arXiv subjects

E. Antonello

Publications and source records attributed to E. Antonello.

At least 19 recordsLinked to original sources

arXiv2021

Solar UV$-$B$/$A radiation is highly effective in inactivating SARS$-$CoV$-$2

Solar UV$-$C photons do not reach Earth's surface, but are known to be endowed with germicidal properties that are also effective on viruses. The effect of softer UV$-$B and UV$-$A photons, which copiously reach the Earth's surface, on viruses are instead little studied, particularly on single$-$stranded RNA viruses. Here we combine our measurements of the action spectrum of Covid$-$19 in response to UV light, Solar irradiation measurements on Earth during the SARS$-$CoV$-$2 pandemics, worldwide recorded Covid$-$19 mortality data and our 'Solar$-$Pump' diffusive model of epidemics to show that (a) UV$-$B$/$A photons have a powerful virucidal effect on the single$-$stranded RNA virus Covid$-$19 and that (b) the Solar radiation that reaches temperate regions of the Earth at noon during summers, is sufficient to inactivate 63\perc of virions in open$-$space concentrations (1.5 x 103 TCID50$/$mL, higher than typical aerosol) in less than 2 min. We conclude that the characteristic seasonality imprint displayed world$-$wide by the SARS$-$Cov$-$2 mortality time$-$series throughout the diffusion of the outbreak (with temperate regions showing clear seasonal trends and equatorial regions suffering, on average, a systematically lower mortality), might have been efficiently set by the different intensity of UV$-$B$/$A Solar radiation hitting different Earth's locations at different times of the year. Our results suggest that Solar UV$-$B$/$A play an important role in planning strategies of confinement of the epidemics, which should be worked out and set up during spring$/$summer months and fully implemented during low$-$solar$-$irradiation periods.

q-bio.PE↗

arXiv2020

Forcing Seasonality of influenza-like epidemics with daily Solar resonance

Seasonality of acute viral respiratory diseases is a well-known and yet not fully understood phenomenon. Several models have been proposed to explain the regularity of yearly recurring outbreaks and the phase-differences observed at different latitudes on Earth. Such models take into account known internal causes, primarily the periodic emergence of new virus variants that evade the host immune response. Yet, this alone, is generally unable to explain the regularity of recurrences and the observed phase-differences. Here we show that seasonality of viral respiratory diseases, as well as its distribution with latitude on Earth, can be fully explained by the virucidal properties of UV-B and A Solar photons through a daily, minute-scale, resonant forcing mechanism. Such an induced periodicity can last, virtually unperturbed, from tens to hundreds of cycles, and even in presence of internal dynamics (host's loss of immunity) much slower than seasonal will, on a long period, generate seasonal oscillations.

q-bio.OT↗

arXiv2014

Bonaparte and the astronomers of Brera Observatory

In Northern Italy, between 1796 and 1814, Napoleon Bonaparte formed a Republic, and then a Kingdom, controlled by France. Milan was the capital of the State, and the Brera Palace was the main cultural centre, as regards both the arts and the sciences. Bonaparte probably intended to strengthen this characteristic of Brera, aiming at increasing its Italian and European relevance. We will discuss in detail in which way he interacted with the astronomers of Brera Observatory, and in particular with Barnaba Oriani, that was considered the local main representative of the 'republique des lettres', that is, the world of literature, arts and sciences. We propose a possible reconstruction of the effects of those complicated historical events on the Italian astronomy and on its relations with the European one.

