Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userHighly reddened type Ia supernova SN 2004ab: another case of anomalous extinction
78
0
0.0
(
0
)
Added by
Devendra Kumar Sahu
Publication date
2017
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
We present optical photometric and spectroscopic results of supernova SN 2004ab, a highly reddened normal type Ia supernova. The total reddening is estimated as $E(B-V)$ = 1.70 $pm$ 0.05 mag. The intrinsic decline rate parameter, $Delta m_{15}(B)_text{true}$ is 1.27 $pm$ 0.05, and $B$-band absolute magnitude at maximum $M_{B}^{text{max}}$ is $-$19.31 $pm$ 0.25 mag. The host galaxy NGC 5054 is found to exhibit anomalous extinction with very low value of $R_V$ = 1.41 $pm$ 0.06 in the direction of SN 2004ab. Peak bolometric luminosity is derived as $log L_text{bol}^text{max}$ = 43.10 $pm$ 0.07 erg,s$^{-1}$. The photospheric velocity measured from absorption minimum of Si,{sc ii} $lambda$6355 line shows a velocity gradient of $dot{v}$ = 90 km,s$^{-1}$,d$^{-1}$, indicating that SN 2004ab is a member of the high velocity gradient (HVG) subgroup. The ratio of strength of Si,{sc ii} $lambda$5972 and $lambda$6355 absorption lines, $cal R$(Si,{sc ii}) is estimated as 0.37, while their pseudo equivalent widths suggest that SN 2004ab belongs to broad line (BL) type subgroup.
rate research
Read More
Correction of Type Ia Supernova brightnesses for extinction by dust has proven to be a vexing problem. Here we study the dust foreground to the highly reddened SN 2012cu, which is projected onto a dust lane in the galaxy NGC 4772. The analysis is based on multi-epoch, spectrophotometric observations spanning 3,300 - 9,200 {AA}, obtained by the Nearby Supernova Factory. Phase-matched comparison of the spectroscopically twinned SN 2012cu and SN 2011fe across 10 epochs results in the best-fit color excess of (E(B-V), RMS) = (1.00, 0.03) and total-to-selective extinction ratio of (RV , RMS) = (2.95, 0.08) toward SN 2012cu within its host galaxy. We further identify several diffuse interstellar bands, and compare the 5780 {AA} band with the dust-to-band ratio for the Milky Way. Overall, we find the foreground dust-extinction properties for SN 2012cu to be consistent with those of the Milky Way. Furthermore we find no evidence for significant time variation in any of these extinction tracers. We also compare the dust extinction curve models of Cardelli et al. (1989), ODonnell (1994), and Fitzpatrick (1999), and find the predictions of Fitzpatrick (1999) fit SN 2012cu the best. Finally, the distance to NGC4772, the host of SN 2012cu, at a redshift of z = 0.0035, often assigned to the Virgo Southern Extension, is determined to be 16.6$pm$1.1 Mpc. We compare this result with distance measurements in the literature.
Recent observations have revealed that some Type Ia supernovae exhibit narrow, time-variable Na I D absorption features. The origin of the absorbing material is controversial, but it may suggest the presence of circumstellar gas in the progenitor system prior to the explosion, with significant implications for the nature of the supernova progenitors. We present the third detection of such variable absorption, based on six epochs of high-resolution spectroscopy of the Type Ia supernova SN 2007le from Keck and the HET. The data span ~3 months, from 5 days before maximum light to 90 days after maximum. We find that one component of the Na D absorption lines strengthened significantly with time, indicating a total column density increase of ~2.5 x 10^12 cm^-2. The changes are most prominent after maximum light rather than at earlier times when the UV flux from the SN peaks. As with SN 2006X, we detect no change in the Ca II H&K lines over the same time period, rendering line-of-sight effects improbable and suggesting a circumstellar origin for the absorbing material. Unlike the previous two SNe exhibiting variable absorption, SN 2007le is not highly reddened (E_B-V = 0.27 mag), also pointing toward circumstellar rather than interstellar absorption. Photoionization models show that the data are consistent with a dense (10^7 cm^-3) cloud or clouds of gas located ~0.1 pc from the explosion. These results broadly support the single-degenerate scenario previously proposed to explain the variable absorption, with mass loss from a nondegenerate companion star responsible for providing the circumstellar gas. We also present tentative evidence for narrow Halpha emission associated with the SN, which will require followup observations at late times to confirm. [abridged]
