Kathy; Sánchez, Eusebio; Schubnell, Michael; Sevilla-Noarbe, Ignacio; Sobreira, Flávia; Suchyta, Eric; Swanson, Molly E. C.; Tarle, Gregory; Walker, Alistair R.; Wester, William

    2016-12-01

    Host galaxy identification is a crucial step for modern supernova (SN) surveys such as the Dark Energy Survey and the Large Synoptic Survey Telescope, which will discover SNe by the thousands. Spectroscopic resources are limited, and so in the absence of real-time SN spectra these surveys must rely on host galaxy spectra to obtain accurate redshifts for the Hubble diagram and to improve photometric classification of SNe. In addition, SN luminosities are known to correlate with host-galaxy properties. Therefore, reliable identification of host galaxies is essential for cosmology and SN science. We simulate SN events and their locations within their host galaxies to develop and test methods for matching SNe to their hosts. We use both real and simulated galaxy catalog data from the Advanced Camera for Surveys General Catalog and MICECATv2.0, respectively. We also incorporate “hostless” SNe residing in undetected faint hosts into our analysis, with an assumed hostless rate of 5%. Our fully automated algorithm is run on catalog data and matches SNe to their hosts with 91% accuracy. We find that including a machine learning component, run after the initial matching algorithm, improves the accuracy (purity) of the matching to 97% with a 2% cost in efficiency (true positive rate). Although the exact results are dependent on the details of the survey and the galaxy catalogs used, the method of identifying host galaxies we outline here can be applied to any transient survey.

  17. Presupernova models and supernovae

    NASA Technical Reports Server (NTRS)

    Sugimoto, D.; Nomoto, K.

    1980-01-01

    The present status of theories of presupernova stellar evolution and the triggering mechanisms of supernova explosions are reviewed. The validity of the single-star approximation for stellar core evolution is considered, and the central density and temperature of the stellar core are discussed. Attention is then given to the results of numerical models of supernova explosions by carbon deflagration of an intermediate mass star, resulting in the total disruption of the star; the photodissociation of iron nuclei in a massive star, resulting in neutron star or black hole formation; and stellar core collapse triggered by electron capture in stars of mass ranging between those of the intermediate mass and massive stars, resulting in neutron star formation despite oxygen deflagration. Helium and carbon combustion and detonation in accreting white dwarfs and the gravitational collapse triggered by electron-pair creation in supermassive stars are also discussed, and problems requiring future investigation are indicated.

  18. Binary progenitors of supernovae

    NASA Astrophysics Data System (ADS)

    Trimble, V.

    1984-12-01

    Among the massive stars that are expected to produce Type II, hydrogen-rich supernovae, the presence of a close companion can increase the main sequence mass needed to yield a collapsing core. In addition, due to mass transfer from the primary to the secondary, the companion enhances the stripping of the stellar hydrogen envelope produced by single star winds and thereby makes it harder for the star to give rise to a typical SN II light curve. Among the less massive stars that may be the basis for Type I, hydrogen-free supernovae, a close companion could be an innocent bystander to carbon detonation/deflagration in the primary. It may alternatively be a vital participant which transfers material to a white dwarf primary and drives it to explosive conditions.

  19. Presupernova models and supernovae

    NASA Technical Reports Server (NTRS)

    Sugimoto, D.; Nomoto, K.

    1980-01-01

    The present status of theories of presupernova stellar evolution and the triggering mechanisms of supernova explosions are reviewed. The validity of the single-star approximation for stellar core evolution is considered, and the central density and temperature of the stellar core are discussed. Attention is then given to the results of numerical models of supernova explosions by carbon deflagration of an intermediate mass star, resulting in the total disruption of the star; the photodissociation of iron nuclei in a massive star, resulting in neutron star or black hole formation; and stellar core collapse triggered by electron capture in stars of mass ranging between those of the intermediate mass and massive stars, resulting in neutron star formation despite oxygen deflagration. Helium and carbon combustion and detonation in accreting white dwarfs and the gravitational collapse triggered by electron-pair creation in supermassive stars are also discussed, and problems requiring future investigation are indicated.

  20. Supernova Science Center

    SciTech Connect

    S. E. Woosley

    2008-05-05

    The Supernova Science Center (SNSC) was founded in 2001 to carry out theoretical and computational research leading to a better understanding of supernovae and related transients. The SNSC, a four-institutional collaboration, included scientists from LANL, LLNL, the University of Arizona (UA), and the University of California at Santa Cruz (UCSC). Intitially, the SNSC was funded for three years of operation, but in 2004 an opportunity was provided to submit a renewal proposal for two years. That proposal was funded and subsequently, at UCSC, a one year no-cost extension was granted. The total operational time of the SNSC was thus July 15, 2001 - July 15, 2007. This document summarizes the research and findings of the SNSC and provides a cummulative publication list.

  1. Superluminous Supernovae hydrodynamic models

    NASA Astrophysics Data System (ADS)

    Orellana, M.

    2017-07-01

    We use our radiation hydrodynamic code in order to simulate magnetar powered Superluminous Supernovae (SLSNe). It is assumed that a central rapidly rotating magnetar deposits all its rotational energy into the ejecta where is added to the usual power. The magnetar luminosity and spin-down timescale are adopted as the free parameters of the model. For the case of ASASSN-15lh, which has been claimed as the most luminous supernova ever discovered, we have found physically plausible magnetar parameters can reproduce the overall shape of the bolometric light curve (LC) provided the progenitor mass is ≍ 8M⊙. The ejecta dynamics of this event shows signs of the magnetar energy input which deviates the expansion from the usually assumed homologous behaviour. Our numerical experiments lead us to conclude that the hydrodynamical modeling is necessary in order to derive the properties of powerful magnetars driving SLSNe.

  2. Supernova research with VLBI

    NASA Astrophysics Data System (ADS)

    Bartel, Norbert; Bietenholz, Michael F.

    2016-06-01

    Core-collapse supernovae have been monitored with VLBI from shortly after the explosion to many years thereafter. Radio emission is produced as the ejecta hit the stellar wind left over from the dyingstar. Images show the details of the interaction as the shock front expands into the circumstellar medium. Measurements of the velocity and deceleration of the expansion provide information on both the ejecta and the circumstellar medium. VLBI observations can also search for the stellar remnant of the explosion, a neutron star or a black hole. Combining the transverse expansion rate with the radial expansion rate from optical spectra allows a geometric determination of the distance to the host galaxy. We will present results from recent VLBI observations, focus on their interpretations, and show updated movies of supernovae from soon after their explosion to the present.

  3. Supernova 1987A!

    PubMed

    Woosley, S E; Phillips, M M

    1988-05-06

    Light from the brightest supernova in almost 400 years arrived at Earth on 23 February 1987. Although located 160,000 light years away in a satellite galaxy of our own known as the Large Magellanic Cloud, this supernova's relative proximity compared to all others that have been observed in modern times has allowed observations, which were never possible before, to be made from space, from detectors on the ground and carried by balloons and airplanes, and from neutrino detectors deep underground. What emerges is a greater understanding of one of the most violent events in the universe, the death of a massive star. For the most part, theoretical expectations have been borne out, but some major surprises have made the event all the more fascinating.

  4. STAR FORMATION IN ULTRA-FAINT DWARFS: CONTINUOUS OR SINGLE-AGE BURSTS?

    SciTech Connect

    Webster, David; Bland-Hawthorn, Joss; Sutherland, Ralph

    2015-01-30

    We model the chemical evolution of six ultra-faint dwarfs (UFDs): Bootes I, Canes Venatici II, Coma Berenices, Hercules, Leo IV, and Ursa Major I based on their recently determined star formation histories. We show that two single-age bursts cannot explain the observed [α/Fe] versus [Fe/H] distribution in these galaxies and that some self-enrichment is required within the first burst. An alternative scenario is modeled, in which star formation is continuous except for short interruptions when one or more supernovae temporarily blow the dense gas out from the center of the system. This model allows for self-enrichment and can reproduce the chemical abundances of the UFDs in which the second burst is only a trace population. We conclude that the most likely star formation history is one or two extended periods of star formation, with the first burst lasting for at least 100 Myr. As found in earlier work, the observed properties of UFDs can be explained by formation at a low mass (M{sub vir}∼10{sup 7} M{sub ⊙}), rather than being stripped remnants of much larger systems.

  5. Core bounce supernovae

    SciTech Connect

    Cooperstein, J.

    1987-01-01

    The gravitational collapse mechanism for Type II supernovae is considered, concentrating on the direct implosion - core bounce - hydrodynamic explosion picture. We examine the influence of the stiffness of the dense matter equation of state and discuss how the shock wave is formed. Its chances of success are determined by the equation of state, general relativistic effects, neutrino transport, and the size of presupernova iron core. 12 refs., 1 tab.

  6. Are There Hidden Supernovae?

    NASA Astrophysics Data System (ADS)

    Bregman, Jesse; Harker, David; Dunham, E.; Rank, David; Temi, Pasquale

    1997-02-01

    Ames Research Center and UCSC have been working on the development of a Mid IR Camera for the KAO in order to search for extra galactic supernovae. The development of the camera and its associated data reduction software have been successfully completed. Spectral Imaging of the Orion Bar at 6.2 and 7.8 microns demonstrates the derotation and data reduction software which was developed.

  7. Are There Hidden Supernovae?

    NASA Technical Reports Server (NTRS)

    Bregman, Jesse; Harker, David; Dunham, E.; Rank, David; Temi, Pasquale

    1997-01-01

    Ames Research Center and UCSC have been working on the development of a Mid IR Camera for the KAO in order to search for extra galactic supernovae. The development of the camera and its associated data reduction software have been successfully completed. Spectral Imaging of the Orion Bar at 6.2 and 7.8 microns demonstrates the derotation and data reduction software which was developed.

  8. The diffuse supernova neutrino flux

    NASA Astrophysics Data System (ADS)

    Lunardini, Cecilia

    2011-12-01

    I review the status and perspectives of the research on the diffuse flux of (core collapse) supernova neutrinos (DSNνF). Several upper bounds exist on this flux in different detection channels. The strongest is the limit from SuperKamiokande (SK) of 1.2 electron antineutrinos cm-2s-1 at 90% confidence level above 19.3 MeV of neutrino energy. The predictions of the DSNνF depend on the supernova rate and on the neutrino emission in a individual supernova. Above the SK threshold, they range between 0.05 electron antineutrinos cm-2s-1 up to touching the SK limit. The SK bound constrains part of the parameter space of the supernova rate - and indirectly of the star formation rate - only in models with relatively hard neutrino spectra. Experimentally, a feasible and very important goal for the future is the improvement of background discrimination and the resulting lowering of the detection threshold. Theory instead will benefit from reducing the uncertainties on the supernova neutrino emission (either with more precise numerical modeling or with data from a galactic supernova) and on the supernova rate. The latter will be provided precisely by next generation supernova surveys up to a normalization factor. Therefore, the detection of the DSNνF is likely to be precious chiefly to constrain such normalization and to study the physics of neutrino emission in supernovae.

  9. NUCLEOSYNTHESIS IN ELECTRON CAPTURE SUPERNOVAE OF ASYMPTOTIC GIANT BRANCH STARS

    SciTech Connect

    Wanajo, S.; Nomoto, K.; Janka, H.-T.; Kitaura, F. S.; Mueller, B. E-mail: nomoto@astron.s.u-tokyo.ac.jp E-mail: kitaura@mpa-garching.mpg.de

    2009-04-10

    We examine nucleosynthesis in the electron capture supernovae of progenitor asymptotic giant branch stars with an O-Ne-Mg core (with the initial stellar mass of 8.8 M {sub sun}). Thermodynamic trajectories for the first 810 ms after core bounce are taken from a recent state-of-the-art hydrodynamic simulation. The presented nucleosynthesis results are characterized by a number of distinct features that are not shared with those of other supernovae from the collapse of stars with iron core (with initial stellar masses of more than 10 M {sub sun}). First is the small amount of {sup 56}Ni (0.002-0.004 M {sub sun}) in the ejecta, which can be an explanation for the observed properties of faint supernovae such as SNe 2008S and 1997D. In addition, the large Ni/Fe ratio is in reasonable agreement with the spectroscopic result of the Crab nebula (the relic of SN 1054). Second is the large production of {sup 64}Zn, {sup 70}Ge, light p-nuclei ({sup 74}Se, {sup 78}Kr, {sup 84}Sr, and {sup 92}Mo), and in particular, {sup 90}Zr, which originates from the low Y{sub e} (0.46-0.49, the number of electrons per nucleon) ejecta. We find, however, that only a 1%-2% increase of the minimum Y{sub e} moderates the overproduction of {sup 90}Zr. In contrast, the production of {sup 64}Zn is fairly robust against a small variation of Y{sub e} . This provides the upper limit of the occurrence of this type of events to be about 30% of all core-collapse supernovae.

  10. Nucleosynthesis in Electron Capture Supernovae of Asymptotic Giant Branch Stars

    NASA Astrophysics Data System (ADS)

    Wanajo, S.; Nomoto, K.; Janka, H.-T.; Kitaura, F. S.; Müller, B.

    2009-04-01

    We examine nucleosynthesis in the electron capture supernovae of progenitor asymptotic giant branch stars with an O-Ne-Mg core (with the initial stellar mass of 8.8 M sun). Thermodynamic trajectories for the first 810 ms after core bounce are taken from a recent state-of-the-art hydrodynamic simulation. The presented nucleosynthesis results are characterized by a number of distinct features that are not shared with those of other supernovae from the collapse of stars with iron core (with initial stellar masses of more than 10 M sun). First is the small amount of 56Ni (0.002-0.004 M sun) in the ejecta, which can be an explanation for the observed properties of faint supernovae such as SNe 2008S and 1997D. In addition, the large Ni/Fe ratio is in reasonable agreement with the spectroscopic result of the Crab nebula (the relic of SN 1054). Second is the large production of 64Zn, 70Ge, light p-nuclei (74Se, 78Kr, 84Sr, and 92Mo), and in particular, 90Zr, which originates from the low Ye (0.46-0.49, the number of electrons per nucleon) ejecta. We find, however, that only a 1%-2% increase of the minimum Ye moderates the overproduction of 90Zr. In contrast, the production of 64Zn is fairly robust against a small variation of Ye . This provides the upper limit of the occurrence of this type of events to be about 30% of all core-collapse supernovae.

  11. Supernova Dust Factories

    NASA Astrophysics Data System (ADS)

    Gomez, Haley; Consortium, MESS; LCOGT

    2013-01-01

    The origin of interstellar dust in galaxies is poorly understood, particularly the relative contribution from supernovae. We present infrared and submillimeter photometry and spectroscopy from the Herschel Space Observatory of the Galactic remnants Tycho, Kepler and the Crab Nebula, taken as part of the Mass Loss from Evolved StarS program (MESS). Although we detect small amounts of dust surrounding Tycho and Kepler (the remnants of Type Ia supernovae), we show this is due to swept-up interstellar and circumstellar material respectively. The lack of dust grains in the ejecta suggests that Type Ia remnants do not produce substantial quantities of iron-rich dust grains and has important consequences for the ‘missing’ iron mass observed in ejecta. After carefully subtracting the synchrotron and line emission from the Crab, the remaining far-infrared continuum originates from 0.1-0.2 solar masses of dust. These observations suggest that the Crab Nebula has condensed most of the relevant refractory elements into dust and that these grains appear well set to survive their journey into the interstellar medium. In summary, our Herschel observations show that significantly less dust forms in the ejecta of Type Ia supernovae than in the remnants of core-collapse explosions, placing stringent constraints on the environments in which dust and molecules can form.

  12. Type IA Supernovae

    NASA Technical Reports Server (NTRS)

    Wheeler, J. Craig

    1992-01-01

    Spectral calculations show that a model based on the thermonuclear explosion of a degenerate carbon/oxygen white dwarf provides excellent agreement with observations of Type Ia supernovae. Identification of suitable evolutionary progenitors remains a severe problem. General problems with estimation of supernova rates are outlined and the origin of Type Ia supernovae from double degenerate systems are discussed in the context of new rates of explosion per H band luminosity, the lack of observed candidates, and the likely presence of H in the vicinity of some SN Ia events. Re-examination of the problems of triggering Type Ia by accretion of hydrogen from a companion shows that there may be an avenue involving cataclysmic variables, especially if extreme hibernation occurs. Novae may channel accreting white dwarfs to a unique locus in accretion rate/mass space. Systems that undergo secular evolution to higher mass transfer rates could lead to just the conditions necessary for a Type Ia explosion. Tests involving fluorescence or absorption in a surrounding circumstellar medium and the detection of hydrogen stripped from a companion, which should appear at low velocity inside the white dwarf ejecta, are suggested. Possible observational confirmation of the former is described.

  13. Supernovae and neutrinos

    SciTech Connect

    John F. Beacom

    2002-09-19

    A long-standing problem in supernova physics is how to measure the total energy and temperature of {nu}{sub {mu}}, {nu}{sub {tau}}, {bar {nu}}{sub {mu}}, and {bar {nu}}{sub {tau}}. While of the highest importance, this is very difficult because these flavors only have neutral-current detector interactions. We propose that neutrino-proton elastic scattering, {nu} + p {yields} {nu} + p, can be used for the detection of supernova neutrinos in scintillator detectors. It should be emphasized immediately that the dominant signal is on free protons. Though the proton recoil kinetic energy spectrum is soft, with T{sub p} {approx_equal} 2E{sub {nu}}{sup 2}/M{sub p}, and the scintillation light output from slow, heavily ionizing protons is quenched, the yield above a realistic threshold is nearly as large as that from {bar {nu}}{sub e} + p {yields} e{sup +} + n. In addition, the measured proton spectrum is related to the incident neutrino spectrum. The ability to detect this signal would give detectors like KamLAND and Borexino a crucial and unique role in the quest to detect supernova neutrinos.

  14. Supernova Discoveries from the Nearby Supernova Factory (SNfactory)

    DOE Data Explorer

    SNfactory International Collaboration,

    The Nearby Supernova Factory is an experiment designed to collect data on more Type Ia supernovae than have ever been studied in a single project before, and in so doing, to answer some fundamental questions about the nature of the universe. Type Ia supernovae are extraordinarily bright, remarkably uniform objects which make excellent "standard candles" for measuring the expansion rate of the universe. However, such stellar explosions are very rare, occurring only a couple of times per millenium in a typical galaxy, and remaining bright enough to detect only for a few weeks. Previous studies of Type Ia supernovae led to the discovery of the mysterious "dark energy" that is causing the universe to expand at an accelerating rate. To reduce the statistical uncertainties in previous experimental data, extensive spectral and photometric monitoring of more Type Ia supernovae is required. The SNfactory collaboration has built an automated system consisting of specialized software and custom-built hardware that systematically searches the sky for new supernovae, screens potential candidates, then performs multiple spectral and photometric observations on each supernova. These observations are stored in a database to be made available to supernova researchers world-wide for further study and analysis [copied from http://snfactory.lbl.gov/snf/snf-about.html]. Users must register and agree to the open access honor system. Finding charts are in FITS format and may not be accessible through normal browser settings.

  15. 1. Dyea Dock looking south. Note faint evenly spaced circular ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Dyea Dock looking south. Note faint evenly spaced circular dark pieces of grass up through the middle of the picture indicating posts making up the pier. Photograph made from park service cherry picker. - Dyea Dock & Association (Ruins), Skagway, Skagway, AK

  16. The CFHT (MOS/PUMA) faint quasar survey

    NASA Astrophysics Data System (ADS)

    Schade, David

    A multi-aperture spectroscopic survey for faint quasars has been carried out at Canada-France-Hawaii telescope. The survey is capable of reaching two magnitudes deeper into the luminosity function at redshifts greater than 3 than the deepest existing surveys. The technique is discussed and preliminary results are presented.

  17. Slowly fading super-luminous supernovae that are not pair-instability explosions.

    PubMed

    Nicholl, M; Smartt, S J; Jerkstrand, A; Inserra, C; McCrum, M; Kotak, R; Fraser, M; Wright, D; Chen, T-W; Smith, K; Young, D R; Sim, S A; Valenti, S; Howell, D A; Bresolin, F; Kudritzki, R P; Tonry, J L; Huber, M E; Rest, A; Pastorello, A; Tomasella, L; Cappellaro, E; Benetti, S; Mattila, S; Kankare, E; Kangas, T; Leloudas, G; Sollerman, J; Taddia, F; Berger, E; Chornock, R; Narayan, G; Stubbs, C W; Foley, R J; Lunnan, R; Soderberg, A; Sanders, N; Milisavljevic, D; Margutti, R; Kirshner, R P; Elias-Rosa, N; Morales-Garoffolo, A; Taubenberger, S; Botticella, M T; Gezari, S; Urata, Y; Rodney, S; Riess, A G; Scolnic, D; Wood-Vasey, W M; Burgett, W S; Chambers, K; Flewelling, H A; Magnier, E A; Kaiser, N; Metcalfe, N; Morgan, J; Price, P A; Sweeney, W; Waters, C

    2013-10-17

    Super-luminous supernovae that radiate more than 10(44) ergs per second at their peak luminosity have recently been discovered in faint galaxies at redshifts of 0.1-4. Some evolve slowly, resembling models of 'pair-instability' supernovae. Such models involve stars with original masses 140-260 times that of the Sun that now have carbon-oxygen cores of 65-130 solar masses. In these stars, the photons that prevent gravitational collapse are converted to electron-positron pairs, causing rapid contraction and thermonuclear explosions. Many solar masses of (56)Ni are synthesized; this isotope decays to (56)Fe via (56)Co, powering bright light curves. Such massive progenitors are expected to have formed from metal-poor gas in the early Universe. Recently, supernova 2007bi in a galaxy at redshift 0.127 (about 12 billion years after the Big Bang) with a metallicity one-third that of the Sun was observed to look like a fading pair-instability supernova. Here we report observations of two slow-to-fade super-luminous supernovae that show relatively fast rise times and blue colours, which are incompatible with pair-instability models. Their late-time light-curve and spectral similarities to supernova 2007bi call the nature of that event into question. Our early spectra closely resemble typical fast-declining super-luminous supernovae, which are not powered by radioactivity. Modelling our observations with 10-16 solar masses of magnetar-energized ejecta demonstrates the possibility of a common explosion mechanism. The lack of unambiguous nearby pair-instability events suggests that their local rate of occurrence is less than 6 × 10(-6) times that of the core-collapse rate.

  18. Slowly fading super-luminous supernovae that are not pair-instability explosions

    NASA Astrophysics Data System (ADS)

    Nicholl, M.; Smartt, S. J.; Jerkstrand, A.; Inserra, C.; McCrum, M.; Kotak, R.; Fraser, M.; Wright, D.; Chen, T.-W.; Smith, K.; Young, D. R.; Sim, S. A.; Valenti, S.; Howell, D. A.; Bresolin, F.; Kudritzki, R. P.; Tonry, J. L.; Huber, M. E.; Rest, A.; Pastorello, A.; Tomasella, L.; Cappellaro, E.; Benetti, S.; Mattila, S.; Kankare, E.; Kangas, T.; Leloudas, G.; Sollerman, J.; Taddia, F.; Berger, E.; Chornock, R.; Narayan, G.; Stubbs, C. W.; Foley, R. J.; Lunnan, R.; Soderberg, A.; Sanders, N.; Milisavljevic, D.; Margutti, R.; Kirshner, R. P.; Elias-Rosa, N.; Morales-Garoffolo, A.; Taubenberger, S.; Botticella, M. T.; Gezari, S.; Urata, Y.; Rodney, S.; Riess, A. G.; Scolnic, D.; Wood-Vasey, W. M.; Burgett, W. S.; Chambers, K.; Flewelling, H. A.; Magnier, E. A.; Kaiser, N.; Metcalfe, N.; Morgan, J.; Price, P. A.; Sweeney, W.; Waters, C.

    2013-10-01

    Super-luminous supernovae that radiate more than 1044 ergs per second at their peak luminosity have recently been discovered in faint galaxies at redshifts of 0.1-4. Some evolve slowly, resembling models of `pair-instability' supernovae. Such models involve stars with original masses 140-260 times that of the Sun that now have carbon-oxygen cores of 65-130 solar masses. In these stars, the photons that prevent gravitational collapse are converted to electron-positron pairs, causing rapid contraction and thermonuclear explosions. Many solar masses of 56Ni are synthesized; this isotope decays to 56Fe via 56Co, powering bright light curves. Such massive progenitors are expected to have formed from metal-poor gas in the early Universe. Recently, supernova 2007bi in a galaxy at redshift 0.127 (about 12 billion years after the Big Bang) with a metallicity one-third that of the Sun was observed to look like a fading pair-instability supernova. Here we report observations of two slow-to-fade super-luminous supernovae that show relatively fast rise times and blue colours, which are incompatible with pair-instability models. Their late-time light-curve and spectral similarities to supernova 2007bi call the nature of that event into question. Our early spectra closely resemble typical fast-declining super-luminous supernovae, which are not powered by radioactivity. Modelling our observations with 10-16 solar masses of magnetar-energized ejecta demonstrates the possibility of a common explosion mechanism. The lack of unambiguous nearby pair-instability events suggests that their local rate of occurrence is less than 6 × 10-6 times that of the core-collapse rate.

  19. Gravitational Lensing of Supernova Neutrinos

    SciTech Connect

    Mena, Olga; Mocioiu, Irina; Quigg, Chris; /Fermilab

    2006-10-01

    The black hole at the center of the galaxy is a powerful lens for supernova neutrinos. In the very special circumstance of a supernova near the extended line of sight from Earth to the galactic center, lensing could dramatically enhance the neutrino flux at Earth and stretch the neutrino pulse.

  20. Collective neutrino oscillations in supernovae

    SciTech Connect

    Duan, Huaiyu

    2014-06-24

    In a dense neutrino medium neutrinos can experience collective flavor transformation through the neutrino-neutrino forward scattering. In this talk we present some basic features of collective neutrino flavor transformation in the context in core-collapse supernovae. We also give some qualitative arguments for why and when this interesting phenomenon may occur and how it may affect supernova nucleosynthesis.

  1. Constraints on Type IIn supernova progenitor outbursts from the Lick Observatory Supernova Search

    NASA Astrophysics Data System (ADS)

    Bilinski, Christopher; Smith, Nathan; Li, Weidong; Williams, G. Grant; Zheng, WeiKang; Filippenko, Alexei V.

    2015-06-01

    We searched through roughly 12 years of archival survey data acquired by the Katzman Automatic Imaging Telescope (KAIT) as part of the Lick Observatory Supernova Search in order to detect or place limits on possible progenitor outbursts of Type IIn supernovae (SNe IIn). The KAIT data base contains multiple pre-SN images for five SNe IIn (plus one ambiguous case of an SN IIn/imposter) within 50 Mpc. No progenitor outbursts are found using the false discovery rate statistical method in any of our targets. Instead, we derive limiting magnitudes (LMs) at the locations of the SNe. These LMs (typically reaching mR ≈ 19.5 mag) are compared to outbursts of SN 2009ip and η Car, plus additional simulated outbursts. We find that the data for SN 1999el and SN 2003dv are of sufficient quality to rule out events ˜40 d before the main peak caused by initially faint SNe from blue supergiant precursor stars, as in the cases of SN 2009ip and SN 2010mc. These SNe IIn may thus have arisen from red supergiant progenitors, or they may have had a more rapid onset of circumstellar matter interaction. We also estimate the probability of detecting at least one outburst in our data set to be ≳60% for each type of the example outbursts, so the lack of any detections suggests that such outbursts are either typically less luminous (intrinsically or owing to dust) than ˜-13 mag, or not very common among SNe IIn within a few years prior to explosion.

