| 1. |
- France, Kevin, et al.
(författare)
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HST-COS Observations of Hydrogen, Helium, Carbon, and Nitrogen Emission from the SN 1987A Reverse Shock
- 2011
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 743:2, s. 186-
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Tidskriftsartikel (refereegranskat)abstract
- We present the most sensitive ultraviolet observations of Supernova 1987A to date. Imaging spectroscopy from the Hubble Space Telescope-Cosmic Origins Spectrograph shows many narrow (Δv ~ 300 km s-1) emission lines from the circumstellar ring, broad (Δv ~ 10-20 × 103 km s-1) emission lines from the reverse shock, and ultraviolet continuum emission. The high signal-to-noise ratio (>40 per resolution element) broad Lyα emission is excited by soft X-ray and EUV heating of mostly neutral gas in the circumstellar ring and outer supernova debris. The ultraviolet continuum at λ > 1350 Å can be explained by H I two-photon (2s 2 S 1/2-1s 2 S 1/2) emission from the same region. We confirm our earlier, tentative detection of N V λ1240 emission from the reverse shock and present the first detections of broad He II λ1640, C IV λ1550, and N IV] λ1486 emission lines from the reverse shock. The helium abundance in the high-velocity material is He/H = 0.14 ± 0.06. The N V/Hα line ratio requires partial ion-electron equilibration (Te /Tp ≈ 0.14-0.35). We find that the N/C abundance ratio in the gas crossing the reverse shock is significantly higher than that in the circumstellar ring, a result that may be attributed to chemical stratification in the outer envelope of the supernova progenitor. The N/C abundance may have been stratified prior to the ring expulsion, or this result may indicate continued CNO processing in the progenitor subsequent to the expulsion of the circumstellar ring. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.
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| 2. |
- France, Kevin, et al.
(författare)
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Observing Supernova 1987A with the Refurbished Hubble Space Telescope
- 2010
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 329:5999, s. 1624-1627
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Tidskriftsartikel (refereegranskat)abstract
- Observations with the Hubble Space Telescope (HST), conducted since 1990, now offer an unprecedented glimpse into fast astrophysical shocks in the young remnant of supernova 1987A. Comparing observations taken in 2010 with the use of the refurbished instruments on HST with data taken in 2004, just before the Space Telescope Imaging Spectrograph failed, we find that the Ly alpha and H alpha lines from shock emission continue to brighten, whereas their maximum velocities continue to decrease. We observe broad, blueshifted Ly alpha, which we attribute to resonant scattering of photons emitted from hot spots on the equatorial ring. We also detect N v lambda lambda 1239, 1243 angstrom line emission, but only to the red of Ly alpha. The profiles of the N v lines differ markedly from that of H alpha, suggesting that the N4+ ions are scattered and accelerated by turbulent electromagnetic fields that isotropize the ions in the collisionless shock.
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| 3. |
- Bladen, Catherine L., et al.
(författare)
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The TREAT-NMD Duchenne Muscular Dystrophy Registries : Conception, Design, and Utilization by Industry and Academia
- 2013
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Ingår i: Human Mutation. - : Hindawi Limited. - 1059-7794 .- 1098-1004. ; 34:11, s. 1449-1457
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Tidskriftsartikel (refereegranskat)abstract
- Duchenne muscular dystrophy (DMD) is an X-linked genetic disease, caused by the absence of the dystrophin protein. Although many novel therapies are under development for DMD, there is currently no cure and affected individuals are often confined to a wheelchair by their teens and die in their twenties/thirties. DMD is a rare disease (prevalence<5/10,000). Even the largest countries do not have enough affected patients to rigorously assess novel therapies, unravel genetic complexities, and determine patient outcomes. TREAT-NMD is a worldwide network for neuromuscular diseases that provides an infrastructure to support the delivery of promising new therapies for patients. The harmonized implementation of national and ultimately global patient registries has been central to the success of TREAT-NMD. For the DMD registries within TREAT-NMD, individual countries have chosen to collect patient information in the form of standardized patient registries to increase the overall patient population on which clinical outcomes and new technologies can be assessed. The registries comprise more than 13,500 patients from 31 different countries. Here, we describe how the TREAT-NMD national patient registries for DMD were established. We look at their continued growth and assess how successful they have been at fostering collaboration between academia, patient organizations, and industry.
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| 4. |
- Fransson, Claes, et al.
