Search Publications
Very Metal-poor Stars in the Solar Vicinity: Kinematics and Abundance Analysis
Villanova, Sandro; Carraro, Giovanni; Plotnikova, Anastasiia +1 more
Very metal-poor stars contain crucial information on the Milky Way's infancy. In our previous study we derived a mean age of ~13.7 Gyr for a sample of these stars in the Sun's vicinity. In this work, we investigate the chemical and kinematic properties of these stars with the goal of obtaining some insights into their origin and their parent popul…
Origin of the complex iron line structure and spectral variation in Mrk 766
Ebisawa, Ken; Mizumoto, Misaki; Mochizuki, Yuto
Complex Fe-K emission/absorption line features are commonly observed in the 6-11 keV band from Active Galactic Nuclei (AGN). These features are formed in various physical components surrounding the black holes. The Narrow-Line Seyfert 1 (NLS1) galaxy Mrk 766, in particular, exhibits characteristic blue-shifted Fe-K absorption lines caused by the u…
Mid-IR Observations of IRAS, AKARI, WISE/NEOWISE, and Subaru for Large Icy Asteroid (704) Interamnia: A New Perspective of Regolith Properties and Water Ice Fraction
Zhao, Yuhui; Ji, Jianghui; Yang, Bin +3 more
(704) Interamnia is one of the largest asteroids located in the outer main-belt region, which may contain a large amount of water ice underneath its surface. We observe this asteroid using 8.2 m Subaru telescope at mid-infrared wave bands and utilize a thermophysical model for realistic surface layers to analyze mid-infrared data from Subaru along…
XMM-Newton Observations of Two Archival X-Ray Weak Type 1 Quasars: Obscuration Induced X-Ray Weakness and Variability
Brandt, W. N.; Luo, Bin; Yi, Weimin +6 more
We report XMM-Newton observations of two examples of an unclassified type of X-ray weak quasars from the Pu et al. survey of X-ray weak quasars in the Chandra archive, SDSS J083116.62+321329.6 at z = 1.797 and SDSS J142339.87+042041.1 at z = 1.702. They do not belong to the known populations of X-ray weak quasars that show broad absorption lines, …
An irradiated-Jupiter analogue hotter than the Sun
Maoz, Dan; Hallakoun, Na'ama; Leibundgut, Bruno +10 more
Planets orbiting close to hot stars experience intense extreme-ultraviolet radiation, potentially leading to atmosphere evaporation and to thermal dissociation of molecules. However, this extreme regime remains mainly unexplored due to observational challenges. Only a single known ultra-hot giant planet, KELT-9b, receives enough ultraviolet radiat…
The Similar Seven: A Set of Very Alike Exoplanets to Test Correlations between System Parameters and Atmospheric Properties
López-Morales, Mercedes; Jordán, Andrés; Brahm, Rafael +1 more
Studies of exoplanetary atmospheres have found no definite correlations between observed high-altitude aerosols and other system parameters. This could be, in part, because of the lack of homogeneous exoplanet samples for which specific parameters can be isolated and inspected. Here, we present a set of seven exoplanets with very similar system pa…
Post-outburst Evolution of Bona Fide FU Ori-type V2493 Cygnus: A Spectro-photometric Monitoring
Irawati, Puji; Pandey, Rakesh; Sharma, Saurabh +11 more
We present here the results of 8 yr of our near-simultaneous optical-near-infrared spectro-photometric monitoring of the bona fide FU Ori (FUor)-type candidate V2493 Cygnus (V2493 Cyg) starting from 2013 September to 2021 June. During our optical monitoring period (between 2015 October 16 and 2019 December 30), the V2493 Cyg is slowly dimming with…
Identification of 1RXS J165424.6-433758 as a Polar Cataclysmic Variable
Mukai, K.; Troja, E.; Cenko, S. B. +25 more
We present the results of our X-ray, ultraviolet, and optical follow-up campaigns of 1RXS J165424.6-433758, an X-ray source detected with the Swift Deep Galactic Plane Survey. The source X-ray spectrum (Swift and NuSTAR) is described by thermal bremsstrahlung radiation with a temperature of kT = 10.1 ± 1.2 keV, yielding an X-ray (0.3-10 keV8) lumi…
Convective blueshift strengths for 242 evolved stars
Reiners, A.; Zechmeister, M.; Jeffers, S. V. +1 more
Context. With the advent of extreme precision radial velocity (RV) surveys, seeking to detect planets at RV semi-amplitudes of 10 cm s−1, intrinsic stellar variability is the biggest challenge to detecting small exoplanets. To overcome the challenge we must first thoroughly understand all facets of stellar variability. Among those, conv…
Strong gravitational lensing by AGNs as a probe of the quasar-host relations in the distant Universe
Djorgovski, S. G.; Courbin, Frédéric; Sluse, Dominique +4 more
The tight correlations found between the mass of supermassive black holes and the luminosities, stellar masses and velocity dispersions of their host galaxies are often interpreted as a sign of their co-evolution. Studying these correlations across redshift provides a powerful insight into the evolutionary path followed by the quasar and its host …