RAS_WEB (Page 4,427)

Gould Belt Members in X-ray RAVE: Cross-Matching RAVE Stars with 3XMM Point Sources. (arXiv:1901.08859v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Coskunoglu_B/0/1/0/all/0/1">B. Co&#x15f;kuno&#x11f;lu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Plevne_O/0/1/0/all/0/1">O. Plevne</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ozkan_M/0/1/0/all/0/1">M. T. &#xd6;zkan</a> In this paper the results of matching the RAdial Velocity Experiment (RAVE), a spectroscopic Southern hemisphere survey (9 $ < I_{DENIS}Read More →

The CARMENES search for exoplanets around M dwarfs. Activity indicators at visible and near-infrared wavelengths. (arXiv:1901.08861v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Schofer_P/0/1/0/all/0/1">P. Sch&#xf6;fer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jeffers_S/0/1/0/all/0/1">S. V. Jeffers</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Reiners_A/0/1/0/all/0/1">A. Reiners</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shulyak_D/0/1/0/all/0/1">D. Shulyak</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fuhrmeister_B/0/1/0/all/0/1">B. Fuhrmeister</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Johnson_E/0/1/0/all/0/1">E. N. Johnson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zechmeister_M/0/1/0/all/0/1">M. Zechmeister</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ribas_I/0/1/0/all/0/1">I. Ribas</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Quirrenbach_A/0/1/0/all/0/1">A. Quirrenbach</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Amado_P/0/1/0/all/0/1">P. J. Amado</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Caballero_J/0/1/0/all/0/1">J. A. Caballero</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Anglada_Escude_G/0/1/0/all/0/1">G. Anglada-Escud&#xe9;</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bauer_F/0/1/0/all/0/1">F. F. Bauer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bejar_V/0/1/0/all/0/1">V. J. S. B&#xe9;jar</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cortes_Contreras_M/0/1/0/all/0/1">M. Cort&#xe9;s-Contreras</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dreizler_S/0/1/0/all/0/1">S. Dreizler</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Guenther_E/0/1/0/all/0/1">E. W. Guenther</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kaminski_A/0/1/0/all/0/1">A. Kaminski</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kurster_M/0/1/0/all/0/1">M. K&#xfc;rster</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lafarga_M/0/1/0/all/0/1">M. Lafarga</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Montes_D/0/1/0/all/0/1">D. Montes</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Morales_J/0/1/0/all/0/1">J. C. Morales</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pedraz_S/0/1/0/all/0/1">S. Pedraz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tal_Or_L/0/1/0/all/0/1">L. Tal-Or</a> The CARMENES survey is searching for Earth-likeRead More →

Internal Gravity Waves in the Magnetized Solar Atmosphere. II. Energy Transport. (arXiv:1901.08871v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Vigeesh_G/0/1/0/all/0/1">G. Vigeesh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Roth_M/0/1/0/all/0/1">M. Roth</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Steiner_O/0/1/0/all/0/1">O. Steiner</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jackiewicz_J/0/1/0/all/0/1">J. Jackiewicz</a> In this second paper of the series on internal gravity waves (IGWs), we present a study of the generation and propagation of IGWs in a model solar atmosphere with diverse magnetic conditions. A magnetic field free, and three magnetic models that start with an initial, vertical, homogeneous field of 10 G, 50 G, and 100 G magnetic flux density, are simulated using the CO$^{rm 5}$BOLD code. We find that the IGWs are generated in similar manner in all four modelsRead More →

Laser Communication and Coordination Control of Spacecraft Swarms. (arXiv:1901.08875v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Kalita_H/0/1/0/all/0/1">Himangshu Kalita</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vance_L/0/1/0/all/0/1">Leonard Vance</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Reddy_V/0/1/0/all/0/1">Vishnu Reddy</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Thangavelautham_J/0/1/0/all/0/1">Jekan Thangavelautham</a> Swarms of small spacecraft offer whole new capabilities in Earth observation, global positioning and communications compared to a large monolithic spacecraft. These small spacecrafts can provide bigger apertures that increase gain in communication antennas, increase area coverage or effective resolution of distributed cameras and enable persistent observation of ground or space targets. However, there remain important challenges in operating large number of spacecrafts at once. Current methods would require a large number of ground operators monitor and actively control these spacecrafts which posesRead More →