physics.hist-ph↗

arXiv2014

The PLATO 2.0 Mission

PLATO 2.0 has recently been selected for ESA's M3 launch opportunity (2022/24). Providing accurate key planet parameters (radius, mass, density and age) in statistical numbers, it addresses fundamental questions such as: How do planetary systems form and evolve? Are there other systems with planets like ours, including potentially habitable planets? The PLATO 2.0 instrument consists of 34 small aperture telescopes (32 with 25 sec readout cadence and 2 with 2.5 sec candence) providing a wide field-of-view (2232 deg2) and a large photometric magnitude range (4-16 mag). It focusses on bright (4-11 mag) stars in wide fields to detect and characterize planets down to Earth-size by photometric transits, whose masses can then be determined by ground-based radial-velocity follow-up measurements. Asteroseismology will be performed for these bright stars to obtain highly accurate stellar parameters, including masses and ages. The combination of bright targets and asteroseismology results in high accuracy for the bulk planet parameters: 2%, 4-10% and 10% for planet radii, masses and ages, respectively. The planned baseline observing strategy includes two long pointings (2-3 years) to detect and bulk characterize planets reaching into the habitable zone (HZ) of solar-like stars and an additional step-and-stare phase to cover in total about 50% of the sky. PLATO 2.0 will observe up to 1,000,000 stars and detect and characterize hundreds of small planets, and thousands of planets in the Neptune to gas giant regime out to the HZ. It will therefore provide the first large-scale catalogue of bulk characterized planets with accurate radii, masses, mean densities and ages. This catalogue will include terrestrial planets at intermediate orbital distances, where surface temperatures are moderate. Coverage of this parameter range with statistical numbers of bulk characterized planets is unique to PLATO 2.0.

astro-ph.EP↗

arXiv2014

Water-filled telescopes

In this short note we discuss the case of the thought experiments on water-filled telescopes and their realizations during 18th and 19th century. The story of those instruments shows that the scientific progress occurs in a curious way, since there was no stringent reason for the construction of a water-filled telescope.

physics.hist-ph↗

arXiv2013

Cultural Astronomy and Archaeoastronomy: an Italian Experience

A brief review is given of some recent positive developments regarding the reception of archaeoastronomy by the archaeological institutions in Italy. Discussions and problems that are currently going on in this field are also mentioned, such as the separation of the scientific and humanistic disciplines (i.e. the two cultures problem). Suggestions based on contemporary philosophy are also reported. Finally, sky-gazing is proposed as the place where the two cultures could meet, since, taking Plato into account, sky-gazing could be considered the mom of the human knowledge, and of the scientific and humanistic disciplines.

physics.hist-ph↗

arXiv2013

On the Possibility of an Astronomical Perspective in the Study of Human Evolution

The Sapient Paradox is the apparently unexplainable time delay of several ten thousand years following the arrival of Homo sapiens in Asia and Europe and before the introduction of impressive innovations with the agricultural revolution. Renfrew (2007) has suggested that the solution of the paradox has to do with changes in modes of thought that occurred with sedentism. According to Renfrew, this is a subject of study for cognitive archaeology where the final goal would be to understand the formation of the human mind. Several scholars, however, affirm that climatic change was crucial to such a revolution as it would have been very difficult to develop agriculture during the Palaeolithic. In other words, sedentism was not justified during the ice age, and that may be the solution to the paradox. It is widely accepted that climate variations were due to so-called orbital forcing, the slow periodic changes of orbital parameters of the Earth (known also as the Milankovitch theory). These and other astronomical effects on the climate are discussed along with the consequent impact on human evolution. The question then rises as to whether or not it is possible to adopt an astronomical perspective instead of (or complementary to) the cognitive archaeological one. Such would be possible by adopting a different point of reference (that is, from outside), and a non-anthropocentric approach.

physics.pop-ph↗

arXiv2013

Astronomical orientations in sanctuaries of Daunia

Prehistoric sanctuaries of Daunia date back several thousand years. During the Neolithic and Bronze Age the farmers in that region dug hypogea and holes whose characteristics suggest a ritual use. In the present note we summarize the results of the astronomical analysis of the orientation of the row holes in three different sites, and we point out the possible use of the setting of the stars of Centaurus. An interesting archaeological confirmation of an archaeoastronomical prediction is also reported.

