GAA - Grup d'Astronomia i Astrofísica: Enviaments recents
Ara es mostren els items 1-12 de 349
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The unusual planetary nebula nucleus in the Galactic open cluster M37 and six further hot white dwarf candidates
(EDP Sciences, 2023-10-01)
Article
Accés obertPlanetary nebulae in Galactic open star clusters are rare objects; only three are known to date. They are of particular interest because their distance can be determined with high accuracy, allowing one to characterize the ... -
NICER Observations of thermonuclear bursts from 4U 1728-34: detection of oscillations prior to the onset of two bursts
(Institute of Physics (IOP), 2023-11-13)
Article
Accés obertWe present temporal and time-resolved spectral analyses of all the thermonuclear X-ray bursts observed from the neutron star low-mass X-ray binary 4U 1728-34 with NICER from 2017 June to 2019 September. In total, we detected ... -
Main-sequence companions to white dwarfs - II. The age-activity-rotation relation from a sample of Gaia common proper motion pairs
(Oxford University Press, 2023-10-06)
Article
Accés obertMagnetic activity and rotation are related to the age of low-mass main-sequence stars. To further constrain these relations, we study a sample of 574 main-sequence stars members of common proper motion pairs with white ... -
First measurement of the low-energy direct capture in Ne 20 (p,¿) Na 21 and improved energy and strength of the Ec.m.=368 keV resonance
(American Physical Society, 2023-11-22)
Article
Accés restringit per política de l'editorialThe 20Ne(p,¿)21Na reaction is the slowest in the NeNa cycle and directly affects the abundances of the Ne and Na isotopes in a variety of astrophysical sites. Here we report the measurement of its direct capture contribution, ... -
Confirmation of a new resonance in Si 26 and contribution of classical novae to the galactic abundance of Al 26
(American Physical Society, 2023-09-14)
Article
Accés obertThe 25Al(p,¿) reaction has long been highlighted as a possible means to bypass the production of 26Al cosmic ¿ rays in classical nova explosions. However, uncertainties in the properties of key resonant states in 26Si have ... -
Nuclear physics midterm plan at LNS
(Springer, 2023-11-24)
Article
Accés obertThe next years will see the completion of several new facilities at Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali del Sud (LNS) opening up new possibilities in the fields of nuclear structure, nuclear dynamics, ... -
Sub-second infrared variability from the archetypal accreting neutron star 4U 1728-34
(Oxford University Press, 2023-10-25)
Article
Accés obertWe report on the first simultaneous high-time resolution X-ray and infrared (IR) observations of a neutron star low mass X-ray binary in its hard state. We performed ¿h of simultaneous observations of 4U 1728-34 using ... -
General relativistic pulsations of ultra-massive ZZ Ceti stars
(Oxford University Press, 2023-10-01)
Article
Accés obertUltra-massive white dwarf stars are currently being discovered at a considerable rate, thanks to surveys such as the Gaia space mission. These dense and compact stellar remnants likely play a major role in Type Ia supernova ... -
The orbital period of the recurrent nova V2487 Oph revealed
(Oxford University Press, 2023-10-12)
Article
Accés obertWe present the first reliable determination of the orbital period of the recurrent nova V2487 Oph (Nova Oph 1998). We derived a value of 0.753 ± 0.016 d (18.1 ± 0.4 h) from the radial velocity curve of the intense He¿II ... -
Search for 22Na in novae supported by a novel method for measuring femtosecond nuclear lifetimes
(2023-09-22)
Article
Accés obertClassical novae are thermonuclear explosions in stellar binary systems, and important sources of 26Al and 22Na. While ¿ rays from the decay of the former radioisotope have been observed throughout the Galaxy, 22Na remains ... -
Mass-loss and composition of wind ejecta in type I X-ray bursts
(EDP Sciences, 2023-10-17)
Article
Accés obertContext. X-Ray bursts (XRBs) are powerful thermonuclear events on the surface of accreting neutron stars (NSs) where nucleosynthesis of intermediate-mass elements occurs. The high surface gravity of an NS prevents the ... -
The lively accretion disk in NGC 2992. III. Tentative evidence of rapid ultrafast outflow variability
(Institute of Physics (IOP), 2023-06-01)
Article
Accés obertWe report on the 2019 XMM-Newton+NuSTAR monitoring campaign of the Seyfert galaxy NGC 2992, observed at one of its highest flux levels in the X-rays. The time-averaged spectra of the two XMM-Newton orbits show ultrafast ...