64 research outputs found
A Long Serendipitous XMM-Newton Observation of the Intermediate Polar XY Ari
XY Ari is one of the few known eclipsing intermediate polars. We present
results from a detailed analysis of an unpublished archival observation using
XMM-Newton EPIC pn and MOS data in a quiescent state of XY Ari. The X-ray
orbital modulation and spin pulse variations were investigated for energy
dependent modulations in different energy bands. The broad orbital modulation
observed with various observations was confirmed with XMM-Newton at hard X-ray
(>1.6 keV). The EPIC light curves folded at the spin phases show a double peak
profile as expected from two pole accretion. The pulse profile is found to be
energy dependent. Hardness ratio variations and energy modulation depth during
spin modulation can be explained by photoelectric absorption. The
simultaneously fitted EPIC spectra with CEVMKL model yield maximum plasma
temperature of keV with an iron abundance
. We find two intrinsic
partial covering absorption columns of and
with covering
fractions of , respectively. In
addition, a Gaussian emission line at keV with an
equivalent width of eV is required to account for fluorescent
emission from neutral iron. The X-ray luminosity of the source is in the 0.2-10.0 keV energy band.Comment: 12 pages, 9 figures, 2 tables, accepted in MNRA
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PIRATE - the piCETL Astronomical Telescope Explorer
We have set up PIRATE, a remotely operable 35 cm astronomical telescope in a robotic dome at the Observatori Astronomic de Mallorca, to pilot the realtime use of a telescope by distance-leaning students from their home. Remote access software, webpages and course materials for third level Open University students were developed. The experience from the first cohort of students of a 10 week-long project based on PIRATE demonstrates the success of the PIRATE concept for teaching practical science at a distance, and highlights the benefits distance learning students draw from a stimulating framework that facilitates group working
On the HU Aquarii planetary system hypothesis
In this work, we investigate the eclipse timing of the polar binary HU
Aquarii that has been observed for almost two decades. Recently, Qian et al.
attributed large (O-C) deviations between the eclipse ephemeris and
observations to a compact system of two massive jovian companions. We improve
the Keplerian, kinematic model of the Light Travel Time (LTT) effect and
re-analyse the whole currently available data set. We add almost 60 new, yet
unpublished, mostly precision light curves obtained using the time
high-resolution photo-polarimeter OPTIMA, as well as photometric observations
performed at the MONET/N, PIRATE and TCS telescopes. We determine new
mid--egress times with a mean uncertainty at the level of 1 second or better.
We claim that because the observations that currently exist in the literature
are non-homogeneous with respect to spectral windows (ultraviolet, X-ray,
visual, polarimetric mode) and the reported mid--egress measurements errors,
they may introduce systematics that affect orbital fits. Indeed, we find that
the published data, when taken literally, cannot be explained by any unique
solution. Many qualitatively different and best-fit 2-planet configurations,
including self-consistent, Newtonian N-body solutions may be able to explain
the data. However, using high resolution, precision OPTIMA light curves, we
find that the (O-C) deviations are best explained by the presence of a single
circumbinary companion orbiting at a distance of ~4.5 AU with a small
eccentricity and having ~7 Jupiter-masses. This object could be the next
circumbinary planet detected from the ground, similar to the announced
companions around close binaries HW Vir, NN Ser, UZ For, DP Leo or SZ Her, and
planets of this type around Kepler-16, Kepler-34 and Kepler-35.Comment: 20 pages, 18 figures, accepted to Monthly Notices of the Royal
Astronomical Society (MNRAS
Performance Testing of a Novel Off-plane Reflection Grating and Silicon Pore Optic Spectrograph at PANTER
An X-ray spectrograph consisting of radially ruled off-plane reflection
gratings and silicon pore optics was tested at the Max Planck Institute for
extraterrestrial Physics PANTER X-ray test facility. The silicon pore optic
(SPO) stack used is a test module for the Arcus small explorer mission, which
will also feature aligned off-plane reflection gratings. This test is the first
time two off-plane gratings were actively aligned to each other and with a SPO
to produce an overlapped spectrum. The gratings were aligned using an active
alignment module which allows for the independent manipulation of subsequent
gratings to a reference grating in three degrees of freedom using picomotor