We present $UBVRI$ CCD photometry and optical spectra of the type Ia supernova SN 2003hx which appeared in the galaxy NGC 2076, obtained till $sim$ 146 days after the epoch of $B$ band maximum. The supernova reached at maximum brightness in $B$ band on JD 245 2893 $pm$ 1.0 with an apparent magnitude of 14.92 $pm$ 0.01 mag which was estimated by making template fits to the light curves. SN 2003hx is an example of a highly reddened supernova with $E(B-V)$ = 0.56 $pm$ 0.23. We estimate $R_v$ = 1.97 $pm$ 0.54 which indicates the small size of dust particles as compared to their galactic counterparts. The luminosity decline rate is $Delta m_{15}(B)$ = 1.17 $pm$ 0.12 mag and the absolute $B$ band magnitude obtained from the luminosity versus decline rate relation (Phillips et al. 1999) is $M^B_{max}$ = -19.20 $pm$ 0.18 mag. The peak bolometric luminosity indicates that $sim$ 0.66 $M_odot$ mass of $^{56}$ Ni was ejected by the supernova. The spectral evolution indicates the supernova to be a normal type Ia event.
A series of optical and one near-infrared nebular spectra covering the first year of the Type Ia supernova SN 2011fe are presented and modelled. The density profile that proved best for the early optical/ultraviolet spectra, rho-11fe, was extended to lower velocities to include the regions that emit at nebular epochs. Model rho-11fe is intermediate between the fast deflagration model W7 and a low-energy delayed-detonation. Good fits to the nebular spectra are obtained if the innermost ejecta are dominated by neutron-rich, stable Fe-group species, which contribute to cooling but not to heating. The correct thermal balance can thus be reached for the strongest [FeII] and [FeIII] lines to be reproduced with the observed ratio. The 56Ni mass thus obtained is 0.47 +/- 0.05 Mo. The bulk of 56Ni has an outermost velocity of ~8500 km/s. The mass of stable iron is 0.23 +/- 0.03 Mo. Stable Ni has low abundance, ~10^{-2} Mo. This is sufficient to reproduce an observed emission line near 7400 A. A sub-Chandrasekhar explosion model with mass 1.02 Mo and no central stable Fe does not reproduce the observed line ratios. A mock model where neutron-rich Fe-group species are located above 56Ni following recent suggestions is also shown to yield spectra that are less compatible with the observations. The densities and abundances in the inner layers obtained from the nebular analysis, combined with those of the outer layers previously obtained, are used to compute a synthetic bolometric light curve, which compares favourably with the light curve of SN 2011fe.
We present the results based on photometric ($Swift$ UVOT), broad-band polarimetric ($V$ and $R$-band) and optical spectroscopic observations of the Type IIn supernova (SN) 2017hcc. Our study is supplemented with spectropolarimetric data available in literature for this event. The post-peak light curve evolution is slow ($sim$0.2 mag 100 d$^{-1}$ in $b$-band). The spectrum of $sim$+27 d shows a blue continuum with narrow emission lines, typical of a Type IIn SN. Archival polarization data along with the $Gaia$ DR2 distances have been utilized to evaluate the interstellar polarization (ISP) towards the SN direction which is found to be $P_{ISP}$ = 0.17 $pm$ 0.02 per cent and $theta_{ISP}$ = 140$^{circ}$ $pm$ 3$^{circ}$. To extract the intrinsic polarization of SN 2017hcc, both the observed and the literature polarization measurements were corrected for ISP. We noticed a significant decline of $sim$3.5 per cent ($V$-band) in the intrinsic level of polarization spanning a period of $sim$2 months. In contrast, the intrinsic polarization angles remain nearly constant at all epochs. Our study indicates a substantial variation in the degree of asymmetry in either the ejecta and/or the surrounding medium of SN 2017hcc. We also estimate a mass-loss rate of $dot M$ = 0.12 M$_{odot}$ yr$^{-1}$ (for $v_w$ = 20 km s$^{-1}$) which suggests that the progenitor of SN 2017hcc is most likely a Luminous Blue Variable.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