  2. Cosmological and supernova neutrinos

    NASA Astrophysics Data System (ADS)

    Kajino, T.; Aoki, W.; Balantekin, A. B.; Cheoun, M.-K.; Hayakawa, T.; Hidaka, J.; Hirai, Y.; Kusakabe, M.; Mathews, G. J.; Nakamura, K.; Pehlivan, Y.; Shibagaki, S.; Suzuki, T.

    2014-06-01

    The Big Bang nucleosynthesis (BBN) and the cosmic microwave background (CMB) anisotropies are the pillars of modern cosmology. It has recently been suggested that axion which is a dark matter candidate in the framework of the standard model could condensate in the early universe and induce photon cooling before the epoch of the photon last scattering. Although this may render a solution to the overproduction problem of primordial 7Li abundance, there arises another serious difficulty of overproducing D abundance. We propose a hybrid dark matter model with both axions and relic supersymmetric (SUSY) particles to solve both overproduction problems of the primordial D and 7Li abundances simultaneously. The BBN also serves to constrain the nature of neutrinos. Considering non-thermal photons produced in the decay of the heavy sterile neutrinos due to the magnetic moment, we explore the cosmological constraint on the strength of neutrino magnetic moment consistent with the observed light element abundances. Core-collapse supernovae eject huge flux of energetic neutrinos which affect explosive nucleosynthesis of rare isotopes like 7Li, 11B, 92Nb, 138La and 180Ta and r-process elements. Several isotopes depend strongly on the neutrino flavor oscillation due to the Mikheyev-Smirnov-Wolfenstein (MSW) effect. Combining the recent experimental constraints on θ13 with predicted and observed supernova-produced abundance ratio 11B/7Li encapsulated in the presolar grains from the Murchison meteorite, we show a marginal preference for an inverted neutrino mass hierarchy. We also discuss supernova relic neutrinos (SRN) that may indicate the softness of the equation of state (EoS) of nuclear matter and adiabatic conditions of the neutrino oscillation.

  3. Nuclear astrophysics of supernovae

    SciTech Connect

    Cooperstein, J.

    1988-01-01

    In this paper, I'll give a general introduction to Supernova Theory, beginning with the presupernova evolution and ending with the later stages of the explosion. This will be distilled from a colloquium type of talk. It is necessary to have the whole supernova picture in one's mind's eye when diving into some of its nooks and crannies, as it is quite a mess of contradictory ingredients. We will have some discussion of supernova 1987a, but will keep our discussion more general. Second, we'll look at the infall and bounce of the star, seeing why it goes unstable, what dynamics it follows as it collapses, and how and why it bounces back. From there, we will go on to look at the equation of state (EOS) in more detail. We'll consider the cases T = 0 and T > 0. We'll focus on /rho/ < /rho//sub 0/, and then /rho/ > /rho//sub 0/ and the EOS of neutron stars, and whether or not they contain cores of strange matter. There are many things we could discuss here and not enough time. If I had more lectures, the remaining time would focus on two more questions of special interest to nuclear physicists: the electron capture reactions and neutrino transport. If time permitted, we'd have some discussion of the nucleosynthetic reactions in the explosion's debris as well. However, we cannot cover such material adequately, and I have chosen these topics because they are analytically tractable, pedagogically useful, and rather important. 23 refs., 14 figs., 3 tabs.

  4. Cosmological and supernova neutrinos

    SciTech Connect

    Kajino, T.; Aoki, W.; Balantekin, A. B.; Cheoun, M.-K.; Hayakawa, T.; Hidaka, J.; Hirai, Y.; Shibagaki, S.; Kusakabe, M.; Mathews, G. J.; Nakamura, K.; Pehlivan, Y.; Suzuki, T.

    2014-06-24

    The Big Bang nucleosynthesis (BBN) and the cosmic microwave background (CMB) anisotropies are the pillars of modern cosmology. It has recently been suggested that axion which is a dark matter candidate in the framework of the standard model could condensate in the early universe and induce photon cooling before the epoch of the photon last scattering. Although this may render a solution to the overproduction problem of primordial {sup 7}Li abundance, there arises another serious difficulty of overproducing D abundance. We propose a hybrid dark matter model with both axions and relic supersymmetric (SUSY) particles to solve both overproduction problems of the primordial D and {sup 7}Li abundances simultaneously. The BBN also serves to constrain the nature of neutrinos. Considering non-thermal photons produced in the decay of the heavy sterile neutrinos due to the magnetic moment, we explore the cosmological constraint on the strength of neutrino magnetic moment consistent with the observed light element abundances. Core-collapse supernovae eject huge flux of energetic neutrinos which affect explosive nucleosynthesis of rare isotopes like {sup 7}Li, {sup 11}B, {sup 92}Nb, {sup 138}La and {sup 180}Ta and r-process elements. Several isotopes depend strongly on the neutrino flavor oscillation due to the Mikheyev-Smirnov-Wolfenstein (MSW) effect. Combining the recent experimental constraints on θ{sub 13} with predicted and observed supernova-produced abundance ratio {sup 11}B/{sup 7}Li encapsulated in the presolar grains from the Murchison meteorite, we show a marginal preference for an inverted neutrino mass hierarchy. We also discuss supernova relic neutrinos (SRN) that may indicate the softness of the equation of state (EoS) of nuclear matter and adiabatic conditions of the neutrino oscillation.

  5. GALAXY OUTFLOWS WITHOUT SUPERNOVAE

    SciTech Connect

    Sur, Sharanya; Scannapieco, Evan; Ostriker, Eve C. E-mail: sharanya.sur@asu.edu

    2016-02-10

    High surface density, rapidly star-forming galaxies are observed to have ≈50–100 km s{sup −1} line of sight velocity dispersions, which are much higher than expected from supernova driving alone, but may arise from large-scale gravitational instabilities. Using three-dimensional simulations of local regions of the interstellar medium, we explore the impact of high velocity dispersions that arise from these disk instabilities. Parametrizing disks by their surface densities and epicyclic frequencies, we conduct a series of simulations that probe a broad range of conditions. Turbulence is driven purely horizontally and on large scales, neglecting any energy input from supernovae. We find that such motions lead to strong global outflows in the highly compact disks that were common at high redshifts, but weak or negligible mass loss in the more diffuse disks that are prevalent today. Substantial outflows are generated if the one-dimensional horizontal velocity dispersion exceeds ≈35 km s{sup −1}, as occurs in the dense disks that have star-formation rate (SFR) densities above ≈0.1 M{sub ⊙} yr{sup −1} kpc{sup −2}. These outflows are triggered by a thermal runaway, arising from the inefficient cooling of hot material coupled with successive heating from turbulent driving. Thus, even in the absence of stellar feedback, a critical value of the SFR density for outflow generation can arise due to a turbulent heating instability. This suggests that in strongly self-gravitating disks, outflows may be enhanced by, but need not caused by, energy input from supernovae.

  6. Radio Emission from Supernovae

    SciTech Connect

    Weiler, Kurt W.; Panagia, Nino; Sramek, Richard A.; Van Dyk, Schuyler D.; Stockdale, Christopher J.; Kelley, Matthew T.

    2009-05-03

    Study of radio supernovae over the past 27 years includes more than three dozen detected objects and more than 150 upper limits. From this work it is possible to identify classes of radio properties, demonstrate conformance to and deviations from existing models, estimate the density and structure of the circumstellar material and, by inference, the evolution of the presupernova stellar wind, and reveal the last stages of stellar evolution before explosion. It is also possible to detect ionized hydrogen along the line of sight, to demonstrate binary properties of the presupernova stellar system, and to detect dumpiness of the circumstellar material.

  7. CRTS Supernova Candidate

    NASA Astrophysics Data System (ADS)

    Drake, A. J.; Djorgovski, S. G.; Graham, M. J.; Williams, R.; Mahabal, A.; Beshore, E. C.; Larson, S. M.; Hill, R.; Catelan, M.; Christensen, E.

    2008-09-01

    We have detected a likely supernova in CSS images from 24 Sep 2008 UT. The object has the following parameters:

    CSS080924:044524+182425 2008-09-24 UT 11:17:06 RA 04:45:24.00 Dec 18:24:25.1 Mag 17.5 Type SN
    The object is near the edge of galaxy LCSB L0250N (z=0.0155).

  8. Supernova 2002hi

    NASA Astrophysics Data System (ADS)

    Pooley, D.; Lewin, W. H. G.

    2003-01-01

    D. Pooley and W. H. G. Lewin, Massachusetts Institute of Technology, on behalf of a larger collaboration, report the detection of X-ray emission at the position of the type-IIn supernova (SN) 2002hi (IAUC 8006) with the Chandra X-ray observatory: An ACIS-S3 observation of 10 ks was made on Dec. 10.73. In the 0.5-10 keV range, we searched a 2x2 pixel region (approx. 1" by 1") around the reported position of the SN and detected 2 counts.

  9. DISCOVERY OF AN APPARENT HIGH LATITUDE GALACTIC SUPERNOVA REMNANT

    SciTech Connect

    Fesen, Robert A.; Neustadt, Jack M. M.; Black, Christine S.; Koeppel, Ari H. D.

    2015-10-10

    Deep Hα images of a faint emission complex 4.°0 × 5.°5 in angular extent and located far off the Galactic plane at l = 70.°0, b = −21.°5 reveal numerous thin filaments suggestive of a supernova remnant’s (SNR’s) shock emission. Low dispersion optical spectra covering the wavelength range 4500–7500 Å show only Balmer line emissions for one filament while three others show a Balmer dominated spectrum along with weak [N i] 5198, 5200 Å, [O i] 6300, 6364 Å, [N ii] 6583 Å, [S ii] 6716, 6731 Å, and in one case [O iii] 5007 Å line emission. Many of the brighter Hα filaments are visible in near-UV GALEX images presumably due to C iii] 1909 Å line emission. ROSAT All Sky Survey images of this region show a faint crescent-shaped X-ray emission nebula coincident with the portion of the Hα nebulosity closest to the Galactic plane. The presence of long, thin Balmer dominated emission filaments with associated UV emission and coincident X-ray emission suggests this nebula is a high latitude Galactic SNR despite a lack of known associated nonthermal radio emission. Relative line intensities of the optical lines in some filaments differ from commonly observed [S ii]/Hα ≥ 0.4 radiative shocked filaments and typical Balmer filaments in SNRs. We discuss possible causes for the unusual optical SNR spectra.

  10. Radiation-hydrodynamical modelling of underluminous Type II plateau supernovae

    NASA Astrophysics Data System (ADS)

    Pumo, M. L.; Zampieri, L.; Spiro, S.; Pastorello, A.; Benetti, S.; Cappellaro, E.; Manicò, G.; Turatto, M.

    2017-01-01

    With the aim of improving our knowledge about the nature of the progenitors of low-luminosity Type II plateau supernovae (LL SNe IIP), we made radiation-hydrodynamical models of the well-sampled LL SNe IIP 2003Z, 2008bk and 2009md. For these three SNe, we infer explosion energies of 0.16-0.18 foe, radii at explosion of 1.8-3.5 × 1013 cm and ejected masses of 10-11.3 M⊙. The estimated progenitor mass on the main sequence is in the range ˜13.2-15.1 M⊙ for SN 2003Z and ˜11.4-12.9 M⊙ for SNe 2008bk and 2009md, in agreement with estimates from observations of the progenitors. These results together with those for other LL SNe IIP modelled in the same way enable us also to conduct a comparative study on this SN sub-group. The results suggest that (a) the progenitors of faint SNe IIP are slightly less massive and have less energetic explosions than those of intermediate-luminosity SNe IIP; (b) both faint and intermediate-luminosity SNe IIP originate from low-energy explosions of red (or yellow) supergiant stars of low to intermediate mass; (c) some faint objects may also be explained as electron-capture SNe from massive super-asymptotic giant branch stars; and (d) LL SNe IIP form the underluminous tail of the SNe IIP family, where the main parameter `guiding' the distribution seems to be the ratio of the total explosion energy to the ejected mass. Further hydrodynamical studies should be performed and compared to a more extended sample of LL SNe IIP before drawing any conclusion on the relevance of fall-back to this class of events.

  11. Supernova Acceleration Probe: Studying Dark Energy with Type Ia Supernovae

    SciTech Connect

    Albert, J.; Aldering, G.; Allam, S.; Althouse, W.; Amanullah, R.; Annis, J.; Astier, P.; Aumeunier, M.; Bailey, S.; Baltay, C.; Barrelet, E.; Basa, S.; Bebek, C.; Bergstom, L.; Bernstein, G.; Bester, M.; Besuner, B.; Bigelow, B.; Blandford, R.; Bohlin, R.; Bonissent, A.; /Caltech /LBL, Berkeley /Fermilab /SLAC /Stockholm U. /Paris, IN2P3 /Marseille, CPPM /Marseille, Lab. Astrophys. /Yale U. /Pennsylvania U. /UC, Berkeley /Michigan U. /Baltimore, Space Telescope Sci. /Indiana U. /Caltech, JPL /Australian Natl. U., Canberra /American Astron. Society /Chicago U. /Cambridge U. /Saclay /Lyon, IPN

    2005-08-08

    The Supernova Acceleration Probe (SNAP) will use Type Ia supernovae (SNe Ia) as distance indicators to measure the effect of dark energy on the expansion history of the Universe. (SNAP's weak-lensing program is described in a separate White Paper.) The experiment exploits supernova distance measurements up to their fundamental systematic limit; strict requirements on the monitoring of each supernova's properties leads to the need for a space-based mission. Results from pre-SNAP experiments, which characterize fundamental SN Ia properties, will be used to optimize the SNAP observing strategy to yield data, which minimize both systematic and statistical uncertainties. With early R&D funding, we have achieved technological readiness and the collaboration is poised to begin construction. Pre-JDEM AO R&D support will further reduce technical and cost risk. Specific details on the SNAP mission can be found in Aldering et al. (2004, 2005). The primary goal of the SNAP supernova program is to provide a dataset which gives tight constraints on parameters which characterize the dark-energy, e.g. w{sub 0} and w{sub a} where w(a) = w{sub 0} + w{sub a}(1-a). SNAP data can also be used to directly test and discriminate among specific dark energy models. We will do so by building the Hubble diagram of high-redshift supernovae, the same methodology used in the original discovery of the acceleration of the expansion of the Universe that established the existence of dark energy (Perlmutter et al. 1998; Garnavich et al. 1998; Riess et al. 1998; Perlmutter et al. 1999). The SNAP SN Ia program focuses on minimizing the systematic floor of the supernova method through the use of characterized supernovae that can be sorted into subsets based on subtle signatures of heterogeneity. Subsets may be defined based on host-galaxy morphology, spectral-feature strength and velocity, early-time behavior, inter alia. Independent cosmological analysis of each subset of ''like'' supernovae can be

  12. Uncertainties in Supernova Yields

    NASA Astrophysics Data System (ADS)

    Young, Patrick A.; Fryer, C. L.

    2006-12-01

    Theoretical nucleosynthetic yields from supernovae are sensitive to both the details of the progenitor star and the explosion calculation. We attempt to comprehensively identify the sources of uncertainties in these yields. In this poster we concentrate on the variations in yields from a single progenitor arising from common 1-dimensional methods of approximating a supernova explosion. 3-dimensional effects in the explosion and the progenitor and improved physics in the progenitor evolution are also given preliminary consideration. For the 1-dimensional explosions we find that both elemental and isotopic yields for Si and heavier elements are a sensitive function of explosion energy. Also, piston-driven and thermal bomb type explosions have different yields for the same explosion energy. Yields derived from 1-dimensional explosions are non-unique. Bulk yields of common elements can vary by factors of several depending upon the assumptions of the calculation. This work was carried out in part under the auspices of the National Nuclear Security Administration of the U.S. Department of Energy at Los Alamos National Laboratory and supported by Contract No. DE-AC52-06NA25396, by a DOE SciDAC grant DE-FC02-01ER41176, an NNSA ASC grant, and a subcontract to the ASCI FLASH Center at the University of Chicago.

  13. Cassiopeia A supernova

    NASA Image and Video Library

    2017-09-27

    NASA's Fermi Closes on Source of Cosmic Rays New images from NASA's Fermi Gamma-ray Space Telescope show where supernova remnants emit radiation a billion times more energetic than visible light. The images bring astronomers a step closer to understanding the source of some of the universe's most energetic particles -- cosmic rays. This composite shows the Cassiopeia A supernova remnant across the spectrum: Gamma rays (magenta) from NASA's Fermi Gamma-ray Space Telescope; X-rays (blue, green) from NASA's Chandra X-ray Observatory; visible light (yellow) from the Hubble Space Telescope; infrared (red) from NASA's Spitzer Space Telescope; and radio (orange) from the Very Large Array near Socorro, N.M. Credit: NASA/DOE/Fermi LAT Collaboration, CXC/SAO/JPL-Caltech/Steward/O. Krause et al., and NRAO/AUI For more information: www.nasa.gov/mission_pages/GLAST/news/cosmic-rays-source.... NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe. Follow us on Twitter Join us on Facebook

  14. Automated Supernova Discovery (Abstract)

    NASA Astrophysics Data System (ADS)

    Post, R. S.

    2015-12-01

    (Abstract only) We are developing a system of robotic telescopes for automatic recognition of Supernovas as well as other transient events in collaboration with the Puckett Supernova Search Team. At the SAS2014 meeting, the discovery program, SNARE, was first described. Since then, it has been continuously improved to handle searches under a wide variety of atmospheric conditions. Currently, two telescopes are used to build a reference library while searching for PSN with a partial library. Since data is taken every night without clouds, we must deal with varying atmospheric and high background illumination from the moon. Software is configured to identify a PSN, reshoot for verification with options to change the run plan to acquire photometric or spectrographic data. The telescopes are 24-inch CDK24, with Alta U230 cameras, one in CA and one in NM. Images and run plans are sent between sites so the CA telescope can search while photometry is done in NM. Our goal is to find bright PSNs with magnitude 17.5 or less which is the limit of our planned spectroscopy. We present results from our first automated PSN discoveries and plans for PSN data acquisition.

  15. Chandra Observations of the Crab-like Supernova Remnant G21.5-0.9.

    PubMed

    Slane; Chen; Schulz; Seward; Hughes; Gaensler

    2000-04-10

    Chandra observations of the Crab-like supernova remnant G21.5-0.9 reveal a compact central core and spectral variations indicative of synchrotron burn-off of higher energy electrons in the inner nebula. The central core is slightly extended, perhaps indicating the presence of an inner wind-shock nebula surrounding the pulsar. No pulsations are observed from the central region, yielding an upper limit of approximately 40% for the pulsed fraction. A faint outer shell may be the first evidence of the expanding ejecta and blast wave formed in the initial explosion, indicating a composite nature for G21.5-0.9.

  16. Soft X-ray emission from the Lupus Loop and Sn 1006 supernova remnants

    NASA Technical Reports Server (NTRS)

    Winkler, P. F., Jr.; Hearn, D. R.; Richardson, J. A.; Behnken, J. M.

    1979-01-01

    X-ray maps of the Lupus region have been obtained in a raster scan observation from SAS 3. These show the Lupus Loop to be a faint extended source of soft X-rays with a temperature about 2.5 million K. The most prominent feature of the region is the A.D. 1006 supernova remnant, which is unexpectedly bright at 0.2-1.0 keV. One speculative interpretation of the low-energy flux from SN 1006 is as blackbody radiation from a hot neutron star.

  17. Soft X-ray emission from the Lupus Loop and Sn 1006 supernova remnants

    NASA Technical Reports Server (NTRS)

    Winkler, P. F., Jr.; Hearn, D. R.; Richardson, J. A.; Behnken, J. M.

    1979-01-01

    X-ray maps of the Lupus region have been obtained in a raster scan observation from SAS 3. These show the Lupus Loop to be a faint extended source of soft X-rays with a temperature about 2.5 million K. The most prominent feature of the region is the A.D. 1006 supernova remnant, which is unexpectedly bright at 0.2-1.0 keV. One speculative interpretation of the low-energy flux from SN 1006 is as blackbody radiation from a hot neutron star.

  18. The x-ray structure of the supernova remnant W49B

    NASA Technical Reports Server (NTRS)

    Dickel, John R.; Murphy, Rosa; Chu, You-Hua; Garcia, Guillermo; Goscha, Daniel

    1994-01-01

    Comparison of x-ray and radio images of W49B and other supernova remnants (SNR) provides detailed information on the mechanisms responsible for the emission and on the evolution of the remnants. There is faint x-ray emission from all parts of W49B but most of it is concentrated near the center of the remnant, unlike the radio emission which arises in a shell near the periphery. This structure indicates that this SNR is in the adolescent phase of its lifetime.

  19. The Subaru/XMM-Newton Deep Survey (SXDS). V. Optically Faint Variable Object Survey

    NASA Astrophysics Data System (ADS)

    Morokuma, Tomoki; Doi, Mamoru; Yasuda, Naoki; Akiyama, Masayuki; Sekiguchi, Kazuhiro; Furusawa, Hisanori; Ueda, Yoshihiro; Totani, Tomonori; Oda, Takeshi; Nagao, Tohru; Kashikawa, Nobunari; Murayama, Takashi; Ouchi, Masami; Watson, Mike G.; Richmond, Michael W.; Lidman, Christopher; Perlmutter, Saul; Spadafora, Anthony L.; Aldering, Greg; Wang, Lifan; Hook, Isobel M.; Knop, Rob A.

    2008-03-01

    We present our survey for optically faint variable objects using multiepoch (8-10 epochs over 2-4 years) i'-band imaging data obtained with Subaru Suprime-Cam over 0.918 deg2 in the Subaru/XMM-Newton Deep Field (SXDF). We found 1040 optically variable objects by image subtraction for all the combinations of images at different epochs. This is the first statistical sample of variable objects at depths achieved with 8-10 m class telescopes or the Hubble Space Telescope. The detection limit for variable components is i'vari ~ 25.5 mag. These variable objects were classified into variable stars, supernovae (SNe), and active galactic nuclei (AGNs), based on the optical morphologies, magnitudes, colors, and optical-mid-infrared colors of the host objects, spatial offsets of variable components from the host objects, and light curves. Detection completeness was examined by simulating light curves for periodic and irregular variability. We detected optical variability for 36% +/- 2% (51% +/- 3% for a bright sample with i' < 24.4 mag) of X-ray sources in the field. Number densities of variable objects as functions of time intervals Δ t and variable component magnitudes i'vari are obtained. Number densities of variable stars, SNe, and AGNs are 120, 489, and 579 objects deg-2, respectively. Bimodal distributions of variable stars in the color-magnitude diagrams indicate that the variable star sample consists of bright (V ~ 22 mag) blue variable stars of the halo population and faint (V ~ 23.5 mag) red variable stars of the disk population. There are a few candidates of RR Lyrae providing a possible number density of ~10-2 kpc-3 at a distance of >150 kpc from the Galactic center. Based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. Based on observations (program GN-2002B-Q-30) obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a

  20. The LCOGT Supernova Key Project

    NASA Astrophysics Data System (ADS)

    Howell, Dale Andrew; Arcavi, Iair; Hosseinzadeh, Griffin; McCully, Curtis; Valenti, Stefano; Lcogt Supernova Key Project

    2015-01-01

    I present first results from the Las Cumbres Observatory Global Telescope Network (LCOGT) Supernova Key Project. LCOGT is a network of 11 robotic one and two meter telescopes spaced around the globe with imaging and spectroscopic capabilities. The supernova key project is a 3 year program to obtain lightcurves and spectra of at least 450 supernovae. About half are expected to be core-collapse supernovae, and half thermonuclear. We will start light curves and spectroscopy within hours of discovery, and focus on those SNe caught soon after explosion. The goals are fivefold: (1) observe supernovae soon after explosion to search for signs of their progenitors, (2) obtain a large homogeneous sample of supernovae for next generation cosmological studies, (3) obtain a large sample of supernovae for statistical studies comparing groups that are split into different populations, (4) obtain some of the first large samples of the recently discovered classes of rare and exotic explosions, (5) obtain the optical light curves and spectroscopy in support of studies at other wavelengths and using other facilities including UV observations, IR imaging and spectroscopy, host galaxy studies, high resolution spectroscopy, and late-time spectroscopy with large telescopes.

  1. A Newly Discovered Supernova Remnant and MSH 11-62 and 3C58

    NASA Technical Reports Server (NTRS)

    Slane, Patrick O.

    2000-01-01

    CTA 1 is a center-filled supernova remnant (SNR) whose morphology and spectrum indicate the presence of a central pulsar, a synchrotron nebula, and a thermal component associated with the expansion of the blast wave into the interstellar medium. The centrally bright emission surrounds the position of a faint point source of X-rays observed with the ROSAT Position Sensitive Proportional Counter (PSPC). Here we report on Advanced Spacecraft for Cosmology Astrophysics (ASCA) observations that confirm the nonthermal nature of the diffuse emission from the central regions of the remnant. We also present evidence for weak thermal emission that appears to increase in strength toward the outer boundary of the SNR. Thus, CTA 1 appears to be an X-ray composite remnant. Both the aftermath of the explosive supernova event and the energetic compact core are observable.

  2. A Study of Supernova Remnants with Center-Filled X-Ray Morphology

    NASA Technical Reports Server (NTRS)

    Slane, Patrick O.

    1997-01-01

    CTA 1 is a center-filled supernova remnant (SNR) whose morphology and spectrum indicate the presence of a central pulsar, a synchrotron nebula, and a thermal component associated with the expansion of the blast wave into the interstellar medium. The centrally bright emission surrounds the position of a faint point source of x-rays observed with the ROSAT PSPC. Here we report on ASCA observations that confirm the nonthermal nature of the diffuse emission from the central regions of the remnant. We also present evidence for weak thermal emission that appears to increase in strength toward the outer boundary of the SNR. Thus, CTA 1 appears to be an x-ray composite remnant. Both the aftermath of the explosive supernova event and the energetic compact core are observable.

  3. Optical emission from a fast shock wave - The remnants of Tycho's supernova and SN 1006

    NASA Technical Reports Server (NTRS)

    Chevalier, R. A.; Raymond, J. C.

    1978-01-01

    The faint optical filaments in Tycho's supernova remnant appear to be emission from a shock front moving at 5600 km/s. The intensity of the hydrogen lines, the absence of forbidden lines of heavy elements in the spectrum, and the width of the filaments are explained by a model in which a collisionless shock wave is moving into partially neutral gas. The presence of the neutral gas can be used to set an upper limit of approximately 5 x 10 to the 47th power ergs to the energy in ionizing radiation emitted by a Type I supernova. The patchy neutral gas is probably part of the warm neutral component of the interstellar medium. The existing information on the remnant of SN 1006 indicates that its emission is similar in nature to that from Tycho's remnant.

