Intermediate polars are a class of cataclysmic variables in which a white dwarf accretes material from a companion star. The intermediate polar nature confirmation usually derives from the detection of two periods in both $X$-ray and optical photometry. In this respect, the high energy signal is often characterized by modulations on the white dwarf spin and the orbital period. However, noting that the periodograms may be characterized by strong features also at the synodic period and/or other sidebands, the timing analysis of the $X$-ray signal may offer the unique possibility to firmly discover an intermediate polar candidate. Here, we concentrate on a sample of five cataclysmic variable {binary} candidates: {i.e. SAXJ1748.2-2808, 1RXS J211336.1+542226, CXOGC J174622.7-285218, CXOGC J174517.4-290650, and V381 Vel, listed in the IPHome catalogue. Our main aim is to confirm if they belong to the intermediate polar class or not. The results of our analysis show that we can safely assess the intermediate polar nature of all the considered sources, apart for the case of V381 Vel which instead behaves like a cataclysmic variable of the polar subclass. Moreover, the source SAXJ1748.2-2808, previously classified as a HMXB, appears to be, most likely, an intermediate polar variable.

Intermediate polars are members of the cataclysmic variable binary stars. They are characterized by a moderately magnetized white dwarf accreting matter from a cool main-sequence companion star. In many cases, this accretion gives rise to a detectable X-ray emission. VZ Sex is an interesting X-ray source whose nature needs a robust confirmation. Here, we used archived XMM-Newton observations to assign the source to the intermediate polar class. We applied the Lomb–Scargle periodogram method to detect any relevant periodic feature in the 0.1–10 keV light curve and performed a spectral fitting of the X-ray spectrum in order to get information on the on-going accretion mechanism. By inspecting the periodogram, we detected a clear periodic feature at ≃20.3 minutes that we interpret as the spin period of the white dwarf. We additionally found the typical side bands expected as the consequence of the beat between the spin and the orbital period of ≃3.581 hr. The source is characterized by an unabsorbed flux of ≃2.98 × 10−12 erg cm−2 s−1 corresponding to an intrinsic luminosity of ≃7 × 1031 erg s−1 for a distance of ≃433 pc. The existence of such features allows us to classify VZ Sex as a clear member of the intermediate polar class. Furthermore, with the estimated WD spin, the ratio Pspin/Porb is ≃0.09, i.e., consistent with that expected for a typical IP system above the period gap. In addition, the estimated intrinsic luminosity opens the possibility that a bridge linking the normally bright IPs to the faint population of sources does exist.

This contribution concerns the training course that the Astrophysics Group of the University of Salento proposed to the students of the Piano Lauree Scientifiche for the school year 2019-2020. Since the first edition of the Piano Lauree Scientifiche - Fisica of the University of Salento, the proposal of the Astrophysics Laboratory has been varied and every year different topics have been addressed, developing new methodologies for a more attractive teaching and a better education guidance. Arousing great interest from students, this year the proposal of the Astrophysics Group was dedicated to Planetology with a direct laboratory experience focused on the simulation and analysis of impact craters. After an introduction on the minor bodies of the Solar System and on the impact crater physics, the students digitally processed images of the Moon's surface with a dedicated software, obtained the necessary information for the subsequent calculation of the involved physical parameters, and finally processed the results, comparing them with those reported in the literature.

We report on the XMM-Newton observation of HP Cet and Swift J0820.6-2805, two X-ray photon sources that are candidates to be members of the intermediate polar class of cataclysmic variables. If the historical optical light curve of HP Cet shows a periodic feature at $\simeq 96$ minutes, a clear identification of such a signature in the high energy band (apart for a variability on a time scale of $\simeq 8$ minutes as detected by the ROSAT satellite) is lacking. By using XMM-Newton archive data, we clearly identify a feature (at $\simeq 88$ minutes) which is marginally consistent with one of the binary system orbital periods reported in the literature. We also found a signature of a periodic features on the time scale of $\simeq 5.6$ minutes. In the case of Swift J0820.6-2805, the intermediate polar nature was previously unclear and the orbital and the white dwarf spin periods were unknown. Here, the 0.3-10 keV data undoubtedly reveal an orbital period and a white dwarf spin of $\simeq 87.5$ minutes and $\simeq 27.9$ minutes, respectively. The spectral analysis showed that both HP Cet and Swift J0820.6-280 are members of the under-luminous IP subclass since their luminosity in the $0.3-10$ keV band is estimated to be $\simeq 5\times 10^{30}$ erg s$^{-1}$ and $\simeq 3.8\times 10^{29}$ erg s$^{-1}$, respectively.

