Search Publications
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…
Clustered star formation toward Berkeley 87/ON2. I. Multiwavelength census and the population overlap problem
Alves, João; Garcia, Miriam; Jiménez-Bailón, Elena +3 more
Context. Disentangling line-of-sight alignments of young stellar populations is crucial for observational studies of star-forming complexes. This task is particularly problematic in a Cygnus-X subregion where several components, located at different distances, overlap: the Berkeley 87 young massive cluster, the poorly known [DB2001] Cl05 embedded …
Possibility of concentration of nonvolatile species near the surface of comet 67P/Churyumov-Gerasimenko
Nomura, H.; Majumdar, L.; Suzuki, T. +4 more
Context. Cometary materials are thought to be the reservoir of the primitive materials of the Solar System. The recent detection of glycine and CH3NH2 by the ROSINA mass spectrometer in the coma of 67P/Churyumov-Gerasimenko suggests that amino acids and their precursors may have formed in an early evolutionary phase of the So…
Spectral evolution of X-ray pulsar 4U 1901+03 during the 2019 outburst based on Insight-HXMT and NuSTAR observations
Zhang, Shu; Doroshenko, Victor; Tsygankov, Sergey S. +7 more
We report on a detailed spectral analysis of emission from X-ray pulsar 4U 1901+03 using data obtained by the Insight-HXMT and NuSTAR observatories during the 2019 outburst of the source. Thanks to the extensive coverage of the outburst by Insight-HXMT, we were able to investigate the spectral evolution of the source as a function of flux, and com…
X-ray analysis of the Planck-detected triplet-cluster system PLCK G334.8-38
Pointecouteau, Etienne; Douspis, Marian; Aghanim, Nabila +2 more
We conducted an X-ray analysis of one of the two Planck-detected triplet-cluster systems, PLCK G334.8-38.0, with a ∼100 ks deep XMM-Newton data. We find that the system has a redshift of z = 0.37 ± 0.01 but the precision of the X-ray spectroscopy for two members is too low to rule out a projected triplet system, demanding optical spectroscopy for …
Long-term, orbital, and rapid variations of the Be star V923 Aql = HD 183656
Wolf, M.; Harmanec, P.; Bakış, V. +9 more
We present the latest results of a long-term observational project aimed at observing, collecting from the literature, and homogenising the light, colour, and spectral variations of the well-known emission-line Be star V923 Aql. Our analysis of these parameters confirms that all of the observables exhibit cyclic changes with variable cycle length …