Neutrino physics with dark matter detectors. (arXiv:1901.08876v1 [hep-ph]) <a href="http://arxiv.org/find/hep-ph/1/au:+Dutta_B/0/1/0/all/0/1">Bhaskar Dutta</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Strigari_L/0/1/0/all/0/1">Louis E. Strigari</a> Direct dark matter detection experiments will soon be sensitive to neutrinos from astrophysical sources, including the Sun, the atmosphere, and supernova. This sets an important benchmark for these experiments, and opens up a new window in neutrino physics and astrophysics. The detection of these neutrinos will be complementary to accelerator and reactor-based experiments which study neutrinos over the same energy range. Here we review the physics and astrophysics that can be extracted from the detection of these neutrinos, highlighting the potential for identifying new physics in the form of lightRead More →

The cosmic spectral energy distribution in the EAGLE simulation. (arXiv:1901.08878v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Baes_M/0/1/0/all/0/1">Maarten Baes</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Trcka_A/0/1/0/all/0/1">Ana Tr&#x10d;ka</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Camps_P/0/1/0/all/0/1">Peter Camps</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nersesian_A/0/1/0/all/0/1">Angelos Nersesian</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Trayford_J/0/1/0/all/0/1">James Trayford</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Theuns_T/0/1/0/all/0/1">Tom Theuns</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dobbels_W/0/1/0/all/0/1">Wouter Dobbels</a> The cosmic spectral energy distribution (CSED) is the total emissivity as a function of wavelength of galaxies in a given cosmic volume. We compare the observed CSED from the UV to the submm to that computed from the EAGLE cosmological hydrodynamical simulation, post-processed with stellar population synthesis models and including dust radiative transfer using the SKIRT code. The agreement with the data is better than 0.15 dex over the entire wavelength range atRead More →

Deconstructing double-barred galaxies in 2D and 3D. II. Two distinct groups of inner bars. (arXiv:1901.08881v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Lorenzo_Caceres_A/0/1/0/all/0/1">A. de Lorenzo-C&#xe1;ceres</a> (1, 2 and 3), <a href="http://arxiv.org/find/astro-ph/1/au:+Mendez_Abreu_J/0/1/0/all/0/1">J. M&#xe9;ndez-Abreu</a> (1, 2 and 3), <a href="http://arxiv.org/find/astro-ph/1/au:+Thorne_B/0/1/0/all/0/1">B. Thorne</a> (1, 4 and 5), <a href="http://arxiv.org/find/astro-ph/1/au:+Costantin_L/0/1/0/all/0/1">L. Costantin</a> (6 and 7) ((1) University of St Andrews, UK, (2) Instituto de Astrof&#xed;sica de Canarias, Spain, (3) Universidad de La Laguna, Spain, (4) University of Oxford, UK, (5) Princeton University, USA, (6) Osservatorio Astronomico di Brera, Italy, (7) Universita di Padova, Italy) The intrinsic photometric properties of inner and outer stellar bars within 17 double-barred galaxies are thoroughly studied through a photometric analysis consistingRead More →

Modeling the large-scale power deficit. (arXiv:1901.08885v1 [astro-ph.CO]) <a href="http://arxiv.org/find/astro-ph/1/au:+Vitenti_S/0/1/0/all/0/1">Sandro D. P. Vitenti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Peter_P/0/1/0/all/0/1">Patrick Peter</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Valentini_A/0/1/0/all/0/1">Antony Valentini</a> We investigate a set of cosmological models for which the primordial power spectrum has a large-scale power deficit. The standard power-law spectrum is subject to long-wavelength modifications described by some new parameters, resulting in corrections to the anisotropies in the cosmic microwave background. The new parameters are fitted to different data sets: temperature only, temperature and polarization, the low-redshift determination of $H_0$, and baryonic acoustic oscillations. We discuss the statistical significance of the modified spectra, from both frequentist and Bayesian perspectives. Our analysis suggests motivations for consideringRead More →

Triggering magnetar outbursts in 3D force-free simulations. (arXiv:1901.08889v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Carrasco_F/0/1/0/all/0/1">Federico Carrasco</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vigano_D/0/1/0/all/0/1">Daniele Vigan&#xf2;</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Palenzuela_C/0/1/0/all/0/1">Carlos Palenzuela</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pons_J/0/1/0/all/0/1">Jose A. Pons</a> In this letter, we present the first 3D force-free general relativity simulations of the magnetosphere dynamics related to the magnetar outburst/flare phenomenology. Starting from an initial dipole configuration, we adiabatically increase the helicity by twisting the footprints of a spot on the stellar surface and follow the succession of quasi-equilibrium states until a critical twist is reached. Twisting beyond that point triggers instabilities that results in the rapid expansion of magnetic field lines, followed by reconnection, as observed in previous axi-symmetric simulations. IfRead More →