Two meteorite pieces have been recovered in Italy, near the town of Cavezzo (Modena), on 4 January 2020. The associated fireball was observed on the evening of New Year’s Day 2020 by eight all-sky cameras of the PRISMA fireball network, a partner of FRIPON. The computed trajectory had an inclination angle of approximately 68 and a velocity at infinity of 12.8 km s. Together with the relatively low terminal height, estimated as 21.5 km, those values were indicating the significant possibility of a meteorite dropping event, as additionally confirmed by the non zero residual total mass. The strewn-field was computed taking into account the presence of two bright light flashes, revealing that the meteoroid had been very likely subject to fragmentation. Three days after the event, two samples, weighing 3.1 g and 52.2 g, were collected as a result of a dedicated field search and thanks to the involvement of the local people. The two pieces were immediately recognised as freshly fallen fragments of meteorite. The computed orbital elements, compared with the ones of known Near-Earth Asteroids from the NEODyS database, are compatible with one asteroid only; 2013 VC10. The estimated original mass of the meteoroid, 3.5 kg, and size, approximately 13 cm, is so far the smallest among the current 35 cases in which meteorites were recovered from precise strewn-field computation thanks to observational data. This result demonstrates the effectiveness of accurate processing of fireball network data even on challenging events generated by small size meteoroids.

Context: Until recently, camera networks designed for monitoring fireballs worldwide were not fully automated, implying that in case of a meteorite fall, the recovery campaign was rarely immediate. This was an important limiting factor as the most fragile - hence precious - meteorites must be recovered rapidly to avoid their alteration. Aims: The Fireball Recovery and InterPlanetary Observation Network (FRIPON) scientific project was designed to overcome this limitation. This network comprises a fully automated camera and radio network deployed over a significant fraction of western Europe and a small fraction of Canada. As of today, it consists of 150 cameras and 25 European radio receivers and covers an area of about 1.5 million square kilometers.

We show that the optical flare event discovered by Graham et al. (2020) towards the active galactic nucleus J1249+3449 is fully consistent with being a quasar microlensing event due to a $\simeq 0.1 M_{\odot}$ star, although other explanations, such as that, mainly supported by Graham et al. (2020), of being the electromagnetic counterpart associated to a binary black hole merger, cannot be completely excluded at present.

We report on the $XMM$-Newton observation of DW Cnc, a candidate intermediate polar candidate whose historical optical light curve shows the existence of periods at $\simeq 38$, $\simeq 86$ and $\simeq 69$ minutes which were interpreted as the white dwarf spin, the orbital and the spin-orbit beat periodicities. By studying the $0.3-10$ keV light curves, we confirm the existence of a period at $\simeq 38$ minutes and find in the OM light curve a signature for a period at $75\pm 21$ minutes which is consistent with both the orbital and spin-orbit beat. { These findings allow us to unveil without any doubt, the nature of DW Cnc as an accreting intermediate polar. The EPIC and RGS source spectra were analyzed and a best fit model, consisting of a multi-temperature plasma, was found. The maximum temperature found when fitting the data is $kT_{max}\simeq 31$ keV which can be interpreted as an upper limit to the temperature of the shock.

The transient event labelled as TCP J05074264+2447555 recently discovered towards the Taurus region was quickly recognized to be an ongoing microlensing event on a source located at distance of only 700-800 pc from Earth. Here, we show that observations with high sampling rate close to the time of maximum magnification revealed features that imply the presence of a binary lens system with very low-mass ratio components. We present a complete description of the binary lens system, which host an Earth-like planet with most likely mass of 9.2 +/- 6.6 M-circle plus. Furthermore, the source estimated location and detailed Monte Carlo simulations allowed us to classify the event as due to the closest lens system, being at a distance of similar or equal to 380 pc and mass similar or equal to 0.25 M-circle dot.

