Browsing by Author "Valenti, S."

Now showing 1 - 17 of 17
  • No Thumbnail Available
    Item
    Early observations of the nearby Type Ia supernova SN 2015F
    (2017) Cartier, R.; Sullivan, M.; Firth, R. E.; Pignata, G.; Mazzali, P.; Maguire, K.; Childress, M. J.; Arcavi, I.; Ashall, C.; Bassett, B.; Crawford, S. M.; Frohmaier, C.; Galbany, L.; Gal-Yam, A.; Hosseinzadeh, G.; Howell, D. A.; Inserra, C.; Johansson, J.; Kasai, E. K.; McCully, C.; Prajs, S.; Prentice, S.; Schulze, S.; Smartt, S. J.; Smith, K. W.; Smith, M.; Valenti, S.; Young, D. R.
    We present photometry and time series spectroscopy of the nearby Type Ia supernova (SN Ia) SN 2015F over -16 d to +80 d relative to maximum light, obtained as part of the Public ESO Spectroscopic Survey of Transient Objects. SN 2015F is a slightly sub-luminous SN Ia with a decline rate of Delta m15(B) = 1.35 +/- 0.03 mag, placing it in the region between normal and SN 1991bg-like events. Our densely sampled photometric data place tight constraints on the epoch of first light and form of the early-time light curve. The spectra exhibit photospheric C II lambda 6580 absorption until -4 days, and high-velocity Ca II is particularly strong at <-10 d at expansion velocities of 23 000 km s(-1). At early times, our spectral modelling with SYN++ shows strong evidence for iron-peak elements ( Fe (II), Cr (II), Ti (II), and V-II) expanding at velocities > 14 000 km s(-1), suggesting mixing in the outermost layers of the SN ejecta. Although unusual in SN Ia spectra, including VII in the modelling significantly improves the spectral fits. Intriguingly, we detect an absorption feature at similar to 6800 angstrom that persists until maximum light. Our favoured explanation for this line is photospheric Al II, which has never been claimed before in SNe Ia, although detached high-velocity CII material could also be responsible. In both cases, the absorbing material seems to be confined to a relatively narrow region in velocity space. The nucleosynthesis of detectable amounts of Al II would argue against a low-metallicity white dwarf progenitor. We also show that this 6800 feature is weakly present in other normal SN Ia events and common in the SN 1991bg-like sub-class.
  • No Thumbnail Available
    Item
    Massive stars exploding in a He-rich circumstellar medium - V. Observations of the slow-evolving SN Ibn OGLE-2012-SN-006
    (2015) Pastorello, A.; Wyrzykowski, L.; Valenti, S.; Prieto, J. L.; Kozlowski, S.; Udalski, A.; Elias-Rosa, N.; Morales-Garoffolo, A.; Anderson, J. P.; Benetti, S.; Bersten, M.; Botticella, M. T.; Cappellaro, E.; Fasano, G.; Fraser, M.; Gal-Yam, A.; Gillone, M.; Graham, M. L.; Greiner, J.; Hachinger, S.; Howell, D. A.; Inserra, C.; Parrent, J.; Rau, A.; Schulze, S.; Smartt, S. J.; Smith, K. W.; Turatto, M.; Yaron, O.; Young, D. R.; Kubiak, M.; Szymanski, M. K.; Pietrzynski, G.; Soszynski, I.; Ulaczyk, K.; Poleski, R.; Pietrukowicz, P.; Skowron, J.; Mroz, P.
