11. VizieR Online Data Catalog: Photometry of SN 2013gh and iPTF13dge (Ferretti+, 2016)Raphael Ferretti, Tanja Petrushevska, zaključena znanstvena zbirka raziskovalnih podatkov Opis: Measured photometry of type Ia supernovae 2013gh and iPTF13dge are presented. Furthermore, the effective light-curve-width-corrected phase and the natural magnitude in specified filters have been computed. Thereby, the corresponding Galactic absorption (Ax_MW) and the filter corrections (Kx) to the corresponding rest-frame filter for SN 2011fe as described by Amanullah et al. (2015MNRAS.453.3300A) are presented. The corrected magnitude can be obtained as X-AXMW-KX. All corrections have been calculated after the SN 2011fe template has been reddened with the best-fit Fitzpatrick (1999PASP..111...63F) law, for each SN. Furthermore, the V magnitude and corrections for each phase phase are included. The V magnitude was either measured (M) or calculated (D) using the SNooPy model. The V magnitude is only shown for data points used in the colour analysis, with phases between -10 and +35-days. The corrected colour can be obtained as (X-AXMW-KX)-(V-AVMW-KV) and can be compared with the corresponding colour of SN 2011fe in order to study the reddening laws of the SNe.
Ključne besede: Supernovae, Photometry: UBV, Photometry: ugriz, Photometry: ultraviolet
Objavljeno v RUNG: 23.01.2018; Ogledov: 3651; Prenosov: 0
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12. Time-varying sodium absorption in the Type Ia supernova 2013ghRaphael Ferretti, R. Amanullah, Ariel Goobar, Joel Johansson, Tanja Petrushevska, 2016, izvirni znanstveni članek Opis: Context. Temporal variability of narrow absorption lines in high-resolution spectra of Type Ia supernovae (SNe Ia) is studied to
search for circumstellar matter. Time series which resolve the profiles of absorption lines such as Na I D or Ca II H&K are expected
to reveal variations due to photoionisation and subsequent recombination of the gases. The presence, composition, and geometry of
circumstellar matter may hint at the elusive progenitor system of SNe Ia and could also affect the observed reddening law.
Aims. To date, there are few known cases of time-varying Na I D absorption in SNe Ia, all of which occurred during relatively late
phases of the supernova (SN) evolution. Photoionisation, however, is predicted to occur during the early phases of SNe Ia, when the
supernovae peak in the ultraviolet. We attempt, therefore, to observe early-time absorption-line variations by obtaining high-resolution
spectra of SNe before maximum light.
Methods. We have obtained photometry and high-resolution spectroscopy of SNe Ia 2013gh and iPTF 13dge, to search for absorptionline
variations. Furthermore, we study interstellar absorption features in relation to the observed photometric colours of the SNe.
Results. Both SNe display deep Na I D and Ca II H&K absorption features. Furthermore, small but significant variations are detected
in a feature of the Na I D profile of SN 2013gh. The variations are consistent with either geometric effects of rapidly moving or patchy
gas clouds or photoionisation of Na I gas at R ≈ 1019 cm from the explosion.
Conclusions. Our analysis indicates that it is necessary to focus on early phases to detect photoionisation effects of gases in the
circumstellar medium of SNe Ia. Different absorbers such as Na I and Ca II can be used to probe for matter at different distances from
the SNe. The nondetection of variations during early phases makes it possible to put limits on the abundance of the species at those
distances.
Ključne besede: supernovae: general – supernovae: individual: SN 2013gh – dust, extinction – circumstellar matter –
supernovae: individual: iPTF 13dge
Objavljeno v RUNG: 23.01.2018; Ogledov: 3486; Prenosov: 0
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13. THE RISE OF SN 2014J IN THE NEARBY GALAXY M82Ariel Goobar, Joel Johansson, Rahman Amanullah, Yi Cao, Mansi Kasliwal, Raphael Ferretti, Peter Nugent, Daniel Perley, Avishay Gal-Yam, Eran Ofek, S. P. Tendulkar, M. Dennefeld, Stefano Valenti, Iair Arcavi, D.P.K. Banerjee, V. Venkataraman, Brad Cenko, Tanja Petrushevska, T.J. Dupuy, M.C. Liu, 2014, izvirni znanstveni članek Opis: 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, nearIR,
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, RV 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.
Ključne besede: dust, extinction – galaxies: individual (Messier 82) – supernovae: individual (SN 2014J)
Objavljeno v RUNG: 22.01.2018; Ogledov: 3891; Prenosov: 0 (1 glas)
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