Connecting planet formation and astrochemistry: Refractory carbon depletion leading to super-stellar C/O in giant planetary atmospheres. (arXiv:1901.08896v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Cridland_A/0/1/0/all/0/1">Alex J. Cridland</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Eistrup_C/0/1/0/all/0/1">Christian Eistrup</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dishoeck_E/0/1/0/all/0/1">Ewine F. van Dishoeck</a> [Abridged] Combining a time-dependent astrochemical model with a model of planet formation and migration, we compute the carbon-to-oxygen ratio (C/O) of a range of planetary embryos starting their formation in the inner solar system (1-3 AU). The volatile and ice abundance of relevant carbon and oxygen bearing molecular species are determined through a complex chemical kinetic code which includes both gas and grain surface chemistry. This is combined with a model for the abundance ofRead More →

Differential Astrometric Framework for the Jupiter Relativistic Experiment with Gaia. (arXiv:1901.08903v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Abbas_U/0/1/0/all/0/1">Ummi Abbas</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Bucciarelli_B/0/1/0/all/0/1">Beatrice Bucciarelli</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Lattanzi_M/0/1/0/all/0/1">Mario G. Lattanzi</a> (1) ((1) INAF- Osservatorio Astrofisico di Torino) We employ differential astrometric methods to establish a small field reference frame stable at the micro-arcsecond ($mu$as) level on short timescales using high-cadence simulated observations taken by Gaia in February 2017 of a bright star close to the limb of Jupiter, as part of the relativistic experiment on Jupiter’s quadrupole. We achieve sub$mu$as-level precision along scan through a suitable transformation of the field angles into a small-field tangent plane and a least-squares fit overRead More →

The orbital parameters of the gamma-ray binary LMC P3. (arXiv:1901.08911v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Soelen_B/0/1/0/all/0/1">B. van Soelen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Komin_N/0/1/0/all/0/1">N. Komin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kniazev_A/0/1/0/all/0/1">A. Kniazev</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vaisanen_P/0/1/0/all/0/1">P. V&#xe4;is&#xe4;nen</a> LMC P3 is the most luminous gamma-ray binary discovered to date and the first detected outside of the Galaxy, with an orbital period of 10.301 d. We report on optical spectroscopic observations undertaken with the Southern African Large Telescope (SALT) using the High Resolution spectrograph (HRS). We find the binary is slightly eccentric, $e = 0.40pm0.07$, and place the time of periastron at HJD $2457412.13 pm 0.29$. Stellar model fitting finds an effective temperature of $T_{rm eff} = 36351 pm 53$Read More →

Gamma-ray burst localisation strategies for the SPHiNX hard X-ray polarimeter. (arXiv:1901.08948v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Heckmann_L/0/1/0/all/0/1">L. Heckmann</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Iyer_N/0/1/0/all/0/1">N. K. Iyer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kiss_M/0/1/0/all/0/1">M. Kiss</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pearce_M/0/1/0/all/0/1">M. Pearce</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Xie_F/0/1/0/all/0/1">F. Xie</a> SPHiNX is a proposed gamma-ray burst (GRB) polarimeter mission operating in the energy range 50-600 keV with the aim of studying the prompt emission phase. The polarisation sensitivity of SPHiNX reduces as the uncertainty on the GRB sky position increases. The stand-alone ability of the SPHiNX design to localise GRB positions is explored via Geant4 simulations. Localisation at the level of a few degrees is possible using three different routines. This results in a large fraction (>Read More →

Enrichment of the Galactic disc with neutron capture elements: Sr. (arXiv:1901.08955v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Mishenina_T/0/1/0/all/0/1">T. Mishenina</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pignatari_M/0/1/0/all/0/1">M. Pignatari</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gorbaneva_T/0/1/0/all/0/1">T. Gorbaneva</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bisterzo_S/0/1/0/all/0/1">S. Bisterzo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Travaglio_C/0/1/0/all/0/1">C. Travaglio</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Thielemann_F/0/1/0/all/0/1">F. K. Thielemann</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Soubiran_C/0/1/0/all/0/1">C.Soubiran</a> The enrichment history of heavy neutron-capture elements in the Milky Way disc provides fundamental information about the chemical evolution of our Galaxy and about the stellar sources that made those elements. In this work we give new observational data for Sr, the element at the first neutron-shell closure beyond iron, N=50, based on the analysis of the high resolution spectra of 276 Galactic disc stars. The Sr abundance was derived by comparingRead More →

Opacity calculations for stellar astrophysics. (arXiv:1901.08959v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Pain_J/0/1/0/all/0/1">Jean-Christophe Pain</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gilleron_F/0/1/0/all/0/1">Franck Gilleron</a> Opacity is a key ingredient of stellar structure and evolution. In the present work, we recall the role of opacity in asteroseismology, focusing mainly on two kinds of astrophysical objects: $beta$ Cephei-type stars, and the Sun. The detailed opacity code SCO-RCG for local-thermodynamic-equilibrium plasmas is described and interpretation of laser and Z-pinch experiments are presented and discussed. The possible role of multi-photon processes on radiative accelerations is outlined, and the main aspects of opacity modeling which should be improved are mentioned. Opacity is a key ingredient of stellar structure and evolution. InRead More →