    We present optical observations of the peculiar Type Ibn supernova (SN Ibn) OGLE-2012-SN-006, discovered and monitored by the Optical Gravitational Lensing Experiment-IV survey, and spectroscopically followed by Public ESO Spectroscopic Survey of Transient Objects (PESSTO) at late phases. Stringent pre-discovery limits constrain the explosion epoch with fair precision to JD = 245 6203.8 +/- 4.0. The rise time to the I-band light-curve maximum is about two weeks. The object reaches the peak absolute magnitude M-I = -19.65 +/- 0.19 on JD = 245 6218.1 +/- 1.8. After maximum, the light curve declines for about 25 d with a rate of 4 mag (100 d)(-1). The symmetric I-band peak resembles that of canonical Type Ib/c supernovae (SNe), whereas SNe Ibn usually exhibit asymmetric and narrower early-time light curves. Since 25 d past maximum, the light curve flattens with a decline rate slower than that of the Co-56-Fe-56 decay, although at very late phases it steepens to approach that rate. However, other observables suggest that the match with the Co-56 decay rate is a mere coincidence, and the radioactive decay is not the main mechanism powering the light curve of OGLE-2012-SN-006. An early-time spectrum is dominated by a blue continuum, with only a marginal evidence for the presence of He I lines marking this SN type. This spectrum shows broad absorptions bluewards than 5000 angstrom, likely O II lines, which are similar to spectral features observed in superluminous SNe at early epochs. The object has been spectroscopically monitored by PESSTO from 90 to 180 d after peak, and these spectra show the typical features observed in a number of SN 2006jc-like events, including a blue spectral energy distribution and prominent and narrow (v(FWHM) approximate to 1900 km s(-1)) He I emission lines. This suggests that the ejecta are interacting with He-rich circumstellar material. The detection of broad (10(4) km s(-1)) O I and Ca II features likely produced in the SN ejecta (including the [OI] lambda lambda 6300,6364 doublet in the latest spectra) lends support to the interpretation of OGLE-2012-SN-006 as a core-collapse event.
  • No Thumbnail Available
    Item
    On the nature of hydrogen-rich superluminous supernovae
    (2018) Inserra, C.; Smartt, S. J.; Gall, E. E. E.; Leloudas, G.; Chen, T-W.; Schulze, S.; Jerkstrand, A.; Nicholl, M.; Anderson, J. P.; Arcavi, I.; Benetti, S.; Cartier, R. A.; Childress, M.; Della Valle, M.; Flewelling, H.; Fraser, M.; Gal-Yam, A.; Gutierrez, C. P.; Hosseinzadeh, G.; Howell, D. A.; Huber, M.; Kankare, E.; Kruehler, T.; Magnier, E. A.; Maguire, K.; McCully, C.; Prajs, S.; Primak, N.; Scalzo, R.; Schmidt, B. P.; Smith, M.; Smith, K. W.; Tucker, B. E.; Valenti, S.; Wilman, M.; Young, D. R.; Yuan, F.
    We present two hydrogen-rich superluminous supernovae (SLSNe): SN2103hx and PS 15br. These objects, together with SN2008es, are the only SLSNe showing a distinct, broad H alpha feature during the photospheric phase; also, they show no sign of strong interaction between fast moving ejecta and circumstellar shells in their early spectra. Despite the fact that the peak luminosity of PS 15br is fainter than that of the other two objects, the spectrophotometric evolution is similar to SN2103hx and different from any other supernova in a similar luminosity space. We group all of them as SLSNe II and hence they are distinct from the known class of SLSN IIn. Both transients show a strong, multicomponent H alpha emission after 200 d past maximum, which we interpret as an indication of the interaction of the ejecta with an asymmetric, clumpy circumstellar material. The spectra and photometric evolution of the two objects are similar to Type II supernovae, although they have much higher luminosity and evolve on slower time-scales. This is qualitatively similar to how SLSNe I compare with normal type Ic, in that the former are brighter and evolve more slowly. We apply a magnetar and an interaction semi-analytical code to fit the light curves of our two objects and SN2008es. The overall observational data set would tend to favour the magnetar, or central engine, model as the source of the peak luminosity, although the clear signature of late-time interaction indicates that interaction can play a role in the luminosity evolution of SLSNe II at some phases.
  • No Thumbnail Available
    Item
    SN 2004aw
    (2006) Taubenberger, S.; Pastorello, A.; Mazzali, P. A.; Valenti, S.; Pignata, G.; Sauer, D. N.; Arbey, A.; Baernbantner, O.; Benetti, S.; Della Valle, A.; Deng, J.; Elias-Rosa, N.; Filippenko, A. V.; Foley, R. J.; Goobar, A.; Kotak, R.; Li, W.; Meikle, P.; Mendez, J.; Patat, F.; Pian, E.; Ries, C.; Ruiz-Lapuente, P.; Salvo, M.; Stanishev, V.; Turatto, M.; Hillebrandt, W.