  4. First Results from Supernova Diversity and Rate Evolution (SUDARE) Survey at VST

    NASA Astrophysics Data System (ADS)

    Botticella, M. T.; Cappellaro, E.; Pignata, G.; Grado, A.; Limatola, L.; Della Valle, M.; Vaccari, M.; Greggio, L.; Spiro, S.; Bufano, F.; Tomasella, L.; Covone, G.; Capaccioli, M.; Napolitano, N.; Marchetti, L.; Gonzales-Solares, E.; Jarvis, M.; Radovich, M.; Benetti, S.; Pastorello, A.; Turatto, M.; Paolillo, M.; Schipani, P.; Baruffolo, A.; Cascone, E.

    Despite the key role played by Supernovae (SNe) in discovering the accelerating expansion of the Universe, there are still fundamental questions to answer about their progenitor systems and explosion mechanisms. Furthermore the discovery of a significant number of both exceptionally bright and extremely faint SNe, as well as peculiar events, suggests the existence of an unexpected diversity. Important clues on the SN progenitors can be derived by examining the rate of type Ia and core collapse SNe. With this goal in mind we started the SUpernova Diversity And Rate Evolution (SUDARE) programme currently running at the VLT Survey Telescope (VST). We present a measurement of the volumetric SN rates as a function of redshift for the first 2 years of data from SUDARE.

  5. X-ray Counterparts of Infrared Faint Radio Sources

    NASA Astrophysics Data System (ADS)

    Schartel, Norbert

    2011-10-01

    Infrared Faint Radio Sources (IFRS) are radio sources with extremely faint or even absent infrared emission in deep Spitzer Surveys. Models of their spectral energy distributions, the ratios of radio to infrared flux densities and their steep radio spectra strongly suggest that IFRS are AGN at high redshifts (2

  6. Faint High Orbit Debris Observations with ISON Optical Network

    NASA Astrophysics Data System (ADS)

    Molotov, I.; Agapov, V.

    New cooperation for global monitoring of space objects at high orbits, International Scientific Optical Network (ISON), is appeared under auspices of the Keldysh Institute of Applied Mathematics of the Russian Academy of Sciences. ISON provides the observations of faint deep space debris in cooperation with team of the Astronomical Institute of the University of Bern (AIUB) since 2004. It is jointly discovered already about 500 faint space debris fragments at high orbits and almost 200 of them are continuously tracked with ISON. Presence of space debris clouds created in earlier suspected fragmentations of GEO objects is proved by long deterministic observations of individual members of the clouds. For the first time, a large amount of data on long time intervals is obtained for objects with high area-to-mass ratio (AMR). Till present, the uncatalogued faint deep debris are discovering mainly with Teide ESA OGS telescope and Crimean observatory in Nauchny, while object tracking is providing by cooperation of the 0.5-2.6-m class telescopes including Zimmerwald, Gissar, Mondy, Abastumany, Arkhyz, Mayaki, Andrushivka and Terskol. During 2009 it is planned to join several telescopes with large field of view (1.3 - 2.3 degree) in Ussuriysk, Krasnojarsk, Mondy, Nauchniy, Andrushivka, Abastumani, Mayaki and Kitab into semi-automatic network in order to try to establish the faint debris quasi continuous orbit maintenance. It is planned to use survey mode for this purpose as it is adjusted now for brighter GEO objects with ISON survey subsystem of 22-cm telescopes. Along with sensors development, it is elaborated and tested a few survey modes and algorithm permitting to find correlation between short arc tracks of non-correlated objects in order to discovery of new objects and to establish their orbits.

  7. The Faint Globular Cluster in the Dwarf Galaxy Andromeda I

    NASA Astrophysics Data System (ADS)

    Caldwell, Nelson; Strader, Jay; Sand, David J.; Willman, Beth; Seth, Anil C.

    2017-09-01

    Observations of globular clusters in dwarf galaxies can be used to study a variety of topics, including the structure of dark matter halos and the history of vigorous star formation in low-mass galaxies. We report on the properties of the faint globular cluster (M V -3.4) in the M31 dwarf galaxy Andromeda I. This object adds to the growing population of low-luminosity Local Group galaxies that host single globular clusters.

  8. HUBBLE'S SEARCH FOR FAINT FIELD STARS IN GALACTIC HALO

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Left A NASA Hubble Space Telescope image of a randomly selected area of sky taken to search for faint red stars that might constitute dark matter in our Milky Way Galaxy. (Dark matter is material of an unknown type that makes up most of the mass of our galaxy). If the dark matter in our Galaxy was made of faint red stars -- as many scientists have previously conjectured -- then about 38 such stars should have been visible in this HST image. The simulated stars (diamond-shaped symbols), based on theoretical calculations, illustrate what scientists would have seen if the dark matter were locked-up in faint red stars. These surprising results rule out dim stars as an explanation for dark matter in our Galaxy. Right The unmodified HST image shows the region is actually so devoid of stars that far more distant background galaxies can easily be seen. The field is in the constellation Eridanus, far outside the plane of our Milky Way Galaxy. This region was chosen to highlight stars in the galactic halo, where dark matter exists, and to avoid the contribution of faint stars in the plane of the Galaxy. Technical Information: The image was constructed from seven exposures totaling almost three hours of searching by HST. The field shown is about 1.5 arc-minutes across. The image was taken in near-infrared light (814 nm) with the Wide Field Planetary Camera 2, on Feb 8, 1994. This observation is part of the HST parallel observing program. Credit: J Bahcall, Institute for Advance Study, Princeton and NASA

  9. HUBBLE'S SEARCH FOR FAINT FIELD STARS IN GALACTIC HALO

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Left A NASA Hubble Space Telescope image of a randomly selected area of sky taken to search for faint red stars that might constitute dark matter in our Milky Way Galaxy. (Dark matter is material of an unknown type that makes up most of the mass of our galaxy). If the dark matter in our Galaxy was made of faint red stars -- as many scientists have previously conjectured -- then about 38 such stars should have been visible in this HST image. The simulated stars (diamond-shaped symbols), based on theoretical calculations, illustrate what scientists would have seen if the dark matter were locked-up in faint red stars. These surprising results rule out dim stars as an explanation for dark matter in our Galaxy. Right The unmodified HST image shows the region is actually so devoid of stars that far more distant background galaxies can easily be seen. The field is in the constellation Eridanus, far outside the plane of our Milky Way Galaxy. This region was chosen to highlight stars in the galactic halo, where dark matter exists, and to avoid the contribution of faint stars in the plane of the Galaxy. Technical Information: The image was constructed from seven exposures totaling almost three hours of searching by HST. The field shown is about 1.5 arc-minutes across. The image was taken in near-infrared light (814 nm) with the Wide Field Planetary Camera 2, on Feb 8, 1994. This observation is part of the HST parallel observing program. Credit: J Bahcall, Institute for Advance Study, Princeton and NASA

  10. Supernova 2013by: a Type IIL supernova with a IIP-like light-curve drop★

    NASA Astrophysics Data System (ADS)

    Valenti, S.; Sand, D.; Stritzinger, M.; Howell, D. A.; Arcavi, I.; McCully, C.; Childress, M. J.; Hsiao, E. Y.; Contreras, C.; Morrell, N.; Phillips, M. M.; Gromadzki, M.; Kirshner, R. P.; Marion, G. H.

    2015-04-01

    We present multiband ultraviolet and optical light curves, as well as visual-wavelength and near-infrared spectroscopy of the Type II linear (IIL) supernova (SN) 2013by. We show that SN 2013by and other SNe IIL in the literature, after their linear decline phase that start after maximum, have a sharp light-curve decline similar to that seen in SNe IIP. This light-curve feature has rarely been observed in other SNe IIL due to their relative rarity and the intrinsic faintness of this particular phase of the light curve. We suggest that the presence of this drop could be used as a physical parameter to distinguish between subclasses of SNe II, rather than their light-curve decline rate shortly after peak. Close inspection of the spectra of SN 2013by indicate asymmetric line profiles and signatures of high-velocity hydrogen. Late (˜90 d after explosion) near-infrared spectra of SN 2013by exhibit oxygen lines, indicating significant mixing within the ejecta. From the late-time light curve, we estimate that 0.029 M⊙ of 56Ni was synthesized during the explosion. It is also shown that the V-band light-curve slope is responsible for part of the scatter in the luminosity (V magnitude 50 d after explosion) versus 56Ni relation. Our observations of SN 2013by and other SNe IIL through the onset of the nebular phase indicate that their progenitors are similar to those of SNe IIP.

  11. Faint Submillimeter Galaxies Behind the Frontier Field Clusters

    NASA Astrophysics Data System (ADS)

    Hsu, Li-Yen; Cowie, Lennox; Barger, Amy; Wang, Wei-Hao; Chen, Chian-Chou

    2015-08-01

    Faint submillimeter galaxies are the major contributors to the submillimeter extragalactic background light and hence the dominant star-forming population in the dusty universe. Determining how much these galaxies overlap the optically selected samples is critical to fully account for the cosmic star formation history. To explore this faint submillimeter population, we have been observing nine galaxy clusters with the SCUBA-2 camera on the James Clerk Maxwell Telescope, including five of the clusters in the HST Frontier Fields program. We have also been using the Submillimeter Array to determine the positions of our detected sources precisely. Our recent observations have discovered several high-redshift dusty galaxies with far-infrared luminosities similar to that of the Milky Way or luminous infrared galaxies but which are undetected in current deep radio, optical and near-infrared images. These remarkable results suggest that a substantial amount of star formation in even the faint submillimeter population may be hidden from rest-frame optical surveys.

  12. Spectrophotometric Redshifts in the Faint Infrared Grism Survey

    NASA Astrophysics Data System (ADS)

    Pharo, John; Malhotra, Sangeeta; Rhoads, James E.

    2016-06-01

    We have combined HST grism spectroscopy and deep broadband imaging to measure spectro-photometric redshifts (SPZs) of faint galaxies. Using a technique pioneered by Ryan et al. 2007, one can combine spectra and photometry to yield an SPZ that is more accurate than pure photometric redshifts, and can probe more deeply than ground-based spectroscopic redshifts. By taking mid-resolution spectra from the HST Faint Infrared Grism Survey (FIGS), SPZs can be found for measurements potentially down to 27th magnitude (the typical brightness of a dwarf galaxy at redshift ˜1.5). A galaxy’s redshift is vital for understanding its place in the growth and evolution of the universe. The measurement of high-accuracy SPZs for FIGS sources will improve the faint-end and high-redshift portions of the luminosity function, and make possible a robust analysis of the FIGS fields for signs of Large Scale Structure (LSS). The improved redshift and distance measurements allowed for the identification of a structure at z=0.83 in one of the FIGS fields.

  13. The faint end of the galaxy luminosity function

    NASA Technical Reports Server (NTRS)

    Treyer, Marie A.; Silk, Joseph

    1994-01-01

    The evolution of the B- and K-band luminosity functions of galaxies is inferred in a relatively model-independent way from deep spectroscopic and photometric surveys. We confirm earlier evidence by Eales for an increase in the amplitude of the B-band galaxy luminosity function at modest redshift (z less than or approx. 0.2). We find in addition that the slope of the faint end of the luminosity function must systematically steepen and progress toward more luminous galaxies with increasing lookback time, assuming that the galaxy redshift distribution may be smoothly extrapolated 2 mag fainter than observed, as suggested by recent gravitational lensing studies. This evolution is shown to be color-dependent, and we predict the near-infrared color distribution of faint galaxies. The luminosity function of blue (B - K less than or approx. 4) galaxies in the range 0.2 less than or approx. z less than or approx. 1 can be represented by a Schechter function with characteristic light density phi(sup *) L(sup *) comparable to that of present-day late-type galaxies, but with a steeper faint end slope alpha approx. 1.4.

  14. Spectral and Temporal Properties of the Ultra-Luminous X-Ray Pulsar in M82 from 15 Years of Chandra Observations and Analysis of the Pulsed Emission Using NuSTAR

    NASA Technical Reports Server (NTRS)

    Brightman, Murray; Harrison, Fiona; Walton, Dominic J.; Fuerst, Felis; Zezas, Andreas; Bachetti, Matteo; Grefenstette, Brian; Ptak, Andrew; Tendulkar, Shriharsh; Yukita, Mihoko

    2016-01-01

    The recent discovery by Bachetti et al. of a pulsar in M82 that can reach luminosities of up to 10(exp 40) erg s(exp -1), a factor of approximately 100 times the Eddington luminosity for a 1.4 solar mass compact object, poses a challenge for accretion physics. In order to better understand the nature of this source and its duty cycle, and in light of several physical models that have been subsequently published, we conduct a spectral and temporal analysis of the 0.58 keV X-ray emission from this source from 15 years of Chandra observations. We analyze 19 ACIS observations where the point-spread function (PSF) of the pulsar is not contaminated by nearby sources. We fit the Chandra spectra of the pulsar with a power-law model and a disk blackbody model, subjected to interstellar absorption in M82. We carefully assess for the effect of pile-up in our observations, where four observations have a pile-up fraction of 10, which we account for during spectral modeling with a convolution model. When fitted with a power-law model, the average photon index when the source is at high luminosity (LX greater than 10(exp 39) erg s(exp -1) is equal to gamma 1.33 +/-.0.15. For the disk blackbody model, the average temperature is T(sub in) 3.24 +/- 0.65 keV, the spectral shape being consistent with other luminous X-ray pulsars. We also investigated the inclusion of a soft excess component and spectral break, finding that the spectra are also consistent with these features common to luminous X-ray pulsars. In addition, we present spectral analysis from NuSTAR over the 3-50 keV range where we have isolated the pulsed component. We find that the pulsed emission in this band is best fit by a power-law with a high-energy cutoff, where gamma is equal to 0.6 +/- 0.3 and E(sub C) is equal to 14(exp +5) (sub -3)) keV. While the pulsar has previously been identified as a transient, we find from our longer-baseline study that it has been remarkably active over the 15-year period, where for 9

  15. Spectral and Temporal Properties of the Ultra-Luminous X-Ray Pulsar in M82 from 15 Years of Chandra Observations and Analysis of the Pulsed Emission Using NuSTAR

    NASA Technical Reports Server (NTRS)

    Brightman, Murray; Harrison, Fiona; Walton, Dominic J.; Fuerst, Felis; Zezas, Andreas; Bachetti, Matteo; Grefenstette, Brian; Ptak, Andrew; Tendulkar, Shriharsh; Yukita, Mihoko

    2016-01-01

    The recent discovery by Bachetti et al. of a pulsar in M82 that can reach luminosities of up to 10(exp 40) erg s(exp -1), a factor of approximately 100 times the Eddington luminosity for a 1.4 solar mass compact object, poses a challenge for accretion physics. In order to better understand the nature of this source and its duty cycle, and in light of several physical models that have been subsequently published, we conduct a spectral and temporal analysis of the 0.58 keV X-ray emission from this source from 15 years of Chandra observations. We analyze 19 ACIS observations where the point-spread function (PSF) of the pulsar is not contaminated by nearby sources. We fit the Chandra spectra of the pulsar with a power-law model and a disk blackbody model, subjected to interstellar absorption in M82. We carefully assess for the effect of pile-up in our observations, where four observations have a pile-up fraction of 10, which we account for during spectral modeling with a convolution model. When fitted with a power-law model, the average photon index when the source is at high luminosity (LX greater than 10(exp 39) erg s(exp -1) is equal to gamma 1.33 +/-.0.15. For the disk blackbody model, the average temperature is T(sub in) 3.24 +/- 0.65 keV, the spectral shape being consistent with other luminous X-ray pulsars. We also investigated the inclusion of a soft excess component and spectral break, finding that the spectra are also consistent with these features common to luminous X-ray pulsars. In addition, we present spectral analysis from NuSTAR over the 3-50 keV range where we have isolated the pulsed component. We find that the pulsed emission in this band is best fit by a power-law with a high-energy cutoff, where gamma is equal to 0.6 +/- 0.3 and E(sub C) is equal to 14(exp +5) (sub -3)) keV. While the pulsar has previously been identified as a transient, we find from our longer-baseline study that it has been remarkably active over the 15-year period, where for 9

  16. Spectral and Temporal Properties of the Ultraluminous X-Ray Pulsar in M82 from 15 years of Chandra Observations and Analysis of the Pulsed Emission Using NuSTAR

    NASA Astrophysics Data System (ADS)

    Brightman, Murray; Harrison, Fiona; Walton, Dominic J.; Fuerst, Felix; Hornschemeier, Ann; Zezas, Andreas; Bachetti, Matteo; Grefenstette, Brian; Ptak, Andrew; Tendulkar, Shriharsh; Yukita, Mihoko

    2016-01-01

    The recent discovery by Bachetti et al. of a pulsar in M82 that can reach luminosities of up to 1040 erg s-1, a factor of ˜100 times the Eddington luminosity for a 1.4 M⊙ compact object, poses a challenge for accretion physics. In order to better understand the nature of this source and its duty cycle, and in light of several physical models that have been subsequently published, we conduct a spectral and temporal analysis of the 0.5-8 keV X-ray emission from this source from 15 years of Chandra observations. We analyze 19 ACIS observations where the point-spread function (PSF) of the pulsar is not contaminated by nearby sources. We fit the Chandra spectra of the pulsar with a power-law model and a disk blackbody model, subjected to interstellar absorption in M82. We carefully assess for the effect of pile-up in our observations, where four observations have a pile-up fraction of >10%, which we account for during spectral modeling with a convolution model. When fitted with a power-law model, the average photon index when the source is at high luminosity (LX > 1039 erg s-1) is Γ = 1.33 ± 0.15. For the disk blackbody model, the average temperature is Tin = 3.24 ± 0.65 keV, the spectral shape being consistent with other luminous X-ray pulsars. We also investigated the inclusion of a soft excess component and spectral break, finding that the spectra are also consistent with these features common to luminous X-ray pulsars. In addition, we present spectral analysis from NuSTAR over the 3-50 keV range where we have isolated the pulsed component. We find that the pulsed emission in this band is best fit by a power-law with a high-energy cutoff, where Γ = 0.6 ± 0.3 and {E}{{C}}={14}-3+5 keV. While the pulsar has previously been identified as a transient, we find from our longer-baseline study that it has been remarkably active over the 15-year period, where for 9/19 (47%) observations that we analyzed, the pulsar appears to be emitting at a luminosity in excess of

  17. Was Fritz Zwicky's "Type V" SN 1961V a Genuine Supernova?

    NASA Astrophysics Data System (ADS)

    Filippenko, Alexei V.; Barth, Aaron J.; Bower, Geoffrey C.; Ho, Luis C.; Stringfellow, Guy S.; Goodrich, Robert W.; Porter, Alain C.

    1995-11-01

    In 1989, Goodrich and collaborators suggested that SN 1961V, a very peculiar Type II (Zwicky's "Type V") supernova, was not the final explosion of a star at the end of its life, but rather the giant eruption of a massive, luminous blue variable, like n Car. To test this hypothesis, we have used the Hubble Space Telescope to obtain optical images of the site of SN 1961V. There is a cluster of faint (V ~ 24-25 mag), blue [(V-I)_0_ = -0.4-0.5 mag] stars around the general location of the supernova. We also see a very faint (V = 25.6 +/- 0.3 mag), much redder [(V-I)_0_ = 1.7 mag] star barely resolved from one of the blue stars. Its brightness and colors are consistent with those of a highly reddened O-type star, as predicted by Goodrich et al. Moreover, it is the star formally closest to the known radio position of SN 1961V; the coordinates are identical, to within the uncertainties. Thus, we tentatively identify this as the post eruption star of SN 1961V; it survived the giant eruption, which was not a genuine supernova, and it is now red due to a substantial envelope of dust (A_V_ ~ 4.1 mag). However, the current data do not allow us to eliminate the possibility that this star is an unrelated red supergiant or a peculiar supernova remnant. Alternatively, the blue object adjacent to it may be the actual post- eruption star of SN 1961V. If so, the envelope of dust is not as thick: A_V_ ~ 2.2-3.2 mag, but perhaps somewhat larger if the object's colors are significantly affected by a blue light echo of SN 1961V.

  18. Supernova 1987A: The Supernova of a Lifetime

    NASA Astrophysics Data System (ADS)

    Kirshner, Robert

    2017-01-01

    Supernova 1987A, the brightest supernova since Kepler's in 1604, was detected 30 years ago at a distance of 160 000 light years in the Large Magellanic Cloud, a satellite galaxy of the Milky Way. Visible with the naked eye and detected with the full range of technology constructed since Kepler's time, SN 1987A has continued to be a rich source of empirical information to help understand supernova explosions and their evolution into supernova remnants. While the light output has faded by a factor of 10 000 000 over those 30 years, instrumentation, like the Hubble Space Telescope, the Chandra X-ray Observatory, and the Atacama Large Millimeter Array has continued to improve so that this supernova continues to be visible in X-rays, ultraviolet light, visible light, infrared light and in radio emission. In this review, I will sketch what has been learned from these observations about the pre-supernova star and its final stages of evolution, the explosion physics, the energy sources for emission, and the shock physics as the expanding debris encounters the circumstellar ring that was created about 20 000 years before the explosion. Today, SN 1987A is making the transition to a supernova remnant- the energetics are no longer dominated by the radioactive elements produced in the explosion, but by the interaction of the expanding debris with the surrounding gas. While we are confident that the supernova explosion had its origin in gravitational collapse, careful searches for a compact object at the center of the remnant place upper limits of a few solar luminosities on that relic. Support for HST GO programs 13401 and 13405 was provided by NASA through grants from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  19. Thermonuclear supernova models, and observations of Type Ia supernovae

    SciTech Connect

    Bravo, E.; Garcia-Senz, D.; Badenes, C.

    2005-10-21

    In this paper, we review the present state of theoretical models of thermonuclear supernovae, and compare their predictions with the constraints derived from observations of Type Ia supernovae. The diversity of explosion mechanisms usually found in one-dimensional simulations is a direct consequence of the impossibility to resolve the flame structure under the assumption of spherical symmetry. Spherically symmetric models have been successful in explaining many of the observational features of Type Ia supernovae, but they rely on two kinds of empirical models: one that describes the behaviour of the flame on the scales unresolved by the code, and another that takes account of the evolution of the flame shape. In contrast, three-dimensional simulations are able to compute the flame shape in a self-consistent way, but they still need a model for the propagation of the flame in the scales unresolved by the code. Furthermore, in three dimensions the number of degrees of freedom of the initial configuration of the white dwarf at runaway is much larger than in one dimension. Recent simulations have shown that the sensitivity of the explosion output to the initial conditions can be extremely large. New paradigms of thermonuclear supernovae have emerged from this situation, as the Pulsating Reverse Detonation. The resolution of all these issues must rely on the predictions of observational properties of the models, and their comparison with current Type Ia supernova data, including X-ray spectra of Type Ia supernova remnants.

  20. Particle-based ablation model for faint meteors

    NASA Astrophysics Data System (ADS)

    Stokan, E.; Campbell-Brown, M.

    2014-07-01

    Modeling the ablation of meteoroids as they enter the atmosphere is a way of determining their physical structure and elemental composition. This can provide insight into the structure of parent bodies when combined with an orbit computed from observations. The Canadian Automated Meteor Observatory (CAMO) is a source of new, high-resolution observations of faint meteors [1]. These faint objects tend to have pre-atmospheric masses around 10^{-5} kg, corresponding to a radius of 1 mm. A wide-field camera with a 28° field of view provides guidance to a high-resolution camera that tracks meteors in flight with 1.5° field of view. Meteors are recorded with a scale of 4 m per pixel at a range of 135 km, at 110 frames per second, allowing us to investigate detailed meteor morphology. This serves as an important new constraint for ablation models, in addition to meteor brightness (lightcurves) and meteoroid deceleration. High-resolution observations of faint meteors have revealed that contemporary ablation models are not able to predict meteor morphology, even while matching the observed lightcurve and meteoroid deceleration [2]. This implies that other physical processes, in addition to fragmentation, must be considered for faint meteor ablation. We present a new, particle-based approach to modeling the ablation of small meteoroids. In this model, we simulate the collisions between atmospheric particles and the meteoroid to determine the rate of evaporation and deceleration. Subsequent collisions simulated between evaporated meteoroid particles and ambient atmospheric particles then produce light that would be observed by high-resolution cameras. Preliminary results show simultaneous agreement with meteor morphology, lightcurves, and decelerations recorded with CAMO. A sample comparison of simulated and observed meteor morphology is given in the attached figure. Several meteoroids are well-represented as solid, stony bodies, but some require modeling as a dustball [3

  1. A massive star origin for an unusual helium-rich supernova in an elliptical galaxy.

    PubMed

    Kawabata, K S; Maeda, K; Nomoto, K; Taubenberger, S; Tanaka, M; Deng, J; Pian, E; Hattori, T; Itagaki, K

    2010-05-20

    The unusual helium-rich (type Ib) supernova SN 2005E is distinguished from all supernovae hitherto observed by its faint and rapidly fading light curve, prominent calcium lines in late-phase spectra and lack of any mark of recent star formation near the supernova location. These properties are claimed to be explained by a helium detonation in a thin surface layer of an accreting white dwarf. Here we report that the observed properties of SN 2005cz, which appeared in an elliptical galaxy, resemble those of SN 2005E. We argue that these properties are best explained by a core-collapse supernova at the low-mass end (8-12 solar masses) of the range of massive stars that explode. Such a low-mass progenitor lost its hydrogen-rich envelope through binary interaction, had very thin oxygen-rich and silicon-rich layers above the collapsing core, and accordingly ejected a very small amount of radioactive (56)Ni and oxygen. Although the host galaxy NGC 4589 is an elliptical, some studies have revealed evidence of recent star-formation activity, consistent with the core-collapse model.

  2. Supernova Candidate from CSS

    NASA Astrophysics Data System (ADS)

    Drake, A. J.; Mahabal, A.; Djorgovski, S. G.; Williams, R.; Graham, M. J.; Christensen, E.; Beshore, E. C.; Larson, S. M.

    2008-06-01

    We have detected a likely Supernova in Catalina Sky Survey images from 11 Jun 2008 UT. The object has the following parameters:

    CSS080611:121642+410211 2008-06-11 UT 04:52:41 RA 12:16:41.53 Dec 41:02:11.2 Mag 17.7 Type SN
    The object is near the edge of galaxy SDSSJ121642.18+410223.7 (z = 0.039, mags: g~ 17.9, r~17.6, i~17.3, z~17.5).