physics.hist-ph↗

arXiv2013

Prehistoric sanctuaries in Daunia

Daunia is a region in northern Apulia with many interesting archaeological sites, particularly of the Neolithic and Bronze Age. Beginning from the fifth millennium BC, the farmers living in the wide plain of Daunia dug hypogea and holes in sites that could be considered prehistoric sanctuaries. The characteristics of the rows of holes indicate a ritual use, and the archaeologists tend to exclude other applications, such as post holes and cultivations. The rows have possibly an astronomical orientation, and in the sanctuary discovered near Ordona, some stars of the Centaurus-Crux group (may be alpha Centauri itself) could have been used as targets. In past centuries, astronomers and scholars have remarked this spectacular region of the sky, and its possible relevance for the ancient civilizations was pointed out for example by G.V. Schiaparelli in 1903. In his work on the astronomy in the Old Testament, he mentioned in particular the observations of the astronomer W.S. Jacob and of other scholars. It would be probably worth to make simulations in order to reproduce the 'Jacob effect', that is the diffused light (a sort of faint twilight) produced by such very rich stellar region of the sky.

physics.hist-ph↗

arXiv2013

The myths of the Bear

Following previous works on ancient myths in Greek and Latin literature regarding Ursa Major, and the possible relation with the ancient shape of the constellation, we discuss further this case in the light of the evolution of Homo sapiens and the ethnographic records of populations of Eurasia and North America.

physics.pop-ph↗

arXiv2013

Boscovich and the Brera Observatory

In the mid 18th century both theoretical and practical astronomy were cultivated in Milan by Barnabites and Jesuits. In 1763 R.G. Boscovich was appointed to the chair of mathematics of the University of Pavia in the Duchy of Milan, and the following year he designed an observatory for the Jesuit Collegium of Brera. The Specola was built in 1765 and it became quickly one of the main European observatories. We discuss the relation between Boscovich and Brera in the framework of a short biography. An account is given of the initial research activity in the Specola, of the departure of Boscovich from Milan in 1773 and his coming back just before his death.

physics.hist-ph↗

arXiv2005

Probable nonradial g-mode pulsation in early A-type stars

A survey for line profile variability in early A-type stars has been performed in order to detect nonradial pulsation signatures. The star HR 6139, with spectral type A2V and estimated T_eff=8800 K, shows evident line profile variations that can be explained by oscillations in prograde g-modes. This feature and the known photometric variability are similar to those observed in the Slowly Pulsating B-type stars. However HR 6139 is much cooler than the cool border of the instability strip of such variables, and it is hotter than the blue edge of the delta Scuti instability strip. There are indications of a tiny variability also in other four objects, whose nature is not yet clear.

astro-ph↗

arXiv2004

GAUDI: a preparatory archive for the COROT mission

The GAUDI database (Ground-based Asteroseismology Uniform Database Interface, http://sdc.laeff.esa.es/gaudi/) is a preparatory archive for the COROT (COnvection, ROtation and planetary Transits, http://www.astrsp-mrs.fr/projets/corot/) mission developed at LAEFF (Laboratory for Space Astrophysics and Theoretical Physics, http://www.laeff.esa.es). Its intention is to make the ground-based observations obtained in the preparation of the asteroseismology programme available in a simple and efficient way. It contains spectroscopic and photometric data together with inferred physical parameters for more than 1500 objects gathered since January 1998 in 6 years of observational campaigns. In this paper, the main functionalities and characteristics of the system are described. The observations have been collected at ESO-La Silla, Telescopio Nazionale Galileo, Observatoire de Haute-Provence, South African Astronomical Observatory, Tautenberg Observatory and Sierra Nevada Observatory.

astro-ph↗

arXiv2002

The effects of blending on the light curve shape of Cepheids

A short analysis is presented of the effects on the cepheid light curve shape, i.e. on the Fourier parameters usually adopted for its description, of the blending of the stellar image with other close stars. The conclusion is that, within reasonable error, the effects are in general small and the Fourier decomposition is confirmed to be a useful tool for pulsation mode discrimination. A large effect has been found on the phase differences in a narrow period range corresponding to the known resonance centers between pulsation modes.

