123 research outputs found
Multiwavelength appearance of Vela Jr.: Is it up to expectations?
Vela Jr. is one of the youngest and likely nearest among the known galactic
supernova remnants (SNRs). Discovered in 1997 it has been studied since then at
quite a few wavelengths, that spread over almost 20 decades in energy. Here we
present and discuss Vela Jr. properties revealed by these multiwavelength
observations, and confront them with the SNR model expectations. Questions that
remained unanswered at the time of publication of the paper of Iyudin et al.
(2005), e.g. what is the nature of the SNR's proposed central compact source
CXOU J085201.4-461753, and why is the ISM absorption column density apparently
associated with RX J0852.0-4622 much greater than the typical column of the
Vela SNR, can be addressed using the latest radio and X-ray observations of
Vela Jr.. These, and other related questions are addressed in the following.Comment: 8 pages, 7 figures. Accepted for publication in ESA SP-622,
Proceedings of the 6th INTEGRAL Workshop held in Moscow, Russia, July 02-08,
200
Resonant Scattering and Recombination in CAL 87
The eclipsing supersoft X-ray binary CAL 87 has been observed with Chandra on
August 13/14, 2001 for nearly 100 ksec, covering two full orbital cycles and
three eclipses. The shape of the eclipse light curve derived from the
zeroth-order photons indicates that the size of the X-ray emission region is
about 1.5 solar radii. The ACIS/LETG spectrum is completely dominated by
emission lines without any noticeable continuum. The brightest emission lines
are significantly redshifted and double-peaked, suggestive of emanating in a
2000 km/s wind. We model the X-ray spectrum by a mixture of recombination and
resonant scattering. This allows us to deduce the temperature and luminosity of
the ionizing source to be kT = 50-100 eV and L_X = 5E37 erg/s.Comment: To appear in Proceedings of IAU Coll. 194 "Compact binaries in the
Galaxy and beyond" (Rev. Mex. A&A Conf. Series), eds. G. Tovmassian and E.
Sio
Interstellar absorptions and shocked clouds towards supernova remnant RX J0852.0-4622
We present results of survey of interstellar absorptions towards supernova
remnant (SNR) RX J0852.0-4622. The distribution of KI absorbers along the
distance of the background stars is indicative of a local region (d<600pc)
strongly depopulated by KI line-absorbing clouds. This fact is supported by the
behavior of the interstellar extinction. We find four high-velocity CaII
components with velocities of >100km/s towards three stars and identify them
with shocked clouds of Vela SNR. We reveal and measure acceleration of two
shocked clouds at the approaching and receding sides of Vela SNR along the same
sight line. The clouds acceleration, velocity, and CaII column density are used
to probe cloud parameters. The total hydrogen column density of both
accelerating clouds is found to be similar (~6*10^{17} cm) which
indicates that possibly there is a significant amount of small-size clouds in
the vicinity of Vela SNR.Comment: accepted in MNRA
Gamma-radiation with E gamma 5 MeV detected from Seyfert galaxy 3C120 and region with 1" = 190 deg and b" = 20 deg
The observation of the Galaxy anticenter region in gamma-rays with E gamma = 5 / 100 MeV was made by gamma-telescope Natalya-1 in a balloon flight. The flight was performed at the ceiling 5.1 + or - 0.1 g/sq cm, magnetic cutoff being 17 GV. The description of the instrument and the analysis of the experiment conditions are given. The tracks of electron-positron pairs generated by gamma-quanta in the convertors were detected by wire spark chambers. The recorded events were classified manually by an operator using a graphic display into three classes: pairs, single and bad events. The arrival angle of gamma-quanta and their energy for selected gamma-ray events (pairs and singles) were determined through multiple scattering of pair components in the convertors. On the basis of the data obtained the celestial maps were made in gamma-rays for E sub gamma 5 MeV and E gamma 20 MeV energy ranges
Improved COMPTEL maps of the milky way
In the course of the mission we have gradually developed an analysis method that separates in an iterative manner the celestial emission and the (a priori unknown) instrumental background. It has become our standard analysis tool for point sources. We illustrate here that this method is widely applicable now. It provides mutually consistent sets of model-fitting parameters (spectra) and sky maps, both for continuum and line studies. Because of the wide applicability, it has been possible to make various cross-checks while building up confidence in this procedure
Search for broad absorption lines in spectra of stars in the field of supernova remnant RX J0852.0-4622 (Vela Jr.)
Supernova remnant (SNR) RX J0852.0-4622 is one of the youngest and is most
likely the closest among known galactic supernova remnants (SNRs). It was
detected in X-rays, the 44Ti gamma-line, and radio. We obtain and analyze
medium-resolution spectra of 14 stars in the direction towards the SNR RX
J0852.0-4622 in an attempt to detect broad absorption lines of unshocked ejecta
against background stars. Spectral synthesis is performed for all the stars in
the wavelength range of 3740-4020AA to extract the broad absorption lines of Ca
II related to the SNR RX J0852.0-4622. We do not detect any broad absorption
line and place a 3-sigma upper limit on the relative depths of <0.04 for the
broad Ca II absorption produced by the SNR. We detect narrow low and high
velocity absorption components of Ca II. High velocity |V(LSR)|=100-140 km/s
components are attributed to radiative shocks in clouds engulfed by the old
Vela SNR. The upper limit to the absorption line strength combined with the
width and flux of the 44Ti gamma-ray line 1.16 MeV lead us to conclude that SNR
RX J0852.0-4622 was probably produced by an energetic SN Ic explosion.Comment: 9 pages, 8 figures, accepted in A&
Are Ti44-Producing Supernovae Exceptional?
According to standard models supernovae produce radioactive Ti, which
should be visible in gamma-rays following decay to Ca for a few
centuries. ^{44}^{44}\tau \simeq\simeq\simeq^{44}Ti gamma-ray sources, but only
one is clearly seen, the 340-year-old Cas A SNR. Furthermore, supernovae which
produce much ^{44}Ti yields, their spatial
distributions, and statistical arguments can be stretched so that this apparent
disagreement may be accommodated within reasonable expectations, or if we have
to revise some or all of the above aspects to bring expectations in agreement
with the observations. We conclude that either core collapse supernovae have
been improbably rare in the Galaxy during the past few centuries, or
^{44}^{40}^{44}$Ca.Comment: 23 pages, 14 figures, accepted for publication in Astronomy and
Astrophysics 2006. Correcting the SN type of Tycho in Table B.1. and add its
associated reference
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