  3. The Vela Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Raymond, John C.

    We wish to obtain both emission and absorption line observations of the Vela Supernova remnant. The filament we wish to study in emission is the brightest filament in the SNR, so it will provide a spectrum twice the quality of any in existence. It is also located at the edge of an unusual bulge in the SNR, and it can be used to test the level of departure from pressure equilibrium in the remnant, which is useful as a test of evaporative models of SNR evolution. The absorption line studies will look for evidence of the drastically unstable behavior of shocks above 150 km/s predicted by Innes and Giddings. Four of the stars studied by Jenkins, Silk and Wallerstein showed marginal evidence for two positive or two negative high velocity components. If these multiple velocity components are confirmed, they support the secondary shock predictions of Innes and Giddings.

  4. Pulsars and supernova remnants

    SciTech Connect

    Narayan, R.; Schaudt, K.J.

    1988-02-01

    With the recent discovery of the pulsar PSR 1951 + 22 in CTB 80, four pulsars are now known in supernova remnants (SNRs) of the plerion and composite classes. It is argued that this success rate of pulsar detections implies that young fast pulsars have long fan-beams that enable them to be seen from most directions. Based on calculations that use a pulsar luminosity model and allow for selection effects, it is suggested that the best SNRs for future pulsar searches are 3C 58, MSH 11-62, G24.7 + 0.6, and MSH 15-56. It is also concluded that the failure to detect pulsars in shell SNRs implies either that there are no pulsars in these SNRs or that the pulsars are unusually weak, possibly due to slow rotation or weak magnetic fields. 25 references.

  5. Variety in Supernovae

    NASA Astrophysics Data System (ADS)

    Turatto, Massimo; Benetti, Stefano; Cappellaro, Enrico

    Detailed observations of a growing number of supernovae have determined a bloom of new peculiar events. In this paper we take a short tour through the SN diversity and discuss some important, physical issues related to it. Because of the role of SN Ia in determining the cosmological parameters, it is crucial to understand the physical origin of even subtle, observed differences. An important issue is also the reddening correction. We believe that the measure of interstellar lines on medium resolution spectra of SNe can be used to derive lower limits on the interstellar extinction. A few physical parameters of the progenitor, namely radius, mass, density structure and angular momentum, may explain most of the diversity of core-collapse events. In addition, if the ejecta expand into a dense circumstellar medium the ejecta-CSM interaction may dominate the observed outcome and provide a mean to probe the mass loss history of the SN progenitor in the last stages of its evolution.

  6. Dimming supernovae without cosmic acceleration.

    PubMed

    Csáki, Csaba; Kaloper, Nemanja; Terning, John

    2002-04-22

    We present a simple model where photons propagating in extragalactic magnetic fields can oscillate into very light axions. The oscillations may convert some of the photons, departing a distant supernova, into axions, making the supernova appear dimmer and hence more distant than it really is. Averaging over different configurations of the magnetic field we find that the dimming saturates at about one-third of the light from the supernovae at very large redshifts. This results in a luminosity distance versus redshift curve almost indistinguishable from that produced by the accelerating Universe, if the axion mass and coupling scale are m approximately 10(-16) eV, M approximately 4 x 10(11) GeV. This phenomenon may be an alternative to the accelerating Universe for explaining supernova observations.

  7. Supernova olivine from cometary dust

    NASA Technical Reports Server (NTRS)

    Messenger, Scott; Keller, Lindsay P.; Lauretta, Dante S.

    2005-01-01

    An interplanetary dust particle contains a submicrometer crystalline silicate aggregate of probable supernova origin. The grain has a pronounced enrichment in 18O/16O (13 times the solar value) and depletions in 17O/16O (one-third solar) and 29Si/28Si (<0.8 times solar), indicative of formation from a type II supernova. The aggregate contains olivine (forsterite 83) grains <100 nanometers in size, with microstructures that are consistent with minimal thermal alteration. This unusually iron-rich olivine grain could have formed by equilibrium condensation from cooling supernova ejecta if several different nucleosynthetic zones mixed in the proper proportions. The supernova grain is also partially encased in nitrogen-15-rich organic matter that likely formed in a presolar cold molecular cloud.

  8. Hardy Star Survives Supernova Blast

    NASA Image and Video Library

    2014-03-20

    This composite image contains data from Chandra (purple) that provides evidence for the survival of a companion star from the blast of a supernova explosion. Chandra's X-rays reveal a point-like source in the supernova remnant at the location of a massive star. The data suggest that mass is being pulled away from the massive star towards a neutron star or a black hole companion. If confirmed, this would be only the third binary system containing both a massive star and a neutron star or black hole ever found in the aftermath of a supernova. This supernova remnant is found embedded in clouds of ionized hydrogen, which are shown in optical light (yellow and cyan) from the MCELS survey, along with additional optical data from the DSS (white).

  9. Supernova Remnant in 3-D

    NASA Image and Video Library

    2009-01-06

    For the first time, a multiwavelength three-dimensional reconstruction of a supernova remnant has been created. This visualization of Cassiopeia A, or Cas A, the result of an explosion approximately 330 years ago, uses data from several NASA telescopes.

  10. Supernova olivine from cometary dust.

    PubMed

    Messenger, Scott; Keller, Lindsay P; Lauretta, Dante S

    2005-07-29

    An interplanetary dust particle contains a submicrometer crystalline silicate aggregate of probable supernova origin. The grain has a pronounced enrichment in 18O/16O (13 times the solar value) and depletions in 17O/16O (one-third solar) and 29Si/28Si (<0.8 times solar), indicative of formation from a type II supernova. The aggregate contains olivine (forsterite 83) grains <100 nanometers in size, with microstructures that are consistent with minimal thermal alteration. This unusually iron-rich olivine grain could have formed by equilibrium condensation from cooling supernova ejecta if several different nucleosynthetic zones mixed in the proper proportions. The supernova grain is also partially encased in nitrogen-15-rich organic matter that likely formed in a presolar cold molecular cloud.

  11. Spectroscopic classification of supernova candidates

    NASA Astrophysics Data System (ADS)

    Hodgkin, S. T.; Hall, A.; Fraser, M.; Campbell, H.; Wyrzykowski, L.; Kostrzewa-Rutkowska, Z.; Pietro, N.

    2014-09-01

    We report the spectroscopic classification of four supernovae at the 2.5m Isaac Newton Telescope on La Palma, using the Intermediate Dispersion Spectrograph and the R300V grating (3500-8000 Ang; ~6 Ang resolution).

  12. Fritz Zwicky: Novae Become Supernovae

    NASA Astrophysics Data System (ADS)

    Koenig, T.

    2005-12-01

    The Swiss physicist Fritz Zwicky (1898-1974) dabbled in a plethora of disciplines, including astronomy and astrophysics. His dabblings were with vested interest and he has left quite an impact. His first great success was his nova research. In the early 1930s, while supermarkets and Superman were flying, he labelled the distinctly brighter nova Supernova. It had been believed that novae were the collision of two stars, but Zwicky came to recognize supernovae as a phenomenon quite distinct from novae. He and Walter Baade explained supernova by melding astronomy and physics and in this aim they created neutron stars, explained the origin of cosmic rays, initiated the first sky survey, and confirmed that a number of historical novae were indeed supernovae. This was truly an important work in the history of astrophysics.

  13. Simulation of Kepler Supernova Explosion

    NASA Image and Video Library

    This video shows a simulation of the Kepler supernova as it interacts with material expelled by the giant star companion to the white dwarf before the latter exploded. It was assumed that the bulk ...

  14. SUB-CHANDRASEKHAR MASS MODELS FOR SUPERNOVAE

    SciTech Connect

    Woosley, S. E.; Kasen, Daniel

    2011-06-10

    For carbon-oxygen white dwarfs accreting hydrogen or helium at rates in the range {approx}(1-10) x 10{sup -8} M{sub sun} yr{sup -1}, a variety of explosive outcomes is possible well before the star reaches the Chandrasekhar mass. These outcomes are surveyed for a range of white dwarf masses (0.7-1.1 M{sub sun}), accretion rates ((1-7) x 10{sup -8} M{sub sun} yr{sup -1}), and initial white dwarf temperatures (0.01 and 1 L{sub sun}). The results are particularly sensitive to the convection that goes on during the last few minutes before the explosion. Unless this convection maintains a shallow temperature gradient and unless the density is sufficiently high, the accreted helium does not detonate. Below a critical helium ignition density, which we estimate to be (5-10) x 10{sup 5} g cm{sup -3}, either helium novae or helium deflagrations result. The hydrodynamics, nucleosynthesis, light curves, and spectra of a representative sample of detonating and deflagrating models are explored. Some can be quite faint indeed, powered at peak for a few days by the decay of {sup 48}Cr and {sup 48}V. Only the hottest, most massive white dwarfs considered with the smallest helium layers, show reasonable agreement with the light curves and spectra of common Type Ia supernovae (SNe Ia). For the other models, especially those involving lighter white dwarfs, the helium shell mass exceeds 0.05 M{sub sun} and the mass of the {sup 56}Ni that is synthesized exceeds 0.01 M{sub sun}. These explosions do not look like ordinary SNe Ia or any other frequently observed transient.

  15. Stellar Death by Weak or Failed Supernovae

    NASA Astrophysics Data System (ADS)

    Adams, Scott Michael

    Core collapse supernovae (SNe) - the violent deaths of massive stars - are among the most luminous events in the Universe and play an important role in galaxy evolution and the production and distribution of the heavy elements necessary for planet formation and life. Despite decades of effort it is still unclear how these SNe explode. While SNe have been identified with close to the maximum theoretically possible energies, the lower bounds on SN energies and luminosities are less well-constrained. There is also no requirement that the core collapse always results in a successful SN explosion. In fact, there are multiple lines of evidence that suggest that 10 - 30% of core collapses might result in failed SNe, forming a black hole without a dramatic external explosion. The primary focus of this dissertation is to explore the lower bounds of the possible explosion energies and luminosities of core-collapse SNe. I discuss three observational strategies to help understand how massive stars die. Due to the development of advanced facilities for the detection of neutrinos and gravitational waves, the next Galactic SN will offer an unprecedented opportunity to study the SN explosion mechanism. To aid preparations for this event, I model the distance, extinction, and magnitude probability distributions for a Galactic SN, its shock breakout radiation, and progenitor. I also analyze the archetypes of two types of SN "impostors" and show that they may be genuine SNe, but with energies lower than previously observed. I present results from an ambitious survey that has been monitoring a million massive stars for 7 years to search for failed SNe. I follow-up the first identified failed SN candidate and find that the massive stellar progenitor appears to have vanished leaving behind a faint, fading IR source that may be due to fallback accretion onto a newly formed black hole. Finally, I set new constraints on the fraction of core collapses that result in failed SNe.

  16. Establishing a Network of faint DA white dwarfs as Spectrophotometric Standards

    NASA Astrophysics Data System (ADS)

    Saha, Abhijit; Narayan, Gautham; Holberg, Jay; Matheson, Thomas; Olszewski, Edward; Stubbs, Christopher; Bohlin, Ralph; Sabbi, Elena; Deustua, Susana; Rest, Armin; Axelrod, Tim; MacKenty, John W.; Camarota, Larry; Gilliland, Ron

    2015-08-01

    Systematic uncertainties in photometric calibration are the dominant source of error in current type Ia supernova dark energy studies, as well as other forefront cosmology efforts, e.g. photo-redshift determinations for weak lensing mass tomography. Current and next-generation ground-based all-sky surveys require a network of calibration stars with 1) known SEDs (to properly and unambiguously take into account filter differences), and 2) that are on a common photometric zeropoint scale across the sky to sub-percent accuracy. We are using a combination of HST panchromatic photometry and ground based spectroscopy to establish such an essential network of faint primary photometric standards, exploiting the well-understood spectral energy distributions of DA white dwarf stars that are free from the complications of observing through the Earth's time-variable atmosphere. The Balmer features in the spectra are used to deduce the two parameters (temperature and log(g)) from which we model the spectral energy distribution (SED) from these stars which have pure hydrogen atmospheres. By comparing against panchromatic broadband HST photometry, and allowing for an achromatic zero-point adjustment and mild scaling of the interstellar reddening, we find that model prediction and observation agree to a few milli-mag. By combining the zero-point and reddening adjustments with the modeled SED, for each star we obtain the incident SED above the terrestrial atmosphere, thus establishing these objects as spectrophotometric standards. We are pursuing 23 objects between 16 and 19 mag spread over the sky uniformly around the equator and northern mid-latitudes, with plans to extend this to southern latitudes. This precision photometric heritage from HST will benefit essentially all existing and upcoming survey projects, and in prticular, directly addresses one of the current barriers to understanding the nature of dark energy.

  17. Supernova Modeling: Progress and Challenges

    SciTech Connect

    Cardall, Christian Y

    2012-01-01

    Neutrinos play important roles in the pre-collapse evolution, explosion, and aftermath of core-collapse supernovae. Detected neutrino signals from core-collapse supernovae would provide insight into the explosion mechanism and unknown neutrino mixing parameters. Achieving these goals requires large-scale, multiphysics simulations. For many years, several groups have performed such simulations with increasing realism. Current simulations and plans for future work of the Oak Ridge group are described.

  18. SUPERNOVA EXPLOSIONS OF SUPER-ASYMPTOTIC GIANT BRANCH STARS: MULTICOLOR LIGHT CURVES OF ELECTRON-CAPTURE SUPERNOVAE

    SciTech Connect

    Tominaga, Nozomu; Blinnikov, Sergei I.; Nomoto, Ken'ichi E-mail: Sergei.Blinnikov@itep.ru

    2013-07-01

    An electron-capture supernova (ECSN) is a core-collapse supernova (CCSN) explosion of a super-asymptotic giant branch (SAGB) star with a main-sequence mass M{sub MS} {approx} 7-9.5 M{sub Sun }. The explosion takes place in accordance with core bounce and subsequent neutrino heating and is a unique example successfully produced by first-principle simulations. This allows us to derive a first self-consistent multicolor light curve of a CCSN. Adopting the explosion properties derived by the first-principle simulation, i.e., the low explosion energy of 1.5 Multiplication-Sign 10{sup 50} erg and the small {sup 56}Ni mass of 2.5 Multiplication-Sign 10{sup -3} M{sub Sun }, we perform a multi-group radiation hydrodynamics calculation of ECSNe and present multicolor light curves of ECSNe of SAGB stars with various envelope masses and hydrogen abundances. We demonstrate that a shock breakout has a peak luminosity of L {approx} 2 Multiplication-Sign 10{sup 44} erg s{sup -1} and can evaporate circumstellar dust up to R {approx} 10{sup 17} cm for the case of carbon dust, that the plateau luminosity and plateau duration of ECSNe are L {approx} 10{sup 42} erg s{sup -1} and t {approx} 60-100 days, respectively, and that a plateau is followed by a tail with a luminosity drop by {approx}4 mag. The ECSN shows a bright and short plateau that is as bright as typical Type II plateau supernovae, and a faint tail that might be influenced by the spin-down luminosity of a newborn pulsar. Furthermore, the theoretical models are compared with ECSN candidates: SN 1054 and SN 2008S. We find that SN 1054 shares the characteristics of the ECSNe. For SN 2008S, we find that its faint plateau requires an ECSN model with a significantly low explosion energy of E {approx} 10{sup 48} erg.

  19. Ozone Depletion from Nearby Supernovae

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil; Laird, Claude M.; Jackman, Charles H.; Cannizzo, John K.; Mattson, Barbara J.; Chen, Wan; Bhartia, P. K. (Technical Monitor)

    2002-01-01

    Estimates made in the 1970's indicated that a supernova occurring within tens of parsecs of Earth could have significant effects on the ozone layer. Since that time improved tools for detailed modeling of atmospheric chemistry have been developed to calculate ozone depletion, and advances have been made also in theoretical modeling of supernovae and of the resultant gamma ray spectra. In addition, one now has better knowledge of the occurrence rate of supernovae in the galaxy, and of the spatial distribution of progenitors to core-collapse supernovae. We report here the results of two-dimensional atmospheric model calculations that take as input the spectral energy distribution of a supernova, adopting various distances from Earth and various latitude impact angles. In separate simulations we calculate the ozone depletion due to both gamma rays and cosmic rays. We find that for the combined ozone depletion from these effects roughly to double the 'biologically active' UV flux received at the surface of the Earth, the supernova must occur at approximately or less than 8 parsecs.

  20. First supernova companion star found

    NASA Astrophysics Data System (ADS)

    2004-01-01

    Supernova 1993J exploding hi-res Size hi-res: 222 kb Credits: ESA and Justyn R. Maund (University of Cambridge) Supernova 1993J exploding (artist’s impression) New observations with the Hubble Space Telescope allow a look into a supernova explosion under development. In this artist’s view the red supergiant supernova progenitor star (left) is exploding after having transferred about 10 solar masses of hydrogen gas to the blue companion star (right). This interaction process happened over about 250 years and affected the supernova explosion to such an extent that SN 1993J was later known as one of the most peculiar supernovae ever seen. Supernova 1993J exploding hi-res Size hi-res: 4200 kb Credits: ESA and Justyn R. Maund (University of Cambridge) The site of the Supernova 1993J explosion A virtual journey into one of the spiral arms of the grand spiral Messier 81 (imaged with the Isaac Newton Telescope on La Palma, left) reveals the superb razor-sharp imaging power of the NASA/ESA Hubble Space Telescope (Hubble’s WFPC2 instrument, below). The close-up (with Hubble’s ACS, to the right) is centred on the newly discovered companion star to Supernova 1993J that itself is no longer visible. The quarter-circle around the supernova companion is a so-called light echo originating from sheets of dust in the galaxy reflecting light from the original supernova explosion. Supernova 1993J explosing site hi-res Size hi-res: 1502 kb Credits: ESA and Justyn R. Maund (University of Cambridge) Close-up of the Supernova 1993J explosion site (ACS/HRC image) This NASA/ESA Hubble Space Telescope image shows the area in Messier 81 where Supernova 1993J exploded. The companion to the supernova ‘mother star’ that remains after the explosion is seen in the centre of the image. The image is taken with Hubble’s Advanced Camera for Surveys and is a combination of four exposures taken with ACS’ High Resolution Camera. The exposures were taken through two near-UV filters (250W

  1. Things begin to happen around Supernova 1987A

    NASA Astrophysics Data System (ADS)

    1994-01-01

    -nebula'', only two arcsec across, surrounding SN 1987A; it was interpreted as interactions between pre-existing circumstellar material and a shell of matter which was thrown off a few thousand years ago when a red giant star evolved into the blue star that eventually exploded. The best images of this nebula were first obtained by the Hubble Space Telescope in 1990. There are also faint outer nebular loops around SN 1987A. It is thought that they trace the outer rim of a large bubble that was formed by the outflowing ``wind'' of matter from the star that later exploded. During the past years, astronomers working at large telescopes in the southern hemisphere have conducted unsuccessful searches for a pulsar inside SN 1987A. Although most theories predict the emergence of a very compact object at the centre of a supernova, even very detailed investigations reaching very faint light levels have so far not been able to prove the existence of such an object in SN 1987A. RECENT CHANGES IN THE RING But the development of SN 1987A is not yet over. After the first seven years, it is now about to enter a new phase. In a Circular of the International Astronomical Union, astronomers Li-Fan Wang (Beijing Observatory) and E. Joseph Wampler (European Southern Observatory) have just reported that changes are seen in the inner ring nebula around SN 1987A when the latest NTT observations are compared with those carried out over the past two years. The distribution of light along the ring has recently changed dramatically. It is now found to be gradually increasing in brightness at several locations. This is most easily seen on images obtained in the light of ionised nitrogen which enhances the contrast between the SN 1987A ring nebulae and their surroundings. Following computer sharpening of December 1993 CCD pictures to a resolution of 0.2 arcseconds - corresponding to the angle subtended by a coin of 1 cm diameter at a distance of 10 km - it is clear that the ring emission regions are now

  2. The Search for Lensed Supernovae

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2017-01-01

    Type Ia supernovae that have multiple images due to gravitational lensing can provide us with a wealth of information both about the supernovae themselves and about our surrounding universe. But how can we find these rare explosions?Clues from Multiple ImagesWhen light from a distant object passes by a massive foreground galaxy, the galaxys strong gravitational pull can bend the light, distorting our view of the backgroundobject. In severe cases, this process can cause multiple images of the distant object to appear in the foreground lensing galaxy.An illustration of gravitational lensing. Light from the distant supernova is bent as it passes through a giant elliptical galaxy in the foreground, causing multiple images of the supernova to appear to be hosted by the elliptical galaxy. [Adapted from image by NASA/ESA/A. Feild (STScI)]Observations of multiply-imaged Type Ia supernovae (explosions that occur when white dwarfs in binary systems exceed their maximum allowed mass) could answer a number of astronomical questions. Because Type Ia supernovae are standard candles, distant, lensed Type Ia supernovae can be used to extend the Hubble diagram to high redshifts. Furthermore, the lensing time delays from the multiply-imaged explosion can provide high-precision constraints on cosmological parameters.The catch? So far, weve only found one multiply-imaged Type Ia supernova: iPTF16geu, discovered late last year. Were going to need a lot more of them to develop a useful sample! So how do we identify themutiply-imaged Type Ias among the many billions of fleeting events discovered in current and future surveys of transients?Searching for AnomaliesAbsolute magnitudes for Type Ia supernovae in elliptical galaxies. None are expected to be above -20 in the B band, so if we calculate a magnitude for a Type Ia supernova thats larger than this, its probably not hosted by the galaxy we think it is! [Goldstein Nugent 2017]Two scientists from University of California, Berkeley and

  3. Distribution of Faint Atomic Gas in Hickson Compact Groups

    NASA Astrophysics Data System (ADS)

    Borthakur, Sanchayeeta; Yun, Min Su; Verdes-Montenegro, Lourdes; Heckman, Timothy M.; Zhu, Guangtun; Braatz, James A.

    2015-10-01

    We present 21 cm H i observations of four Hickson Compact Groups (HCGs) with evidence for a substantial intragroup medium using the Robert C. Byrd Green Bank Telescope (GBT). By mapping H i emission in a region of 25‧ × 25‧ (140-650 kpc) surrounding each HCG, these observations provide better estimates of H i masses. In particular, we detected 65% more H i than that detected in the Karl G. Jansky Very Large Array (VLA) imaging of HCG 92. We also identify whether the diffuse gas has the same spatial distribution as the high surface brightness (HSB) H i features detected in the VLA maps of these groups by comparing the H i strengths between the observed and modeled masses based on VLA maps. We found that the H i observed with the GBT has a similar spatial distribution to the HSB structures in HCG 31 and HCG 68. Conversely, the observed H i distributions in HCG 44 and HCG 92 were extended and showed significant offsets from the modeled masses. Most of the faint gas in HCG 44 lies to the northeast-southwest region and in HCG 92 lies in the northwest region of their respective groups. The spatial and dynamical similarities between the total (faint+HSB) and the HSB H i indicate that the faint gas is of tidal origin. We found that the gas will survive ionization by the cosmic UV background and the escaping ionizing photons from the star-forming regions and stay primarily neutral for at least 500 Myr.

  4. DISTRIBUTION OF FAINT ATOMIC GAS IN HICKSON COMPACT GROUPS

    SciTech Connect

    Borthakur, Sanchayeeta; Heckman, Timothy M.; Zhu, Guangtun; Yun, Min Su; Verdes-Montenegro, Lourdes; Braatz, James A.

    2015-10-10

    We present 21 cm H i observations of four Hickson Compact Groups (HCGs) with evidence for a substantial intragroup medium using the Robert C. Byrd Green Bank Telescope (GBT). By mapping H i emission in a region of 25′ × 25′ (140–650 kpc) surrounding each HCG, these observations provide better estimates of H i masses. In particular, we detected 65% more H i than that detected in the Karl G. Jansky Very Large Array (VLA) imaging of HCG 92. We also identify whether the diffuse gas has the same spatial distribution as the high surface brightness (HSB) H i features detected in the VLA maps of these groups by comparing the H i strengths between the observed and modeled masses based on VLA maps. We found that the H i observed with the GBT has a similar spatial distribution to the HSB structures in HCG 31 and HCG 68. Conversely, the observed H i distributions in HCG 44 and HCG 92 were extended and showed significant offsets from the modeled masses. Most of the faint gas in HCG 44 lies to the northeast–southwest region and in HCG 92 lies in the northwest region of their respective groups. The spatial and dynamical similarities between the total (faint+HSB) and the HSB H i indicate that the faint gas is of tidal origin. We found that the gas will survive ionization by the cosmic UV background and the escaping ionizing photons from the star-forming regions and stay primarily neutral for at least 500 Myr.

  5. How Bright Can Supernovae Get?

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-04-01

    Supernovae enormous explosions associated with the end of a stars life come in a variety of types with different origins. A new study has examined how the brightest supernovae in the Universe are produced, and what limits might be set on their brightness.Ultra-Luminous ObservationsRecent observations have revealed many ultra-luminous supernovae, which haveenergies that challenge our abilities to explain them usingcurrent supernova models. An especially extreme example is the 2015 discovery of the supernova ASASSN-15lh, which shone with a peak luminosity of ~2*1045 erg/s, nearly a trillion times brighter than the Sun. ASASSN-15lh radiated a whopping ~2*1052 erg in the first four months after its detection.How could a supernova that bright be produced? To explore the answer to that question, Tuguldur Sukhbold and Stan Woosley at University of California, Santa Cruz, have examined the different sources that could produce supernovae and calculated upper limits on the potential luminosities ofeach of these supernova varieties.Explosive ModelsSukhbold and Woosley explore multiple different models for core-collapse supernova explosions, including:Prompt explosionA stars core collapses and immediately explodes.Pair instabilityElectron/positron pair production at a massive stars center leads to core collapse. For high masses, radioactivity can contribute to delayed energy output.Colliding shellsPreviously expelled shells of material around a star collide after the initial explosion, providing additional energy release.MagnetarThe collapsing star forms a magnetar a rapidly rotating neutron star with an incredibly strong magnetic field at its core, which then dumps energy into the supernova ejecta, further brightening the explosion.They then apply these models to different types of stars.Setting the LimitThe authors show that the light curve of ASASSN-15lh (plotted in orange) can be described by a model (black curve) in which a magnetar with an initial spin period of 0.7 ms

  6. The ESSENCE Supernova Survey: Survey Optimization, Observations, and Supernova Photometry

    SciTech Connect

    Miknaitis, Gajus; Pignata, G.; Rest, A.; Wood-Vasey, W.M.; Blondin, S.; Challis, P.; Smith, R.C.; Stubbs, C.W.; Suntzeff, N.B.; Foley, R.J.; Matheson, T.; Tonry, J.L.; Aguilera, C.; Blackman, J.W.; Becker, A.C.; Clocchiatti, A.; Covarrubias, R.; Davis, T.M.; Filippenko, A.V.; Garg, A.; Garnavich, P.M.; /Fermilab /Chile U., Catolica /Cerro-Tololo InterAmerican Obs. /Harvard-Smithsonian Ctr. Astrophys. /Harvard U. /UC, Berkeley, Astron. Dept. /NOAO, Tucson /Inst. Astron., Honolulu /Res. Sch. Astron. Astrophys., Weston Creek /Washington U., Seattle, Astron. Dept. /Bohr Inst. /Notre Dame U. /KIPAC, Menlo Park /Texas A-M /European Southern Observ. /Ohio State U., Dept. Astron. /Baltimore, Space Telescope Sci. /Johns Hopkins U. /Stockholm U.