(författare)
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HIGH-DENSITY CIRCUMSTELLAR INTERACTION IN THE LUMINOUS TYPE IIn SN 2010jl : THE FIRST 1100 DAYS
- 2014
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 797:2
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Tidskriftsartikel (refereegranskat)abstract
- Hubble Space Telescope and ground-based observations of the Type IIn supernova (SN) 2010jl are analyzed, including photometry and spectroscopy in the ultraviolet, optical, and near-IR bands, 26-1128 days after first detection. At maximum, the bolometric luminosity was similar to 3 x 10(43) erg s(-1) and even at 850 days exceeds 10(42) erg s(-1). A near-IR excess, dominating after 400 days, probably originates in dust in the circumstellar medium (CSM). The total radiated energy is greater than or similar to 6.5x10(50) erg, excluding the dust component. The spectral lines can be separated into one broad component that is due to electron scattering and one narrow with expansion velocity similar to 100 km s(-1) from the CSM. The broad component is initially symmetric around zero velocity but becomes blueshifted after similar to 50 days, while remaining symmetric about a shifted centroid velocity. Dust absorption in the ejecta is unlikely to explain the line shifts, and we attribute the shift instead to acceleration by the SN radiation. From the optical lines and the X-ray and dust properties, there is strong evidence for large-scale asymmetries in the CSM. The ultraviolet lines indicate CNO processing in the progenitor, while the optical shows a number of narrow coronal lines excited by the X-rays. The bolometric light curve is consistent with a radiative shock in an r(-2) CSM with a mass-loss rate of M similar to 0.1 M(circle dot)yr(-1). The total mass lost is greater than or similar to 3 M-circle dot. These properties are consistent with the SN expanding into a CSM characteristic of a luminous blue variable progenitor with a bipolar geometry. The apparent absence of nuclear processing is attributed to a CSM that is still opaque to electron scattering.
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| 5. |
- Marion, G. H., et al.
(författare)
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TYPE IIb SUPERNOVA SN 2011dh : SPECTRA AND PHOTOMETRY FROM THE ULTRAVIOLET TO THE NEAR-INFRARED
- 2014
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 781:2, s. 69-
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Tidskriftsartikel (refereegranskat)abstract
- We report spectroscopic and photometric observations of the Type IIb SN 201 ldh obtained between 4 and 34 days after the estimated date of explosion (May 31.5 UT). The data cover a wide wavelength range from 2000 angstrom in the ultraviolet (UV) to 2.4 mu m in the near-infrared (NIR). Optical spectra provide line profiles and velocity measurements of H I, He I, Call, and Fe It that trace the composition and kinematics of the supernova (SN). NIR spectra show that helium is present in the atmosphere as early as 11 days after the explosion. A UV spectrum obtained with the Space Telescope Imaging Spectrograph reveals that the UV flux for SN 2011dh is low compared to other SN IIb. Modeling the spectrum with SYNOW suggests that the UV deficit is due to line blanketing from TinH and Co II. The HI and He I velocities in SN 2011dh are separated by about 4000 km s(-1) at all phases. A velocity gap is consistent with models for a preexplosion structure in which a hydrogen-rich shell surrounds the progenitor. We estimate that the H shell of SN 2011dh is approximate to 8 times less massive than the shell of SN 1993J and approximate to 3 times more massive than the shell of SN 2008ax. Light curves (LCs) for 12 passbands are presented: UVW2, UVM2, UVW1, U, u', B, V, r', i', J, H, and Ks. In the B band, SN 2011dh reached peak brightness of 13.17 mag at 20.0 +/- 0.5 after the explosion. The maximum bolometric luminosity of 1.8 +/- 0.2 x 10(42) erg s(-1) occurred approximate to 22 days after the explosion. NIR emission provides more than 30% of the total bolometric flux at the beginning of our observations, and the NIR contribution increases to nearly 50% of the total by day 34. The UV produces 16% of the total flux on day 4, 5% on day 9, and 1% on day 34. We compare the bolometric LCs of SN 2011dh, SN 2008ax, and SN 1993J. The LC are very different for the first 12 days after the explosions, but all three SN IIb display similar peak luminosities, times of peak, decline rates, and colors after maximum. This suggests that the progenitors of these SN IIb may have had similar compositions and masses, but they exploded inside hydrogen shells that have a wide range of masses. SN 2011dh was well observed, and a likely progenitor star has been identified in preexplosion images. The detailed observations presented here will help evaluate theoretical models for this SN and lead to a better understanding of SN IIb.
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