    Optical and near-infrared (near-IR) observations of the Type Ic supernova (SN Ic) 2004aw are presented, obtained from -3 to +413 d with respect to the B-band maximum. The photometric evolution is characterized by a comparatively slow post-maximum decline of the light curves. The peaks in redder bands are significantly delayed relative to the bluer bands, the I-band maximum occurring 8.4 d later than that in B. With an absolute peak magnitude of -18.02 in the V band the SN can be considered fairly bright, but not exceptional. This also holds for the U through I bolometric light curve, where SN 2004aw has a position intermediate between SNe 2002ap and 1998bw. Spectroscopically SN 2004aw provides a link between a normal SN Ic like SN 1994I and the group of broad-lined SNe Ic. The spectral evolution is rather slow, with a spectrum at day +64 being still predominantly photospheric. The shape of the nebular [O-I] lambda lambda 6300, 6364 line indicates a highly aspherical explosion. Helium cannot be unambiguously identified in the spectra, even in the near-IR. Using an analytical description of the light-curve peak we find that the total mass of the ejecta in SN 2004aw is 3.5-8.0 M-circle dot, significantly larger than that in SN 1994I, although not as large as in SN 1998bw. The same model suggests that about 0.3 M-circle dot of Ni-56 has been synthesized in the explosion. No connection to a GRB can be firmly established.
  • No Thumbnail Available
    Item
    Supernova 2011ds = Psn J20022093-2013134
    (2011) Howerton, S.; Drake, A. J.; Djorgovski, S. G.; Mahabal, A.; Graham, M. J.; Williams, R.; Prieto, J. L.; Catelan, Marcio; McNaught, R. H.; Garradd, G.; Beshore, E. C.; Larson, S. M.; Christensen, E.; Valenti, S.; Benetti, S.
    Report the discovery of an apparent supernova in public images from the Catalina Sky Survey; it was confirmed in images obtained with the Siding Spring Survey (SSS). SN 2011 UT R.A. (2000.0) Decl. Mag. Offset 2011ds May 13.42 20 02 20.93 -20 13 13.4 16.6 6" W, 17" N The variable was designated PSN J20022093-2013134 when posted at the Central Bureau's TOCP webpage and is here designated SN 2011ds based on the spectroscopic confirmation that is detailed below. Further magnitudes for 2011ds: Apr. 11.74 [19.0 (SSS); May 14.69, 16.6 (SSS); 15.721, 16.6 (Joseph Brimacombe, Coral Towers Observatory, Cairns, Australia, 30-cm telescope + STL6K camera + red filter; position end figures 20s.92, 12".8). Brimacombe's image is posted at URL http://www.flickr.com/photos/43846774@N02/5724709574/. S. Valenti and S. Benetti, Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova, on behalf of a larger collaboration, report that a low-signal-to-noise spectrogram (range 330-750 nm; resolution 1.5 nm) of PSN J20022093-2013134 = SN 2011ds, obtained on June 26.43 UT with the European Southern Observatory's New Technology Telescope (+ EFOSC2), is consistent with that of a type-II supernova. The spectrum indeed shows strong hydrogen H-alpha at 669.1 nm, mainly in emission with a full-width-at-half-maximum of about 7400 km/s....
  • No Thumbnail Available
    Item
    Supernova 2011ga in Pgc 69458 = Psn J22402742+0311580
    (2011) Drake, A. J.; Djorgovski, S. G.; Mahabal, A.; Graham, M. J.; Williams, R.; Prieto, J. L.; Catelan, Marcio; Beshore, E. C.; Larson, S. M.; Christensen, E.; Valenti, S.; Benetti, S.; Tomasella, L.; Ochner, P.; Pastorello, A.; Marion, G. H.
