Search Publications
X-ray astronomy comes of age
Wilkes, Belinda J.; Schartel, Norbert; Santos-Lleo, Maria +1 more
The Chandra X-ray Observatory (Chandra) and the X-ray Multi-Mirror Mission (XMM-Newton) continue to expand the frontiers of knowledge about high-energy processes in the Universe. These groundbreaking observatories lead an X-ray astronomy revolution: revealing the physical processes and extreme conditions involved in producing cosmic X-rays in obje…
Energy deposition in Saturn's equatorial upper atmosphere
Hu, X.; Galand, M.; Yelle, R. V. +6 more
We construct Saturn equatorial neutral temperature and density profiles of H, H2, He, and CH4, between 10-12 and 1 bar using measurements from Cassini's Ion Neutral Mass Spectrometer (INMS) taken during the spacecraft's final plunge into Saturn's atmosphere on 15 September 2017, combined with previous deeper atmosp…
Martian Atmospheric Thermal Structure and Dust Distribution During the MY 34 Global Dust Storm From ACS TIRVIM Nadir Observations
Forget, F.; Montmessin, F.; Korablev, O. +14 more
The Thermal InfraRed channel in honor of professor Vassili Ivanovich Moroz (TIRVIM) of the Atmospheric Chemistry Suite onboard ExoMars Trace Gas Orbiter has continuously monitored the Martian atmosphere from 13 March 2018 until 2 December 2019, covering almost a complete Martian Year (MY). In the nadir mode of observations, infrared spectra obtain…
Kharkiv database of asteroid absolute magnitudes: Comparative analysis with other datasets
Muinonen, K.; Penttilä, A.; Kwiatkowski, T. +9 more
We present a database of the absolute magnitudes of asteroids named the Kharkiv Asteroid Absolute Magnitude Database (KhAAMD). The database includes a homogeneous set of the absolute magnitudes for about 400 asteroids in the new HG1G2 magnitude system. We performed a comparative analysis of the asteroid absolute magnitudes be…
Black holes at cosmic dawn in the redshifted 21cm signal of HI
Mirabel, I. F.; Rodríguez, L. F.
The first stars (Pop III stars) and Black Holes (BHs) formed in galaxies at Cosmic Dawn (CD) have not been observed and remain poorly constrained. Theoretical models predict that indirect insights of those Pop III stars and BHs could be imprinted as an absorption signal in the 21cm line of the atomic hydrogen (HI) in the cold Intergalactic Medium …
Solar Energetic Particle Time Series Analysis with Python
Dresing, Nina; Vainio, Rami; Price, Daniel J. +6 more
Solar Energetic Particles (SEPs) are charged particles accelerated within the solar atmosphere or the interplanetary space by explosive phenomena such as solar flares or Coronal Mass Ejections (CMEs). Once injected into the interplanetary space, they can propagate towards Earth, causing space weather related phenomena. For their analysis, interpla…
Semi-supervised classification and clustering analysis for variable stars
Catelan, M.; Protopapas, P.; Pichara, K. +1 more
The immense amount of time series data produced by astronomical surveys has called for the use of machine learning algorithms to discover and classify several million celestial sources. In the case of variable stars, supervised learning approaches have become commonplace. However, this needs a considerable collection of expert-labelled light curve…
Path-lengths in the quiet Sun transition region using O IV lines from IRIS
Del Zanna, Giulio; Rao, Yamini K.; Mason, Helen E. +1 more
We use spectroscopic diagnostics to determine different plasma parameters in the transition region of the quiet Sun. The electron number density from O IV lines using high-resolution spectral observations from the Interface Region Imaging Spectrograph (IRIS) are estimated to be around 1010 cm-3, in agreement with literature v…
Broad-band spectral analysis of Mrk 926 using multi-epoch X-ray observations
Buisson, D. J. K.; Russell, T. D.; Lohfink, A. M. +3 more
The X-ray spectra of some active galactic nuclei (AGNs) show a soft X-ray excess, emission in excess to the extrapolated primary X-ray continuum below 2 keV. Recent studies have shown that this soft excess can be described well as originating from either a relativistic ionized reflection, the extreme blurring of the reprocessed emission from the i…
Discovery of non-equilibrium ionization plasma associated with the North Polar Spur and Loop I
Kataoka, Jun; Sofue, Yoshiaki; Yamamoto, Marino
We investigated the detailed plasma condition of the North Polar Spur (NPS)/Loop I using archival Suzaku data. In previous research, collisional ionization equilibrium (CIE) have been assumed for X-ray plasma state, but we also assume non-equilibrium ionization (NEI) to check the plasma condition in more detail. We found that most of the plasma in…