Search Publications
A NuSTAR study of the 55 ks hard X-ray pulse-phase modulation in the magnetar 4U 0142+61
Enoto, Teruaki; Makishima, Kazuo; Nakazawa, Kazuhiro +1 more
Archival NuSTAR data of the magnetar 4U 0142+61, acquired in 2014 March for a total time span of 258 ks, were analyzed. This is to reconfirm the 55 ks modulation in the hard X-ray pulse phases of this source, found with a Suzaku observation in 2009 (Makishima et al., 2014, Phys. Rev. Lett., 112, 171102). Indeed, the 10-70 keV X-ray pulsation, dete…
An 11 Earth-mass, Long-period Sub-Neptune Orbiting a Sun-like Star
López-Morales, Mercedes; Latham, David W.; Mayo, Andrew W. +27 more
Although several thousands of exoplanets have now been detected and characterized, observational biases have led to a paucity of long-period, low-mass exoplanets with measured masses and a corresponding lag in our understanding of such planets. In this paper we report the mass estimation and characterization of the long-period exoplanet Kepler-538…
Dust production in the debris disk around HR 4796 A
Ménard, F.; Augereau, J. -C.; Bayo, A. +21 more
Context. Debris disks are the natural by-products of the planet formation process. Scattered or polarized light observations are mostly sensitive to small dust grains that are released from the grinding down of bigger planetesimals.
Aims: High angular resolution observations at optical wavelengths can provide key constraints on the radial and…
Investigating dynamical properties of evolved Galactic open clusters
Corradi, W. J. B.; Santos, J. F. C.; Maia, F. F. S. +1 more
Context. The stellar content of Galactic open clusters is gradually depleted during their evolution as a result of internal relaxation and external interactions. The final residues of the long-term evolution of open clusters are called open cluster remnants. These are sparsely populated structures that can barely be distinguished from the field. <…
Infrared luminosity functions based on 18 mid-infrared bands: revealing cosmic star formation history with AKARI and Hyper Suprime-Cam*
Momose, Rieko; Hashimoto, Tetsuya; Goto, Tomotsugu +21 more
Much of star formation is obscured by dust. For a complete understanding of the cosmic star formation history (CSFH), infrared (IR) census is indispensable. AKARI carried out deep mid-infrared observations using its continuous nine-band filters in the North Ecliptic Pole (NEP) field (5.4 deg2). This took a significant amount of the sate…
Constraining models of activity on comet 67P/Churyumov-Gerasimenko with Rosetta trajectory, rotation, and water production measurements
Jorda, L.; Kührt, E.; Mottola, S. +11 more
Aims: We use four observational data sets, mainly from the Rosetta mission, to constrain the activity pattern of the nucleus of comet 67P/Churyumov-Gerasimenko (67P).
Methods: We developed a numerical model that computes the production rate and non-gravitational acceleration of the nucleus of comet 67P as a function of time, taking into …
Fluctuation of the background sky in the Hubble Extremely Deep Field (XDF) and its origin
Matsumoto, Toshio; Tsumura, Kohji
We performed a fluctuation analysis of the Hubble Extremely Deep Field (XDF) at four optical wavelength bands and found large fluctuations that are significantly brighter than those expected for ordinary galaxies. Good cross-correlations with flat spectra are found down to {0{^''.}2}, indicating the existence of a spatial structure even…
Plasma properties of suprathermal electrons near comet 67P/Churyumov-Gerasimenko with Rosetta
Henri, P.; Goldstein, R.; Galand, M. +6 more
Context. The Rosetta spacecraft escorted comet 67P/Churyumov-Gerasimenko from 2014 to September 2016. The mission provided in situ observations of the cometary plasma during different phases of the cometary activity, which enabled us to better understand its evolution as a function of heliocentric distance.
Aims: In this study, different elec…
Speckle Observations and Orbits of Multiple Stars
Torres, Guillermo; Latham, David W.; Tokovinin, Andrei +2 more
We report results of speckle-interferometric monitoring of visual hierarchical systems using the newly commissioned instrument NN-EXPLORE Exoplanet and Stellar Speckle Imager at the 3.5 m WIYN telescope. During one year, 390 measurements of 129 resolved subsystems were made, while some targets were unresolved. Using our astrometry and archival dat…
Constraining the Johannsen deformation parameter ɛ3 with black hole x-ray data
Tripathi, Ashutosh; Abdikamalov, Askar B.; Ayzenberg, Dimitry +2 more
We extend our previous work on tests of the Kerr black hole hypothesis using x-ray reflection spectroscopy and we infer observational constraints on the Johannsen deformation parameter ɛ3 . We analyze a NuSTAR observation of the stellar-mass black hole in GS 1354-645, Suzaku data of the supermassive black holes in Ark 564, 1H0419-577, a…