actuators which are controllable external to the test chamber. We report the
line spread functions of the spectrograph and the actively aligned gratings,
and plans for future development.Comment: Draft Version March 19, 201
A deep Large Binocular Telescope view of the Canes Venatici I dwarf galaxy
We present the first deep color-magnitude diagram of the Canes Venatici I
(CVnI) dwarf galaxy from observations with the wide field Large Binocular
Camera on the Large Binocular Telescope. Reaching down to the main-sequence
turnoff of the oldest stars, it reveals a dichotomy in the stellar populations
of CVnI: it harbors an old (> 10 Gyr), metal-poor ([Fe/H] ~ -2.0) and spatially
extended population along with a much younger (~ 1.4-2.0 Gyr), 0.5 dex more
metal-rich, and spatially more concentrated population. These young stars are
also offset by 64_{-20}^{+40} pc to the East of the galaxy center. The data
suggest that this young population, which represent ~ 3-5 % of the stellar mass
of the galaxy within its half-light radius, should be identified with the
kinematically cold stellar component found by Ibata et al. (2006). CVnI
therefore follows the behavior of the other remote MW dwarf spheroidals which
all contain intermediate age and/or young populations: a complex star formation
history is possible in extremely low-mass galaxies.Comment: 4 pages, 3 figures, accepted for publication in ApJL. Minor changes,
conclusions unchange
Re-testing the JET-X Flight Module No. 2 at the PANTER facility
The Joint European X-ray Telescope (JET-X) was the core instrument of the
Russian Spectrum-X-gamma space observatory. It consisted of two identical soft
X-ray (0.3 - 10 keV) telescopes with focusing optical modules having a measured
angular resolution of nearly 15 arcsec. Soon after the payload completion, the
mission was cancelled and the two optical flight modules (FM) were brought to
the Brera Astronomical Observatory where they had been manufactured. After 16
years of storage, we have utilized the JET-X FM2 to test at the PANTER X-ray
facility a prototype of a novel X-ray polarimetric telescope, using a Gas Pixel
Detector (GPD) with polarimetric capabilities in the focal plane of the FM2.
The GPD was developed by a collaboration between INFN-Pisa and INAF-IAPS. In
the first phase of the test campaign, we have re-tested the FM2 at PANTER to
have an up-to-date characterization in terms of angular resolution and
effective area, while in the second part of the test the GPD has been placed in
the focal plane of the FM2. In this paper we report the results of the tests of
the sole FM2, using an unpolarized X-ray source, comparing the results with the
calibration done in 1996.Comment: Author's accepted manuscript posted to arXiv.org as permitted by
Springer's Self-Archiving Policy. The final publication is available at
http://rd.springer.com/article/10.1007%2Fs10686-013-9365-
Performance Testing of a Large-Format Reflection Grating Prototype for a Suborbital Rocket Payload
The soft X-ray grating spectrometer on board the Off-plane Grating Rocket
Experiment (OGRE) hopes to achieve the highest resolution soft X-ray spectrum
of an astrophysical object when it is launched via suborbital rocket. Paramount
to the success of the spectrometer are the performance of the reflection
gratings populating its reflection grating assembly. To test current grating
fabrication capabilities, a grating prototype for the payload was fabricated
via electron-beam lithography at The Pennsylvania State University's Materials
Research Institute and was subsequently tested for performance at Max Planck
Institute for Extraterrestrial Physics' PANTER X-ray Test Facility. Bayesian
modeling of the resulting data via Markov chain Monte Carlo (MCMC) sampling
indicated that the grating achieved the OGRE single-grating resolution
requirement of at the 94% confidence level.
The resulting posterior probability distribution suggests that this
confidence level is likely a conservative estimate though, since only a finite
parameter space was sampled and the model could not constrain the upper
bound of to less than infinity. Raytrace simulations of the system found
that the observed data can be reproduced with a grating performing at
. It is therefore postulated that the behavior of the obtained
posterior probability distribution can be explained by a finite
measurement limit of the system and not a finite limit on . Implications
of these results and improvements to the test setup are discussed.Comment: 25 pages, 16 figures, preprint of an article accepted for publication
in the Journal of Astronomical Instrumentation \copyright 2020 [copyright
World Scientific Publishing Company]
[https://www.worldscientific.com/worldscinet/jai
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