Search results for "Astrophysics"
showing 10 items of 8341 documents
Gaia-ESO Survey: Global properties of clusters Trumpler 14 and 16 in the Carina nebula
2017
Aims: We present the first extensive spectroscopic study of the global population in star clusters Trumpler 16, Trumpler 14, and Collinder 232 in the Carina nebula, using data from the Gaia-ESO Survey, down to solar-mass stars. Methods: In addition to the standard homogeneous survey data reduction, a special processing was applied here because of the bright nebulosity surrounding Carina stars. Results: We find about 400 good candidate members ranging from OB types down to slightly subsolar masses. About 100 heavily reddened early-type Carina members found here were previously unrecognized or poorly classified, including two candidate O stars and several candidate Herbig Ae/Be stars. Their l…
Three-Dimensional Simulations of Solar Wind Preconditioning and the 23 July 2012 Interplanetary Coronal Mass Ejection
2020
Predicting the large-scale eruptions from the solar corona and their propagation through interplanetary space remains an outstanding challenge in solar- and helio-physics research. In this article, we describe three dimensional magnetohydrodynamic simulations of the inner heliosphere leading up to and including the extreme interplanetary coronal mass ejection (ICME) of 23 July 2012, developed using the code PLUTO. The simulations are driven using the output of coronal models for Carrington rotations 2125 and 2126 and, given the uncertainties in the initial conditions, are able to reproduce an event of comparable magnitude to the 23 July ICME, with similar velocity and density profiles at 1 …
HADES RV programme with HARPS-N at TNG: XII. The abundance signature of M dwarf stars with planets
2020
[Context] Most of our current knowledge on planet formation is still based on the analysis of main sequence, solar-type stars. Conversely, detailed chemical studies of large samples of M dwarfs hosting planets are still missing.
The Gaia-ESO Survey: Structural and dynamical properties of the young cluster Chamaeleon i
2017
Investigating the physical mechanisms driving the dynamical evolution of young star clusters is fundamental to our understanding of the star formation process and the properties of the Galactic field stars. The young (~2 Myr) and partially embedded cluster Chamaeleon I is one of the closest laboratories for the study of the early stages of star cluster dynamics in a low-density environment. The aim of this work is to study the structural and kinematical properties of this cluster combining parameters from the high-resolution spectroscopic observations of the Gaia-ESO Survey with data from the literature. Our main result is the evidence of a large discrepancy between the velocity dispersion …
The Gaia-ESO Survey: evidence of atomic diffusion in M67?
2018
Investigating the chemical homogeneity of stars born from the same molecular cloud at virtually the same time is very important for our understanding of the chemical enrichment of the interstellar medium and with it the chemical evolution of the Galaxy. One major cause of inhomogeneities in the abundances of open clusters is stellar evolution of the cluster members. In this work, we investigate variations in the surface chemical composition of member stars of the old open clusterM67 as a possible consequence of atomic diffusion effects taking place during the main-sequence phase. The abundances used are obtained from high-resolution UVES/FLAMES spectra within the framework of the Gaia-ESO S…
First determination of β-delayed multiple neutron emission beyond A = 100 through direct neutron measurement : The P2n value of 136Sb
2018
Background: β-delayed multiple neutron emission has been observed for some nuclei with A≤100, being the Rb100 the heaviest β2n emitter measured to date. So far, only 25P2n values have been determined for the ≈300 nuclei that may decay in this way. Accordingly, it is of interest to measure P2n values for the other possible multiple neutron emitters throughout the chart of the nuclides. It is of particular interest to make such a measurement for nuclei with A>100 to test the predictions of theoretical models and simulation tools for the decays of heavy nuclei in the region of very neutron-rich nuclei. In addition, the decay properties of these nuclei are fundamental for the understanding of a…
Precision Mass Measurements on Neutron-Rich Rare-Earth Isotopes at JYFLTRAP : Reduced Neutron Pairing and Implications for r-Process Calculations
2018
The rare-earth peak in the r-process abundance pattern depends sensitively on both the astrophysical conditions and subtle changes in nuclear structure in the region. This work takes an important step towards elucidating the nuclear structure and reducing the uncertainties in r-process calculations via precise atomic mass measurements at the JYFLTRAP double Penning trap. Nd158, Pm160, Sm162, and Gd164-166 have been measured for the first time, and the precisions for Nd156, Pm158, Eu162,163, Gd163, and Tb164 have been improved considerably. Nuclear structure has been probed via two-neutron separation energies S2n and neutron pairing energy metrics Dn. The data do not support the existence of…
Difficulties in learning astronomy in High School
2013
Recebido em 10/5/2012; Aceito em 3/9/2012; Publicado em 1/3/2013El objetivo de este trabajo es conocer las dificultades de aprendizaje de la astronom´ia del alumnado al finalizarla educaci´on secundaria de nuestro pa´is (16 anos)˜ y si la ensenanza˜ las tiene en cuenta. Para ello se ha realizadoun cuestionario a estudiantes y una red de an´alisis de textos, en los que se investigan cuestiones relativas a laastronom´ia de posici´on, la astrof´isica y la cosmolog´ia. Se han aplicado a 113 alumnos que ya hab´ian estudiado eltema y a 14 manuales, respectivamente. Los resultados muestran que el alumnado sigue sin comprender aspectosb´asicos de la astronom´ia, pese a la reiteraci´on en la ensenanza…
Zemes mīti debesīs. Zvaigžņu atlantu virtuālā izstāde
2021
Latvijas Universitātes Muzeja Frīdriha Candera un Latvijas astronomijas kolekcijā glabājas bagātīga 18., 19. un 20. gadsimta zvaigžņu atlantu kolekcija, kas uzskatāmi ataino zvaigžņotās debess kartēšanas vēsturi. Vecākajam no atlantiem ir gandrīz 300 gadu. Divdesmit zvaigžņu atlanti, kas tapuši līdz 1940. gadam, tagad pieejami apskatei Muzeja virtuālajā izstādē „Zemes mīti debesīs”.
Astronoma Alfrēda Žaggera publikācijas
2020
Latvijas Universitātes Muzeja virtuālajā izstādē „Astronoma Alfrēda Žaggera publikācijas” iespējams iepazīties ar pazīstamā astronoma dzīves gājumu (1878 – 1956) un darbību Latvijas Universitātes Astronomiskās observatorijas direktora amatā, lūkojoties caur viņa publikāciju prizmu.