39 research outputs found
Extensive Spectroscopy and Photometry of the Type IIP Supernova 2013ej
We present extensive optical (, , and open CCD) and
near-infrared () photometry for the very nearby Type IIP SN ~2013ej
extending from +1 to +461 days after shock breakout, estimated to be MJD
. Substantial time series ultraviolet and optical spectroscopy
obtained from +8 to +135 days are also presented. Considering well-observed SNe
IIP from the literature, we derive bolometric calibrations from
and unfiltered measurements that potentially reach 2\% precision with a
color-dependent correction. We observe moderately strong Si II
as early as +8 days. The photospheric velocity () is
determined by modeling the spectra in the vicinity of Fe II
whenever observed, and interpolating at photometric epochs based on a
semianalytic method. This gives km s at +50
days. We also observe spectral homogeneity of ultraviolet spectra at +10--12
days for SNe IIP, while variations are evident a week after explosion. Using
the expanding photosphere method, from combined analysis of SN 2013ej and SN
2002ap, we estimate the distance to the host galaxy to be
Mpc, consistent with distance estimates from other methods. Photometric and
spectroscopic analysis during the plateau phase, which we estimated to be
days long, yields an explosion energy of
ergs, a final pre-explosion progenitor mass of ~M and a
radius of ~R. We observe a broken exponential profile beyond
+120 days, with a break point at + days. Measurements beyond this
break time yield a Ni mass of ~M.Comment: 29 pages, 23 figures, 15 tables, Published in The Astrophisical
Journa
The Weakening Outburst of the Young Eruptive Star V582 Aur
V582 Aur is a pre-main sequence FU Orionis type eruptive star, which entered
a brightness minimum in 2016 March due to changes in the line-of-sight
extinction. Here, we present and analyze new optical , , and
band multiepoch observations and new near-infrared , and band
photometric measurements from 2018 January2019 February, as well as publicly
available mid-infrared WISE data. We found that the source shows a significant
opticalnear-infrared variability, and the current brightness minimum has not
completely finished yet. If the present dimming originates from the same
orbiting dust clump that caused a similar brightness variation in 2012, than
our results suggest a viscous spreading of the dust particles along the orbit.
Another scenario is that the current minimum is caused by a dust structure,
that is entering and leaving the inner part of the system. The WISE
measurements could be consistent with this scenario. Our long-term data, as
well as an accretion disk modeling hint at a general fading of V582 Aur,
suggesting that the source will reach the quiescent level in 80 years.Comment: 8 pages, 4 figures, accepted for publication in Ap
Evolution of the Type IIb SN 2011fu
The UBVRI photometric follow-up of SN 2011fu has been initiated a few days after the explosion, shows a rise followed by steep decay in all bands and shares properties very similar to that seen in case of SN 1993J, with a possible detection of the adiabatic cooling phase at very early epochs. The spectral modeling performed with SYNOW suggests that the early-phase line velocities for H and Fe ii features were ~ 16000 km s−1 and ~ 14000 km s−1, respectively. Studies of rare class of type IIb SNe are important to understand the evolution of the possible progenitors of core-collapse SNe in more details
Absolute Distances to Nearby Type Ia Supernovae via Light Curve Fitting Methods
We present a comparative study of absolute distances to a sample of very nearby, bright Type Ia supernovae (SNe) derived from high cadence, high signal-to-noise, multi-band photometric data. Our sample consists of four SNe: 2012cg, 2012ht, 2013dy and 2014J. We present new homogeneous, high-cadence photometric data in Johnson-Cousins BVRI and Sloan g' r' i' z' bands taken from two sites (Piszkesteto and Baja, Hungary), and the light curves are analyzed with publicly available light curve fitters (MLCS2k2, SNooPy2 and SALT2.4). When comparing the best-fit parameters provided by the different codes, it is found that the distance moduli of moderately reddened SNe Ia agree within less than or similar to 0.2 mag, and the agreement is even better (less than or similar to 0.1 mag) for the highest signal-to-noise BVRI data. For the highly reddened SN 2014J the dispersion of the inferred distance moduli is slightly higher. These SN-based distances are in good agreement with the Cepheid distances to their host galaxies. We conclude that the current state-of-the-art light curve fitters for Type Ia SNe can provide consistent absolute distance moduli having less than similar to 0.1-0.2 mag uncertainty for nearby SNe. Still, there is room for future improvements to reach the desired similar to 0.05 mag accuracy in the absolute distance modulus
Absolute Distances to Nearby Type Ia Supernovae via Light Curve Fitting Methods