    2007-01-08

    We describe the implementation and optimization of the ESSENCE supernova survey, which we have undertaken to measure the equation of state parameter of the dark energy. We present a method for optimizing the survey exposure times and cadence to maximize our sensitivity to the dark energy equation of state parameter w = P/{rho}c{sup 2} for a given fixed amount of telescope time. For our survey on the CTIO 4m telescope, measuring the luminosity distances and redshifts for supernovae at modest redshifts (z {approx} 0.5 {+-} 0.2) is optimal for determining w. We describe the data analysis pipeline based on using reliable and robust image subtraction to find supernovae automatically and in near real-time. Since making cosmological inferences with supernovae relies crucially on accurate measurement of their brightnesses, we describe our efforts to establish a thorough calibration of the CTIO 4m natural photometric system. In its first four years, ESSENCE has discovered and spectroscopically confirmed 102 type Ia SNe, at redshifts from 0.10 to 0.78, identified through an impartial, effective methodology for spectroscopic classification and redshift determination. We present the resulting light curves for the all type Ia supernovae found by ESSENCE and used in our measurement of w, presented in Wood-Vasey et al. (2007).

  7. Intermediate-band photometry of faint standard stars

    NASA Technical Reports Server (NTRS)

    Dawson, D. W.

    1976-01-01

    The David Dunlap Observatory system uses six intermediate-band filters whose central wavelengths were chosen to cover important features in the spectrum of a late-type star. Calibrations of the color indices with physical parameters, allow one to estimate T sub eff, log g, Fe/H, M sub v and reddening directly from the photometry. Although a number of standards lists exist, only a small fraction of the stars is fainter than V=6. It is desirable to add to the numbers of faint standards. Results are presented of photometry of sixteen stars obtained during a program of variable-star photometry at Blue Mesa Observatory.

  8. A survey for faint variable objects in SA 57

    SciTech Connect

    Trevese, D.; Pittella, G.; Kron, R.G.; Koo, D.C.; Bershady, M.; Roma, Osservatorio Astronomico; ESA, European Space Research Institute, Frascati; Yerkes Observatory, Williams Bay, WI; Space Telescope Science Institute, Baltimore, MD; Lick Observatory, Santa Cruz, CA; Chicago Univ., IL )

    1989-07-01

    Nine Mayall 4 m prime-focus Kodak IIIa-J plates spanning an 11-yr baseline are analyzed in a uniform manner for the detection of variable objects to B = 22.6 at the level of Sigma of about 0.1 mag. Techniques are developed that succeed in independently finding objects already known to be variable, namely a sample of QSOs. Few additional objects were identified as variables with high certainty. The principal result, therefore, is an upper limit both to variable QSOs not previously identified by other techniques, and an upper limit at faint magnitudes on other classes of variable objects. 21 refs.

  9. Are the infrared-faint radio sources pulsars?

    NASA Astrophysics Data System (ADS)

    Cameron, A. D.; Keith, M.; Hobbs, G.; Norris, R. P.; Mao, M. Y.; Middelberg, E.

    2011-07-01

    Infrared-faint radio sources (IFRS) are objects which are strong at radio wavelengths but undetected in sensitive Spitzer observations at infrared wavelengths. Their nature is uncertain and most have not yet been associated with any known astrophysical object. One possibility is that they are radio pulsars. To test this hypothesis we undertook observations of 16 of these sources with the Parkes Radio Telescope. Our results limit the radio emission to a pulsed flux density of less than 0.21 mJy (assuming a 50 per cent duty cycle). This is well below the flux density of the IFRS. We therefore conclude that these IFRS are not radio pulsars.

  10. Measuring the Universe with Supernovae

    NASA Astrophysics Data System (ADS)

    Kirshner, Robert

    1996-05-01

    Supernova explosions lead to luminous optical objects which can be used to measure distances in the Universe. Supernova 1987A in the nearby Large Magellanic Cloud provides a direct geometric distance to this galaxy, and a check on the Cepheid variable star distance scale. Using observations of SN 1987A with the Hubble Space Telescope, we find a distance of 51 ± 3 kiloparsec which is consistent with the Cepheid scale. Type II supernovae, which result from the core collapse of a massive star, emit a spectrum which can be accurately modeled. Based on understanding of the radiation transport through the expanding atmospheres, observations of SN II provide distances to 18 galaxies at redshifts up to 14500 km s-1. These distances agree within the errors with distances found from Cepheids, and correspond to a value of the Hubble Contant of 72 ± 7 km s-1Mpc-1. Finally, the Type Ia supernovae, thought to arise from the thermonuclear incineration of a carbon-oxygen white dwarf, provide the best and the brightest tools for measuring extragalactic distances. Careful study shows that these supernovae are not identical, but that there is a well-determined relation between the supernova luminosity and the time history of its light emission: the supernova light curve. Recent work on the ``Multicolor Light Curve Shape Method'' accounts for this effect in an optimal way, and allows an independent determination of the absorption by dust along the line of sight for each object. Using a sample of 20 SN Ia, and calibrating this with distances determined by Hubble Space Telescope observations of Cepheids yields a Hubble Constant of 65 ± 6 km s-1Mpc-1. This corresponds to an age of the Universe (for Ω = 0 ) of about 15 billion years, which is consistent with the age of the elements and the age of globular cluster stars.

  11. Supernova Explosions Stay In Shape

    NASA Astrophysics Data System (ADS)

    2009-12-01

    At a very early age, children learn how to classify objects according to their shape. Now, new research suggests studying the shape of the aftermath of supernovas may allow astronomers to do the same. A new study of images from NASA's Chandra X-ray Observatory on supernova remnants - the debris from exploded stars - shows that the symmetry of the remnants, or lack thereof, reveals how the star exploded. This is an important discovery because it shows that the remnants retain information about how the star exploded even though hundreds or thousands of years have passed. "It's almost like the supernova remnants have a 'memory' of the original explosion," said Laura Lopez of the University of California at Santa Cruz, who led the study. "This is the first time anyone has systematically compared the shape of these remnants in X-rays in this way." Astronomers sort supernovas into several categories, or "types", based on properties observed days after the explosion and which reflect very different physical mechanisms that cause stars to explode. But, since observed remnants of supernovas are leftover from explosions that occurred long ago, other methods are needed to accurately classify the original supernovas. Lopez and colleagues focused on the relatively young supernova remnants that exhibited strong X-ray emission from silicon ejected by the explosion so as to rule out the effects of interstellar matter surrounding the explosion. Their analysis showed that the X-ray images of the ejecta can be used to identify the way the star exploded. The team studied 17 supernova remnants both in the Milky Way galaxy and a neighboring galaxy, the Large Magellanic Cloud. For each of these remnants there is independent information about the type of supernova involved, based not on the shape of the remnant but, for example, on the elements observed in it. The researchers found that one type of supernova explosion - the so-called Type Ia - left behind relatively symmetric, circular

  12. Light-echo spectroscopy of historic Supernovae

    NASA Astrophysics Data System (ADS)

    Krause, Oliver

    Young Galactic supernova remnants are unique laboratories for supernova physics. Due to their proximity they provide us with the most detailed view of the outcome of a supernova. However, the exact spectroscopic types of their original explosions have been undetermined so far -hindering to link the wealth of multi-wavelength knowledge about their remnants with the diverse population of supernovae. Light echoes, reflektions of the brilliant supernova burst of light by interstellar dust, provide a unique opportunity to reobserve today -with powerful scientific instruments of the 21st century -historic supernova exlosions even after hundreds of years and to conclude on their nature. We report on optical light-echo spectroscopy of two famous Galactic supernovae: Tycho Brahe's SN 1572 and the supernova that created the Cassiopeia A remnant around the year 1680. These observations finally recovered the missing spectroscopic classifications and provide new constraints on explosion models for future studies.

  13. Open Supernova Catalog objects subsample characteristics

    NASA Astrophysics Data System (ADS)

    Khyzhniak, E. V.; Arkhangelskaja, I. V.; Lyapin, A. R.

    2017-01-01

    The homogeneous subsample characteristics understanding is necessary for the investigation of any astrophysical objects redshift distribution, for example, gamma-ray bursts. The type Ia supernovae considered as a homogeneous subsample because of suggestion that these luminous events might be used as standard candles for cosmological measurements occurs since the earliest studies of supernovae in 1938. The parameters of our Metagalaxy Ω and Λ were determine due sample of Ia supernovae from the Supernova Cosmology Project analysis in 1998. Since then more than 4000 supernovae were added. The results of the redshift distribution analysis for supernova from the two catalogues (Asiago Supernova Catalogue and Open Supernova Catalog) are presented in this work. The ability to use an analyzed dataset as homogeneous subsample also is discussed

  14. Discovery of Three ASAS-SN Supernovae

    NASA Astrophysics Data System (ADS)

    Brimacombe, J.; Brown, J. S.; Vallely, P.; Stanek, K. Z.; Kochanek, C. S.; Shields, J.; Thompson, T. A.; Holoien, T. W.-S.; Shappee, B. J.; Prieto, J. L.; Bersier, D.; Dong, Subo; Bose, S.; Chen, Ping; Conseil, E.; Marples, P.; Stone, G.

    2017-09-01

    During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN, Shappee et al. 2014), using data from the quadruple 14-cm "Cassius" telescope in Cerro Tololo, Chile, we discovered three new transient sources, most likely supernovae.

  15. Supernovae - Still a challenge

    NASA Astrophysics Data System (ADS)

    Reddy, F.

    1983-12-01

    Historical data on supernovae (SN) occurrences are surveyed, together with present models for the physical processes occurring during the events. Type I SN feature low intensity hydrogen lines, while the hydrogen lines are prominant in Type II phenomena. Only Type I events seem to occur in elliptical galaxies, implying that the Type I events involve relatively old, low-mass objects. Both types occur in spatial galaxies, although the Type II objects are usually located in gas-rich stellar nurseries of the spiral arms, suggesting the Type II SN progenitor stars are only a few million years old. The light curves of Type I SN maintain a peak brightness significantly longer than do Type II SN, whose brightness declines irregularly. The incineration of a white dwarf that could account for observations of nickel abundances in a Type I burst, which may be confined to binary systems, is outlined. Processes that occur in a core bounce in a Type II SN, when a massive star collapses and gravitational energy abruptly changes into expansive energy, are discussed.

  16. Supernova Remnants And GLAST

    SciTech Connect

    Slane, Patrick; /Harvard-Smithsonian Ctr. Astrophys.

    2011-11-29

    It has long been speculated that supernova remnants represent a major source of cosmic rays in the Galaxy. Observations over the past decade have ceremoniously unveiled direct evidence of particle acceleration in SNRs to energies approaching the knee of the cosmic ray spectrum. Nonthermal X-ray emission from shell-type SNRs reveals multi-TeV electrons, and the dynamical properties of several SNRs point to efficient acceleration of ions. Observations of TeV gamma-ray emission have confirmed the presence of energetic particles in several remnants as well, but there remains considerable debate as to whether this emission originates with high energy electrons or ions. Equally uncertain are the exact conditions that lead to efficient particle acceleration. Based on the catalog of EGRET sources, we know that there is a large population of Galactic gamma-ray sources whose distribution is similar to that of SNRs.With the increased resolution and sensitivity of GLAST, the gamma-ray SNRs from this population will be identified. Their detailed emission structure, along with their spectra, will provide the link between their environments and their spectra in other wavebands to constrain emission models and to potentially identify direct evidence of ion acceleration in SNRs. Here I summarize recent observational and theoretical work in the area of cosmic ray acceleration by SNRs, and discuss the contributions GLAST will bring to our understanding of this problem.

  17. A Supernova's Shockwaves

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Supernovae are the explosive deaths of the universe's most massive stars. In death, these volatile creatures blast tons of energetic waves into the cosmos, destroying much of the dust surrounding them.

    This false-color composite from NASA's Spitzer Space Telescope and NASA's Chandra X-ray Observatory shows the remnant of one such explosion. The remnant, called N132D, is the wispy pink shell of gas at the center of this image. The pinkish color reveals a clash between the explosion's high-energy shockwaves and surrounding dust grains.

    In the background, small organic molecules called polycyclic aromatic hydrocarbons are shown as tints of green. The blue spots represent stars in our galaxy along this line of sight.

    N132D is located 163,000 light-years away in a neighboring galaxy called, the Large Magellanic Cloud.

    In this image, infrared light at 4.5 microns is mapped to blue, 8.0 microns to green and 24 microns to red. Broadband X-ray light is mapped purple. The infrared data were taken by Spitzer's infrared array camera and multiband imaging photometer, while the X-ray data were captured by Chandra.

  18. A Supernova's Shockwaves

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Supernovae are the explosive deaths of the universe's most massive stars. In death, these volatile creatures blast tons of energetic waves into the cosmos, destroying much of the dust surrounding them.

    This false-color composite from NASA's Spitzer Space Telescope and NASA's Chandra X-ray Observatory shows the remnant of one such explosion. The remnant, called N132D, is the wispy pink shell of gas at the center of this image. The pinkish color reveals a clash between the explosion's high-energy shockwaves and surrounding dust grains.

    In the background, small organic molecules called polycyclic aromatic hydrocarbons are shown as tints of green. The blue spots represent stars in our galaxy along this line of sight.

    N132D is located 163,000 light-years away in a neighboring galaxy called, the Large Magellanic Cloud.

    In this image, infrared light at 4.5 microns is mapped to blue, 8.0 microns to green and 24 microns to red. Broadband X-ray light is mapped purple. The infrared data were taken by Spitzer's infrared array camera and multiband imaging photometer, while the X-ray data were captured by Chandra.

  19. Supernovae. Old supernova dust factory revealed at the Galactic center.

    PubMed

    Lau, R M; Herter, T L; Morris, M R; Li, Z; Adams, J D

    2015-04-24

    Dust formation in supernova ejecta is currently the leading candidate to explain the large quantities of dust observed in the distant, early universe. However, it is unclear whether the ejecta-formed dust can survive the hot interior of the supernova remnant (SNR). We present infrared observations of ~0.02 solar masses of warm (~100 kelvin) dust seen near the center of the ~10,000-year-old Sagittarius A East SNR at the Galactic center. Our findings indicate the detection of dust within an older SNR that is expanding into a relatively dense surrounding medium (electron density ~10(3) centimeters(-3)) and has survived the passage of the reverse shock. The results suggest that supernovae may be the dominant dust-production mechanism in the dense environment of galaxies of the early universe.

  20. The Shape of Superluminous Supernovae

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-11-01

    What causes the tremendous explosions of superluminous supernovae? New observations reveal the geometry of one such explosion, SN 2015bn, providing clues as to its source.A New Class of ExplosionsImage of a type Ia supernova in the galaxy NGC 4526. [NASA/ESA]Supernovae are powerful explosions that can briefly outshine the galaxies that host them. There are several different classifications of supernovae, each with a different physical source such as thermonuclear instability in a white dwarf, caused by accretion of too much mass, or the exhaustion of fuel in the core of a massive star, leading to the cores collapse and expulsion of its outer layers.In recent years, however, weve detected another type of supernovae, referred to as superluminous supernovae. These particularly energetic explosions last longer months instead of weeks and are brighter at their peaks than normal supernovae by factors of tens to hundreds.The physical cause of these unusual explosions is still a topic of debate. Recently, however, a team of scientists led by Cosimo Inserra (Queens University Belfast) has obtained new observations of a superluminous supernova that might help address this question.The flux and the polarization level (black lines) along the dominant axis of SN 2015bn, 24 days before peak flux (left) and 28 days after peak flux (right). Blue lines show the authors best-fitting model. [Inserra et al. 2016]Probing GeometryInserra and collaborators obtained two sets of observations of SN 2015bn one roughly a month before and one a month after the superluminous supernovas peak brightness using a spectrograph on the Very Large Telescope in Chile. These observations mark the first spectropolarimetric data for a superluminous supernova.Spectropolarimetry is the practice of obtaining information about the polarization of radiation from an objects spectrum. Polarization carries information about broken spatial symmetries in the object: only if the object is perfectly symmetric can it

  1. TIME-VARYING POTASSIUM IN HIGH-RESOLUTION SPECTRA OF THE TYPE IA SUPERNOVA 2014J

    SciTech Connect

    Graham, M. L.; Weiss, L. M.; Shen, K. J.; Kelly, P. L.; Zheng, W.; Filippenko, A. V.; Marcy, G. W.; Valenti, S.; Howell, D. A.; Fulton, B. J.; Burt, J.; Rivera, E. J.

    2015-03-10

    We present a time series of the highest resolution spectra yet published for the nearby Type Ia supernova (SN Ia) 2014J in M82. They were obtained at 11 epochs over 33 days around peak brightness with the Levy Spectrograph (resolution R ≈ 110,000) on the 2.4 m Automated Planet Finder telescope at Lick Observatory. We identify multiple Na i D and K i absorption features as well as absorption by Ca ii H and K and several of the more common diffuse interstellar bands (DIBs). We see no evolution in any component of Na i D, Ca ii, or in the DIBs, but do establish the dissipation/weakening of the two most blueshifted components of K i. We present several potential physical explanations, finding the most plausible to be photoionization of circumstellar material, and discuss the implications of our results with respect to the progenitor scenario of SN 2014J.

  2. Observing Gravitational Waves from the Next Nearby Core-Collapse Supernova

    NASA Astrophysics Data System (ADS)

    Gossan, Sarah; Ott, Christian; Kalmus, Peter; Sutton, Patrick; Zanolin, Michele; Moesta, Philipp; Kijbunchoo, Nutsinee; Stuver, Amber

    2015-04-01

    The next galactic core-collapse supernova (CCSN) has already exploded, and its electromagnetic (EM) waves, neutrinos, and gravitational waves (GWs) may arrive at any moment. We present an extensive study on prospective detection scenarios for GWs from CCSNe in the Milky Way, Large Magellanic Cloud, NGC 6822, M31, and M82. We make statements on the detectibility of astrophysically-motivated signals (including waveforms from state-of-the-art 3D CCSN simulations). We utilize real GW detector data, recolored to the predicted noise power spectral densities of the Advanced LIGO (aLIGO) and Advanced Virgo (AdVirgo) detectors at early (~2015-2017) and late (~2018-2020) times. We consider various uncertainties in the GW arrival time to investigate sensitivity improvements when arrival time information is provided by neutrino or EM information. This research was supported in part by NSF Award Nos. PHY-1151197 and PHY-1404569.

  3. empiriciSN: Supernova parameter generator

    NASA Astrophysics Data System (ADS)

    Holoien, Thomas W.-S.; Marshall, Philip J.; Wechsler, Risa H.

    2017-08-01

    empiriciSN generates realistic supernova parameters given photometric observations of a potential host galaxy, based entirely on empirical correlations measured from supernova datasets. It is intended to be used to improve supernova simulation for DES and LSST. It is extendable such that additional datasets may be added in the future to improve the fitting algorithm or so that additional light curve parameters or supernova types may be fit.

  4. NASA's Great Observatories May Unravel 400-Year Old Supernova Mystery

    NASA Astrophysics Data System (ADS)

    2004-10-01

    behind the shock front. These regions also show up in the HST observations and also align with the faint rim of material seen in the SST data. Cooler X-ray gas, lower-energy X-rays, resides in a thick interior shell and marks the location of the material expelled from the exploded star. There have been six known supernovas in our Milky Way over the past 1,000 years. Kepler's is the only one, which astronomers do not know what type of star exploded. By combining information from all three Great Observatories, astronomers may find the clues they need. "It's really a situation where the total is greater than the sum of the parts," Blair said. "When the analysis is complete, we will be able to answer several questions about this enigmatic object." Information and images from this research is available on the Web at: http://www.nasa.gov http://hubblesite.org/newscenter/newsdesk/archive/releases/2004/29/ http://chandra.harvard.edu and http://www.spitzer.caltech.edu/

  5. Supernova explosions in the Universe.

    PubMed

    Burrows, A

    2000-02-17

    During the lifetime of our Milky Way galaxy, there have been something like 100 million supernova explosions, which have enriched the Galaxy with the oxygen we breathe, the iron in our cars, the calcium in our bones and the silicon in the rocks beneath our feet. These exploding stars also influence the birth of new stars and are the source of the energetic cosmic rays that irradiate us on the Earth. The prodigious amount of energy (approximately 10(51), or approximately 2.5 x 10(28) megatonnes of TNT equivalent) and momentum associated with each supernova may even have helped to shape galaxies as they formed in the early Universe. Supernovae are now being used to measure the geometry of the Universe, and have recently been implicated in the decades-old mystery of the origin of the gamma-ray bursts. Together with major conceptual advances in our theoretical understanding of supernovae, these developments have made supernovae the centre of attention in astrophysics.

  6. Detectability of Ultra Faint Dwarf Galaxies with Gaia

    NASA Astrophysics Data System (ADS)

    Mateu, C.; Antoja, T.; Aguilar, L.; Figueras, F.; Brown, A.; Antiche, E.; Hernández-Pérez, F.; Valenzuela, O.; Aparicio, A.; Hidalgo, S.; Velázquez, H.

    2014-07-01

    We present a technique to detect Ultra-Faint Dwarf Galaxies (UFDs) in the Galactic Halo, using sky and proper motion information.The method uses wavelet transforms to detect peaks in the sky and proper motion planes, and to evaluate the probability of these being stochastic fluctuations. We aim to map thoroughly the detection limits of this technique. For this, we have produced a library of 15,000 synthetic UFDs, embedded in the Gaia Universe Model Snapshot (GUMS) background (Robin et al. 2012), each at a different distance, different luminosity, half-light radius, velocity dispersion and center-of-mass velocity, varying in ranges that extend well beyond those spanned by known classical and ultra-faint dSphs. We use these synthetic UFDs as a benchmark to characterize the completeness and detection limits of our technique, and present our results as a function of different physical and observable parameters of the UFDs (see full poster for more details at https://gaia.ub.edu/Twiki/pub/GREATITNFC/ProgramFinalconference/Poster_UFGX_Bcn_C_Mateu.pdf).

  7. A Tool for Optimizing Observation Planning for Faint Moving Objects

    NASA Astrophysics Data System (ADS)

    Arredondo, Anicia; Bosh, Amanda S.; Levine, Stephen

    2016-10-01

    Observations of small solar system bodies such as trans-Neptunian objects and Centaurs are vital for understanding the basic properties of these small members of our solar system. Because these objects are often very faint, large telescopes and long exposures may be necessary, which can result in crowded fields in which the target of interest may be blended with a field star. For accurate photometry and astrometry, observations must be planned to occur when the target is free of background stars; this restriction results in limited observing windows. We have created a tool that can be used to plan observations of faint moving objects. Features of the tool include estimates of best times to observe (when the object is not too near another object), a finder chart output, a list of possible astrometric and photometric reference stars, and an exposure time calculator. This work makes use of the USNOFS Image and Catalogue Archive operated by the United States Naval Observatory, Flagstaff Station (S.E. Levine and D.G. Monet 2000), the JPL Horizons online ephemeris service (Giorgini et al. 1996), the Minor Planet Center's MPChecker (http://cgi.minorplanetcenter.net/cgi-bin/checkmp.cgi), and source extraction software SExtractor (Bertin & Arnouts 1996). Support for this work was provided by NASA SSO grant NNX15AJ82G.

  8. The faint radio AGN population in the spotlight

    NASA Astrophysics Data System (ADS)

    Herrera Ruiz, Noelia; Middelberg, Enno

    2016-08-01

    To determine the AGN component in the faint radio population is fundamental in galaxy evolution studies. A relatively easy and direct way to determine which galaxies do have a radio-active AGN is a detection using the Very Long Baseline Interferometry (VLBI) technique. The goal of this project is to study with statistically relevant numbers the faint radio source population using VLBI observations. To achieve this goal, the project is divided into two parts. In the first part, we have observed ~3000 radio sources in the COSMOS extragalactic field with the Very Long Baseline Array (VLBA) at 1.4GHz. We have detected 468 sources. In the second part, we have observed ~200 radio sources in the COSMOS field with extremely high sensitivity using the VLBA together with the Green Bank Telescope (GBT) at 1.4GHz, to explore an even fainter population in the flux density regime of tens of uJy. We are currently calibrating this data. In this overview I will present the survey design, observations, and calibration, along with some first results.

  9. NIFTE: The Near Infrared Faint-Object Telescope Experiment

    NASA Technical Reports Server (NTRS)

    Bock, James J.; Lange, Andrew E.; Matsumoto, T.; Eisenhardt, Peter B.; Hacking, Perry B.; Schember, Helene R.

    1994-01-01

    The high sensitivity of large format InSb arrays can be used to obtain deep images of the sky at 3-5 micrometers. In this spectral range cool or highly redshifted objects (e.g. brown dwarfs and protogalaxies) which are not visible at shorter wavelengths may be observed. Sensitivity at these wavelengths in ground-based observations is severly limited by the thermal flux from the telescope and from the earth's atmosphere. The Near Infrared Faint-Object Telescope Experiment (NIFTE), a 50 cm cooled rocket-borne telescope combined with large format, high performance InSb arrays, can reach a limiting flux less than 1 micro-Jy(1-sigma) over a large field-of-view in a single flight. In comparison, the Infrared Space Observatory (ISO) will require days of observation to reach a sensitivity more than one order of magnitude worse over a similar area of the sky. The deep 3-5 micrometer images obtained by the rocket-borne telescope will assist in determining the nature of faint red objects detected by ground-based telescopes at 2 micrometers, and by ISO at wavelengths longer than 5 micrometers.

  10. Theory and phenomenology of supernova neutrinos

    SciTech Connect

    Lunardini, Cecilia

    2015-07-15

    The theory and phenomenology of supernova neutrinos is reviewed, with focus on the most recent advancements on the neutrino flux predicted by supernova numerical models, on neutrino oscillations inside the star and in the Earth, and on the physics of the diffuse supernova neutrino background. Future directions of research are briefly summarized.

  11. Supernova Discoveries 2010–2011: Statistics and Trends

    NASA Astrophysics Data System (ADS)

    Gal-Yam, Avishay; Mazzali, P. A.; Manulis, I.; Bishop, D.

