We report on the discovery of SN 2014J in the nearby galaxy M 82. Given its

The wavelength-dependence of the extinction of Type Ia SN 2014J in the nearby galaxy M82 has been measured using UV to near-IR photometry obtained with the Hubble Space Telescope, the Nordic Optical Telescope, and the Mount Abu Infrared Telescope. This is the first time that the reddening of a SN Ia is characterized over the full wavelength range of 0.2-2 µm. A total-toselective extinction, R V ≥ 3.1, is ruled out with high significance. The best fit at maximum using a Galactic type extinction law yields R V = 1.4 ± 0.1. The observed reddening of SN 2014J is also compatible with a power-law extinction, A λ /A V = (λ/λ V ) p as expected from multiple scattering of light, with p = −2.1 ± 0.1. After correction for differences in reddening, SN 2014J appears to be very similar to SN 2011fe over the 14 broad-band filter lightcurves used in our study.

We present optical and near infrared (NIR) observations of the nearby Type Ia SN 2014J. Seventeen optical and twenty-three NIR spectra were obtained from 10 days before (−10d) to 10 days after (+10d) the time of maximum B-band brightness. The relative strengths of absorption features and their patterns of development can be compared at one day intervals throughout most of this period. Carbon is not detected in the optical spectra, but we identify C I λ1.0693 in the NIR spectra. We find that Mg II lines with high oscillator strengths have higher initial velocities than other Mg II lines. We show that the velocity differences can be explained by differences in optical depths due to oscillator strengths. The spectra of SN 2014J show it is a normal SN Ia, but many parameters are near the boundaries between normal and high-velocity subclasses. The velocities for O I, Mg II, Si II, S II, Ca II and Fe II suggest that SN 2014J has a layered structure with little or no mixing. That result is consistent with the delayed detonation explosion models. We also report photometric observations, obtained from −10d to +29d, in the U BV RIJH and K s bands. SN 2014J is about 3 magnitudes fainter than a normal SN Ia at the distance of M82, which we attribute to extinction in the host. The template fitting package SNooPy is used to interpret the light curves and to derive photometric parameters. Using R V = 1.46, which is consistent with previous studies, SNooPy finds that A V = 1.80 for E(B−V ) host = 1.23±0.01 mag. The maximum B-band brightness of −19.19±0.10 mag was reached on February 1.74 UT ±0.13 days and the supernova had a decline parameter of ∆m 15 = 1.11 ± 0.02 mag.

The nova outburst experienced in 2010 by the symbiotic binary Mira V407 Cyg has been extensively studied at optical and infrared wavelengths with both photometric and spectroscopic observations. This outburst, reminiscent of similar events displayed by RS Oph, can be described as a very fast He/N nova erupting while being deeply embedded in the dense wind of its cool giant companion. The hard radiation from the initial thermonuclear flash ionizes and excites the wind of the Mira over great distances (recombination is observed on a time scale of 4 days). The nova ejecta is found to progressively decelerate with time as it expands into the Mira wind. This is deduced from line widths which change from a FWHM of 2760 km/s on day +2.3 to 200 km/s on day +196. The wind of the Mira is massive and extended enough for an outer neutral and unperturbed region to survive at all outburst phases.Comment: MNRAS Letter, in pres

We present spectroscopic and photometric results of Nova V1280 Sco which were discovered in outburst in early 2007 February. The large number of spectra obtained of the object leads to one of the most extensive, near-infrared spectral studies of a classical nova. The spectra evolve from a P-Cygni phase to an emission-line phase and at a later stage is dominated by emission from the dust that formed in this nova. A detailed model is computed to identify and study characteristics of the spectral lines. Inferences from the model address the vexing question of which novae have the ability to form dust. It is demonstrated, and strikingly corroborated with observations, that the presence of lines in the early spectra of low-ionization species like Na and Mg -indicative of low-temperature conditions -appears to be reliable indicators that dust will form in the ejecta. It is theoretically expected that mass loss during a nova outburst is a sustained process. Spectroscopic evidence for such a sustained mass loss, obtained by tracing the evolution of a P-Cygni feature in the Brackett γ line, is presented here allowing a lower limit of 25-27 d to be set for the mass-loss duration. Photometric data recording the novas extended 12 d climb to peak brightness after discovery are used to establish an early fireball expansion and also show that the ejection began well before maximum brightness. The JHK light curves indicate the nova had a fairly strong second outburst ∼100 d after the first.

Abstract. JHK spectroscopic and photometric observations are reported for the enigmatic, nova-like, variable V445 Puppis which erupted at the end of 2000. The near-IR spectra are hydrogen-deficient and unusually rich in CI lines. The important CI lines are found to be positioned at 1.133, 1.166, 1.175, 1.189, 1.26 and 1.689 µm. Model calculations for the CI lines are done to make the identification of the lines secure. Photometric data, taken on January 2.90 UT, 2001 shortly after the outburst, show the formation of an optically thin dust shell around V445 Puppis. The temperature and upper limit for the mass of the dust shell are estimated to be 1800 K and M dust ∼ 10 −9 M respectively. A subsequent episode of massive dust formationindicated by the observed, deep visual dimming -is also seen in JHK images of early November 2001. V445 Puppis has shown two unusual properties for a nova: (i) the hydrogen-deficiency and He/C enrichment of the object as seen from optical and IR data and (ii) synchrotron radio emission which was detected nearly a year after its outburst by other workers. The strange nature of the object is discussed and it is shown that it is difficult to place it in the known categories of eruptive variables viz. novae (classical, recurrent or symbiotic); born-again AGB stars; the new class of eruptive variables like V838 Mon; and RCB/HdC stars. Tentative evidence for an accretion disk and binarity of the V445 Puppis system is presented. It is debated whether V445 Puppis is a rare helium nova or a unique object.

Near-infrared spectra are presented for the recent 2006 outburst of the recurrent nova RS Ophiuchi.We report the rare detection of an infrared shock wave as the nova ejecta plows into the preexisting wind of the secondary in the RS Oph system consisting of a white dwarf (WD) primary and a red giant secondary. The evolution of the shock is traced through a free expansion stage to a decelerative phase. The behavior of the shock velocity with time is found to be broadly consistent with current shock models. The present observations also imply that the WD in the RS Oph system has a high mass indicating that it could be a potential Type Ia supernova (SN Ia) candidate. We also discuss the results from a recent study showing that the near-IR continuum from the recent RS Oph eruption does not originate in an expanding fireball. However, the present work shows that the IR line emission does have an origin in an expanding shock wave.

Abstract.We report results from our monitoring of the BL Lac object Mrk 421 in the near-IR J band. The observations, aimed at studying the intraday variability (IDV) of the object, were carried out systematically over an extended (and near-continuous) period of eight nights from the 1.2 m Mount Abu Infrared Telescope, India. There are limited studies for Mrk 421 in the J band for such an extended period. The observation epoch for this study (25 February-5 March 2003) was chosen to significantly overlap other concurrent studies of Mrk 421 in the X-ray/γ-ray regions being conducted using the Rossi X-ray timing explorer (RXTE) and the solar tower atmospheric Cherenkov effect experiment (STACEE). Hence these results could be useful for a multi-wavelength analysis of the variability behavior of Mrk 421. We find that Mrk 421 was quite active during the observed period and showed significant IDV and short term variability. A maximum variation of 0.89 mag is seen over the entirety of the observed period. Flaring activity, with typical brightness variations of ∼0.4, are also seen on several occasions. The extent of the variability observed by us is compared with the results of other similar studies of Mrk 421 in the J band.