322 research outputs found
NOT Stockholm Supernovae
This proceeding contribution is a short summary of the invited talk about
observational supernova science at Stockholm University that has been conducted
at the Nordic Optical Telescope over the past 25 years, and some expectations
for the future.Comment: Conference proceeding for NOT - a telescope for the futur
High Resolution Spectroscopy of Balmer-Dominated Shocks in the RCW 86, Kepler and SN 1006 Supernova Remnants
We report results from high resolution optical spectroscopy of three
non-radiative galactic supernova remnants, RCW 86, Kepler's supernova remnant
and SN 1006. We have measured the narrow component H-alpha line widths in
Balmer-dominated filaments in RCW 86 and SN 1006, as well as the narrow
component width in a Balmer-dominated knot in Kepler's SNR. The narrow
component line widths measured in RCW 86 and Kepler's SNR show FWHM of 30-40
km/s, similar to what has been seen in other Balmer-dominated remnants. Of the
remnants in our sample, SN 1006 is the fastest shock (~3000 km/s). The narrow
component H-alpha and H-beta lines in this remnant have a FWHM of merely 21
km/s. Comparing the narrow component widths measured in our sample with those
measured in other remnants shows that the width of the narrow component does
not correlate in a simple way with the shock velocity. The implications for the
pre-heating mechanism responsible for the observed line widths are discussed.Comment: Accepted by A&
Deep optical imaging of the gamma-ray pulsar J1048-5832 with the VLT
(abridged) PSR J1048-5832 is a young Vela-like pulsar that was recently
detected in gamma-rays with Fermi, and also in X-rays with Chandra and
XMM-Newton. It powers a compact PWN visible in X-rays. We present deep optical
observations with the ESO Very Large Telescope to search for optical
counterparts of the pulsar and its nebula and to explore their multi-wavelength
emission properties. The data were obtained in V and R bands and compared with
archival data in other spectral domains. We do not detect the pulsar in the
optical and derive informative upper limits of R > 28.1 mag and V > 28.4 mag
for its brightness. Using a red-clump star method, we estimate an interstellar
extinction towards the pulsar of 2 mag, which is consistent with the absorbing
column density derived form X-rays. The respective distance agrees with the
dispersion measure distance. We reanalyse the Chandra X-ray data and compare
the dereddened upper limits with the unabsorbed X-ray spectrum of the pulsar.
We find that regarding its optical-X-ray spectral properties this gamma-ray
pulsar is not distinct from other pulsars detected in both ranges. However,
like the Vela pulsar, it is very inefficient in the optical and X-rays. Among a
dozen optical sources overlapping with the pulsar X-ray nebula we find one with
V = 26.9 and R = 26.3 mag, whose colour is slightly bluer then that of the
field stars and consistent with the peculiar colours typical for pulsar nebula
features. It positionally coincides with a relatively bright feature of the
pulsar X-ray nebula, resembling the Crab wisp and locating in 2 arcsec from the
pulsar. We suggest this source as a counterpart candidate to the feature. Based
on the substantial interstellar extinction towards the pulsar and its optical
inefficiency, further optical studies should be carried out at longer
wavelengths.Comment: 8 pages, 7 figures, 3 tables, accepted for publication in Astronomy
and Astrophysic
Optical and Infrared Observations of Radioactive Elements in Supernovae
At late phases the powering of supernova light curves is often provided by
the decay of radioactive elements synthesized in the explosions. This is
unambiguously revealed when the light curve decline follows the half life time
of the decaying elements, and the bolometric luminosity then directly provides
the mass of ejected radioactive material. I will focus on the best observed
element, Nickel-56, and demonstrate that different supernovae eject different
amounts of this element. SN 1994W ejected very small amounts of nickel,
possibly caused by black hole formation. SN 1998bw may instead have ejected
more Nickel-56 than any other supernova to date.
I will also discuss our ISO non-detection of [Fe II] 26 micron in SN 1987A,
which can be used to estimate an upper limit on the mass of ejected radioactive
Titanium-44.Comment: 9 pages, 3 figures, In press in New Astronomy Review
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