    Report the discovery of an apparent supernova in unfiltered Catalina Sky Survey (CSS) images: SN 2011 UT R.A. (2000.0) Decl. Mag. Offset 2011ga Sep. 18.25 22 40 27.42 + 3 11 58.0 17.3 18".2 W, 7".4 N The new object was designated PSN J22402742+0311580 when it was posted at the Central Bureau's TOCP webpage and is here designated SN 2011ga based on the spectroscopic report below. Additional CCD magnitudes for 2011ga (unfiltered unless noted otherwise: July 2.38 UT, [19.3 (CSS); Sept. 19.179, 16.5 (Joseph Brimacombe, Cairns, Australia; infrared filter, wavelength > 700 nm; image posted at URL http://www.flickr.com/photos/43846774@N02/6177998402/); 19.320, 17.2 (Brimacombe; position end figures 27s.38, 58".9; image posted at website URL http://www.flickr.com/photos/43846774@N02/6168832131/). S. Valenti, S. Benetti, L. Tomasella, and P. Ochner, Osservatorio Astronomico di Padova, Istituto Nazionale di Astrofisica; and A. Pastorello, Dipartimento di Astronomia, Universita di Padova, on behalf of a larger collaboration, report that a spectrogram of PSN J22402742+0311580 = SN 2011ga, obtained on Sept. 24.91 UT, suggests that it is a type-Ia supernova observed close to B-band maximum. The velocity of the ejected material, as deduced from the position of the minimum of the Si II lines, is about 10600 km/s. G. H. Marion, Harvard-Smithsonian Center for Astrophysics (CfA), on behalf of the CfA Supernova Group, report that a spectrum (range 340-740 nm) of PSN J22402742+0311580 = 2011ga was obtained on Sept. 27 UT by Marion with the F. L. Whipple Observatory 1.5-m telescope (+ FAST). Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) shows that the object is a type-Ia supernova a few days after maximum light. The best-fit template spectrum is that of SN 2003du at +2 days. The velocity of the Si II 635.5-nm feature is estimated to be approximately 10800 km/s, using the SNID estimated redshift of z = 0.040....
  • No Thumbnail Available
    Item
    Supernova 2011gb = Psn J01334294+3448371
    (2011) Drake, A. J.; Djorgovski, S. G.; Mahabal, A.; Graham, M. J.; Williams, R.; Prieto, J. L.; Catelan, Marcio; Beshore, E. C.; Larson, S. M.; Christensen, E.; Denisenko, D.; Brimacombe, J.; Valenti, S.; Benetti, S.; Tomasella, L.; Ochner, P.; Pastorello, A.
    Report the discovery of an apparent supernova in unfiltered Catalina Sky Survey (CSS) images: SN 2011 UT R.A. (2000.0) Decl. Mag. Offset 2011gb Sep. 24.30 1 33 42.94 +34 48 37.1 16.1 4".5 W, 1".1 S The new object was designated PSN J01334294+3448371 when it was posted at the Central Bureau's TOCP webpage and is here designated SN 2011gb based on the spectroscopic report below. Additional CCD magnitudes for 2011gb (unfiltered unless noted otherwise): Jan. 16.23, [18.5 (CSS); Sept. 24.850, 15.9 (D. Denisenko, Moscow, Russia; 0.20-m f/5 reflector + Meade DSI Pro II camera; position end figures 42s.84, 36".8; image posted at the following website URL: http://pics.livejournal.com/bigdenru/pic/000a957p/); 24.897, 15.5 (Paolo Corelli, Pagnacco, Italy; 0.45-m f/4.5 telescope; position end figures 42s.8, 36".8; nearby galaxy centered at position end figures 43s.35, 37".9); 25.187, 16.3 (J. Brimacombe, Cairns, Australia; position end figures 42s.86, 37".0; image posted at URL http://www.flickr.com/photos/43846774@N02/6186780582/); 26.875, 16.3 (Nick James, Chelmsford, Essex, England; Celestron 11 telescope + ST9XE camera; position end figures 42s.84, 36".9; UCAC-3 reference stars). S. Valenti, S. Benetti, L. Tomasella, and P. Ochner, Osservatorio Astronomico di Padova, Istituto Nazionale di Astrofisica; and A. Pastorello, Dipartimento di Astronomia, Universita di Padova, on behalf of a larger collaboration, report that a spectrogram of PSN J01334294+3448371 = SN 2011gb, obtained on Sept. 25.06 UT, suggests that it is a type-Ia supernova observed a few weeks after B-band maximum at a redshift z = 0.014....
  • No Thumbnail Available
    Item
    Supernova 2011gf = Psn J21122427-0748521
    (2011) Drake, A. J.; Djorgovski, S. G.; Mahabal, A.; Graham, M. J.; Williams, R.; Prieto, J. L.; Catelan, Marcio; Beshore, E. C.; Larson, S. M.; Christensen, E.; Valenti, S.; Benetti, S.; Tomasella, L.; Ochner, P.; Pastorello, A.; Marion, G. H.
