Mon.Not.Roy.Astron.Soc. 357 (2005) 1059-1067 In recent years, an increasing number of publications have been addressed to
the peculiar and mysterious pre-main sequence star V582 Mon, also known as KH
...15D. This extraordinary T Tauri star, located in the young star cluster NGC
2264, appears as to be an eclipsing variable. In the present paper, we report a
unique and self-consistent set of light curves in the blue and near-infrared
bands, spanning a 15-year interval (epoch 1955-1970). Our photometric data show
clearly the beginning of the eclipse stage occurred in early 1958 in the blue,
and perhaps around four years later in the infrared. The light curve period
turns out to be the same reported by recent observations (about 48.3 days), so
that no evidence for a period change results. On the other hand, in our data
the light curve shape appears as sinusoidal and is therefore different from the
one displayed today. The photometric behaviour, determined with time-series and
colour-index analysis, suggests that V582 Mon (KH 15D) could be initially
surrounded by an accretion disk/torus seen edge-on, with subsequent thin dust
formation at the beginning of the blue radiation absorption. The dust could
then aggregate into larger particles providing the transition between selective
and total absorption, accompanied with eclipsing variability in the infrared.
The minima of the periodic light curve become deeper due to the increasing
dimension and number of dust grains, and then flattens due to a contraction in
the disk.
Science with the New Generation of High Energy Gamma-ray
Experiments, Forum special publ., August 2003, p. 63 We discuss some open problems in the understanding of the Early Solar System
abundances ...of short-lived radioactive isotopes, and the important clarification
expected on this matter by precise measurements of the average galactic
abundances of 26Al and 60Fe, through their gamma-ray lines.
e-ASTROGAM (‘enhanced ASTROGAM’) is a breakthrough Observatory space mission, with a detector composed by a Silicon tracker, a calorimeter, and an anticoincidence system, dedicated to the study of ...the non-thermal Universe in the photon energy range from 0.3 MeV to 3 GeV – the lower energy limit can be pushed to energies as low as 150 keV for the tracker, and to 30 keV for calorimetric detection. The mission is based on an advanced space-proven detector technology, with unprecedented sensitivity, angular and energy resolution, combined with polarimetric capability. Thanks to its performance in the MeV–GeV domain, substantially improving its predecessors, e-ASTROGAM will open a new window on the non-thermal Universe, making pioneering observations of the most powerful Galactic and extragalactic sources, elucidating the nature of their relativistic outflows and their effects on the surroundings. With a line sensitivity in the MeV energy range one to two orders of magnitude better than previous generation instruments, e-ASTROGAM will determine the origin of key isotopes fundamental for the understanding of supernova explosion and the chemical evolution of our Galaxy. The mission will provide unique data of significant interest to a broad astronomical community, complementary to powerful observatories such as LIGO-Virgo-GEO600-KAGRA, SKA, ALMA, E-ELT, TMT, LSST, JWST, Athena, CTA, IceCube, KM3NeT, and LISA.
Mon.Not.Roy.Astron.Soc. 348 (2004) 1379 About twenty years of radio observations in five bands (from 4.8 to 37 GHz)
of the BL Lac object GC 0109+224 (S2 0109+22, RGB J0112+227), are presented and
...analysed together with the optical data. Over the past ten years this blazar
has exhibited enhanced activity. There is only weak correlation between radio
and optical flares delays, usually protracted on longer timescales in the radio
with respect to the optical. In some cases no radio flare counterpart was
observed for the optical outbursts. The radio variability, characterised by
peaks superposition, shows hints of some characteristic timescales (around the
3-4 years), and a fluctuation mode between the flickering and the shot noise.
The reconstructed spectral energy distribution, poorly monitored at high
energies, is preliminarily parameterised with a synchrotron-self Compton
description. The smooth synchrotron continuum, peaked in the near-IR-optical
bands, strengthens the hypothesis that this source could be an intermediate
blazar. Moreover the intense flux in millimetre bands, and the optical and
X-ray brightness, might suggest a possible detectable gamma-ray emission.
In recent years, an increasing number of publications have been addressed to the peculiar and mysterious pre-main sequence star V582 Mon, also known as KH 15D. This extraordinary T Tauri star, ...located in the young star cluster NGC 2264, appears as to be an eclipsing variable. In the present paper, we report a unique and self-consistent set of light curves in the blue and near-infrared bands, spanning a 15-year interval (epoch 1955-1970). Our photometric data show clearly the beginning of the eclipse stage occurred in early 1958 in the blue, and perhaps around four years later in the infrared. The light curve period turns out to be the same reported by recent observations (about 48.3 days), so that no evidence for a period change results. On the other hand, in our data the light curve shape appears as sinusoidal and is therefore different from the one displayed today. The photometric behaviour, determined with time-series and colour-index analysis, suggests that V582 Mon (KH 15D) could be initially surrounded by an accretion disk/torus seen edge-on, with subsequent thin dust formation at the beginning of the blue radiation absorption. The dust could then aggregate into larger particles providing the transition between selective and total absorption, accompanied with eclipsing variability in the infrared. The minima of the periodic light curve become deeper due to the increasing dimension and number of dust grains, and then flattens due to a contraction in the disk.
We discuss some open problems in the understanding of the Early Solar System abundances of short-lived radioactive isotopes, and the important clarification expected on this matter by precise ...measurements of the average galactic abundances of 26Al and 60Fe, through their gamma-ray lines.
About twenty years of radio observations in five bands (from 4.8 to 37 GHz) of the BL Lac object GC 0109+224 (S2 0109+22, RGB J0112+227), are presented and analysed together with the optical data. ...Over the past ten years this blazar has exhibited enhanced activity. There is only weak correlation between radio and optical flares delays, usually protracted on longer timescales in the radio with respect to the optical. In some cases no radio flare counterpart was observed for the optical outbursts. The radio variability, characterised by peaks superposition, shows hints of some characteristic timescales (around the 3-4 years), and a fluctuation mode between the flickering and the shot noise. The reconstructed spectral energy distribution, poorly monitored at high energies, is preliminarily parameterised with a synchrotron-self Compton description. The smooth synchrotron continuum, peaked in the near-IR-optical bands, strengthens the hypothesis that this source could be an intermediate blazar. Moreover the intense flux in millimetre bands, and the optical and X-ray brightness, might suggest a possible detectable gamma-ray emission.
