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Source publication
CCD UBVRI photometry is presented for type IIn SN 2005kd. The maximum luminosity exceeded Mv=-19.8, and SN remained brighter than -18 mag for about 400 days. While overall photometric evolution is quite similar to SN 1997cy, SN 2005kd shows a plateau at phases between 119 and 311 days past explosion, which is a unique feature for SN IIn.
Similar publications
Multiband photometric observations and their evaluation to instrumental magnitudes were performed using standard Johnson-Cousins filters (B, V, Rc) as well r and g Sloan filters, and not standard ones (R, G, B, and Clear filters). These were recorded from 9 observatories and from the MicroObservatory Robotic Telescope Network. The results describe...
Citations
In this paper, we report accurate Chandra positions for two ultraluminous X-ray sources (ULXs): NGC 7319-X4 at Right Ascension (RA) = 339°.029 17(2), Declination (Dec.)
= 33°.974 76(2) and NGC 5474-X1 at RA = 211°.248 59(3), Dec. = 53°.635 84(3). We perform bore-sight corrections on the Chandra X-ray satellite observations of these sources to get these accurate positions of the X-ray sources and match these positions
with archival optical data from the Wide Field Planetary Camera 2 (WFPC2) onboard the Hubble Space Telescope. We do not find the optical counterparts; the limiting absolute magnitudes of the observations in the WFPC2 standard magnitude
system are B=−7.9, V=−8.7 and I=−9.3 for NGC 7319-X4 and U=−6.4 for NGC 5474-X1. We report on the X-ray spectral properties and find evidence for X-ray variability in NGC 5474-X1.
Finally, we briefly discuss several options for the nature of these ULXs.
We present observations of SDF-05M05, an unusual optical transient discovered
in the Subaru Deep Field (SDF). The duration of the transient is > ~800 d in
the observer frame, and the maximum brightness during observation reached
approximately 23 mag in the i' and z' bands. The faint host galaxy is clearly
identified in all 5 optical bands of the deep SDF images. The photometric
redshift of the host yields z~0.6 and the corresponding absolute magnitude at
maximum is ~-20. This implies that this event shone with an absolute magnitude
brighter than -19 mag for approximately 300 d in the rest frame, which is
significantly longer than a typical supernova and ultra-luminous supernova. The
total radiated energy during our observation was 1x10^51 erg. The light curves
and color evolution are marginally consistent with some of luminous IIn
supernova. We suggest that the transient may be a unique and peculiar supernova
at intermediate redshift.
We present the photometric and spectroscopic study of the very luminous type IIn SN 2006gy for a time period spanning more than one year. The evolution of multiband light curves, the pseudobolometric (BVRI) light curve, and an extended spectral sequence is used to derive constraints on the origin and evolution of the supernova (SN). A broad, bright (MR ~ –21.7) peak characterizes all monochromatic light curves. Afterward, rapid luminosity fading (γR
~ 3.2 mag(100 days)-1) is followed by a phase of slow luminosity decline (γR
~ 0.4 mag(100 days)-1) between days ~ 170 and ~ 237. At late phases (>237 days), because of the large luminosity drop (>3 mag), only upper visibility limits are obtained in the B, R, and I bands. In the near-infrared, two K-band detections on days 411 and 510 open new issues about dust formation or infrared echo scenarios. At all epochs, the spectra are characterized by the absence of broad P-Cygni profiles and a multicomponent Hα profile, which are the typical signatures of type IIn SNe. Hα velocities of FWHM ≈ 3200 km s-1 and FHWM ≈ 9000 km s-1 are measured around the maximum phase for the intermediate and high velocity components, respectively, and they slowly evolve with time. After maximum, spectroscopic and photometric similarities are found between SN 2006gy and bright, interaction-dominated SNe (e.g., SN 1997cy, SN 1999E, and SN 2002ic). This suggests that ejecta-circumsteller material (CSM) interaction plays a key role in SN 2006gy about six to eight months after maximum, sustaining the late-time light curve. Alternatively, the late luminosity may be related to the radioactive decay of ~ 3 M
☉ of 56Ni. Models of the light curve in the first 170 days suggest that the progenitor was a compact star (R ~ (6-8) × 1012 cm, M
ej ~ 5-14 M
☉) and that the SN ejecta collided with massive (6-10 M
☉), opaque clumps of previously ejected material. These clumps do not completely obscure the SN photosphere, such that at its peak, the luminosity is due both to the decay of 56Ni and to interaction with CSM. Neither an extraordinarily large explosion energy nor a supermassive star is required to explain the observational data.
In this paper we report the discovery of CXO J122518.6+144545, a peculiar X-ray source with a position 3.6 ± 0.2 arcsec off-nuclear
from a Sloan Digital Sky Survey Data Release 7 (SDSS DR7) z= 0.0447 galaxy. The 3.6 arcsec offset corresponds to 3.2 kpc at the distance of the galaxy. The 0.3–8 keV X-ray flux of this
source is 5 × 10−14 erg cm−2 s−1 and its 0.3–8 keV luminosity is 2.2 × 1041 erg s−1 (2.7 × 1041 erg s−1; 0.5–10 keV) assuming that the source belongs to the associated galaxy. We find a candidate optical counterpart in archival
Hubble Space Telescope/Advanced Camera for Surveys g′-band observations of the field containing the galaxy obtained on 2003 June 16. The observed magnitude of g′= 26.4 ± 0.1 corresponds to an absolute magnitude of −10.1. We discuss the possible nature of the X-ray source and its associated
candidate optical counterpart and conclude that the source is either a very blue Type IIn supernova, an ultraluminous X-ray
source with a very bright optical counterpart or a recoiling supermassive black hole.
Recent observations suggest that Type IIn supernovae (SNe IIn) may exhibit
late-time (>100 days) infrared (IR) emission from warm dust more than other
types of core-collapse SNe. Mid-IR observations, which span the peak of the
thermal spectral energy distribution, provide useful constraints on the
properties of the dust and, ultimately, the circumstellar environment,
explosion mechanism, and progenitor system. Due to the low SN IIn rate (<10% of
all core-collapse SNe), few IR observations exist for this subclass. The
handful of isolated studies, however, show late-time IR emission from warm dust
that, in some cases, extends for five or six years post-discovery. While
previous Spitzer/IRAC surveys have searched for dust in SNe, none have targeted
the Type IIn subclass. This article presents results from a warm Spitzer/IRAC
survey of the positions of all 68 known SNe IIn within a distance of 250 Mpc
between 1999 and 2008 that have remained unobserved by Spitzer more than 100
days post-discovery. The detection of late-time emission from ten targets
(~15%) nearly doubles the database of existing mid-IR observations of SNe IIn.
Although optical spectra show evidence for new dust formation in some cases,
the data show that in most cases the likely origin of the mid-IR emission is
pre-existing dust, which is continuously heated by optical emission generated
by ongoing circumstellar interaction between the forward shock and
circumstellar medium. Furthermore, an emerging trend suggests that these SNe
decline at ~1000--2000 days post-discovery once the forward shock overruns the
dust shell. The mass-loss rates associated with these dust shells are
consistent with luminous blue variable (LBV) progenitors.