La scoperta dei pianeti extrasolari (PE) è certamente uno degli sviluppi più eccitanti dell’astrofisica dell’ultimo quarto di secolo. Sebbene per secoli filosofi e scienziati abbiano considerato l’esistenza di PE orbitanti attorno alle stelle, è stato solo con la scoperta di 51 Pegasi b nel 1995 da parte dei due astronomi svizzeri Mayor e Queloz [1] che si è avuta la prima prova diretta della non unicità del nostro sistema solare. In effetti, dopo l’affermazione di Giordano Bruno dell’esistenza di un numero infinito di mondi abitati da esseri intelligenti, il primo cacciatore di pianeti fu Christian Huygens che, nel XVII secolo, puntò il suo telescopio verso diverse stelle, ma realizzò subito che l’impresa non aveva speranza di successo con le capacità osservative del tempo. I tre secoli successivi hanno visto solo falsi allarmi e scoperte presunte. In un articolo fondamentale del 1952, Otto Struve [2] propose per la prima volta di usare misure di alta precisione della velocità radiale delle stelle per cercare PE. Ma si dovette aspettare il 1995 per dimostrare che la tecnica suggerita funzionava realmente sul campo. I pianeti, paragonati alle stelle, sono corpi celesti piuttosto piccoli ed emettono una quantità trascurabile di radiazione. Ciononostante gli astronomi sono stati capaci di sviluppare una serie di sofisticate tecniche osservative adatte a scoprire tracce della loro presenza. Tra le cinque tecniche principali 1 utilizzate per scoprire i pianeti extrasolari, ognuna con i suoi pregi e difetti, citiamo le velocità radiali, i transiti, l’astrometria, la rivelazione diretta (o direct imaging), ed infine la microlente gravitazionale. Quest’ulti-

SN 2015J was discovered on 2015 April 27th and is classified as an SN IIn. At first, it appeared to be an orphan SN candidate, i.e., without any clear identification of its host galaxy. Here, we present an analysis of the observations carried out by the VLT 8 m class telescope with the FORS2 camera in the R band and the Magellan telescope (6.5 m) equipped with the IMACS Short-Camera (V and I filters) and the FourStar camera (Ks filter). We show that SN 2015J resides in what appears to be a very compact galaxy, establishing a relation between the SN event and its natural host. We also present and discuss archival and new X-ray data centered on SN 2015J. At the time of the supernova explosion, Swift/XRT observations were made and a weak X-ray source was detected at the location of SN 2015J. Almost one year later, the same source was unambiguously identified during serendipitous observations by Swift/XRT and XMM-Newton, clearly showing an enhancement of the 0.3-10 keV band flux by a factor similar or equal to 30 with respect to the initial state. Swift/XRT observations show that the source is still active in the X-rays at a level of similar or equal to 0.05 counts s(-1). The unabsorbed X-ray luminosity derived from the XMM-Newton slew and SWIFT observations, L-x similar or equal to 5 x 10(41) erg s(-1), places SN 2015J among the brightest young supernovae in X-rays.

The search for biosignatures in the soil of Mars is a major objective of the planet exploration, but the detection of such structures is not straightforward due to the degradation of the organic material. In a previous work our group has analyzed the spectral reaction to thermal processing of biomineral carbonate samples including fresh and fossil shells. We found that two terrestrial fossil shells collected from clay deposits preserve their biomineral characteristics much better than coeval fossils not embedded in clay layers.In the present paper we extend our analysis to a set of fossils found in three different terrestrial clay deposits. Our results confirm that the level of degradation may be much lower than the standard values if fossils are surrounded by clay minerals. As a result these fossils have a spectroscopic response to thermal treatment which make them much more distinguishable from their abiotic counterparts than coeval fossils not collected from clay deposits. This result implies that the phyllosilicates regions recently discovered on Mars may represent very interesting environments that can provide conditions favorable to preserve evidence of biomarkers, and hence can be regarded as good candidate locations for their detection. (C) 2010 Elsevier Inc. All rights reserved.

One of the main aims of the next Mars space missions will be to characterize biochemically the surface and underground of the planet in the search for elementary forms of life. Laboratory analyses devoted to the study of techniques able to recognize the biological origin of samples, carried out on Earth analogues of Martian ground, are fundamental support for the planning of suitable instrumentation and the subsequent analyses of data. Here we present the results of infrared transmission spectroscopic studies on old biological carbonates with different degrees of degradation, including carbonates linked to primitive terrestrial living organisms (fossil stromatolites), performed to evidence spectroscopic peculiarities and their likely dependence on the age of formation. We also report preliminary measurements using reflectance spectroscopy, a technique more likely to be performed directly in situ on the surface of Mars.