astro-ph↗

arXiv2002

V39: an unusual object in the field of IC 1613

The variable star V39 in the field of IC 1613 is discussed in the light of the available photometric and new spectroscopic data. It has strong emission Balmer lines, and the observed characteristics could be explained by a W Vir pulsating star with a period of 14.341 d, located at more than 115 kpc, that is in the very outer halo of our Galaxy. It should have an apparent companion, a long period (1118d) red variable, belonging to IC 1613. The main uncertainty in this interpretation is an emission feature at 668.4 nm, which we tentatively identified as a He I line.

astro-ph↗

arXiv2002

Variable stars in nearby galaxies. VI. Frequency-period distribution of Cepheids in IC 1613 and other galaxies of the Local Group

The frequency--period distribution and other properties of Cepheids in IC 1613 are discussed and compared with those of stars in our Galaxy (Milky Way), LMC, SMC, M31 and M33. Taking into account the observational limitations and related incompleteness, it is concluded that the frequency-period distribution of Cepheids in IC 1613 is similar to that of SMC; we suspect that a much larger number of stars exist in IC 1613 with a period of less than 2 d that have not yet been detected. A discussion of the deficiency of fundamental mode Cepheids with periods in the range 8 - 10 d in the Milky Way, M31 and M33 is reported. The present data are not sufficient to verify if this is produced by a real bimodal frequency--period distribution or whether depends on the lack of pulsating stars in such a period range due to pulsational stability reasons. Some arguments are presented in favor of a bimodal distribution that is a function of the average metallicity. The Milky Way, M31 and M33 have the two maxima located at the same periods, about 5 and 13 d, respectively. A comment on very long period Cepheids is also given.

astro-ph↗

arXiv2002

Variable stars in nearby galaxies. V. Search for Cepheids in Field A of NGC 6822

The results of a CCD survey for variability of stars in the nearby galaxy NGC 6822 are presented. The goal of the survey was to obtain good light curves of Cepheids for Fourier decomposition and to detect shorter period Cepheids. Since the program was carried out with a relatively small telescope, the Dutch 0.9 m at ESO-La Silla, the observations were unfiltered (white light, or Wh-band). The analysis revealed the presence of more than 130 variable stars. 21 population I Cepheids are detected; 6 of them were already known from previous works (Kayser, 1967). For at least three Cepheids, however, the previous identification or period was wrong. Some probable population II (W Vir) stars are also identified. The dispersion of the fundamental mode Cepheid PL relation appears to be small.

astro-ph↗

arXiv1999

Variable stars in nearby galaxies. II. Population I and II Cepheids in Field A of IC 1613

The light curves of Cepheids and other variable stars in Field A of IC 1613, obtained with a CCD and no filter ($Wh$ photometry), have been analyzed. It is possible to separate first overtone from fundamental mode population I Cepheids taking into account the pulsation amplitude, the shape of the light curve and the period. The expected separation is verified in the period--luminosity $PL$ diagram. Light curve Fourier parameters have been compared with those of Magellanic Clouds and galactic Cepheids, in order to point out the effects of the very low metallicity of IC 1613 on the light curve shape. Population II Cepheids of IC 1613 can be discriminated from those of population I in the $PL$ diagram, and, taking into account their color, from other red or blue variables. Their $PL$ relation is consistent with that observed in globular clusters, nearby dwarf spheroidal galaxies and LMC. We have shown it is possible to apply the single-phase method for deriving standard photometry $PL$ relations for population I and II Cepheids; therefore with just one accurate $BVRI$ observation it is possible to use the population I Cepheids for distance determinations. Some unusual stars have been identified on the basis of periods, light curve shapes and colors; they appear to be pulsating stars laying on the extension of $PL$ relation of known anomalous Cepheids. A firmer classification of these and other faint stars requires further deeper multicolor observations.

astro-ph↗