ALMA photometry of extragalactic radio sources. (arXiv:1901.08976v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Bonato_M/0/1/0/all/0/1">M. Bonato</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Liuzzo_E/0/1/0/all/0/1">E. Liuzzo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Herranz_D/0/1/0/all/0/1">D. Herranz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gonzalez_Nuevo_J/0/1/0/all/0/1">J. Gonzalez-Nuevo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bonavera_L/0/1/0/all/0/1">L. Bonavera</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tucci_M/0/1/0/all/0/1">M. Tucci</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Massardi_M/0/1/0/all/0/1">M. Massardi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zotti_G/0/1/0/all/0/1">G. De Zotti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Negrello_M/0/1/0/all/0/1">M. Negrello</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zwaan_M/0/1/0/all/0/1">M. A. Zwaan</a> We present a new catalogue of ALMA observations of 3,364 bright, compact radio sources, mostly blazars, used as calibrators. These sources were observed between May 2011 and July 2018, for a total of 47,115 pointings in different bands and epochs. We have exploited the ALMA data to validate the photometry given in the new Planck Multi-frequency Catalogue of Non-thermal sources (PCNT), for which an externalRead More →

$N$-body chaos and the continuum limit in numerical simulations of self-gravitating systems, revisited. (arXiv:1901.08981v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Cintio_P/0/1/0/all/0/1">Pierfrancesco Di Cintio</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Casetti_L/0/1/0/all/0/1">Lapo Casetti</a> We revise the r^{o}le of discreteness and chaos in the dynamics of self-gravitating systems by means of $N$-body simulations with active and frozen potentials, starting from spherically symmetric stationary states and considering the orbits of single particles as well as the orbits of the system in the full $2N$-dimensional phase space. We investigate the dependence on $N$ of the largest Lyapunov exponent both of single particle orbits and of the full $N$-body system. We also show that the use of frozen $N$-body potentialsRead More →

Modelling Ion Populations in Astrophysical Plasmas: Carbon in the Solar Transition Region. (arXiv:1901.08992v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Dufresne_R/0/1/0/all/0/1">R.P. Dufresne</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zanna_G/0/1/0/all/0/1">G. Del Zanna</a> A collisional-radiative model for carbon has been developed to determine ion populations in lower-temperature, higher-density plasmas, such as the solar transition region. These conditions mean the often-used coronal approximation no longer holds for the modelling. The most up-to-date atomic rates have been employed for the processes which influence the populations in these regions. In the absence of level-resolved rates for electron-impact direct ionisation and excitation-autoionisation, new calculations have been made using atomic codes. Comparison with laboratory cross-sections and previous studies, where available, show satisfactoryRead More →

Global radiation signature from early structure formation. (arXiv:1901.08994v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Liu_B/0/1/0/all/0/1">Boyuan Liu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jaacks_J/0/1/0/all/0/1">Jason Jaacks</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Finkelstein_S/0/1/0/all/0/1">Steven L. Finkelstein</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bromm_V/0/1/0/all/0/1">Volker Bromm</a> We use cosmological hydrodynamic zoom-in simulations to study early structure formation in two dark matter (DM) cosmologies, a standard CDM model, and a warm DM (WDM) model with a particle mass of $m_{chi}c^{2}=3$ keV. We focus on DM haloes with virial masses $Msim 10^{10} M_{odot}$. We find that the first star formation activity is delayed by $sim 200$ Myr in the WDM model, with similar delays for metal enrichment and the formation of the second generation of stars. However, the differences between theRead More →

The puzzling high velocity G5 supergiant star HD 179821 : new insight from Gaia DR2 data. (arXiv:1901.08995v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Parthasarathy_M/0/1/0/all/0/1">M. Parthasarathy</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jasniewicz_G/0/1/0/all/0/1">G. Jasniewicz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Thevenin_F/0/1/0/all/0/1">F. Th&#xe9;venin</a> HD 179821 is classified as G5 Ia star. From the IRAS colors and spectral energy distributions it was classified as a post-AGB star. But some studies classify it as a massive (30 to 19 Msun ) post-red supergiant evolving to become a Type II supernova. Its mass and evolutionary status remained a hotly debated question even after several detailed spectroscopic studies as the distance was not known. We use the parallax of HD 179821 from the second GaiaRead More →