    2013-07-01

    We have inspected all supernova discoveries reported during 2010 and 2011, a total of 538 events during 2010 and 926 events during 2011. This number includes a small number of supernova impostors (bright extragalactic eruptions) but not novae or events that turned out to be Galactic stars. We examine the statistics of all discovered objects, as well as those of the subset of spectroscopically-confirmed events. In these 2 years we see the rise of wide-field non-targeted supernova surveys to prominence, with the largest numbers of events reported by the CRTS and PTF surveys (572 and 393 events in total respectively, contributing together 74% of all reported discoveries in 2011), followed by the integrated contribution of numerous amateurs (184 events). Among spectroscopically-confirmed events the PTF (393 events) leads, followed by CRTS (170 events), and amateur discoveries (144 events). Traditional galaxy-targeted surveys, such as LOSS and CHASE, maintain a strong contribution (86 and 61 events, respectively) with high spectroscopic completeness (∼90%). It is interesting to note that the community managed to provide substantial spectroscopic follow-up for relatively brighter amateur discoveries ( = 16.5 mag), but significant less help for fainter (and much more numerous) events promptly released by the CRTS ( = 18.6 mag). Inspecting discovery magnitude and redshift distributions we find that PS1 discoveries have similar properties ( = 21.6 mag, = 0.23) to events found in previous seasons by cosmology-oriented projects (e.g., SDSS-II), while PTF ( = 19.2 mag, = 0.095) and CRTS ( = 18.6 mag, = 0.049) populate the relatively unexplored phase space of faint supernovae (SNe) (>19 mag) in nearby galaxies (mainly PTF), and events at 0.05 < z < 0.2 (CRTS and PTF). Examining the specific question of reporting channels over the previous dozen years, we find that traditional reports via CBET telegrams now account only for a minority of SN

  12. Red supergiants as supernova progenitors

    NASA Astrophysics Data System (ADS)

    Davies, Ben

    2017-09-01

    It is now well-established from pre-explosion imaging that red supergiants (RSGs) are the direct progenitors of Type-IIP supernovae. These images have been used to infer the physical properties of the exploding stars, yielding some surprising results. In particular, the differences between the observed and predicted mass spectrum has provided a challenge to our view of stellar evolutionary theory. However, turning what is typically a small number of pre-explosion photometric points into the physical quantities of stellar luminosity and mass requires a number of assumptions about the spectral appearance of RSGs, as well as their evolution in the last few years of life. Here I will review what we know about RSGs, with a few recent updates on how they look and how their appearance changes as they approach supernova. This article is part of the themed issue 'Bridging the gap: from massive stars to supernovae'.

  13. Dynamics of Kepler's supernova remnant

    NASA Technical Reports Server (NTRS)

    Borkowski, Kazimierz J.; Blondin, John M.; Sarazin, Craig L.

    1992-01-01

    Observations of Kepler's SNR have revealed a strong interaction with the ambient medium, far in excess of that expected at a distance of about 600 pc away from the Galactic plane where Kepler's SNR is located. This has been interpreted as a result of the interaction of supernova ejecta with the dense circumstellar medium (CSM). Based on the bow-shock model of Bandiera (1985), we study the dynamics of this interaction. The CSM distribution consists of an undisturbed stellar wind of a moving supernova progenitor and a dense shell formed in its interaction with a tenuous interstellar medium. Supernova ejecta drive a blast wave through the stellar wind which splits into the transmitted and reflected shocks upon hitting this bow-shock shell. We identify the transmitted shock with the nonradiative, Balmer-dominated shocks found recently in Kepler's SNR. The transmitted shock most probably penetrated the shell in the vicinity of the stagnation point.

  14. Featured Image: Modeling Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-05-01

    This image shows a computer simulation of the hydrodynamics within a supernova remnant. The mixing between the outer layers (where color represents the log of density) is caused by turbulence from the Rayleigh-Taylor instability, an effect that arises when the expanding core gas of the supernova is accelerated into denser shell gas. The past standard for supernova-evolution simulations was to perform them in one dimension and then, in post-processing, manually smooth out regions that undergo Rayleigh-Taylor turbulence (an intrinsically multidimensional effect). But in a recent study, Paul Duffell (University of California, Berkeley) has explored how a 1D model could be used to reproduce the multidimensional dynamics that occur in turbulence from this instability. For more information, check out the paper below!CitationPaul C. Duffell 2016 ApJ 821 76. doi:10.3847/0004-637X/821/2/76

  15. Dynamics of Kepler's supernova remnant

    NASA Technical Reports Server (NTRS)

    Borkowski, Kazimierz J.; Blondin, John M.; Sarazin, Craig L.

    1992-01-01

    Observations of Kepler's SNR have revealed a strong interaction with the ambient medium, far in excess of that expected at a distance of about 600 pc away from the Galactic plane where Kepler's SNR is located. This has been interpreted as a result of the interaction of supernova ejecta with the dense circumstellar medium (CSM). Based on the bow-shock model of Bandiera (1985), we study the dynamics of this interaction. The CSM distribution consists of an undisturbed stellar wind of a moving supernova progenitor and a dense shell formed in its interaction with a tenuous interstellar medium. Supernova ejecta drive a blast wave through the stellar wind which splits into the transmitted and reflected shocks upon hitting this bow-shock shell. We identify the transmitted shock with the nonradiative, Balmer-dominated shocks found recently in Kepler's SNR. The transmitted shock most probably penetrated the shell in the vicinity of the stagnation point.

  16. Software Based Supernova Recognition

    NASA Astrophysics Data System (ADS)

    Walters, Stephen M.

    2014-05-01

    This paper describes software for detecting Supernova (SN) in images. The software can operate in real-time to discover SN while data is being collected so the instrumentation can immediately be re-tasked to perform spectroscopy or photometry of a discovery. Because the instrumentation captures two images per minute, the realtime budget is constrained to 30 seconds per target, a challenging goal. Using a set of two to four images, the program creates a "Reference" (REF) image and a "New" (NEW) image where all images are used in both NEW and REF but any SN survives the combination process only in the NEW image. This process produces good quality images having similar noise characteristics but without artifacts that might be interpreted as SN. The images are then adjusted for seeing and brightness differences using a variant of Tomaney and Crotts method of Point Spread Function (PSF) matching after which REF is subtracted from NEW to produce a Difference (DIF) image. A Classifier is then trained on a grid of artificial SN to estimate the statistical properties of four attributes and used in a process to mask false positives that can be clearly identified as such. Further training to avoid any remaining false positives sets the range, in standard deviations for each attribute, that the Classifier will accept as a valid SN. This training enables the Classifier to discriminate between SN and most subtraction residue. Lastly, the DIF image is scanned and measured by the Classifier to find locations where all four properties fall within their acceptance ranges. If multiple locations are found, the one best conforming to the training estimates is chosen. This location is then declared as a Candidate SN, the instrumentation re-tasked and the operator notified.

  17. Evolution of clustered supernovae

    NASA Astrophysics Data System (ADS)

    Vasiliev, Evgenii O.; Shchekinov, Yuri A.; Nath, Biman B.

    2017-07-01

    We study the merging and evolution of isolated supernova (SN) remnants in a stellar cluster into a collective superbubble, with the help of 3D hydrodynamic simulations. We particularly focus on the transition stage when the isolated SN remnants gradually combine to form a superbubble. We find that when the SN rate is high (νsn ˜ 10-9 pc-3 yr-1), the merging phase lasts for ˜104 yr, for n = 1-10 cm-3, and the merging phase lasts for a longer time (˜0.1 Myr or more) for lower SN rates (νsn ≤ 10-10 pc-3 yr-1). During this transition phase, the growing superbubble is filled with dense and cool fragments of shells, and most of the energy is radiated away during this merging process. After passing through the intermediate phase, the superbubble eventually settles on to a new power-law wind asymptote that is smaller than estimated in a continuous wind model. This results in a significant (more than several times) underestimation of the mechanical luminosity needed to feed the bubble. We determine the X-ray and H α surface brightnesses as functions of time for such merging SNe in a stellar cluster and find that clusters with high SN rate shine predominantly in soft X-rays and H α. In particular, a low value of the volume-averaged H α-to-H β ratio and its large spread can be a good indicator of the transition phase of merging SNe.

  18. Nature of type 1 Supernovae

    NASA Technical Reports Server (NTRS)

    Shklovskiy, I. S.

    1980-01-01

    The nature of type 1 supernovae (SN 1) is discussed through a comparison of observational evidence and theoretical perspectives relating to both type 1 and 2 supernovae. In particular two hypotheses relating to SN 1 phenomenon are examined: the first proposing that SN 1 are components of binary systems in which, at a comparatively late stage of evolution, overflow of the mass occurs; the second considers pre-SN 1 to be recently evolved stars with a mass greater than 1.4 solar mass (white dwarfs). In addition, an explanation of the reduced frequency of flares of SN 1 in spiral galaxies as related to that in elliptical galaxies is presented.

  19. Dust around Type Ia supernovae

    SciTech Connect

    Wang, Lifan

    2005-10-20

    An explanation is given of the low value of R lambda triple bond A lambda/E(B - V), the ratio of absolute to selective extinction deduced from Type Ia supernova observations. The idea involves scattering by dust clouds located in the circumstellar environment, or at the highest velocity shells of the supernova ejecta. The scattered light tends to reduce the effective R lambda in the optical, but has an opposite effect in the ultraviolet. The presence of circumstellar dust can be tested by ultraviolet to near infrared observations and by multi-epoch spectropolarimetry of SNe Ia.

  20. Educational Resources on Supernovae for Children

    NASA Astrophysics Data System (ADS)

    Struck, James T.

    The National Science Education Standards (1996, National Academy Press) suggest mention of objects like the ``sun, moon, stars" in grades K-4 and element formation in grades 9-12. Children's librarians and some astronomy librarians should know about some of the resources for children on supernovae not only because supernovae are critical to higher element formation, but also to educate others about the universe's expansion and stars. In addition, basic bibliometrics on these resources yields lessons on the importance of using many indexes, the pattern of literature for children on supernovae, the types of resources on supernovae, and the scattering of resources/information for children on supernovae.

  1. Magnetar-Powered Supernovae in Two Dimensions. I. Superluminous Supernovae

    NASA Astrophysics Data System (ADS)

    Chen, Ke-Jung; Woosley, S. E.; Sukhbold, Tuguldur

    2016-11-01

    Previous studies have shown that the radiation emitted by a rapidly rotating magnetar embedded in a young supernova can greatly amplify its luminosity. These one-dimensional studies have also revealed the existence of an instability arising from the piling up of radiatively accelerated matter in a thin dense shell deep inside the supernova. Here, we examine the problem in two dimensions and find that, while instabilities cause mixing and fracture this shell into filamentary structures that reduce the density contrast, the concentration of matter in a hollow shell persists. The extent of the mixing depends upon the relative energy input by the magnetar and the kinetic energy of the inner ejecta. The light curve and spectrum of the resulting supernova will be appreciably altered, as will the appearance of the supernova remnant, which will be shellular and filamentary. A similar pile up and mixing might characterize other events where energy is input over an extended period by a centrally concentrated source, e.g., a pulsar, radioactive decay, a neutrino-powered wind, or colliding shells. The relevance of our models to the recent luminous transient ASASSN-15lh is briefly discussed.

  2. THE SUBLUMINOUS AND PECULIAR TYPE Ia SUPERNOVA PTF 09dav

    SciTech Connect

    Sullivan, M.; Ofek, E. O.; Blake, S.; Podsiadlowski, P.; Kasliwal, M. M.; Cooke, J.; Quimby, R.; Kulkarni, S. R.; Nugent, P. E.; Thomas, R. C.; Poznanski, D.; Howell, D. A.; Arcavi, I.; Gal-Yam, A.; Hook, I. M.; Mazzali, P.; Bildsten, L.; Bloom, J. S.; Cenko, S. B.; Law, N.

    2011-05-10

    PTF 09dav is a peculiar subluminous Type Ia supernova (SN) discovered by the Palomar Transient Factory (PTF). Spectroscopically, it appears superficially similar to the class of subluminous SN1991bg-like SNe, but it has several unusual features which make it stand out from this population. Its peak luminosity is fainter than any previously discovered SN1991bg-like SN Ia (M{sub B} {approx} -15.5), but without the unusually red optical colors expected if the faint luminosity were due to extinction. The photospheric optical spectra have very unusual strong lines of Sc II and Mg I, with possible Sr II, together with stronger than average Ti II and low velocities of {approx}6000 km s{sup -1}. The host galaxy of PTF09dav is ambiguous. The SN lies either on the extreme outskirts ({approx}41 kpc) of a spiral galaxy or in an very faint (M{sub R} {>=} -12.8) dwarf galaxy, unlike other 1991bg-like SNe which are invariably associated with massive, old stellar populations. PTF 09dav is also an outlier on the light-curve-width-luminosity and color-luminosity relations derived for other subluminous SNe Ia. The inferred {sup 56}Ni mass is small (0.019 {+-} 0.003 M{sub sun}), as is the estimated ejecta mass of 0.36 M{sub sun}. Taken together, these properties make PTF 09dav a remarkable event. We discuss various physical models that could explain PTF 09dav. Helium shell detonation or deflagration on the surface of a CO white dwarf can explain some of the features of PTF 09dav, including the presence of Sc and the low photospheric velocities, but the observed Si and Mg are not predicted to be very abundant in these models. We conclude that no single model is currently capable of explaining all of the observed signatures of PTF 09dav.

  3. The VLT Measures the Shape of a Type Ia Supernova

    NASA Astrophysics Data System (ADS)

    2003-08-01

    . " Measuring them requires an instrument that is very sensitive and very stable . " The VLT observation of SN 2001el in NGC 1448 ESO PR Photo 24a/03 ESO PR Photo 24a/03 [Preview - JPEG: 620 x 400 pix - 156k [Normal - JPEG: 1240 x 800 pix - 396k] ESO PR Photo 24b/03 ESO PR Photo 24b/03 [Preview - JPEG: 400 x 524 pix - 104k [Normal - JPEG: 800 x 1047 pix - 240k] Captions : PR Photo 24a/03 shows the spiral galaxy NGC 1448, as seen in an archive image from the Digital Sky Survey (Courtesy of STScI) and as seen close to the brightness maximum of the supernova using EMMI on the NTT. SN 2001el is marked by the arrow. The field measures 4.5 x 4.5 arcmin 2 ; North is up and east is right. PR Photo 24b/03 illustrates the optical spectrum of SN 2001el in NGC 1448 (upper panel). The middle and lower panels show the corresponding fractional polarisations. They measure the different numbers of photons oscillating in perpendicular directions; they are directly related to the geometry of the supernova. The shaded area indicates the spectral signatures of high-velocity matter in the expanding envelope. The measurement in faint and distant light sources of differences at a level of less than one percent is a considerable observational challenge. "However, the ESO Very Large Telescope (VLT) offers the precision, the light collecting power, as well as the specialized instrumentation required for such a demanding polarimetric observation" , explains Dietrich Baade . "But this project would not have been possible without the VLT being operated in service mode. It is indeed impossible to predict when a supernova will explode and we need to be ready all the time. Only service mode allows observations at short notice. Some years ago, it was a farsighted and courageous decision by ESO's directorate to put so much emphasis on Service Mode. And it was the team of competent and devoted ESO astronomers on Paranal who made this concept a practical success" , he adds. The astronomers [1] used the VLT multi

  4. Are supernovae recorded in indigenous astronomical traditions?

    NASA Astrophysics Data System (ADS)

    Hamacher, Duane W.

    2014-07-01

    Novae and supernovae are rare astronomical events that would have had an influence on the skywatching peoples who witnessed them. Although several bright novae/supernovae have been visible during recorded human history, there are many proposed but no confirmed accounts of supernovae in indigenous oral traditions or material culture. Criteria are established for confirming novae/supernovae in oral traditions and material culture, and claims from around the world are discussed to determine if they meet these criteria. Aboriginal Australian traditions are explored for possible descriptions of novae/supernovae. Although representations of supernovae may exist in Aboriginal traditions, there are currently no confirmed accounts of supernovae in Indigenous Australian oral or material traditions.

  5. Long Gamma-Ray Bursts without Visible Supernovae: A Case Study of Redshift Estimators and Alleged Novel Objects

    NASA Astrophysics Data System (ADS)

    Dado, Shlomo; Dar, Arnon; De Rújula, A.; Plaga, Rainer

    2008-05-01

    It has been argued that the observational limits on a supernova (SN) associated with GRB 060614 convincingly exclude a SN akin to SN 1998bw as its originator and provide evidence for a new class of long-duration GRBs. We discuss this issue in the contexts of indirect "redshift estimators" and of the fireball and cannonball models of GRBs. The latter explains the unusual properties of GRB 060614: at its debated but favored low redshift (0.125), they are predicted, as opposed to exceptional, if the associated core-collapse SN is of a recently discovered, very faint type. We take the occasion to discuss the association between GRBs and SNe.

  6. A Comprehensive Survey of Neptune's Small Moons and Faint Rings

    NASA Astrophysics Data System (ADS)

    Showalter, Mark

    2009-07-01

    We will use a subarray of the WFC3/UVIS to study the inner rings, arcs and moons of Neptune with a sensitivity that exceeds that achieved by any previous observations, including Voyager 2 during its 1989 flyby. Our study will reveal any inner moons down to V magnitude 25, corresponding to a radius 20 km {assuming 9% albedo}, to address a peculiar, apparent truncation in the size distribution of inner moons and to look for the "shepherds" and source bodies for Neptune's dusty rings. {For comparison, the radius of Neptune's smallest known regular moon, Naiad, is 33 km.} Monitoring of the arcs at fine resolution and sensitivity will reveal their ongoing evolution more clearly and will enable us to assess the role of Galatea, whose resonant perturbations are widely believed to confine the arcs. Our study will also reveal any broad, faint rings with optical depth 10^-6, comparable to those now known to encircle all of the other giant planets.

  7. A sample of Swift/SDSS faint blazars

    NASA Astrophysics Data System (ADS)

    Fraga, Bernardo; Giommi, Paolo; Turriziani, Sara

    2015-12-01

    We aim here to provide a complete sample of faint (fr ≳ 1 mJy, fx ≳ 10-15 erg cm-2 s-1) blazars and blazar candidates serendipitously discovered in deep Swift images centered on Gamma-ray bursts (GRBs). By stacking all available images, we obtain exposures ranging from 104 to more than a million seconds. Since GRBs are thought to explode randomly across the sky, this set of deep fields can be considered as an unbiased survey of ≈ 12 square degrees of extragalactic sky, with sensitivities reaching a few 10-15 erg cm-2 s-1 in the 0.5-2 keV band. We then derive the x-ray Log N Log S and show that, considering that our sample may be contaminated by sources other than blazars, we are in agreement with previous estimations based on data and simulations.

  8. Faint Object Camera observations of a globular cluster nova field

    NASA Technical Reports Server (NTRS)

    Margon, Bruce; Anderson, Scott F.; Downes, Ronald A.; Bohlin, Ralph C.; Jakobsen, Peter

    1991-01-01

    The Faint Object Camera onboard Hubble Space Telescope has obtained U and B images of the field of Nova Ophiuchi 1938 in the globular cluster M14 (NGC 6402). The candidate for the quiescent nova suggested by Shara et al. (1986) is clearly resolved into at least six separate images, probably all stellar, in a region of 0.5 arcsec. Although two of these objects are intriguing as they are somewhat ultraviolet, the actual nova counterpart remains ambiguous, as none of the images in the field has a marked UV excess. Many stars within the 1.4 arcsec (2 sigma) uncertainty of the nova outburst position are viable counterparts if only astrometric criteria are used for selection. The 11 x 11 arcsec frames easily resolve several hundred stars in modest exposures, implying that HST even in its current optical configuration will be unique for studies of very crowded fields at moderate (B = 22) limiting magnitudes.

  9. Tomography of faint spinning objects: From molecules to viruses

    NASA Astrophysics Data System (ADS)

    Ourmazd, Abbas

    2010-03-01

    A new generation of powerful algorithms is poised to enable the determination of the three-dimensional structure of objects ranging from single molecules to beating hearts and breathing lungs. At one extreme, new algorithms are paving the way to atomic-level mapping of the conformations of biological molecules with femtosecond time resolution. At the other, they are driving ultra-low-dose tomography of non-stationary, faintly scattering macroscopic objects. These approaches combine concepts from information theory, graph theory, Riemannian geometry, and scattering physics to reconstruct objects at signal levels orders of magnitude below what was previously thought possible. We describe how data from a new generation of X-ray Free Electron Lasers or existing electron microscopes can be used to reconstruct the structure and conformational continuum of individual molecules, viruses, and potentially living cells.

  10. Clustering Effect on the Number Count of Faint Galaxies

    NASA Astrophysics Data System (ADS)

    Yamashita, K.

    1992-08-01

    We have tested the cosmological model of Ω0 = 1 and Λ = 0 against the faint galaxy number count taking the clustering effect of galaxies into account. The evolution of the large scale structure is simulated numerically by means of the particle mesh method in three dimensional space. We use 643 particles and the same number of mesh cells. We have found that the flat Friedmann-Robertson-Walker model without the cosmological constant does not explain the excess of the number count observed by Tyson even if the clustering effect is taken into account, provided the cluster size and the correlation length among clusters are less than the simulation box size of 128 h-1 Mpc. The clustering on scales larger than 128 h-1 Mpc is also considered.

  11. The faint young sun-climate paradox - Continental influences

    NASA Technical Reports Server (NTRS)

    Endal, A. S.; Schatten, K. H.

    1982-01-01

    We examine the various mechanisms which have been proposed to compensate for the climatic effects of a 30% increase in the solar luminosity over the past 4 1/2 billion years. Although atmospheric greenhouse effects have received most attention, other mechanisms may have played a role of comparable importance. In particular, we note that the development of continents during the past 2 1/2 billion years could have had a significant secular effect on the atmosphere-ocean heat transport system. As a result, past climates may have been less susceptible to complete freeze-over. A simple energy balance model is used to demonstrate the magnitude of this effect. Because the CO2 greenhouse effect is not the only means of compensating for solar evolution, the faint-young-sun problem should not be used to infer past levels of atmospheric CO2.

  12. Epidemic faintness and syncope in a school marching band.

    PubMed

    Levine, R J

    1977-11-28

    On Sept 21, 1973, during and following a football game at which they had participated, 57 members of an Alabama high school marching band (and one accompanying adult) experienced an illness characterized by headache, nausea, weakness, or dizziness. Six girls fainted. Thirty-six students were treated at a hospital emergency room. Those who had played wind instruments and had worn heavier uniforms including an impermeable plastic jacket overlay were affected earlier and more frequently than the others. Several organic causes were examined in an epidemiologic investigation and considered unlikely to explain the epidemic. Female preponderance, a bimodal epidemic curve, hyperventilation, relapses, and clinical features characterized by subjective complaints in the absence of physical findings suggested a syncopal reaction to heat exacerbated and propagated by mass hysteria.

  13. Faint UBVRI Standard Star Fields at +50° Declination

    NASA Astrophysics Data System (ADS)

    Clem, James L.; Landolt, Arlo U.

    2016-10-01

    Precise and accurate CCD-based UBVRI photometry is presented for ˜2000 stars distributed around the sky in a declination zone centered approximately at +50°. Their photometry has been calibrated to the standard Johnson UBV and Kron-Cousins RI systems through observations of the UBVRI standard stars presented in the various works of Landolt. The magnitude and color range for these stars are 12 ≲ V ≲ 22 and -0.3 ≲ (B - V) ≲ 1.8, respectively. Each star averages 13 measures in each UBVRI filter from data taken on 41 different photometric nights obtained over a 21 month period. Hence, there now exists a network of faint UBVRI photometric standard stars centered on the declination zones δ = -50°, 0°, and +50°.

  14. Faint Object Camera observations of a globular cluster nova field

    NASA Technical Reports Server (NTRS)

    Margon, Bruce; Anderson, Scott F.; Downes, Ronald A.; Bohlin, Ralph C.; Jakobsen, Peter

    1991-01-01

    The Faint Object Camera onboard Hubble Space Telescope has obtained U and B images of the field of Nova Ophiuchi 1938 in the globular cluster M14 (NGC 6402). The candidate for the quiescent nova suggested by Shara et al. (1986) is clearly resolved into at least six separate images, probably all stellar, in a region of 0.5 arcsec. Although two of these objects are intriguing as they are somewhat ultraviolet, the actual nova counterpart remains ambiguous, as none of the images in the field has a marked UV excess. Many stars within the 1.4 arcsec (2 sigma) uncertainty of the nova outburst position are viable counterparts if only astrometric criteria are used for selection. The 11 x 11 arcsec frames easily resolve several hundred stars in modest exposures, implying that HST even in its current optical configuration will be unique for studies of very crowded fields at moderate (B = 22) limiting magnitudes.

  15. Do the enigmatic ``Infrared-Faint Radio Sources'' include pulsars?

    NASA Astrophysics Data System (ADS)

    Hobbs, George; Middelberg, Enno; Norris, Ray; Keith, Michael; Mao, Minnie; Champion, David

    2009-04-01

    The Australia Telescope Large Area Survey (ATLAS) team have surveyed seven square degrees of sky at 1.4GHz. During processing some unexpected infrared-faint radio sources (IFRS sources) were discovered. The nature of these sources is not understood, but it is possible that some of these sources may be pulsars within our own galaxy. We propose to observe the IFRS sources with steep spectral indices using standard search techniques to determine whether or not they are pulsars. A pulsar detection would 1) remove a subset of the IFRS sources from the ATLAS sample so they would not need to be observed with large optical/IR telescopes to find their hosts and 2) be intrinsically interesting as the pulsar would be a millisecond pulsar and/or have an extreme spatial velocity.

  16. Morphology and astrometry of Infrared-Faint Radio Sources

    NASA Astrophysics Data System (ADS)

    Middelberg, Enno; Norris, Ray; Randall, Kate; Mao, Minnie; Hales, Christopher

    2008-10-01

    Infrared-Faint Radio Sources, or IFRS, are an unexpected class of object discovered in the Australia Telescope Large Area Survey, ATLAS. They are compact 1.4GHz radio sources with no visible counterparts in co-located (relatively shallow) Spitzer infrared and optical images. We have detected two of these objects with VLBI, indicating the presence of an AGN. These observations and our ATLAS data indicate that IFRS are extended on scales of arcseconds, and we wish to image their morphologies to obtain clues about their nature. These observations will also help us to select optical counterparts from very deep, and hence crowded, optical images which we have proposed. With these data in hand, we will be able to compare IFRS to known object types and to apply for spectroscopy to obtain their redshifts.

  17. MEASURING SIZES OF ULTRA-FAINT DWARF GALAXIES

    SciTech Connect

    Munoz, Ricardo R.; Padmanabhan, Nikhil; Geha, Marla

    2012-02-01

    The discovery of ultra-faint dwarf (UFD) galaxies in the halo of the Milky Way extends the faint end of the galaxy luminosity function to a few hundred solar luminosities. This extremely low luminosity regime poses a significant challenge for the photometric characterization of these systems. We present a suite of simulations aimed at understanding how different observational choices related to the properties of a low-luminosity system impact our ability to determine its true structural parameters such as half-light radius and central surface brightness. We focus on estimating half-light radii (on which mass estimates depend linearly) and find that these numbers can have up to 100% uncertainties when relatively shallow photometric surveys, such as the Sloan Digital Sky Survey, are used. Our simulations suggest that to recover structural parameters within 10% or better of their true values: (1) the ratio of the field of view to the half-light radius of the satellite must be greater than three, (2) the total number of stars, including background objects should be larger than 1000, and (3) the central to background stellar density ratio must be higher than 20. If one or more of these criteria are not met, the accuracy of the resulting structural parameters can be significantly compromised. In the context of future surveys such as Large Synoptic Survey Telescope, the latter condition will be closely tied to our ability to remove unresolved background galaxies. Assessing the reliability of measured structural parameters will become increasingly critical as the next generation of deep wide-field surveys detects UFDs beyond the reach of current spectroscopic limits.