    Report the discovery of an apparent supernova in unfiltered Catalina Sky Survey images: SN 2011 UT R.A. (2000.0) Decl. Mag. Offset 2011gf Sep. 18.19 21 12 24.27 - 7 48 52.1 16.6 23".5 E, 21".8 N This variable was designated PSN J21122427-0748521 when it was posted on the Central Bureau's TOCP webpage and is here designated SN 2011gf based on the spectroscopic report below. Joseph Brimacombe, Cairns, Australia, reports unfiltered CCD mag 16.1 and position end figures 24s.31, 51".8 from an image taken on Sept. 19.266 UT; he has posted his image at the following website URL: http://www.flickr.com/photos/43846774@N02/6167975455/. S. Valenti, S. Benetti, L. Tomasella, and P. Ochner, Osservatorio Astronomico di Padova, Istituto Nazionale di Astrofisica; and A. Pastorello, Dipartimento di Astronomia, Universita di Padova, on behalf of a larger collaboration, report that a spectrogram (range 360-810 nm; resolution 2.2 nm) of PSN J21122427-0748521 = SN 2011gf, obtained on Sept. 25.90 UT, suggestss that it is a type-Ia supernova. Cross-correlation with a library of supernova spectra via the "GELATO" code (Harutyunyan et al. 2008, A.Ap. 488, 383; available at URL https://gelato.tng.iac.es/login.cgi), suggest a normal type-Ia supernova close to the B-band maximum at a redshift of z = 0.0277 (Sloan Digital Sky Survey, via the NED website). The expansion velocity deduced from the Si II 635.5-nm minimum is about 11100 km/s. G. H. Marion, Harvard-Smithsonian Center for Astrophysics (CfA), on behalf of the CfA Supernova Group, report that a spectrum (range 340-740 nm) of PSN J21122427-0748521 = 2011gf was obtained on Sept. 27 UT by Marion with the F. L. Whipple Observatory 1.5-m telescope (+ FAST). Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) shows that 2011gf is a type-Ia supernova a few days after maximum light. The best-fit template spectrum is that of SN 2007F at +4 days. The velocity of the Si II 635.5-nm feature is estimated to be approximately 11600 km/s, using the SNID estimated redshift of z = 0.027....
  • No Thumbnail Available
    Item
    Supernova 2011gp in UGC 3119 = Psn J04390804+1131516
    (2011) Howerton, S.; Drake, A. J.; Djorgovski, S. G.; Mahabal, A.; Graham, M. J.; Williams, R.; Prieto, J. L.; Catelan, Marcio; Beshore, E. C.; Larson, S. M.; Christensen, E.; Valenti, S.; Cappellaro, E.; Benetti, S.; Turatto, M.; Pastorello, A.
    Report the discovery of an apparent supernova in public images from the Mount Lemmon Survey: SN 2011 UT R.A. (2000.0) Decl. Mag. Offset 2011gp Sep. 30.45 4 39 08.04 +11 31 51.6 18.4 5".1 E, 1".7 N This variable was designated PSN J04390804+1131516 when it was posted on the Central Bureau's TOCP webpage and is here designated SN 2011?? based on the spectroscopic report below. S. Valenti, E. Cappellaro, S. Benetti, Osservatorio Astronomico di Padova, Istituto Nazionale di Astrofisica (INAF); M. Turatto, Osservatorio Astronomico di Trieste, INAF; and A. Pastorello, Dipartimento di Astronomia, Universita di Padova, on behalf of a larger collaboration, report that a spectrogram (range 360-810 nm; resolution 2.2 nm) of PSN J04390804+1131516 = SN 2011gp, obtained on Sept. 30.95 UT with the Ekar-Copernico 1.82-m telescope (+ AFOSC), shows a red continuum, strong H_alpha emission, Na I D, and other lines typical of type-II supernovae. Cross-correlation with a library of supernova spectra via the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024), suggests that 2011gp is a couple of months after maximum light....
  • No Thumbnail Available
    Item
    Supernova 2011gx in ESO 252-G10 = Tcp J05060576-4503003
    (2011) Howerton, S.; Drake, A. J.; Djorgovski, S. G.; Mahabal, A.; Graham, M. J.; Williams, R.; Prieto, J. L.; Catelan, Marcio; McNaught, R. H.; Garradd, G.; Beshore, E. C.; Larson, S. M.; Christensen, E.; Ochner, P.; Valenti, S.; Benetti, S.; Pastorello, A.; Tomasella, L.; Bufano, F.
