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Spectroscopic analysis of accretion/ejection signatures in the Herbig Ae/Be stars HD 261941 and V590 Mon
Lebreton, Y.; Alencar, S. H. P.; Alecian, E. +2 more
Herbig Ae/Be (HAeBe) stars are the intermediate-mass analogues of low-mass T Tauri stars. Both groups may present signs of accretion, outflow, and IR excess related to the presence of circumstellar discs. Magnetospheric accretion models are generally used to describe accreting T Tauri stars, which are known to have magnetic fields strong enough to…
Dark Energy Survey identification of a low-mass active galactic nucleus at redshift 0.823 from optical variability
De Vicente, Juan; García-Bellido, Juan; Gaztanaga, Enrique +57 more
We report the identification of a low-mass active galactic nucleus (AGN), DES J0218-0430, in a redshift z = 0.823 galaxy in the Dark Energy Survey (DES) Supernova field. We select DES J0218-0430 as an AGN candidate by characterizing its long-term optical variability alone based on DES optical broad-band light curves spanning over 6 yr. An archival…
A Modern Guide to Quantitative Spectroscopy of Massive OB Stars
Simón-Díaz, Sergio
Quantitative spectroscopy is a powerful technique from which we can extract information about the physical properties and surface chemical composition of stars. In this chapter, I guide the reader through the main ideas required to get initiated in the learning process to become an expert in the application of state-of-the-art quantitative spectro…
Modeling Photoionized Turbulent Material in the Circumgalactic Medium. II. Effect of Turbulence within a Stratified Medium
Safarzadeh, Mohammadtaher; Buie, Edward, II; Gray, William J. +1 more
The circumgalactic medium (CGM) of nearby star-forming galaxies shows clear indications of O VI absorption accompanied by little to no detectable N V absorption. This unusual spectral signature, accompanied by highly nonuniform absorption from lower-ionization-state species, indicates that the CGM must be viewed as a dynamic, multiphase medium, su…
Detection of 2-4 GHz Continuum Emission from ɛ Eridani
Hallinan, G.; Chatterjee, S.; Cordes, J. M. +2 more
The nearby star ɛ Eridani has been a frequent target of radio surveys for stellar emission and extraterrestrial intelligence. Using deep 2-4 GHz observations with the Very Large Array, we have uncovered a 29 µJy compact, steady continuum radio source coincident with ɛ Eridani to within 0"06 (≲2σ; 0.2 au at the distance of the star). Combinin…
The inner view of NGC 1052 using multiple X-ray observations
Papadakis, I. E.; Osorio-Clavijo, N.; González-Martín, O. +2 more
In this paper, we present a multi-epoch analysis of NGC 1052, a prototypical low-luminisity active galactic nucleus, using XMM-Newton, Suzaku and NuSTAR observations taken from 2001 to 2017. This is the first time that results from NuSTAR observations have been reported for NGC 1052. Regarding technical aspects, we found a wavelength-dependent cal…
Physical parameters of selected Gaia mass asteroids
Geier, S.; Pál, A.; Molnár, L. +36 more
Context. Thanks to the Gaia mission, it will be possible to determine the masses of approximately hundreds of large main belt asteroids with very good precision. We currently have diameter estimates for all of them that can be used to compute their volume and hence their density. However, some of those diameters are still based on simple thermal m…
Monitoring clumpy wind accretion in supergiant fast-X-ray transients with XMM-Newton
Romano, P.; Ferrigno, C.; Bozzo, E.
Supergiant fast-X-ray transients (SFXTs) are a sub-class of supergiant high-mass X-ray binaries hosting a neutron star accreting from the stellar wind of a massive OB companion. Compared to the classical systems, SFXTs display a pronounced variability in X-rays that has long been (at least partly) ascribed to the presence of clumps in the stellar …
Timing of the accreting millisecond pulsar IGR J17591-2342: evidence of spin-down during accretion
Sanna, A.; Ray, P. S.; Di Salvo, T. +8 more
We report on the phase-coherent timing analysis of the accreting millisecond X-ray pulsar IGR J17591-2342, using Neutron Star Interior Composition Explorer (NICER) data taken during the outburst of the source between 2018 August 15 and 2018 October 17. We obtain an updated orbital solution of the binary system. We investigate the evolution of the …
NGTS J214358.5-380102 - NGTS discovery of the most eccentric known eclipsing M-dwarf binary system
Jackman, James A. G.; Wheatley, Peter J.; Bayliss, Daniel +23 more
We present the discovery of NGTS J214358.5-380102, an eccentric M-dwarf binary discovered by the Next-Generation Transit Survey (NGTS). The system period of 7.618 d is greater than many known eclipsing M-dwarf binary systems. Its orbital eccentricity of $0.323^{+0.0014}_{-0.0037}$ is large relative to the period and semimajor axis of the binary. G…