  18. The very soft X-ray emission of X-ray-faint early-type galaxies

    NASA Technical Reports Server (NTRS)

    Pellegrini, S.; Fabbiano, G.

    1994-01-01

    A recent reanaylsis of Einstein data, and new ROSAT observations, have revealed the presence of at least two components in the X-ray spectra of X-ray faint early-type galaxies: a relatively hard component (kT greater than 1.5 keV), and a very soft component (kT approximately 0.2-0.3 keV). In this paper we address the problem of the nature of the very soft component and whether it can be due to a hot interstellar medium (ISM), or is most likely originated by the collective emission of very soft stellar sources. To this purpose, hydrodynamical evolutionary sequences for the secular behavior of gas flows in ellipticals have been performed, varying the Type Ia supernovae rate of explosion, and the dark matter amount and distribution. The results are compared with the observational X-ray data: the average Einstein spectrum for six X-ray faint early-type galaxies (among which are NGC 4365 and NGC 4697), and the spectrum obtained by the ROSAT pointed observation of NGC 4365. The very soft component could be entirely explained with a hot ISM only in galaxies such as NGC 4697, i.e., when the depth of the potential well-on which the average ISM temperature strongly depends-is quite shallow; in NGC 4365 a diffuse hot ISM would have a temperature larger than that of the very soft component, because of the deeper potential well. So, in NGC 4365 the softest contribution to the X-ray emission comes certainly from stellar sources. As stellar soft X-ray emitters, we consider late-type stellar coronae, supersoft sources such as those discovered by ROSAT in the Magellanic Clouds and M31, and RS CVn systems. All these candidates can be substantial contributors to the very soft emission, though none of them, taken separately, plausibly accounts entirely for its properties. We finally present a model for the X-ray emission of NGC 4365, to reproduce in detail the results of the ROSAT pointed observation, including the Position Sensitive Proportional Counter (PSPC) spectrum and radial

  19. Radio studies of extragalactic supernovae.

    PubMed

    Weiler, K W; Sramek, R A; Panagia, N

    1986-03-14

    Some exploding stars (supernovae) are powerful emitters of centimeter radio radiation. Detailed observations have shown that these supernovae quickly become detectable in the radio range, first at shorter wavelengths (higher frequencies) and later at progressively longer and longer wavelengths (lower frequencies). This part of the phenomenon appears to be well explained by a monotonic decrease in the amount of ionized material surrounding the radio-emitting regions as the shock from the explosion travels outward. The radio emission itself is of a nonthermal, synchrotron origin, as is the case in most bright cosmic radio sources. Once the absorption effects become negligible, the radio intensity declines with time until reaching the detection limit of the telescope. Models suggest that the absorbing material originates in a dense wind of matter lost by the supernova progenitor star, or by its companion if it is in a binary system, in the last stages of evolution before the explosion. The synchrotron radio emission can be generated either externally by the shock wave from the explosion propagating through this same high density stellar wind or internally by a rapidly rotating neutron star, which is the collapsed core of the exploded star. Present results appear to favor the former model for at least the first several years after the supernova explosion, although the latter model remains viable.

  20. Instabilities and the Supernova Mechanism

    NASA Astrophysics Data System (ADS)

    Burrows, Adam; Hayes, John

    1994-12-01

    Core collapse supernovae are thought to be powered not dynamically by the direct piston mechanism of core bounce, but by neutrino heating after the bounce shock has stalled into accretion. The theory we will describe provides a paradigm for understanding the neutrino heating mechanism. Both the critical condition for instability and the explosion energy are very steep functions of the driving neutrino luminosity. We will present recent 1D and 2D hydrodynamic calculations in which the basics of the supernova mechanism are elucidated. The shock wave that stalls within ten milliseconds of its creation during the collapse and bounce of the core of a massive star leaves behind it unstable lepton and entropy profiles that can drive a violent Rayleigh-Taylor overturn. Furthermore, the core neutrino luminosities can establish unstable entropy gradients near the shock 50 milliseconds after bounce. John Hayes, Bruce Fryxell and I have demonstrated the possible existence of a convective boost in the neutrino luminosities due to core lepton overturn that can ignite a supernova explosion and have verified the potential importance of nu -driven ``Bethe'' convection near the shock. Issues that surround the residual neutron star mass, the (56) Ni yields, the supernova energies, the progenitors, and the nucleosynthetic consequences will also be addressed.

  1. Cosmology from High Redshift Supernovae

    NASA Astrophysics Data System (ADS)

    Garnavich, Peter

    The discovery of a correlation between the light curve shape and intrinsic b rightness has made Type Ia supernovae exceptionally accurate distance indicators out to cosmologically interesting redshifts. Ground-based searches and follow-up as well as Hubble S pace Telescope observations of Type Ia supernovae have produced a significant number of object s with redshifts between 0.3 and 1.0. The distant SNe, when combined with a local samp le analyzed in the same way, provide reliable constraints on the deceleration and age of th e Universe. Early this year, an analysis of a handful of Type Ia events indicated that the deceleration was too small for gravitating matter alone to make a flat Universe. A larger sa mple of supernovae gives the surprising result that the Universe is accelerating, implying the exi stence of a cosmological constant or some other exotic form of energy. The success of this research has depended on the development of algorithms and software to register, scale and subtract CCD images taken weeks apart and to search for var iable objects. A good fraction of the point-sources identified are asteroids, variable stars, or AGN, so spectra are needed to confirm the identification as a Type Ia supernova and obt ain a redshift. The best candidates are followed photometrically to construct light curves. The steps to transform the observed light curves into cosmologically interestin g results will also be described.

  2. Nonstandard neutrino interactions in supernovae

    NASA Astrophysics Data System (ADS)

    Stapleford, Charles J.; Väänänen, Daavid J.; Kneller, James P.; McLaughlin, Gail C.; Shapiro, Brandon T.

    2016-11-01

    Nonstandard interactions (NSI) of neutrinos with matter can significantly alter neutrino flavor evolution in supernovae with the potential to impact explosion dynamics, nucleosynthesis, and the neutrinos signal. In this paper, we explore, both numerically and analytically, the landscape of neutrino flavor transformation effects in supernovae due to NSI and find a new, heretofore unseen transformation processes can occur. These new transformations can take place with NSI strengths well below current experimental limits. Within a broad swath of NSI parameter space, we observe symmetric and standard matter-neutrino resonances for supernovae neutrinos, a transformation effect previously only seen in compact object merger scenarios; in another region of the parameter space we find the NSI can induce neutrino collective effects in scenarios where none would appear with only the standard case of neutrino oscillation physics; and in a third region the NSI can lead to the disappearance of the high density Mikheyev-Smirnov-Wolfenstein resonance. Using a variety of analytical tools, we are able to describe quantitatively the numerical results allowing us to partition the NSI parameter according to the transformation processes observed. Our results indicate nonstandard interactions of supernova neutrinos provide a sensitive probe of beyond the Standard Model physics complementary to present and future terrestrial experiments.

  3. The supernova: A stellar spectacle

    NASA Technical Reports Server (NTRS)

    Straka, W. C.

    1976-01-01

    The life of a star, the supernova, related objects and their importance in astronomy and science in general are discussed. Written primarily for science teachers of secondary school chemistry, physics, and earth sciences, the booklet contains a glossary, reference sources, suggested topics for discussion, and projects for individual or group assignment.

  4. Supernova neutrinos and explosive nucleosynthesis

    SciTech Connect

    Kajino, T.; Aoki, W.; Cheoun, M.-K.; Hayakawa, T.; Hidaka, J.; Hirai, Y.; Shibagaki, S.; Mathews, G. J.; Nakamura, K.; Suzuki, T.

    2014-05-09

    Core-collapse supernovae eject huge amount of flux of energetic neutrinos. We studied the explosive nucleosyn-thesis in supernovae and found that several isotopes {sup 7}Li, {sup 11}B, {sup 92}Nb, {sup 138}La and {sup 180}Ta as well as r-process nuclei are affected by the neutrino interactions. The abundance of these isotopes therefore depends strongly on the neutrino flavor oscillation due to the Mikheyev-Smirnov-Wolfenstein (MSW) effect. We discuss first how to determine the neutrino temperatures in order to explain the observed solar system abundances of these isotopes, combined with Galactic chemical evolution of the light nuclei and the heavy r-process elements. We then study the effects of neutrino oscillation on their abundances, and propose a novel method to determine the still unknown neutrino oscillation parameters, mass hierarchy and θ{sub 13}, simultaneously. There is recent evidence that SiC X grains from the Murchison meteorite may contain supernova-produced light elements {sup 11}B and {sup 7}Li encapsulated in the presolar grains. Combining the recent experimental constraints on θ{sub 13}, we show that our method sug-gests at a marginal preference for an inverted neutrino mass hierarchy. Finally, we discuss supernova relic neutrinos that may indicate the softness of the equation of state (EoS) of nuclear matter as well as adiabatic conditions of the neutrino oscillation.

  5. The Supernova - A Stellar Spectacle.

    ERIC Educational Resources Information Center

    Straka, W. C.

    This booklet is part of an American Astronomical Society curriculum project designed to provide teaching materials to teachers of secondary school chemistry, physics, and earth science. The following topics concerning supernovae are included: the outburst as observed and according to theory, the stellar remnant, the nebular remnant, and a summary…

  6. Pulsational Pair-instability Supernovae

    NASA Astrophysics Data System (ADS)

    Woosley, S. E.

    2017-02-01

    The final evolution of stars in the mass range 70-140 {\\text{}}{M}⊙ is explored. Depending upon their mass loss history and rotation rates, these stars will end their lives as pulsational pair-instability supernovae (PPISN) producing a great variety of observational transients with total durations ranging from weeks to millennia and luminosities from 1041 to over 1044 erg s-1. No nonrotating model radiates more than 5× {10}50 erg of light or has a kinetic energy exceeding 5× {10}51 erg, but greater energies are possible, in principle, in magnetar-powered explosions, which are explored. Many events resemble SNe Ibn, SNe Icn, and SNe IIn, and some potential observational counterparts are mentioned. Some PPISN can exist in a dormant state for extended periods, producing explosions millennia after their first violent pulse. These dormant supernovae contain bright Wolf-Rayet stars, possibly embedded in bright X-ray and radio sources. The relevance of PPISN to supernova impostors like Eta Carinae, to superluminous supernovae, and to sources of gravitational radiation is discussed. No black holes between 52 and 133 {\\text{}}{M}⊙ are expected from stellar evolution in close binaries.

  7. Freeze, flight, fight, fright, faint: adaptationist perspectives on the acute stress response spectrum.

    PubMed

    Bracha, H Stefan

    2004-09-01

    This article reviews the existing evolutionary perspectives on the acute stress response habitual faintness and blood-injection-injury type-specific phobia (BIITS phobia). In this article, an alternative evolutionary perspective, based on recent advances in evolutionary psychology, is proposed. Specifically, that fear-induced faintness (eg, fainting following the sight of a syringe, blood, or following a trivial skin injury) is a distinct Homo sapiens-specific extreme-stress survival response to an inescapable threat. The article suggests that faintness evolved in response to middle paleolithic intra-group and inter-group violence (of con-specifics) rather than as a pan-mammalian defense response, as is presently assumed. Based on recent literature, freeze, flight, fight, fright, faint provides a more complete description of the human acute stress response sequence than current descriptions. Faintness, one of three primary physiological reactions involved in BIITS phobia, is extremely rare in other phobias. Since heritability estimates are higher for faintness than for fears or phobias, the author suggests that trait-faintness may be a useful complement to trait-anxiety as an endophenotype in research on the human fear circuitry. Some implications for the forthcoming Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition as well as for clinical, health services, and transcriptomic research are briefly discussed.

  8. A study of ultraviolet absorption lines through the complete Galactic halo by the analysis of HST faint object spectrograph spectra of active Galactic nuclei, 1

    NASA Technical Reports Server (NTRS)

    Burks, Geoffrey S.; Bartko, Frank; Shull, J. Michael; Stocke, John T.; Sachs, Elise R.; Burbidge, E. Margaret; Cohen, Ross D.; Junkkarinen, Vesa T.; Harms, Richard J.; Massa, Derck

    1994-01-01

    The ultraviolet (1150 - 2850 A) spectra of a number of active galactic nuclei (AGNs) observed with the Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) have been used to study the properties of the Galactic halo. The objects that served as probes are 3C 273, PKS 0454-220, Pg 1211+143, CSO 251, Ton 951, and PG 1351+640. The equivalent widths of certain interstellar ions have been measured, with special attention paid to the C IV/C II and Si IV/Si II ratios. These ratios have been intercompared, and the highest values are found in the direction of 3C 273, where C IV/C II = 1.2 and Si IV/Si II greater than 1. These high ratios may be due to a nearby supernova remnant, rather than to ionized gas higher up in the Galactic halo. Our data give some support to the notion that QSO metal-line systems may arise from intervening galaxies which contain high supernova rates, galactic fountains, and turbulent mixing layers.

  9. A study of ultraviolet absorption lines through the complete Galactic halo by the analysis of HST faint object spectrograph spectra of active Galactic nuclei, 1

    NASA Technical Reports Server (NTRS)

    Burks, Geoffrey S.; Bartko, Frank; Shull, J. Michael; Stocke, John T.; Sachs, Elise R.; Burbidge, E. Margaret; Cohen, Ross D.; Junkkarinen, Vesa T.; Harms, Richard J.; Massa, Derck

    1994-01-01

    The ultraviolet (1150 - 2850 A) spectra of a number of active galactic nuclei (AGNs) observed with the Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) have been used to study the properties of the Galactic halo. The objects that served as probes are 3C 273, PKS 0454-220, Pg 1211+143, CSO 251, Ton 951, and PG 1351+640. The equivalent widths of certain interstellar ions have been measured, with special attention paid to the C IV/C II and Si IV/Si II ratios. These ratios have been intercompared, and the highest values are found in the direction of 3C 273, where C IV/C II = 1.2 and Si IV/Si II greater than 1. These high ratios may be due to a nearby supernova remnant, rather than to ionized gas higher up in the Galactic halo. Our data give some support to the notion that QSO metal-line systems may arise from intervening galaxies which contain high supernova rates, galactic fountains, and turbulent mixing layers.

  10. Core-collapse supernova simulations

    NASA Astrophysics Data System (ADS)

    Mueller, Bernhard

    2017-01-01

    Core-collapse supernovae, the deaths of massive stars, are among the most spectacular phenomena in astrophysics: Not only can supernovae outshine their host galaxy for weeks; they are also laboratories for the behavior of matter at supranuclear densities, and one of the few environments where collective neutrino effects can become important. Moreover, supernovae play a central role in the cosmic matter cycle, e.g., as the dominant producers of oxygen in the Universe. Yet the mechanism by which massive stars explode has eluded us for decades, partly because classical astronomical observations across the electromagnetic spectrum cannot directly probe the supernovae ``engine''. Numerical simulations are thus our primary tool for understanding the explosion mechanism(s) of massive stars. Rigorous modeling needs to take a host of important physical ingredients into account, such as the emission and partial reabsorption of neutrinos from the young proto-neutron star, multi-dimensional fluid motions, general relativistic gravity, the equation of state of nuclear matter, and magnetic fields. This is a challenging multi-physics problem that has not been fully solved yet. Nonetheless, as I shall argue in this talk, recent first-principle 3D simulations have gone a long way towards demonstrating the viability of the most popular explosion scenario, the ``neutrino-driven mechanism''. Focusing on successful explosion models of the MPA-QUB-Monash collaboration, I will discuss possible requirements for robust explosions across a wide range of progenitors, such as accurate neutrino opacities, stellar rotation, and seed asymmetries from convective shell burning. With the advent of successful explosion models, supernova theory can also be confronted with astronomical observations. I will show that recent 3D models come closer to matching observed explosion parameters (explosion energies, neutron star kicks) than older 2D models, although there are still discrepancies. This work has

  11. NASA Space Observatories Glimpse Faint Afterglow of Nearby Stellar Explosion

    NASA Astrophysics Data System (ADS)

    2005-10-01

    Intricate wisps of glowing gas float amid a myriad of stars in this image created by combining data from NASA's Hubble Space Telescope and Chandra X-ray Observatory. The gas is a supernova remnant, cataloged as N132D, ejected from the explosion of a massive star that occurred some 3,000 years ago. This titanic explosion took place in the Large Magellanic Cloud, a nearby neighbor galaxy of our own Milky Way. The complex structure of N132D is due to the expanding supersonic shock wave from the explosion impacting the interstellar gas of the LMC. Deep within the remnant, the Hubble visible light image reveals a crescent-shaped cloud of pink emission from hydrogen gas, and soft purple wisps that correspond to regions of glowing oxygen emission. A dense background of colorful stars in the LMC is also shown in the Hubble image. The large horseshoe-shaped gas cloud on the left-hand side of the remnant is glowing in X-rays, as imaged by Chandra. In order to emit X-rays, the gas must have been heated to a temperature of about 18 million degrees Fahrenheit (10 million degrees Celsius). A supernova-generated shock wave traveling at a velocity of more than four million miles per hour (2,000 kilometers per second) is continuing to propagate through the low-density medium today. The shock front where the material from the supernova collides with ambient interstellar material in the LMC is responsible for these high temperatures. Chandra image of N132D Chandra image of N132D, 2002 It is estimated that the star that exploded as a supernova to produce the N132D remnant was 10 to 15 times more massive than our own Sun. As fast-moving ejecta from the explosion slam into the cool, dense interstellar clouds in the LMC, complex shock fronts are created. A supernova remnant like N132D provides a rare opportunity for direct observation of stellar material, because it is made of gas that was recently hidden deep inside a star. Thus it provides information on stellar evolution and the

  12. A Deep Search with HST for Late Time Supernova Signatures in the Hosts of XRF 011030 and XRF 020427

    NASA Technical Reports Server (NTRS)

    Patel, Sandeep; Kouveliotou, Chryssa; Levan, Andrew; Fruchter, Andrew; Rol, Evert; Rhoads, James; Gorosabel, Javier; Ramirez-Ruiz, Enrico; Hjorth, Jens; Wijers, Ralph

    2004-01-01

    X-ray Flashes (XRFs), are, like Gamma-Ray Bursts (GRBs) thought to signal the collapse of massive stars in distant galaxies. Many models posit that the isotropic equivalent energies of XRFs are lower than those for GRBs, such that they are visible hom a reduced range of distances when compared with GRBs. Here we present the results of two epoch Hubble Space Telescope imaging of two XRFs. These images taken approximately 45 and 200 days post bust reveal no evidence for an associated supernova in either case. Supernovae such as SN 1998bw would have been visible out to z approximately 1.5 in each case, while faint supernovae such as SN 2002ap would be visible to z approximately 1. At these distances the bursts would not fit the observed correlations between E(sub p) and E(sub iso) and would have required extremely luminous X-ray afterglows. We conclude that should these XRFs reside at low redshift, it is necessary either that their line of sight is heavily extinguished, or that XRFs, unlike GRBs do not have temporally coincident supernovae.

  13. A Deep Search with HST for Late Time Supernova Signatures in the Hosts of XRF 011030 and XRF 020427

    NASA Technical Reports Server (NTRS)

    Patel, Sandeep; Kouveliotou, Chryssa; Levan, Andrew; Fruchter, Andrew; Rol, Evert; Rhoads, James; Gorosabel, Javier; Ramirez-Ruiz, Enrico; Hjorth, Jens; Wijers, Ralph

    2004-01-01

    X-ray Flashes (XRFs), are, like Gamma-Ray Bursts (GRBs) thought to signal the collapse of massive stars in distant galaxies. Many models posit that the isotropic equivalent energies of XRFs are lower than those for GRBs, such that they are visible hom a reduced range of distances when compared with GRBs. Here we present the results of two epoch Hubble Space Telescope imaging of two XRFs. These images taken approximately 45 and 200 days post bust reveal no evidence for an associated supernova in either case. Supernovae such as SN 1998bw would have been visible out to z approximately 1.5 in each case, while faint supernovae such as SN 2002ap would be visible to z approximately 1. At these distances the bursts would not fit the observed correlations between E(sub p) and E(sub iso) and would have required extremely luminous X-ray afterglows. We conclude that should these XRFs reside at low redshift, it is necessary either that their line of sight is heavily extinguished, or that XRFs, unlike GRBs do not have temporally coincident supernovae.

  14. Spitzer observations of SN 2014J and properties of mid-IR emission in Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Johansson, J.; Goobar, A.; Kasliwal, M. M.; Helou, G.; Masci, F.; Tinyanont, S.; Jencson, J.; Cao, Y.; Fox, O. D.; Kromer, M.; Amanullah, R.; Banerjee, D. P. K.; Joshi, V.; Jerkstrand, A.; Kankare, E.; Prince, T. A.

    2017-04-01

    SN 2014J in M 82 is the closest Type Ia supernova (SN Ia) in decades. The proximity allows for detailed studies of supernova physics and provides insights into the circumstellar and interstellar environment. In this work, we analyse Spitzer mid-infrared (mid-IR) data of SN 2014J in the 3.6 and 4.5 μm wavelength range, together with several other nearby and well-studied SNe Ia. We compile the first composite mid-IR light-curve templates from our sample of SNe Ia, spanning the range from before peak brightness well into the nebular phase. Our observations indicate that SNe Ia form a very homogeneous class of objects at these wavelengths. Using the low-reddening supernovae for comparison, we constrain possible thermal emission from circumstellar dust around the highly reddened SN 2014J. We also study SNe 2006X and 2007le, where the presence of matter in the circumstellar environment has been suggested. No significant mid-IR excess is detected, allowing us to place upper limits on the amount of pre-existing dust in the circumstellar environment. For SN 2014J, Mdust ≲ 10- 5 M⊙ within rdust ∼ 1017 cm, which is insufficient to account for the observed extinction. Similar limits are obtained for SNe 2006X and 2007le.

  15. Unmasking the Supernova Impostors

    NASA Astrophysics Data System (ADS)

    Kochanek, C. S.; Szczygieł, D. M.; Stanek, K. Z.

    2012-10-01

    The canonical picture of a supernova impostor is a short (~months) -11 <~ MV <~ -14 optical transient from a massive (M * >~ 40 M ⊙) star during which the star ejects a dense shell of material. Dust formed in the ejecta then obscures the star. In this picture, the geometric expansion of the shell leads to clear predictions for the evolution of the optical depths and hence the evolution of the optical through mid-IR emissions. Here, we review the theory of this standard model and then examine the impostors SN 1954J, SN 1997bs, SN 1999bw, SN 2000ch, SN 2001ac, SN 2002bu, SN 2002kg, and SN 2003gm, as well as the potential archetype η Carinae. SN 1999bw, SN 2000ch, SN 2001ac, SN 2002bu, and SN 2003gm all show mid-IR emission indicative of dust, and the luminosities of SN 1999bw, SN 2001ac, SN 2002bu, and SN 2003gm are dominated by dust emission. We find only upper limits on dust emission from SN 1954J, SN 1997bs, and SN 2002kg. The properties of these sources are, however, broadly inconsistent with the predictions of the canonical model. Based on their mid-IR properties, there are at least three classes of objects being labeled as "impostors." The first class, containing the luminous blue variable (LBV) SN 2002kg and the non-LBV SN 2000ch, consists of variable stars with little or no dust formation as a consequence of the transient. The second class contains the "classical" impostors SN 1954J, SN 1997bs, and (maybe) SN 2003gm that may be weaker analogs of η Carinae. However, if these sources are stellar eruptions, the visual transient is simply a signal that the star is entering a phase with high mass-loss rates and dust formation that must last far longer than the observed optical transient. The third class consists of the SN 2008S-like transients, SN 1999bw, SN 2001ac, SN 2002bu, and (maybe) SN 2003gm, which are obscured by dust re-forming in a pre-existing wind after it was destroyed by an explosive transient. For all three classes of source, there are no cases

  16. Cobalt-56 γ-ray emission lines from the type Ia supernova 2014J.

    PubMed

    Churazov, E; Sunyaev, R; Isern, J; Knödlseder, J; Jean, P; Lebrun, F; Chugai, N; Grebenev, S; Bravo, E; Sazonov, S; Renaud, M

    2014-08-28

    A type Ia supernova is thought to be a thermonuclear explosion of either a single carbon-oxygen white dwarf or a pair of merging white dwarfs. The explosion fuses a large amount of radioactive (56)Ni (refs 1-3). After the explosion, the decay chain from (56)Ni to (56)Co to (56)Fe generates γ-ray photons, which are reprocessed in the expanding ejecta and give rise to powerful optical emission. Here we report the detection of (56)Co lines at energies of 847 and 1,238 kiloelectronvolts and a γ-ray continuum in the 200-400 kiloelectronvolt band from the type Ia supernova 2014J in the nearby galaxy M82. The line fluxes suggest that about 0.6 ± 0.1 solar masses of radioactive (56)Ni were synthesized during the explosion. The line broadening gives a characteristic mass-weighted ejecta expansion velocity of 10,000 ± 3,000 kilometres per second. The observed γ-ray properties are in broad agreement with the canonical model of an explosion of a white dwarf just massive enough to be unstable to gravitational collapse, but do not exclude merger scenarios that fuse comparable amounts of (56)Ni.

  17. Proposed searches for candidate sources of gravitational waves in a nearby core-collapse supernova survey

    NASA Astrophysics Data System (ADS)

    Heo, Jeong-Eun; Yoon, Soyoung; Lee, Dae-Sub; Kong, In-taek; Lee, Sang-Hoon; van Putten, Maurice H. P. M.; Della Valle, Massimo

    2016-01-01

    Gravitational wave bursts in the formation of neutron stars and black holes in energetic core-collapse supernovae (CC-SNe) are of potential interest to LIGO-Virgo and KAGRA. Events nearby are readily discovered using moderately sized telescopes. CC-SNe are competitive with mergers of neutron stars and black holes, if the fraction producing an energetic output in gravitational waves exceeds about 1%. This opportunity motivates the design of a novel Sejong University Core-CollapsE Supernova Survey (SUCCESS), to provide triggers for follow-up searches for gravitational waves. It is based on the 76 cm Sejong university telescope (SUT) for weekly monitoring of nearby star-forming galaxies, i.e., M51, M81-M82 and blue dwarf galaxies from the unified nearby galaxy catalog with an expected yield of a few hundred per year. Optical light curves will be resolved for the true time-of-onset for probes of gravitational waves by broadband time-sliced matched filtering.

  18. Bright Type-Ia Supernova PSN J09554214+6940260 and Observing Campaign

    NASA Astrophysics Data System (ADS)

    Waagen, Elizabeth O.; Templeton, Matthew R.

