Search Publications
RR Lyrae stars as seen by the Kepler space telescope
Szabó, Róbert; Plachy, Emese
The unprecedented photometric precision along with the quasi-continuous sampling provided by the Kepler space telescope revealed new and unpredicted phenomena that reformed and invigorated RR Lyrae star research. The discovery of period doubling and the wealth of low- amplitude modes enlightened the complexity of the pulsation behavior and guided …
Broad-line region configuration of the supermassive binary black hole candidate PG1302-102 in the relativistic Doppler boosting scenario
Lu, Youjun; Ge, Junqiang; Ji, Xiang +2 more
PG1302-102 is thought to be a supermassive binary black hole (BBH) system according to the periodical variations of its optical and UV photometry, which may be interpreted as being due to the relativistic Doppler boosting of the emission mainly from the disk around the secondary black hole (BH) modulated by its orbital motion. In this paper, we in…
Class imbalance problem in short-term solar flare prediction
Wan, Jie; Fu, Jun-Feng; Liu, Jin-Fu +3 more
Using data-driven algorithms to accurately forecast solar flares requires reliable data sets. The solar flare dataset is composed of many non-flaring samples with a small percentage of flaring samples. This is called the class imbalance problem in data mining tasks. The prediction model is sensitive to most classes of the original data set during …
Tangent Directions of the Cusp Boundary Derived From the Simulated Soft X Ray Image
Wang, Chi; Sun, Tianran; Wang, Xue
The magnetospheric cusp plays an essential role in mass and energy transportation from the solar wind to the geo space environment. Recent development of the X ray imaging technique makes it possible to study the large scale properties of the cusp region from a global view. As the detected X ray signals will be integrated along the line of sight (…
Magnetic field and activity phenomena of the K2 dwarf V471 Tau
Donati, J. -F.; Klein, B.; Zaire, B.
We analyse spectropolarimetric data of the pre-cataclysmic variable binary system V471 Tau obtained with ESPaDOnS at the Canada-France-Hawaii Telescope in two observational campaigns (in 2004 November/December and 2005 December). Using Zeeman-Doppler imaging, we reconstruct the distribution of brightness map and large-scale magnetic field of the K…
Microlensing predictions: impact of Galactic disc dynamical models
Zang, Weicheng; Mao, Shude; Zhang, Xiangyu +1 more
Galactic model plays an important role in the microlensing field, not only for analyses of individual events but also for statistics of the ensemble of events. However, the Galactic models used in the field vary, and some are unrealistically simplified. Here, we tested three Galactic disc dynamic models; the first is a simple standard model that w…
Globules and pillars in Cygnus X. III. Herschel and upGREAT/SOFIA far-infrared spectroscopy of the globule IRAS 20319+3958 in Cygnus X
Comerón, F.; Schneider, N.; Bontemps, S. +11 more
IRAS 20319+3958 in Cygnus X South is a rare example of a free-floating globule (mass ~240 M⊙, length ~1.5 pc) with an internal H II region created by the stellar feedback of embedded intermediate-mass stars, in particular, one Herbig Be star. In Schneider et al. 2012, (A&A, 542, L18) and Djupvik et al. 2017, (A&A, 599, A37), we …
Mapping the tilt of the Milky Way bulge velocity ellipsoids with ARGOS and Gaia DR2
Lewis, Geraint F.; Bland-Hawthorn, Joss; Koposov, Sergey E. +4 more
Until the recent advent of Gaia Data Release 2 (DR2) and deep multi-object spectroscopy, it has been difficult to obtain 6D phase space information for large numbers of stars beyond 4 kpc, in particular towards the Galactic Centre, where dust and crowding are significant. We combine line-of-sight velocities from the Abundances and Radial velocity …
Evolved massive stars at low-metallicity. IV. Using the 1.6 µm H-bump to identify red supergiant stars: Case study of NGC 6822
Yang, Ming; Bonanos, Alceste Z.; Gao, Jian +9 more
We present a case study in which we used a novel method to identify red supergiant (RSG) candidates in NGC 6822 based on their 1.6 µm H-bump. We collected 32 bands of photometric data for NGC 6822 ranging from the optical to the mid-infrared, derived from Gaia, PS1, LGGS, VHS, UKIRT, IRSF, HAWK-I, Spitzer, and WISE. Using the theoretical spe…
Topographic correction of HiRISE and CaSSIS images: Validation and application to color observations of Martian albedo features
Pajola, M.; Cremonese, G.; Thomas, N. +5 more
The topographic correction of satellite images has to be applied to both disentangle albedo features from illumination effects induced by local topography and perform spectrophotometric analyses of planetary surfaces. This work focuses on the modeling and removal of surface brightness variations induced by topography, referred as topographic shadi…