68 research outputs found
The schmidt 67/92 robotic telescope - roboschmidt user manual
The 67/91 Schmidt telescope is the largest instrument of this type in
Italy. It was officially commissioned in 1966; in 1991
the telescope was moved to mount Ekar, near the Copernico 1.82m
telescope, in order to take advantage of the higher altitude and lower
light pollution.
In 2017 the telescope has been considerably refurbished (new CCD
camera, new filters, autoguider) and remotely controlled.
Starting from May, 2020 updates of both hardware and software
allowed the implementation of the fully robotic operational mode .
The observing blocks (OB) are submitted at any time by the PIs of the
proposals or their collaborators. The Robotic System has a
rapid-response capability that allows it to interrupt regular
observations in order to observe transient phenomena with high
priority
Optical observations of a SN 2002cx-like peculiar supernova SN 2013en in UGC 11369
We present optical observations of a SN 2002cx-like supernova SN 2013en in
UGC 11369, spanning from a phase near maximum light (t= +1 d) to t= +60 d with
respect to the R-band maximum. Adopting a distance modulus of mu=34.11 +/- 0.15
mag and a total extinction (host galaxy+Milky Way) of mag, we
found that SN 2013en peaked at mag, which is underluminous
compared to the normal SNe Ia. The near maximum spectra show lines of Si II, Fe
II, Fe III, Cr II, Ca II and other intermediate-mass and iron group elements
which all have lower expansion velocities (i.e., ~ 6000 km/s). The photometric
and spectroscopic evolution of SN 2013en is remarkably similar to those of SN
2002cx and SN 2005hk, suggesting that they are likely to be generated from a
similar progenitor scenario or explosion mechanism.Comment: 8 pages, 8 figures, 3 tables, accepted for publication in MNRA
A high resolution, multi-epoch spectral atlas of peculiar stars including RAVE, GAIA and HERMES wavelength ranges
We present an Echelle+CCD, high S/N, high resolution (R = 20\,000)
spectroscopic atlas of 108 well-known objects representative of the most common
types of peculiar and variable stars. The wavelength interval extends from 4600
to 9400 Ang, and includes the RAVE, Gaia and HERMES wavelength ranges.
Multi-epoch spectra are provided for the majority of observed stars. A total of
425 spectra of peculiar stars are presented, which have been collected during
56 observing nights between November 1998 and August 2002. The spectra are
given in FITS format and heliocentric wavelengths, with accurate subtraction of
both the sky background and the scattered light. Auxiliary material useful for
custom applications (telluric dividers, spectro-photometric stars, flat-field
tracings) is also provided. The atlas aims to provide a homogeneous database of
the spectral appearance of stellar peculiarities, a tool useful both for
classification purposes and inter-comparison studies. It could also serve the
planning for and training of automated classification algorithms designed for
RAVE, Gaia, HERMES and other large scale spectral surveys. The spectrum of XX
Oph is discussed in some detail as an example of the content of the present
atlas.Comment: AJ in press (issue 140:6 December 2010
The spectacular evolution of Supernova 1996al over 15 years: a low energy explosion of a stripped massive star in a highly structured environment
Spectrophotometry of SN 1996al carried out throughout 15 years is presented.
The early photometry suggests that SN 1996al is a Linear type-II supernova,
with an absolute peak of Mv ~ -18.2 mag. Early spectra present broad,
asymmetric Balmer emissions, with super-imposed narrow lines with P-Cygni
profile, and He I features with asymmetric, broad emission components. The
analysis of the line profiles shows that the H and He broad components form in
the same region of the ejecta. By day +142, the Halpha profile dramatically
changes: the narrow P-Cygni profile disappears, and the Halpha is fitted by
three emission components, that will be detected over the remaining 15 yrs of
the SN monitoring campaign. Instead, the He I emissions become progressively
narrower and symmetric. A sudden increase in flux of all He I lines is observed
between 300 and 600 days. Models show that the supernova luminosity is
sustained by the interaction of low mass (~1.15 Msun) ejecta, expelled in a low
kinetic energy (~ 1.6 x 10^50 erg) explosion, with highly asymmetric
circumstellar medium. The detection of Halpha emission in pre-explosion archive
images suggests that the progenitor was most likely a massive star (~25 Msun
ZAMS) that had lost a large fraction of its hydrogen envelope before explosion,
and was hence embedded in a H-rich cocoon. The low-mass ejecta and modest
kinetic energy of the explosion are explained with massive fallback of material
into the compact remnant, a 7-8 Msun black hole.Comment: 27 pages, 23 figures, Accepted for publication in MNRA
Supersolar Ni/Fe production in the Type IIP SN 2012ec
SN 2012ec is a Type IIP supernova (SN) with a progenitor detection and
comprehensive photospheric-phase observational coverage. Here, we present Very
Large Telescope and PESSTO observations of this SN in the nebular phase. We
model the nebular [O I] 6300, 6364 lines and find their strength to suggest a
progenitor main-sequence mass of 13-15 Msun. SN 2012ec is unique among
hydrogen-rich SNe in showing a distinct and unblended line of stable nickel [Ni
II] 7378. This line is produced by 58Ni, a nuclear burning ash whose abundance
is a sensitive tracer of explosive burning conditions. Using spectral synthesis
modelling, we use the relative strengths of [Ni II] 7378 and [Fe II] 7155 (the
progenitor of which is 56Ni) to derive a Ni/Fe production ratio of 0.20pm0.07
(by mass), which is a factor 3.4pm1.2 times the solar value. High production of
stable nickel is confirmed by a strong [Ni II] 1.939 micron line. This is the
third reported case of a core-collapse supernova producing a Ni/Fe ratio far
above the solar value, which has implications for core-collapse explosion
theory and galactic chemical evolution models.Comment: Published versio
Spectropolarimetry of Galactic stars with anomalous extinction sightlines
Highly reddened type Ia Supernovae (SNe Ia) with low total-to-selective
visual extinction ratio values, , also show peculiar linear polarization
wavelength dependencies with peak polarizations at short wavelengths
(). It is not clear why sightlines to SNe Ia
display such different continuum polarization profiles from interstellar
sightlines in the Milky Way with similar values. We investigate
polarization profiles of a sample of Galactic stars with low values,
along anomalous extinction sightlines, with the aim to find similarities to the
polarization profiles that we observe in SN Ia sightlines. We undertook
spectropolarimetry of 14 stars, and used archival data for three additional
stars, and run dust extinction and polarization simulations to infer a simple
dust model that can reproduce the observed extinction and polarization curves.
Our sample of Galactic stars with low values and anomalous extinction
sightlines displays normal polarization profiles with an average , and is consistent within 3 to a larger coherent
sample of Galactic stars from literature. Despite the low values of dust
towards the stars in our sample, the polarization curves do not show any
similarity to the continuum polarization curves observed towards SNe Ia with
low values. There is a correlation between the best-fit Serkowski
parameters and , but we did not find any significant
correlation between and . Our simulations show that the
relationship is an intrinsic property of polarization.
Furthermore, we have shown that in order to reproduce polarization curves with
normal and low values, a population of large (a ) interstellar silicate grains must be contained in the dust's
composition.Comment: accepted for publication in A&
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