    2014-01-01

    Announces the discovery of the SN 2014J = PSN J09554214+6940260 in M82 by Stephen J. Fossey (University College London Observatory) at magnitude 11.7 V on 2014 January 21.81 UT. Spectra by Cao et al. (Palomar Transient Factory Collaboration) show PSN J09554214+6940260 is a reddened young Type-Ia supernova discovered before maximum. They also report the best superfit match is SN2002bo at -14d, and that the supernova has a red continuum and deep Na D absorption. Both visual and CCD observations are encouraged. CCD observers are encouraged to perform filtered photometry, and if possible to transform their observations to the standard photometric system of their filters. In addition, rapid V-band time-series has been requested by Dr. Bradley Schaefer (Louisiana State University) for an exploratory search for possible flares or other short-term photometric variations during the outburst. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details and observations.

  19. An SN-Ia in a very faint dwarf galaxy

    NASA Astrophysics Data System (ADS)

    Drake, A. J.; Mahabal, A.; Djorgovski, S. G.; Graham, M. J.; Williams, R.; Myers, A. D.; Catelan, M.; Beshore, E. C.; Larson, S. M.; Christensen, E.

    2009-03-01

    Further to Atel#1937, we confirm the discovery of a type Ia supernova with Palomar 200 observations. The CRTS discovery has the following parameters:

    CSS090213:030920+160505 Discovery 2009-02-13 UT 03:45:55 RA 03:09:19.79 Dec 16:05:05.3 Type SN Ia
    The spectrum of CSS090213:030920+160505 (taken on Feb 25th UT) shows this to be an SN-Ia, 12 days past maximum light with redshift z=0.031+/-0.006.

  20. Serendipitous discovery of the faint solar twin Inti 1

    NASA Astrophysics Data System (ADS)

    Galarza, Jhon Yana; Meléndez, Jorge; Cohen, Judith G.

    2016-05-01

    Context. Solar twins are increasingly the subject of many studies owing to their wide range of applications from testing stellar evolution models to the calibration of fundamental observables; these stars are also of interest because high precision abundances could be achieved that are key to investigating the chemical anomalies imprinted by planet formation. Furthermore, the advent of photometric surveys with large telescopes motivates the identification of faint solar twins in order to set the zero point of fundamental calibrations. Aims: We intend to perform a detailed line-by-line differential analysis to verify whether 2MASS J23263267-0239363 (designated here as Inti 1) is indeed a solar twin. Methods: We determine the atmospheric parameters and differential abundances using high-resolution (R ≈ 50 000), high signal-to-noise (S/N ≈ 110-240 per pixel) Keck/HIRES spectra for our solar twin candidate, the previously known solar twin HD 45184, and the Sun (using reflected light from the asteroid Vesta). Results: For the bright solar twin HD 45184, we found Teff = 5864 ± 9 K, log g = 4.45 ± 0.03 dex, vt = 1.11 ± 0.02 km s-1, and [Fe/H] = 0.04 ± 0.01 dex, which are in good agreement with previous works. Our abundances are in excellent agreement with a recent high-precision work, with an element-to-element scatter of only 0.01 dex. The star Inti 1 has atmospheric parameters Teff = 5837 ± 11 K, log g = 4.42 ± 0.03 dex, vt = 1.04 ± 0.02 km s-1, and [Fe/H] = 0.07 ± 0.01 dex that are higher than solar. The age and mass of the solar twin HD 45184 (3 Gyr and 1.05 M⊙) and the faint solar twin Inti 1 (4 Gyr and 1.04 M⊙) were estimated using isochrones. The differential analysis shows that HD 45184 presents an abundance pattern that is similar to typical nearby solar twins; this means this star has an enhanced refractory relative to volatile elements, while Inti 1 has an abundance pattern closer to solar, albeit somewhat enhanced in refractories. The abundance

  1. Finding Distances to Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-03-01

    Type Ia supernovae are known as standard candles due to their consistency, allowing us to measure distances based on their brightness. But what if these explosions arent quite as consistent as we thought? Due scientific diligence requires careful checks, so a recent study investigates whether the metallicity of a supernovas environment affects the peak luminosity of the explosion.Metallicity Dependence?Type Ia supernovae are incredibly powerful tools for determining distances in our universe. Because these supernovae are formed by white dwarfs that explode when they reach a uniform accreted mass, the supernova peak luminosity is thought to be very consistent. This consistency allows these supernovae to be used as standard candles to measure distances to their host galaxies.But what if that peak luminosity is affected by a factor that we havent taken into account? Theorists have proposed that the luminosities of Type Ia supernovae might depend on the metallicity of their environments with high-metallicity environments suppressing supernova luminosities. If this is true, then we could be systematically mis-measuring cosmological distances using these supernovae.Testing AbundancesSupernova brightnesses vs. the metallicity of their environments. Low-metallicity supernovae (blue shading) and high-metallicity supernovae (red shading) have an average magnitude difference of ~0.14. [Adapted from Moreno-Raya et al. 2016]A team led by Manuel Moreno-Raya, of the Center for Energy, Environment and Technology (CIEMAT) in Spain, has observed 28 Type Ia supernovae in an effort to test for such a metallicity dependence. These supernovae each have independent distance measurements (e.g., from Cepheids or the Tully-Fisher relation).Moreno-Raya and collaborators used spectra from the 4.2-m William Herschel Telescope to estimate oxygen abundances in the region where each of these supernovae exploded. They then used these measurements to determine if metallicity of the local region

  2. Gravitational lensing statistics of amplified supernovae

    NASA Technical Reports Server (NTRS)

    Linder, Eric V.; Wagoner, Robert V.; Schneider, P.

    1988-01-01

    Amplification statistics of gravitationally lensed supernovae can provide a valuable probe of the lensing matter in the universe. A general probability distribution for amplification by compact objects is derived which allows calculation of the lensed fraction of supernovae at or greater than an amplification A and at or less than an apparent magnitude. Comparison of the computed fractions with future results from ongoing supernova searches can lead to determination of the mass density of compact dark matter components with masses greater than about 0.001 solar mass, while the time-dependent amplification (and polarization) of the expanding supernovae constrain the individual masses. Type II supernovae are found to give the largest fraction for deep surveys, and the optimum flux-limited search is found to be at approximately 23d magnitude, if evolution of the supernova rate is neglected.

  3. Improvements to type Ia supernova models

    NASA Astrophysics Data System (ADS)

    Saunders, Clare M.

    Type Ia Supernovae provided the first strong evidence of dark energy and are still an important tool for measuring the accelerated expansion of the universe. However, future improvements will be limited by systematic uncertainties in our use of Type Ia supernovae as standard candles. Using Type Ia supernovae for cosmology relies on our ability to standardize their absolute magnitudes, but this relies on imperfect models of supernova spectra time series. This thesis is focused on using data from the Nearby Supernova Factory both to understand current sources of uncertainty in standardizing Type Ia supernovae and to develop techniques that can be used to limit uncertainty in future analyses. (Abstract shortened by ProQuest.).

  4. White dwarf models for type 1 supernovae and quiet supernovae, and presupernova evolution

    NASA Technical Reports Server (NTRS)

    Nomoto, K.

    1980-01-01

    Supernova mechanisms in accreting white dwarfs are considered with emphasis on deflagration as a plausible mechanism for producing Type I supernovae and electron captures to form quiet supernovae leaving neutron stars. These outcomes depend on accretion rate of helium, initial mass and composition of the white dwarf. The various types of hydrogen shell burning in the presupernova stage are also discussed.

  5. La supernova galattica è in ritardo?

    NASA Astrophysics Data System (ADS)

    Sigismondi, Costantino

    2005-06-01

    After 400 years we are still waiting to see a galactic supernova. A simple galactic model based upon interstellar absorption is shown in order to explain the rate of observed galactic supernovae. The history of variable stars observations in modern epoch is sketched and the hypothesis for Bethlehem Star made by Kepler in occasion of the last galactic supernova, exploded in Ophiuchus on 9 October 1604, is also presented.

  6. Magnetares como fuentes para potenciar supernovas superluminosas

    NASA Astrophysics Data System (ADS)

    Bersten, M. C.; Benvenuto, O. G.

    2016-08-01

    Magnetars have been proposed as one of the possible sources to power the light curve of super-luminous supernovae. We have included the energy deposited by a hypothetical magnetar in our one-dimensional hydrodynamical code, and analyzed the dynamical effect on the supernova ejecta. In particular, we present a model for SN 2011kl, the first object associated with a ultra-long-duration gamma-ray burst. Finally, we show its effect on the light curves of hydrogen rich supernovae.

  7. Connecting supernovae with their environments

    NASA Astrophysics Data System (ADS)

    Galbany, L.

    2017-03-01

    We present MUSE observations of galaxy NGC 7469 from its Science Verification to show how powerful is the combination of high-resolution wide-field integral field spectroscopy with both photometric and spectroscopic observations of supernova (SN) explosions. Using STARLIGHT and H II explorer, we selected all H II regions of the galaxy and produced 2-dimensional maps of the Hα equivalent width, average luminosity-weighted stellar age, and oxygen abundance. We measured deprojected galactocentric distances for all H II regions, and radial gradients for all above-mentioned parameters. We positioned the type Ia SN2008ec in the Branch et al. diagram, and finally discussed the characteristics of the SN parent H II region compared to all other H II regions in the galaxy. In a near future, the AMUSING survey will be able to reproduce this analysis and construct statistical samples to enable the characterization of the progenitors of different supernova types.

  8. SUPERNOVA FALLBACK ONTO MAGNETARS AND PROPELLER-POWERED SUPERNOVAE

    SciTech Connect

    Piro, Anthony L.; Ott, Christian D. E-mail: cott@tapir.caltech.edu

    2011-08-01

    We explore fallback accretion onto newly born magnetars during the supernova of massive stars. Strong magnetic fields ({approx}10{sup 15} G) and short spin periods ({approx}1-10 ms) have an important influence on how the magnetar interacts with the infalling material. At long spin periods, weak magnetic fields, and high accretion rates, sufficient material is accreted to form a black hole, as is commonly found for massive progenitor stars. When B {approx}< 5 x 10{sup 14} G, accretion causes the magnetar to spin sufficiently rapidly to deform triaxially and produces gravitational waves, but only for {approx}50-200 s until it collapses to a black hole. Conversely, at short spin periods, strong magnetic fields, and low accretion rates, the magnetar is in the 'propeller regime' and avoids becoming a black hole by expelling incoming material. This process spins down the magnetar, so that gravitational waves are only expected if the initial protoneutron star is spinning rapidly. Even when the magnetar survives, it accretes at least {approx}0.3 M{sub sun}, so we expect magnetars born within these types of environments to be more massive than the 1.4 M{sub sun} typically associated with neutron stars. The propeller mechanism converts the {approx}10{sup 52} erg of spin energy in the magnetar into the kinetic energy of an outflow, which shock heats the outgoing supernova ejecta during the first {approx}10-30 s. For a small {approx}5 M{sub sun} hydrogen-poor envelope, this energy creates a brighter, faster evolving supernova with high ejecta velocities {approx}(1-3) x 10{sup 4} km s{sup -1} and may appear as a broad-lined Type Ib/c supernova. For a large {approx}> 10 M{sub sun} hydrogen-rich envelope, the result is a bright Type IIP supernova with a plateau luminosity of {approx}> 10{sup 43} erg s{sup -1} lasting for a timescale of {approx}60-80 days.

  9. HST NICMOS snapshot survey of faint galaxies at z < 1

    NASA Astrophysics Data System (ADS)

    Hinkley, S.; Im, M.; DEEP Team

    2000-12-01

    During Cycle 7 HST observations, we have obtained NICMOS H-band images of faint field galaxies for which both HST morphological information (in V and/or I) and spectroscopic redshifts are available. The purpose of the NICMOS observation is to provide their morphology in rest frame NIR wavelengths (8000 - 16000 Å), where the effect of dust extinction is less severe, and to obtain their near infrared (NIR) colors. The objects in our field are partly contained in the Groth Strip being studied in detail by the DEEP team. In addition, we have made use of a software package called GIM2D (Simard et al. 2001). This package is designed to perform detailed 2-dimensional decompositions for images of distant galaxies. Using this software, we have obtained structural parameters for the objects in the H-band to complement those parameters in V and I. We will present: i) color gradients inside elliptical galaxies to test models of their formation; ii) the effect of dust extinction on the properties of field galaxies at 0 < z < 1; iii) evolution of V-H, and V-I colors of bulges as well as the B/T ratio of spiral galaxies as a function of redshift; iv) morphological k-correction. The median redshift of our sample is z ~ 0.5 and this corresponds to about one half of the current age of the universe. This work is supported by the STScI grant GO-07895.02-96A.

  10. Helium shells and faint emission lines from slitless flash spectra

    PubMed Central

    Bazin, Cyril; Koutchmy, Serge

    2013-01-01

    At the time of the two last solar total eclipses of August 1st, 2008 in Siberia and July 11th, 2010 in French Polynesia, high frame rate CCD flash spectra were obtained. These eclipses occurred in quiet Sun period and after. The slitless flash spectra show two helium shells, in the weak Paschen α 4686 Å line of the ionized helium HeII and in the neutral helium HeI line at 4713 Å. The extensions of these helium shells are typically 3 Mm. In prominences, the extension of the interface with the corona is much more extended. The observations and analysis of these lines can properly be done only in eclipse conditions, when the intensity threshold reaches the coronal level, and the parasitic scattered light is virtually zero. Under the layers of 1 Mm above the limb, many faint low FIP lines were also seen in emission. These emission lines are superposed on the continuum containing absorption lines. The solar limb can be defined using the weak continuum appearing between the emission lines at the time of the second and third contact. The variations of the singly ionized iron line, the HeI and HeII lines and the continuum intensity are analyzed. The intensity ratio of ionized to neutral helium is studied for evaluating the ionization rate in low layers up to 2 Mm and also around a prominence. PMID:25685435

  11. Helium shells and faint emission lines from slitless flash spectra.

    PubMed

    Bazin, Cyril; Koutchmy, Serge

    2013-05-01

    At the time of the two last solar total eclipses of August 1st, 2008 in Siberia and July 11th, 2010 in French Polynesia, high frame rate CCD flash spectra were obtained. These eclipses occurred in quiet Sun period and after. The slitless flash spectra show two helium shells, in the weak Paschen α 4686 Å line of the ionized helium HeII and in the neutral helium HeI line at 4713 Å. The extensions of these helium shells are typically 3 Mm. In prominences, the extension of the interface with the corona is much more extended. The observations and analysis of these lines can properly be done only in eclipse conditions, when the intensity threshold reaches the coronal level, and the parasitic scattered light is virtually zero. Under the layers of 1 Mm above the limb, many faint low FIP lines were also seen in emission. These emission lines are superposed on the continuum containing absorption lines. The solar limb can be defined using the weak continuum appearing between the emission lines at the time of the second and third contact. The variations of the singly ionized iron line, the HeI and HeII lines and the continuum intensity are analyzed. The intensity ratio of ionized to neutral helium is studied for evaluating the ionization rate in low layers up to 2 Mm and also around a prominence.

  12. FIGS—Faint Infrared Grism Survey: Description and Data Reduction

    NASA Astrophysics Data System (ADS)

    Pirzkal, Norbert; Malhotra, Sangeeta; Ryan, Russell E.; Rothberg, Barry; Grogin, Norman; Finkelstein, Steven L.; Koekemoer, Anton M.; Rhoads, James; Larson, Rebecca L.; Christensen, Lise; Cimatti, Andrea; Ferreras, Ignacio; Gardner, Jonathan P.; Gronwall, Caryl; Hathi, Nimish P.; Hibon, Pascale; Joshi, Bhavin; Kuntschner, Harald; Meurer, Gerhardt R.; O’Connell, Robert W.; Oestlin, Goeran; Pasquali, Anna; Pharo, John; Straughn, Amber N.; Walsh, Jeremy R.; Watson, Darach; Windhorst, Rogier A.; Zakamska, Nadia L.; Zirm, Andrew

    2017-09-01

    The Faint Infrared Grism Survey (FIGS) is a deep Hubble Space Telescope (HST) WFC3/IR (Wide Field Camera 3 Infrared) slitless spectroscopic survey of four deep fields. Two fields are located in the Great Observatories Origins Deep Survey-North (GOODS-N) area and two fields are located in the Great Observatories Origins Deep Survey-South (GOODS-S) area. One of the southern fields selected is the Hubble Ultra Deep Field. Each of these four fields were observed using the WFC3/G102 grism (0.8 μm–1.15 μm continuous coverage) with a total exposure time of 40 orbits (≈100 kilo-seconds) per field. This reaches a 3σ continuum depth of ≈ 26 AB magnitudes and probes emission lines to ∼ {10}-17 {erg} {{{s}}}-1 {{cm}}-2. This paper details the four FIGS fields and the overall observational strategy of the project. A detailed description of the Simulation Based Extraction (SBE) method used to extract and combine over 10,000 spectra of over 2000 distinct sources brighter than {m}F105W=26.5 mag is provided. High fidelity simulations of the observations is shown to significantly improve the background subtraction process, the spectral contamination estimates, and the final flux calibration. This allows for the combination of multiple spectra to produce a final high quality, deep, 1D spectra for each object in the survey.

  13. Carbon Dioxide Cycling, Climate, Impacts, and the Faint Young Sun

    NASA Technical Reports Server (NTRS)

    Zahnle, K. J.; Sleep, H. H.

    1999-01-01

    Evidence for relatively mild climates on ancient Earth and Mars has been a puzzle in light of the faint early sun. The geologic evidence, although far from conclusive, would appear to indicate that the surfaces of both planets were, if anything, warmer ca. 3-4 Ga than they are now. The astrophysical argument that the sun ought to have brightened approx. 30% since it reached the main sequence is hard to refute. There results a paradox between the icehouse we expect and the greenhouse we think we see. The usual fix has been to posit massive CO2 atmospheres, although reduced gases (e.g., NH3 or CH4 ) have had their partisans. Evidence against siderite in paleosols dated 2.2-2.75 Ga sets a rough upper limit of 30 PAL (present atmospheric levels) on pCO2 at that time. This is an order of magnitude short of what is needed to defeat the fainter sun. We present here an independent argument against high pCO2 on early Earth that applies not only to the Archean but yet more forcefully to the Hadean era. Additional information is contained in the original extended abstract.

  14. Detecting faint nearby companions to geostationary satellites with optical interferometry

    NASA Astrophysics Data System (ADS)

    Schmitt, Henrique R.; Restaino, Sergio R.; Armstrong, J. Thomas; Baines, Ellyn K.

    2017-05-01

    One of the main problems faced by the Space Situational Awareness community is the detection and characterization of faint objects around geosats. Independent of the origin of these objects, whether they are debris or controlled spacecraft, they can potentially harm these assets and contaminate the geobelt environment. The challenge of detecting these companion objects comes from their proximity and brightness ratio relative to geosats. Here we present a novel interferometric fringe nulling technique, aimed at solving these issues. This technique takes advantage of the fact that the presence of companions introduces large phase fluctuations in the fringe phase observed by an interferometer, when the interferometer is observing a target at spatial frequencies where the fringe amplitude is near zero. We describe the ongoing development of this technique at the Navy Precision Optical Interferometer, and the results of simulations of interferometric observations of satellites with companions. We also present the current state of the NPOI and related SSA work being done with this interferometer, as well as undergoing upgrades to the system.

  15. Carbon Dioxide Cycling, Climate, Impacts, and the Faint Young Sun

    NASA Technical Reports Server (NTRS)

    Zahnle, K. J.; Sleep, H. H.

    1999-01-01

    Evidence for relatively mild climates on ancient Earth and Mars has been a puzzle in light of the faint early sun. The geologic evidence, although far from conclusive, would appear to indicate that the surfaces of both planets were, if anything, warmer ca. 3-4 Ga than they are now. The astrophysical argument that the sun ought to have brightened approx. 30% since it reached the main sequence is hard to refute. There results a paradox between the icehouse we expect and the greenhouse we think we see. The usual fix has been to posit massive CO2 atmospheres, although reduced gases (e.g., NH3 or CH4 ) have had their partisans. Evidence against siderite in paleosols dated 2.2-2.75 Ga sets a rough upper limit of 30 PAL (present atmospheric levels) on pCO2 at that time. This is an order of magnitude short of what is needed to defeat the fainter sun. We present here an independent argument against high pCO2 on early Earth that applies not only to the Archean but yet more forcefully to the Hadean era. Additional information is contained in the original extended abstract.

  16. The Faint Object Infrared Camera for the SOFIA Telescope

    NASA Astrophysics Data System (ADS)

    Keller, L. D.; Herter, T. L.; Stacey, G.; Gull, G. E.; Schoenwald, J.; Pirger, B.; Nikola, Tomas

    2002-06-01

    The Faint Object infraRed CAmera for the Sofia Telescope (FORCAST) is a facility-class, mid/far-infrared camera for the Stratospheric Observatory for Infrared Astronomy (SOFIA). FORCAST is a two-channel design with selectable filters for narrowband and broadband imaging in the 5-8, 17-25 micron, and/or 25-40 micron regions. Simultaneous imaging in the two-channels (lambda < 25 microns and lambda > 25 microns) is possible. FORCAST will sample images at 0.75 arcsec/pixel and have a 3.2?x3.2? instantaneous field-of-view. Imaging is diffraction limited for lambda > 15 microns. Since FORCAST operates in the wavelength range where the seeing from SOFIA is best, it will provide the highest spatial resolution possible with SOFIA. FORCAST may eventually support a spectroscopy mode (resolving power, R ~ 300 and R ~ 1000-2000) using silicon grisms mounted in the filter wheels. The science projects planned by the investigator team include multicolor imaging of the galactic center, Vega-like dust clouds, and star formation regions in normal spiral galaxies and active galaxies. This instrument will be of great value to the SOFIA community for imaging of protostellar environments, young star clusters, molecular clouds, and galaxies. We present details of the FORCAST instrument, including filter lists and sensitivity estimates, that will be useful to astronomers intending to use SOFIA for mid-infrared imaging.

  17. FORCAST: the faint object infared camera for the SOFIA telescope

    NASA Astrophysics Data System (ADS)

    Keller, Luke D.; Herter, Terry L.; Stacey, Gordon J.; Gull, George E.; Schoenwald, Justin; Pirger, Bruce; Nikola, Tomas

    2003-02-01

    We report final design details and development progress for the Faint Object Infrared Camera for the SOFIA Telescope (FORCAST). FORCAST is a two-channel camera with selectable filters for continuum and line imaging in the 5-40 micron wavelength region. Simultaneous imaging will be possible in the two-channels--5-25 microns using a Si:As 256×256 blocked impurity band (BIB) detector array, and 25-40 microns using a Si:Sb BIB. FORCAST will sample 0.75 arcseconds per pixel allowing a 3.2'×3.2' instantaneous field-of-view in both channels simultaneously. Imaging will be diffraction limited for lambda > 15 microns. Since FORCAST operates in the wavelength range where the seeing is best from SOFIA, it will provide the highest spatial resolution possible from the airborne observatory. In addition to imaging, the FORCAST optical design provides for a simple upgrade to include spectroscopic observations using grisms mounted in the filter wheels. We report improvements to the optical system and progress in construction of this SOFIA facility instrument and its subsystems. FORCAST will be available for facility testing and astronomical observations at SOFIA first (f)light.

  18. Serendipitous ALMA detections of faint submm galaxies in SERVS

    NASA Astrophysics Data System (ADS)

    Patil, Pallavi; Lacy, Mark; Nyland, Kristina

    2017-01-01

    We present a preliminary ALMA study of faint (<1mJy) submm galaxies with counterparts in the Spitzer Extragalactic Representative Volume Survey (SERVS). SERVS provides post-cryogenic IRAC imaging at 3.6 and 4.5 microns over an 18 deg2 area of the sky over five famous deep fields. The depth of the survey is ~ 2 µJy, and it provides a complete census of galaxies up to z ~ 5. While it is known that bright submm galaxies are associated with dusty, ultra-luminous starforming galaxies at z ~ 2, the sub-mJy population is still not well understood. A key missing piece of information is their morphologies at rest-frame optical wavelengths, which for high-redshift submm galaxies is only accessible through ALMA observations. The high sensitivity, spatial resolution, and positional accuracy of ALMA have enabled us to probe the nature of the sub-mJy population by resolving their spatial extents and improving constraints on their SEDS and photometric redshifts. We are building a catalog of sources by searching the ALMA archive for moderate to deep observations in the area covered by SERVS. This study will help us begin to understand the contribution of obscured star formation to the total star formation rate at high redshift and guide future wide-area surveys of submm galaxies with ALMA.

  19. No climate paradox under the faint early Sun.

    PubMed

    Rosing, Minik T; Bird, Dennis K; Sleep, Norman H; Bjerrum, Christian J

    2010-04-01

    Environmental niches in which life first emerged and later evolved on the Earth have undergone dramatic changes in response to evolving tectonic/geochemical cycles and to biologic interventions, as well as increases in the Sun's luminosity of about 25 to 30 per cent over the Earth's history. It has been inferred that the greenhouse effect of atmospheric CO(2) and/or CH(4) compensated for the lower solar luminosity and dictated an Archaean climate in which liquid water was stable in the hydrosphere. Here we demonstrate, however, that the mineralogy of Archaean sediments, particularly the ubiquitous presence of mixed-valence Fe(II-III) oxides (magnetite) in banded iron formations is inconsistent with such high concentrations of greenhouse gases and the metabolic constraints of extant methanogens. Prompted by this, and the absence of geologic evidence for very high greenhouse-gas concentrations, we hypothesize that a lower albedo on the Earth, owing to considerably less continental area and to the lack of biologically induced cloud condensation nuclei, made an important contribution to moderating surface temperature in the Archaean eon. Our model calculations suggest that the lower albedo of the early Earth provided environmental conditions above the freezing point of water, thus alleviating the need for extreme greenhouse-gas concentrations to satisfy the faint early Sun paradox.

  20. THE PRIMEVAL POPULATIONS OF THE ULTRA-FAINT DWARF GALAXIES

    SciTech Connect

    Brown, Thomas M.; Tumlinson, Jason; Kalirai, Jason S.; Avila, Roberto J.; Ferguson, Henry C. E-mail: tumlinson@stsci.edu E-mail: avila@stsci.edu; and others

    2012-07-01

    We present new constraints on the star formation histories of the ultra-faint dwarf (UFD) galaxies, using deep photometry obtained with the Hubble Space Telescope (HST). A galaxy class recently discovered in the Sloan Digital Sky Survey, the UFDs appear to be an extension of the classical dwarf spheroidals to low luminosities, offering a new front in efforts to understand the missing satellite problem. They are the least luminous, most dark-matter-dominated, and least chemically evolved galaxies known. Our HST survey of six UFDs seeks to determine if these galaxies are true fossils from the early universe. We present here the preliminary analysis of three UFD galaxies: Hercules, Leo IV, and Ursa Major I. Classical dwarf spheroidals of the Local Group exhibit extended star formation histories, but these three Milky Way satellites are at least as old as the ancient globular cluster M92, with no evidence for intermediate-age populations. Their ages also appear to be synchronized to within {approx}1 Gyr of each other, as might be expected if their star formation was truncated by a global event, such as reionization.