    Report the discovery of an apparent supernova in public images from the Siding Spring Survey (SSS). SN 2011 UT R.A. (2000.0) Decl. Mag. Offset 2011gx Oct. 3.69 5 06 05.76 -45 03 00.3 18.3 41".5 W, 10".7 S Nothing was visible at this position on a SSS image from Mar. 5.52 UT (limiting mag 19.5). The object was designated TCP J05060576-4503003 when it was posted on the Central Bureau's TOCP webpage and is here designated SN 2011gx based on the spectroscopic confirmation reported below. Infrared CCD magnitudes (filter bandpass > 700 nm) for 2011gx by Joseph Brimacombe, Cairns, Australia: Oct. 5.584, 16.8 (position end figures 05s.76, 00".7); 6.701, 16.6 (image posted at URL http://www.flickr.com/photos/43846774@N02/6218866501/); 8.780, 16.7; 9.638, 16.5; 10.769, 16.6; 12.675, 16.6 (image posted at website URL http://www.flickr.com/photos/43846774@N02/6238615803/). P. Ochner, S. Valenti, S. Benetti, A. Pastorello, and L. Tomasella, Istituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Padova; and F. Bufano, INAF, Osservatorio Astronomico di Catania, on behalf of a larger collaboration, report that a spectrum of TCP J05060576-4503003 = SN 2011gx, obtained on Oct. 18.17 UT with the New Technology Telescope (+ EFOSC2; range 360-930 nm; resolution 1.8 nm) shows it to be a type-II supernova. The best fit to this spectrum found by GELATO (Harutyunyan et al. 2008, A.Ap. 488, 383; publicly available at https://gelato.tng.iac.es) is with spectra of type- II-plateau supernovae at about one month post-explosion. Together with the classical P-Cyg Balmer features, prominent lines of Ca II, Fe II, and Na I D are detected. Adopting a recessional velocity of 9821 km/s for ESO 252-G10 (Lauberts and Valentijn, 1989, THE SURFACE PHOTOMETRY CATALOGUE OF THE ESO- UPPSALA GALAXIES, European Southern Obsrvatory) the expansion velocity deduced from the H_alpha absorption is about 8000 km/s....
  • No Thumbnail Available
    Item
    Supernova 2011hf
    (2011) Drake, A. J.; Djorgovski, S. G.; Mahabal, A.; Graham, M. J.; Williams, R.; Prieto, J. L.; Catelan, Marcio; Beshore, E. C.; Larson, S. M.; Christensen, E.; Tomasella, L.; Pastorello, A.; Valenti, S.; Benetti, S.
    Report the discovery of an apparent supernova in unfiltered Catalina Sky Survey (CSS) images: SN 2011 UT R.A. (2000.0) Decl. Mag. Offset 2011hf Oct. 17.11 22 16 51.14 - 3 15 55.0 17.7 Nothing was visible at this position on a CSS image taken on Sept. 27.18 UT (limiting mag 20.0). L. Tomasella, A. Pastorello, S. Valenti, and S. Benetti, Istituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Padova, on behalf of a larger collaboration, report that a spectrogram of 2011hf, obtained on Oct. 29.84 UT with the Ekar-Copernico 1.82-m telescope (+ AFOSC; range 360-810 nm; resolution 2.2 nm), is that of a type-Ia supernova at a redshift 0.054. Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) suggests a normal type-Ia supernova about 10 after its B-band maximum brightness....
  • No Thumbnail Available
    Item
    Supernova 2011ig = Psn J01055465-1220486
    (2011) Drake, A. J.; Djorgovski, S. G.; Graham, M. J.; Mahabal, A.; Williams, R.; Prieto, J. L.; Catelan, Marcio; Beshore, E. C.; Larson, S. M.; Christensen, E.; Brimacombe, J.; Valenti, S.; Pastorello, A.; Benetti, S.; Tomasella, L.; Bufano, F.; Ochner, P.