We present a comparative study of absolute distances to a sample of very nearby, bright Type Ia supernovae (SNe) derived from high cadence, high signal-to-noise, multi-band photometric data. Our sample consists of four SNe: 2012cg, 2012ht, 2013dy and 2014J. We present new homogeneous, high-cadence photometric data in Johnson-Cousins BVRI and Sloan g' r' i' z' bands taken from two sites (Piszkesteto and Baja, Hungary), and the light curves are analyzed with publicly available light curve fitters (MLCS2k2, SNooPy2 and SALT2.4). When comparing the best-fit parameters provided by the different codes, it is found that the distance moduli of moderately reddened SNe Ia agree within less than or similar to 0.2 mag, and the agreement is even better (less than or similar to 0.1 mag) for the highest signal-to-noise BVRI data. For the highly reddened SN 2014J the dispersion of the inferred distance moduli is slightly higher. These SN-based distances are in good agreement with the Cepheid distances to their host galaxies. We conclude that the current state-of-the-art light curve fitters for Type Ia SNe can provide consistent absolute distance moduli having less than similar to 0.1-0.2 mag uncertainty for nearby SNe. Still, there is room for future improvements to reach the desired similar to 0.05 mag accuracy in the absolute distance modulus
An UXor among FUors: Extinction-related Brightness Variations of the Young Eruptive Star V582 Aur
V582 Aur is an FU Ori-type young eruptive star in outburst since similar to 1985. The eruption is currently in a relatively constant plateau phase, with photometric and spectroscopic variability superimposed. Here we will characterize the progenitor of the outbursting object, explore its environment, and analyze the temporal evolution of the eruption. We are particularly interested in the physical origin of the two deep photometric dips, one that occurred in 2012 and one that is ongoing since 2016. We collected archival photographic plates and carried out new optical, infrared, and millimeter-wave photometric and spectroscopic observations between 2010 and 2018, with a high sampling rate during the current minimum. Besides analyzing the color changes during fading, we compiled multiepoch spectral energy distributions and fitted them with a simple accretion disk model. Based on pre-outburst data and a millimeter continuum measurement, we suggest that the progenitor of the V582 Aur outburst is a low-mass T Tauri star with average properties. The mass of an unresolved circumstellar structure, probably a disk, is 0.04M(circle dot). The optical and near-infrared spectra demonstrate the presence of hydrogen and metallic lines, show the CO band head in absorption, and exhibit a variable Ha profile. The color variations strongly indicate that both the similar to 1 yr long brightness dip in 2012 and the current minimum since 2016 are caused by increased extinction along the line of sight. According to our accretion disk models, the reddening changed from A(V) = 4.5 to 12.5mag, while the accretion rate remained practically constant. Similarly to the models of the UXor phenomenon of intermediate- and low-mass young stars, orbiting disk structures could be responsible for the eclipses
The Exotic Type Ic Broad-Lined Supernova SN 2018gep: Blurring the Line Between Supernovae and Fast Optical Transients
In the last decade a number of rapidly evolving transients have been
discovered that are not easily explained by traditional supernovae models. We
present optical and UV data on onee such object, SN 2018gep, that displayed a
fast rise with a mostly featureless blue continuum around maximum light, and
evolved to develop broad features more typical of a SN Ic-bl while retaining
significant amounts of blue flux throughout its observations. The blue excess
is most evident in its near-UV flux that is over 4 magnitudes brighter than
other stripped envelope supernovae, but also visible in optical gr colors at
early times. Its fast rise time of days
puts it squarely in the emerging class of Fast Evolving Luminous Transients, or
Fast Blue Optical Transients. With a peak absolute magnitude of M mag it is on the extreme end of both the rise time and peak magnitude
distribution for SNe Ic-bl. Only one other SN Ic-bl has similar properties,
iPTF16asu, for which less of the important early time and UV data have been
obtained. We show that the objects SNe 2018gep and iPTF16asu have similar
photometric and spectroscopic properties and that they overall share many
similarities with both SNe Ic-bl and Fast Evolving Transients. We obtain IFU
observations of the SN 2018gep host galaxy and derive a number of properties
for it. We show that the derived host galaxy properties for both SN 2018gep and
iPTF16asu are overall consistent with the SNe Ic-bl and GRB/SNe sample while
being on the extreme edge of the observed Fast Evolving Transient sample. These
photometric observations are consistent with a simple SN Ic-bl model that has
an additional form of energy injection at early times that drives the observed
rapid, blue rise, and we speculate that this additional power source may
extrapolate to the broader Fast Evolving Transient sample