Optical and Infrared Observations of the Supernova SN 1999el

Abstract

Optical and near-infrared light curves of the Type IIn supernova 1999el in NGC 6951 are presented. A period of 220 days (416 days in the near-infrared) is covered from the first observation obtained a few days before maximum light. Spectroscopic observations are also discussed. Using as a distance calibrator the Type Ia SN 2000E, which occurred some months later in the same galaxy, and fitting a blackbody law to the photometric data we obtain a maximum bolometric luminosity for SN 1999el of ∼ 10 44 erg s −1 . In general, the photometric properties of SN 1999el are very similar to those of SN 1998S, a bright and well studied Type IIn SN, showing a fast decline in all observed bands similar to those of Type II-L SNe. The differences with SN 1998S are analyzed and ascribed to the differences in a pre-existing circumstellar envelope in which dust was already present at the moment of the SN outburst. We infer that light echoes may play a possibly -2significant role in affecting the observed properties of the light curves, although improved theoretical models are needed to account for the data. We conclude that mass loss in the progenitor RG stars is episodic and occurs in an asymmetric way. This implies that collapsing massive stars appear as normal Type II SN if this occurs far from major mass loss episodes, whereas they appear as Type IIn SNe if a large mass loss episode is in progress.Subject headings: supernovae: general -supernovae: individual (SN 1999el)galaxies: individual (NGC 6951) -infrared:stars 1 Based on observations collected with the AZT-24 telescope (Campo Imperatore, Italy), the 1.8-m telescope of the Osservatorio Astronomico di Padova (Asiago, Italy), the TNT telescope operated by the Osservatorio Astronomico di Collurania-Teramo (Teramo, Italy), the Italian National Telescope TNG (La Palma, Canary Islands, Spain), the 1-m telescope of the Observatorio Astronómico Nacional (Tonantzintla, Mexico), the 2.1-m telescope of the Guillermo Haro Observatory (Cananea, Mexico).

Near‐Infrared Observations of the Type Ib Supernova SN 2006jc: Evidence of Interactions with Dust

“…This behavior in the NIR colors during the rebrightening is not only totally at odds with that of other nonstellar objects, like SNe Ia (e.g., Valentini et al 2003), where dust is expected to play quite a marginal role in the light emission, but also different from, e.g., that of a ''dusty'' CC SN like the Type IIn SN 1999el (Di Carlo et al 2002). In the latter case, dust is expected to be the main cause of the observed NIR excess, and, in fact, the NIR colors evolve below the reddening band of the stellar main sequence in an (H À K) versus (J À H) diagram.…”

“…A number of frames were acquired at twilight and used to obtain normalized flat-field images using the differential flat technique, as described in Di Carlo et al (2002). Each sky-subtracted image was flat-field divided accordingly.…”

“…Unfortunately, good NIR light curves ( LCs) spanning until late epochs are available only in a few cases. The observatories of Teramo ( Italy), Rome ( Italy), and Pulkovo (Russia) are involved in a program aimed at providing accurate LCs of SNe in the NIR (Di Carlo et al 2002;Di Paola et al 2002;Valentini et al 2003) by using a dedicated 1 m class telescope equipped with a NIR camera. In the framework of this program, we present the results of our NIR follow-up of SN 2006jc, discovered on 2006 October 9.752 UT (Nakano et al 2006) in the galaxy UGC 4904.…”

Light Echoes of Transients and Variables in the Local Universe

“…These LEs may influence the spectra as well as the light curves of the sources when unresolved, in particular for events like Type II SNe that are likely located in dustrich environments (e.g. Schaefer 1987b;Chugai 1992;Di Carlo et al 2002;Otsuka et al 2012), but they have also been observed for SN 199T (Schmidt et al 1994), a SN Ia that is not necessarily expected to be in such a dust-rich environment. Roscherr & Schaefer (2000) found that LEs cannot explain the extremely long decline of SN IIn like SN 1988Z andSN 1997ab. The suggestion that historical SNe might be studied by their scattered LEs was first made by Zwicky (1940).…”

The discovery and classification of 16 supernovae at high redshifts in ELAIS-S1

“…The spectra and light curves are based on SN 1999el (Di Carlo et al 2002), whereas the absolute B peak magnitude and scatter are obtained from Richardson et al (2002). After compensating for the different cosmological parameters, the resulting peak magnitude is −18.82.…”