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Study on Precursor Activity of the X1.6 Flare in the Great AR 12192 with SDO, IRIS, and Hinode
Lee, Kyoung-Sun; Kusano, Kanya; Bamba, Yumi +1 more
The physical properties and their contribution to the onset of a solar flare are still uncleare even though chromospheric brightening is considered a precursor phenomenon of a flare. Many studies suggested that photospheric magnetic field changes cause destabilization of large-scale coronal structure. We aim to understand how a small photospheric …
The Surface Brightness-color Relations Based on Eclipsing Binary Stars: Toward Precision Better than 1% in Angular Diameter Predictions
Gieren, Wolfgang; Pietrzyński, Grzegorz; Maxted, Pierre F. L. +7 more
In this study we investigate the calibration of surface brightness-color (SBC) relations based solely on eclipsing binary stars. We selected a sample of 35 detached eclipsing binaries with trigonometric parallaxes from Gaia DR1 or Hipparcos whose absolute dimensions are known with an accuracy better than 3% and that lie within 0.3 kpc from the Sun…
Simultaneous Mass Determination for Gravitationally Coupled Asteroids
Chesley, Steven R.; Baer, James
The conventional least-squares asteroid mass determination algorithm allows us to solve for the mass of a large subject asteroid that is perturbing the trajectory of a smaller test asteroid. However, this algorithm is necessarily a first approximation, ignoring the possibility that the subject asteroid may itself be perturbed by the test asteroid,…
The Optical/UV Excess of X-Ray-dim Isolated Neutron Stars. I. Bremsstrahlung Emission from a Strangeon Star Atmosphere
Ge, Mingyu; Li, Zhaosheng; Xu, Renxin +4 more
X-ray-dim isolated neutron stars (XDINSs) are characterized by Planckian spectra in X-ray bands, but show optical/ultraviolet (UV) excesses: the factors by which the measured photometry exceeds those extrapolated from X-ray spectra. To solve this problem, a radiative model of bremsstrahlung emission from a plasma atmosphere is established in the r…
Cosmology with AGN: can we use quasars as standard candles?
Lusso, E.; Risaliti, G.
The nonlinear relation between X-ray and UV luminosity in quasars can be used to estimate their distance. Recently, we have shown that, despite the large dispersion of the relation, a Hubble diagram made of large samples of quasars can provide unique constraints on cosmology at high redshift. Furthermore, the dispersion of the relation is heavily …
Rosetta measurements of lower hybrid frequency range electric field oscillations in the plasma environment of comet 67P
Nilsson, H.; André, M.; Karlsson, T. +6 more
Electric field measurements from cometary environments are very rare but can provide important information on how plasma waves help fashion the plasma environment. The long dwelling time of the Rosetta spacecraft close to comet 67P/Churyumov-Gerasimenko promises to improve this state. We here present the first electric field measurements from 67P,…
The aurorae of Uranus past equinox
Lamy, L.; Badman, S. V.; Cowley, S. W. H. +9 more
The aurorae of Uranus were recently detected in the far ultraviolet with the Hubble Space Telescope (HST) providing a new, so far unique, means to remotely study the asymmetric Uranian magnetosphere from Earth. We analyze here two new HST Uranus campaigns executed in September 2012 and November 2014 with different temporal coverage and under varia…
The Broadband Spectral Variability of Holmberg IX X-1
Harrison, F. A.; Ptak, A.; Stern, D. +9 more
We present results from four new broadband X-ray observations of the extreme ultraluminous X-ray source Holmberg IX X-1 ({L}{{X}}> {10}40 erg s-1), performed by Suzaku and NuSTAR in coordination. Combined with the archival data, we now have broadband observations of this remarkable source from six separate epoch…
How Much Flux Does a Flux Transfer Event Transfer?
Milan, S. E.; Fear, R. C.; Coxon, J. C. +1 more
Flux transfer events are bursts of reconnection at the dayside magnetopause, which give rise to characteristic signatures observed by a range of magnetospheric/ionospheric instrumentation. One outstanding problem is that there is a fundamental mismatch between space-based and ionospheric estimates of the flux that is opened by each flux transfer e…
Improved Point-source Detection in Crowded Fields Using Probabilistic Cataloging
Finkbeiner, Douglas P.; Daylan, Tansu; Portillo, Stephen K. N. +1 more
Cataloging is challenging in crowded fields because sources are extremely covariant with their neighbors and blending makes even the number of sources ambiguous. We present the first optical probabilistic catalog, cataloging a crowded (∼0.1 sources per pixel brighter than 22nd mag in F606W) Sloan Digital Sky Survey r-band image from M2. Probabilis…