Browsing by Author "Roth, M"

Now showing 1 - 4 of 4
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    Investigating new planetary nebulae in the southern hemisphere
    (2000) Kerber, F; Furlan, E; Roth, M; Galaz, G; Chanamé, JC
    The major purpose of the investigation presented in this paper was to prove or disprove the nature of planetary nebula (PN) candidates in the southern hemisphere, selected from the third volume of the Atlas of Galactic Nebulae by Neckel & Vehrenberg. We present imaging and spectroscopic observations of seven PNe, five of them identified for the first time. An additional object probably is an H II region. All observed PNe represent evolved stages, their angular diameter ranging from 15 " to 170 ", and exhibit low surface brightnesses.
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    Simultaneous multiwavelength observations of dwarf novae .1. SU Ursae Majoris: Minihumps at a minioutburst?
    (1996) Echevarria, J; Tovmassian, G; Shara, M; Tapia, M; Bohigas, J; Jones, DHP; Gilmozzi, R; Costero, R; Lopez, JA; Roth, M; Alvarez, M; Rodriguez, LF; DeLara, E; Stover, RJ; MartinezRoger, C; Garzon, F; Asatrian, N; Vogt, N; Szkody, P; Zsoldos, E; Mattei, J; Bateson, FM
    SU Ursae Majoris-the prototype of a subgroup of dwarf novae that display superhumps in superoutbursts has been observed during an international campaign dedicated to the observation of the first day of outburst of dwarf novae during 1986 February. After the start of a brightening was reported, the star was monitored by IUE, ground-based photometry and spectrophotometry, IR-photometry, and radio observations by VLA. However, it did not undergo a normal outburst or a superoutburst.
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    Sn 2005bf
    (2006) Folatelli, G; Contreras, C; Phillips, MM; Woosley, SE; Blinnikov, S; Morrell, N; Suntzeff, NB; Lee, BL; Hamuy, M; González, S; Krzeminski, W; Roth, M; Li, WD; Filippenko, AV; Foley, RJ; Freedman, WL; Madore, BF; Persson, SE; Murphy, D; Boissier, S; Galaz, G; González, L; McCarthy, PJ; McWilliam, A; Pych, W
    We present u'g'r'i'BV photometry and optical spectroscopy of the Type Ib/Ic SN 2005bf covering the first similar to 100 days following discovery. The u'g'BV light curves displayed an unprecedented morphology among Type Ib/Ic supernovae, with an initial maximum some 2 weeks after discovery and a second, main maximum about 25 days after that. The bolometric light curve indicates that SN 2005bf was a remarkably luminous event, radiating at least 6.3 x 10(42) ergs s(-1) at maximum light and a total of 2.1 x 10(49) ergs during the first 75 days after the explosion. Spectroscopically, SN 2005bf underwent a unique transformation from a Type Ic-like event at early times to a typical Type Ib supernova at later phases. The initial maximum in u'g'BV was accompanied by the presence in the spectrum of high-velocity (> 14,000 km s(-1)) absorption lines of Fe II, Ca II, and H I. The photospheric velocity derived from spectra at early epochs was below 10,000 km s(-1), which is unusually low compared with ordinary Type Ib supernovae. We describe one-dimensional computer simulations that attempt to account for these remarkable properties. The most favored model is that of a very energetic (2 x 10(51) ergs), asymmetric explosion of a massive ( 8.3 M-circle dot) Wolf-Rayet WN star that had lost most of its hydrogen envelope. We speculate that an unobserved relativistic jet was launched producing a two-component explosion consisting of ( 1) a polar explosion containing a small fraction of the total mass and moving at high velocity and ( 2) the explosion of the rest of the star. At first, only the polar explosion is observed, producing the initial maximum and the high-velocity absorption-line spectrum resembling a Type Ic event. At late times, this fast- moving component becomes optically thin, revealing the more slowly moving explosion of the rest of the star and transforming the observed spectrum to that of a typical Type Ib supernova. If this scenario is correct, then SN 2005bf is the best example to date of a transition object between normal Type Ib/Ic supernovae and gamma-ray bursts.
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    The Type Ia supernova 1999aw
    (2002) Strolger, LG; Smith, RC; Suntzeff, NB; Phillips, MM; Aldering, G; Nugent, P; Knop, R; Perlmutter, S; Schommer, RA; Ho, LC; Hamuy, M; Krisciunas, K; Germany, LM; Covarrubias, R; Candia, P; Athey, A; Blanc, G; Bonacic, A; Bowers, T; Conley, A; Dahlén, T; Freedman, W; Galaz, G; Gates, E; Goldhaber, G; Goobar, A; Groom, D; Hook, IM; Marzke, R; Mateo, M; McCarthy, P; Méndez, J; Muena, C; Persson, SE; Quimby, R; Roth, M; Ruiz-Lapuente, P; Seguel, J; Szentgyorgyi, A; von Braun, K; Wood-Vasey, WM; York, T
    SN 1999aw was discovered during the first campaign of the Nearby Galaxies Supernova Search project. This luminous, slow-declining [Deltam(15)(B) = 0.81 +/- 0.03] Type Ia supernova was noteworthy in at least two respects. First, it occurred in an extremely low luminosity host galaxy that was not visible in the template images nor in initial subsequent deep imaging. Second, the photometric and spectral properties of this supernova indicate that it very likely was similar to the subclass of Type Ia supernovae whose prototype is SN 1999aa. This paper presents the BVRI and J(s)HK(s) light curves of SN 1999aw ( through similar to100 days past maximum light), as well as several epochs of optical spectra. From these data, we calculate the bolometric light curve and give estimates of the luminosity at maximum light and the initial Ni-56 mass. In addition, we present deep BVI images obtained recently with the Baade 6.5 m telescope at Las Campanas Observatory that reveal the remarkably low-luminosity host galaxy.