177,804 research outputs found
Magie dei sensi: vedere per sinestesia
No full textPoggiani Keller R., D'Agostini C. (a cura di), Soroptimist International d'Italia / Club di Bergamo e Museo Civico di Scienze naturali "E. Caffi" di Bergamo, Stamperia Stefanon
Review: the landscape of gravitational wave astronomy
No full textThe direct detection of gravitational waves from a binary black hole merger has opened a new window in observational astronomy. The first three observing runs of the LIGO/Virgo groundbased interferometers have produced a broad range of scientific results, including the first observationsof a binary neutron star merger and a neutron star-black hole merger. The observations include some exceptional events and other mergers reported in the GWTC-1, GWTC-2, GWTC-2.1, GWTC-3 catalogues, that have allowed tests of general relativity and studies of black hole and neutron star populations. The paper is a concise review of ground-based gravitational wave astronomy and related multi-messenger observations over the electromagnetic spectrum and the neutrino domain. Since the spectrum of gravitational waves extends over a broad frequency range, other techniques for gravitational wave detection outside the sensitivity band of ground-based interferometers will also be discussed
Results from the O3 observing run of the LIGO-Virgo Collaboration
No full textThe third observation run (O3) of Advanced LIGO and Advanced Virgo started in April 2019 and ended in March 2020, with improved sensitivities compared to the previous observing run. The paper will review the science results achieved during the O3 run, that include the catalogs of compact binary mergers and some exceptional events: GW190412, the merger of two black holes with asymmetric masses; GW190425, the second observed binary neutron star merger; GW190521, the first detection of an intermediate mass black hole; GW190814, a system with a secondary that could be either a black hole or a neutron star; GW200105 and GW200115, the first detected neutron star-black hole binary mergers. The impact of detections on astrophysics will also be reviewed
The Nova V5584 Sgr: A Short Review
No full textThe nova V5584 Sgr was discovered during 2009 October. It has been monitored in different domains of the electromagnetic spectrum: optical, infrared and X-rays. The optical and infrared observations suggest that V5584 Sgr is a Fe II nova that formed dust. No X-ray emission was observed around the time of maximum
The spectroscopic evolution of V5584 Sgr (Nova Sgr 2009 No. 4)
No full textWe have secured optical spectroscopy of the nova V5584 Sgr at the Loiano Observatory, Italy, during the post outburst decline. V5584 Sgr showed the presence of nebular lines. We have estimated the decline time by two magnitudes, 27 days, the absolute magnitude at maximum, -7.2 to -7.7, the white dwarf mass, 0.8 to 0.9 M (aS (TM)), the distance, 5.8 to 7.1 kpc
Early spectroscopic observations of four extragalactic novae
No full textWe report the spectroscopic observations of four extragalactic novae in M31 and in M33, secured at Loiano Observatory, Italy. Nova M31 2009-10b is a luminous nova that needed some days to achieve the peak brightness. We confirm that it is a Fe II nova and we show that it is one of the most luminous novae ever observed in M31, showing an evolution close to that of the bright extragalactic novae M31 2007-11d, LMC 1991 and SN 2010U. The novae M31 2010-07a and M31 2011-07b are standard Fe H novae. Nova M33 2010-07a is a Fe II nova that showed a peculiar rebrightening, during which we observed emission lines with P Cyg profiles: we suggest that it is the first observed nova in M33 that underwent a second mass ejection
The spectroscopic evolution of V2467 Cyg (Nova Cygni 2007) in the first months after the outburst
No full textWe present the spectroscopy of nova V2467 Cyg acquired at the Loiano Observatory, Italy, during the first six months after the outburst. We have used the optical spectroscopy to study the physical properties of the ejected material and the photometry to estimate the nova distance. V2467 Cyg is a fast nova, with decline rates by two or three magnitudes Of 7.6 and 14.6 days respectively. The light curve exhibited oscillations during the transition stage. The nova achieved an absolute magnitude at maximum in the range -8.5...-9.1. The distance is in the range 2.6... 3.6 kpc. V2467 Cyg showed ail early appearance of forbidden lines during the transition stage. Its evolution is similar to the behavior of V 1494 Aql. (C) 2009 WILEY-VCH Verlag GmbH & Co, KGaA Weinhei
Multi-messenger Observations of a Binary Neutron Star Merger
No full textOn 2017 August 17 the Advanced LIGO and Advanced Virgo interferometers observed the merger of a binary neutron star system. The INTEGRAL SPI-ACS and Fermi-GBM instruments independently observed the short Gamma Ray Burst GRB 170817A, after a delay of about 1.7 s.
GW170817 was localized within a sky region of about 30 deg2 at a luminosity distance of 40 Mpc.
A worldwide electromagnetic follow-up campaign detected an optical counterpart (SSS17a/AT 2017gfo) in the elliptical galaxy NGC 4993. The optical and infrared spectroscopic observations during the first days after the merger showed the signature of a kilonova. The first X-ray and radio detections of the afterglow occurred at 9 and 16 days after the merger, respectively. The multi-messenger observations suggest that GW170817 was produced by the merger of two neutron stars in the galaxy NGC 4993, followed by the short gamma ray burst GRB 170817A and by a kilonova powered by the radioactive decay of r-process nuclei synthesized in the ejecta. This review is an update of [110], summarizing the multi-messenger observations of GW170817 from the discovery to the late stages
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