    Report the discovery of an apparent supernova in unfiltered Catalina Sky Survey (CSS) images: SN 2011 UT R.A. (2000.0) Decl. Mag. Offset 2011ig Nov. 17.21 1 05 54.65 -12 20 48.6 16.9 0".7 W, 3".7 S The variable was designated PSN J01055465-1220486 when it was posted at the Central Bureau's TOCP webpage and is here designated SN 2011ig based on the spectroscopic confirmation reported below. Additional CCD magnitudes for 2011ig: Oct. 30.28 UT, [17.5 (CSS); Nov. 20.316, 17.5 (J. Brimacombe, Cairns, Australia; luminance filter; position end figures 54s.65, 50".2; image posted at website URL http://www.flickr.com/photos/43846774@N02/6375756043/). S. Valenti, A. Pastorello, S. Benetti, L. Tomasella, F. Bufano, and P. Ochner, Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova, on behalf of a larger collaboration, report that a spectrogram of PSN J01055465-1220486 = SN 2011ig, obtained on Nov. 20.89 UT with the 1.82-m Copernico Telescope (+ AFOSC; range 340-790 nm, resolution 2.2 nm), suggests that it is a 1991T-like type-Ia supernova. Cross-correlation with a library of supernova spectra via the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) indicates that 2011ig is similar to SN 1999aa (Garavini et al. 2004, A.J. 128, 387) around maximum light. Assuming a redshift of z = 0.065, the ejecta velocity deduced from the minimum of the Si II 635-nm line is about 13500 km/s....
  • No Thumbnail Available
    Item
    Supernova 2011iw
    (2011) Mahabal, A.; Drake, A. J.; Djorgovski, S. G.; Graham, M. J.; Williams, R.; Prieto, J. L.; Catelan, Marcio; Beshore, E. C.; Larson, S. M.; Christensen, E.; Tomasella, L.; Benetti, S.; Pastorello, A.; Valenti, S.; Bufano, F.; Altavilla, G.
    Report the discovery of a supernova in unfiltered Catalina Sky Survey (CSS) images: SN 2011 UT R.A. (2000.0) Decl. Mag. 2011iw Nov. 29.09 23 34 48.20 +24 45 01.6 16.9 Nothing was visible at this position on a CSS image from Sept. 19.35 UT (limiting mag 19.5). Spectroscopic follow-up observations (range 400-800 nm) were taken with the Palomar 5-m telescope on Nov. 29.25. The spectrum exhibits strong, narrow Balmer emission lines corresponding to a redshift z = 0.023, which are superimposed on a blue continuum. A broad feature is observed near 610 nm that is likely due to He I. The object is thus identified as a likely type-IIn supernova. L. Tomasella, S. Benetti, A. Pastorello, S. Valenti, and F. Bufano, Istituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Padova; and G. Altavilla, INAF, Osservatorio Astronomico di Bologna, on behalf of a larger collaboration and the Gaia Science Alerts Follow-up Programme, report that spectrograms of 2011iw, obtained on Nov. 30.80 UT with the Asiago 1.82-m Copernico Telescope (+ AFOSC; range 350-820 nm, resolution 2.4 nm) by the Service Telescope Operating Team and with the Cassini 1.52-m telescope (+ BFOSC; range 490-800 nm; resolution 1.4 nm) on Nov. 30.81, show it to be a type-IIn supernova soon after explosion. The spectrum is dominated by a blue continuum and intense Balmer emissions with a composite profile. They consist of an unresolved component overimposed on a broader line (FWHM about 4000 km/s). A broad bump (FWHM about 4600 km/s) is also present close to the He I 587.6-nm transition. The redshift of the supernova (z about 0.0230) has been derived from the narrow emissions of the Balmer lines....
  • No Thumbnail Available
    Item
    Supernova 2011ji
    (2011) Drake, A. J.; Graham, M. J.; Mahabal, A.; Williams, R.; Djorgovski, S. G.; Prieto, J. L.; Catelan, Marcio; Beshore, E. C.; Larson, S. M.; Christensen, E.; Tomasella, L.; Valenti, S.; Benetti, S.; Bufano, F.; Fiaschi, M.; Pastorello, A.; Ochner, P.
