Search Publications
Simple interpretation of the seemingly complicated X-ray spectral variation of NGC 5548
Sugawara, Yasuharu; Ebisawa, Ken; Mizumoto, Misaki +1 more
NGC 5548 is a very well-studied Seyfert 1 galaxy in broad wavelengths. Previous multiwavelength observation campaigns have indicated that its multiple absorbers are highly variable and complex. A previous study applied a two-zone partial covering model with different covering fractions to explain the complex X-ray spectral variation and reported a…
From Atmospheric Evolution to the Search of Species of Astrobiological Interest in the Solar System—Case Studies Using the Planetary Spectrum Generator
Machado, Pedro; Ribeiro, José; Dias, João A.
The study of minor chemical species in terrestrial planets' atmospheres can teach us about the chemistry, dynamics and evolution of the atmospheres through time. Phosphine or methane on terrestrial planets are potential biosignatures, such that their detection may signify the presence of life on a planet. Therefore, the search for these species in…
Earth through the looking glass: how frequently are we detected by other civilizations through photometric microlensing?
Robin, A. C.; Awiphan, S.; Kerins, E. +5 more
Microlensing is proving to be one of the best techniques to detect distant, low-mass planets around the most common stars in the Galaxy. In principle, Earth's microlensing signal could offer the chance for other technological civilizations to find the Earth across Galactic distances. We consider the photometric microlensing signal of Earth to othe…
Detection of Extended Millimeter Emission in the Host Galaxy of 3C 273 and Its Implications for QSO Feedback via High Dynamic Range ALMA Imaging
Saito, Toshiki; Toba, Yoshiki; Matsuoka, Yoshiki +2 more
We estimate the amount of negative feedback energy injected into the interstellar medium (ISM) of the host galaxy of 3C 273, a prototypical radio-loud quasar. We obtained 93, 233, and 343 GHz continuum images with the Atacama Large Millimeter/submillimeter Array (ALMA). After self-calibration and point-source subtraction, we reach an image dynamic…
Measurements of visual double stars with PISCO2 at the Nice 76-cm refractor in 2013-2014
Piccotti, Luca; Rivet, Jean-Pierre; Vakili, Farrokh +11 more
We present relative astrometric and photometric measurements of visual double stars made in 2013-2014 with PISCO2 installed at the 76-cm refractor of the Côte d'Azur Observatory in Nice (France). Our observation list contains orbital couples as well as double stars whose motion is still uncertain. Three different techniques were used for obtaining…
Hubble Space Telescope Imaging of Luminous Extragalactic Infrared Transients and Variables from the Spitzer Infrared Intensive Transients Survey
Gehrz, Robert D.; Bond, Howard E.; Bally, John +6 more
The SPitzer InfraRed Intensive Transients Survey (SPIRITS) searched for luminous infrared (IR) transients and variables in nearly 200 nearby galaxies from 2014 to 2019, using the warm Spitzer telescope at 3.6 and 4.5 µm. Among the SPIRITS variables are IR-bright objects that are undetected in ground-based optical surveys. We classify them as…
Refractory elements in the gas phase for comet 67P/Churyumov-Gerasimenko. Possible release of atomic Na, Si, and Fe from nanograins
De Keyser, Johan; Gombosi, Tamas I.; Berthelier, Jean-Jacques +10 more
Context. Gas-phase sodium, silicon, potassium, and calcium were previously identified in mass spectra recorded in the coma of comet 67P/Churyumov-Gerasimenko, the target of the European Space Agency's Rosetta mission. The major release process for these atoms was identified as sputtering by the solar wind. More recently, remote observations of num…
Multiepoch Optical Spectroscopy of the Post-AGB Star HD 161796
Puķītis, Kārlis; Začs, Laimons; Grankina, Aija
The evolutionary rate of the pulsating post-asymptotic giant branch (post-AGB) star HD 161796 was suspected to be high. Spectra of HD 161796 acquired during a time span of 18 yr are analyzed with the main goal of determining the evolutionary increase in temperature and comparing it with the latest post-AGB star evolutionary models. Inspection of t…
A New Method for Retrieving Electron Density Profiles from the MARSIS Ionograms
Le, Huijun; Liu, Libo; Chen, Yiding +7 more
The Martian ionosphere was actively detected by Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) aboard the Mars Express. The detected echo signal of the MARSIS at an epoch is presented as a function of frequency and time delay to form an ionogram. Some MARSIS ionograms have been processed to obtain the electron density profiles…
Planet Four: Derived South Polar Martian Winds Interpreted Using Mesoscale Modeling
Schwamb, Megan E.; Michaels, Timothy I.; Lintott, Chris J. +3 more
For the first time, model-derived and imagery-derived wind directions and speeds have been compared in Mars's south polar region. Seasonal fan-shaped deposits are routinely observed by HiRISE in the polar regions. They are widely accepted to result from CO2 gas jet eruptions. Fan lengths, sizes, and shapes can provide information about …