Search Publications
A possible far-ultraviolet flux-dependent core mass function in NGC 6357
Giannetti, A.; Massi, F.; Wouterloot, J. G. A. +2 more
Context. NGC 6357 is a galactic star-forming complex (d ~ 1.7 kpc) composed of several HII regions, a few young stellar clusters, and giant molecular clouds. In particular, the HII regions G353.2+0.9, G353.1+0.6, and G353.2+0.7 are associated with three young clusters; the most prominent of these, Pismis 24, contains some of the most massive stars…
Dynamics of nanodust in the vicinity of a stellar corona: Effect of plasma corotation
Czechowski, A.; Mann, I.
Context. In the vicinity of the Sun or other stars, the motion of the coronal and stellar wind plasma must include some amount of corotation, which could affect the dynamics of charged dust particles. In the case of the Sun, this region is now investigated in situ by the Parker Solar Probe. Charged dust particles coming from the vicinity of the Su…
The disk-torus system in active galactic nuclei: possible evidence of highly spinning black holes
Celotti, Annalisa; Ghisellini, Gabriele; Sbarrato, Tullia +1 more
We study the ratio R between the luminosity of the torus and that of the accretion disk, inferred from the relativistic model KERRBB for a sample of approximately 2000 luminosity-selected radio-quiet Type I active galactic nuclei from the Sloan Digital Sky Survey catalog. We find a mean ratio R ≈ 0.8 and a considerable number of sources with R ≳ 1…
Deriving physical parameters of unresolved star clusters. VI. Adaptive aperture photometry of the M31 PHAT star clusters
Stonkutė, Rima; Vansevičius, Vladas; Naujalis, Rokas
Context. This study is the sixth of a series that investigates degeneracy and stochasticity problems present in the determination of the age, mass, extinction, and metallicity of partially resolved or unresolved star clusters in external galaxies when using Hubble Space Telescope broadband photometry. In the fifth publication, it was noticed that …
In-depth investigation of the physical origin of the soft X-ray excess in PG 1448+273
Gu, Qiusheng; Guo, Xiaotong; Ding, Nan +6 more
We present systematic X-ray spectral and variability analyses for the narrow-line Seyfert 1 galaxy (NLsy1), PG 1448+273, using the data from two long-exposure XMM-Newton observations of the source in the different flux states. These X-ray spectral analyses indicate that the two main-stream models of soft X-ray excess, the relativistically smeared …
Ti I lines at 2.2 µm as probes of the cooler regions of sunspots
Solanki, S. K.; Castellanos Durán, J. S.; Tiwari, S. K. +1 more
Context. The sunspot umbra harbours the coolest plasma on the solar surface due to the presence of strong magnetic fields. The atomic lines that are routinely used to observe the photosphere have weak signals in the umbra and are often swamped by molecular lines. This makes it harder to infer the properties of the umbra, especially in the darkest …
Pitch-angle distribution of accelerated electrons in 3D current sheets with magnetic islands
Zharkova, V.; Xia, Q.
Aims: This research aims to explore variations of electron pitch-angle distributions (PADs) during spacecraft crossing of reconnecting current sheets (RCSs) with magnetic islands. Our results can benchmark the sampled characteristic features with realistic PADs derived from in situ observations.
Methods: Particle motion is simulated in 2…
Stellar wind structures in the eclipsing binary system IGR J18027-2016
García, Federico; Fogantini, Federico A.; Chaty, Sylvain +1 more
Context. IGR J18027-2016 is an obscured high-mass X-ray binary formed by a neutron star accreting from the wind of a supergiant companion with a ∼4.57 d orbital period. The source shows an asymmetric eclipse profile that remained stable across several years.
Aims: We aim to investigate the geometrical and physical properties of stellar wind s…
A search for distant, pulsating red giants in the southern halo
Kendall, T. R.; Mauron, N.; Gigoyan, K. S. +1 more
To investigate the asymptotic giant branch (AGB) population in the Galactic halo, we search for pulsating AGB stars at a heliocentric distance D > 50 kpc. Our research is based on the Catalina Southern Survey (CSS) catalogue of variables, comprising 1286 long-period variables (LPVs) with δ < −20°. We first focus on the 77 stars in the cap |b…
Relationship between solar energetic particle intensities and coronal mass ejection kinematics using STEREO/SECCHI field of view
Michalek, Grzegorz; Ravishankar, Anitha
Solar energetic particles (SEPs) accelerated from shocks driven by coronal mass ejections (CMEs) are one of the major causes of geomagnetic storms on Earth. Therefore, it is necessary to predict the occurrence and intensity of such disturbances. For this purpose we analyzed in detail 38 non-interacting halo and partial halo CMEs, as seen by the So…