    Report the discovery of an apparent supernova in unfiltered Mount Lemmon Survey (MLS) images: SN 2011 UT R.A. (2000.0) Decl. Mag. 2011ji Nov. 28.41 9 08 21.16 +16 33 37.1 18.5 Further MLS magnitudes for 2011ji: May 13.21 UT, [19.2; Dec. 24.47, 18.9. L. Tomasella, S. Valenti, S. Benetti, F. Bufano, M. Fiaschi, A. Pastorello, and P. Ochner, Osservatorio Astronomico di Padova, Istituto Nazionale di Astrofisica, on behalf of a larger collaboration, report that a spectrogram of 2011ji, obtained on Dec. 24.02 UT with the Asiago 1.82-m Copernico Telescope (+ AFOSC; range 350-820 nm; resolution 2.4 nm), suggests that 2011ji is a type-Ia supernova around one month after maximum. Using GELATO (Harutyunyan et al. 2008, A.Ap. 488, 383; available at website URL https://gelato.tng.iac.es/login.cgi), the spectrum is found to be similar to that of SN 1999gp at 34 days past maximum. A narrow H_alpha feature is visible in the spectrum, fixing the redshift at z = 0.089. However, because of the poor resolution of the spectrum, it cannot be verified if H_alpha is circumstellar or due to a contaminating H II region....
  • No Thumbnail Available
    Item
    Supernova 2011jk in UGC 3843 = Psn J07274305+2006217
    (2011) Howerton, S.; Drake, A. J.; Djorgovski, S. G.; Mahabal, A.; Graham, M. J.; Williams, R.; Catelan, Marcio; Beshore, E. C.; Larson, S. M.; Christensen, E.; Tomasella, L.; Valenti, S.; Benetti, S.; Bufano, F.; Fiaschi, M.; Pastorello, A.; Ochner, P.
    Report the discovery of an apparent supernova in public images from the Mount Lemmon Survey (MLS): SN 2011 UT R.A. (2000.0) Decl. Mag. Offset 2011jk Nov. 27.39 7 25 43.05 +20 06 21.7 19.2 10".5 W, 13".7 N The variable was designated PSN J07274305+2006217 when it was posted at the Central Bureau's TOCP webpage because the right ascension was originally posted erroneously as 27' instead of the proper 25'; the variable is here designated SN 2011jk based on the spectroscopic confirmation reported below. Additional CCD magnitudes for 2011jk (unfiltered unless noted otherwise): Mar. 5.20 UT, [20.6 (MLS); Nov. 28.319, 18.6 (Joseph Brimacombe, Cairns, Australia; remotely using a 51-cm RCOS telescope + STL11K camera + luminance filter at the New Mexico Skies Observatory near Mayhill, NM, U.S.A.; position end figures 43s.13, 22".0); Dec. 24.42, 19.0 (MLS). Brimacombe's image is posted at website URL http://www.flickr.com/photos/43846774@N02/6421768255/. L. Tomasella, S. Valenti, S. Benetti, F. Bufano, M. Fiaschi, A. Pastorello, and P. Ochner, Osservatorio Astronomico di Padova, Istituto Nazionale di Astrofisica, on behalf of a larger collaboration, report that a low-signal-to-noise spectrogram of PSN J07274305+2006217 = SN 2011jk, obtained on Dec. 23.97 UT with the Asiago 1.82-m Copernico Telescope (+ AFOSC; range 350-820 nm; resolution 2.4 nm), suggests that it is a type-IIP supernova, similar to SN 2005cs (Pastorello et al. 2009, MNRAS 394, 2266) at a couple of months after the explosion....
  • Thumbnail Image
    Item
    Supernova 2013fc in a circumnuclear ring of a luminous infrared galaxy : the big brother of SN. 1998S
    (2016) Kangas, T.; Mattila, S.; Kankare, E.; Lundqvist, P.; Vaisanen, P.; Childress, M.; Pignata, Giuliano; Mccully, C.; Valenti, S.; Romero Cañizales, Cristina
  • Thumbnail Image
    Item
    The young and nearby normal type Ia supernova 2018gv : UV-optical observations and the earliest spectropolarimetry
    (2020) Yang, Y.; Hoeflich, P.; Baade, D.; Maund J. R.; Wang, L.; Brown, P. J.; Stevance, H. F.; Arcavi, I.; Burke, J.; Clocchiatti, Alejandro; Cikota, A.; Gal-Yam, A.; Graham, M. L.; Hiramatsu, D.; Hosseinzadeh, G.; Howell, D. A.; Jha, S. W.; McCully, C.; Patat, F.; Sand, D. J.; Schulze, S.; Spyromilio, J.; Valenti, S.; Vinkó, J.; Wang, X.; Wheeler, J. C.; Yaron, O.; Zhang, J.