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Deriving physical parameters of unresolved star clusters. VI. Adaptive aperture photometry of the M31 PHAT star clusters
Stonkutė, Rima; Vansevičius, Vladas; Naujalis, Rokas
Context. This study is the sixth of a series that investigates degeneracy and stochasticity problems present in the determination of the age, mass, extinction, and metallicity of partially resolved or unresolved star clusters in external galaxies when using Hubble Space Telescope broadband photometry. In the fifth publication, it was noticed that …
The Effects of Magnetic Boundary on the Uniform Distribution of Energetic Particle Intensities Observed by Multiple Spacecraft
Wang, Yang; Lyu, Dan; Xiao, Boxi +1 more
In the decay phase of solar energetic particle (SEP) events, particle intensities observed by widely separated spacecraft usually present comparable intensities (within a factor of 2-3) that evolve similarly in time. The phenomenon of SEP events is called a reservoir, which could be observed frequently in intensive gradual SEP events. In this work…
A study of the long-term activity of five intermediate polars with accretion discs
Šimon, Vojtěch
Intermediate polars (IPs) are cataclysmic variables with mildly magnetized white dwarfs (WDs). This analysis of the long-term optical activity of five examples of IPs with accretion discs used data from the Catalina Real-time Transient Survey, Digital Access to a Sky Century @ Harvard (DASCH) and the American Association of Variable Star Observers…
Analysis of Time-Distance Helioseismology for Detection of Emerging Active Regions
Kosovichev, Alexander G.; Stefan, John T.; Stejko, Andrey M.
A time-distance helioseismic technique, similar to the one used by Ilonidis et al., is applied to two independent numerical models of subsurface sound-speed perturbations to determine the spatial resolution and accuracy of phase travel time shift measurements. The technique is also used to examine pre-emergence signatures of several active regions…
Venus night-side photometry with "cleaned" Akatsuki/IR2 data: Aerosol properties and variations of carbon monoxide
Sato, Takao M.; Satoh, Takehiko; Horinouchi, Takeshi +2 more
We have developed a novel method called Restoration by Simple Subtraction (RSS) to clean and restore the Venus night-side disk in "contaminated" Akatsuki/IR2 images at 2.26 and 1.735 µm. Light spread from the intense day crescent is cancelled by subtracting a near-simultaneous 2.32-µm image (scaled) from a 2.26-µm image. Net-cont…
Three New Late-type Stellar Companions to Very Dusty WISE Debris Disks Identified with SPHERE Imaging
Mamajek, Eric; Hinkley, Sasha; Crossfield, Ian J. M. +8 more
Debris disk stars are good targets for high-contrast imaging searches for planetary systems, since debris disks have been shown to have a tentative correlation with giant planets. We selected 20 stars identified as debris disk hosts by the WISE mission, with particularly high levels of warm dust. We observed these with the VLT/SPHERE high-contrast…
In-depth investigation of the physical origin of the soft X-ray excess in PG 1448+273
Gu, Qiusheng; Guo, Xiaotong; Ding, Nan +6 more
We present systematic X-ray spectral and variability analyses for the narrow-line Seyfert 1 galaxy (NLsy1), PG 1448+273, using the data from two long-exposure XMM-Newton observations of the source in the different flux states. These X-ray spectral analyses indicate that the two main-stream models of soft X-ray excess, the relativistically smeared …
OGLE-2007-BLG-224L: A Direct Test of Terrestrial Parallax
Yee, Jennifer C.; Bailey, Vanessa P.; Shan, Yutong +4 more
We present limits on the lens flux of OGLE-2007-BLG-224 based on MagAO imaging taken seven years after the microlensing event. At the time of the observations, the lens should have been separated from the microlensing source by 292 mas. However, no new sources are detected with MagAO. We place an upper limit on the lens flux of H > 20.57. This …
The Flux of Flux Ropes Embedded Within Magnetic Clouds Near 5 AU
Zhao, Yan; Feng, Hengqiang; Zhao, Guoqing +3 more
Magnetic clouds (MCs) are an important kind of interplanetary coronal mass ejections and generally treated as giant flux ropes. Previous researches indicates that the rope structure of MCs may be destructed as they move away from the solar surface. In this paper, we made a statistic study of the azimuthal flux of flux ropes embedded within MCs nea…
No Evidence for Time Variation in Saturn's Internal Magnetic Field
Cao, Hao; Bloxham, Jeremy; Moore, Kimberly M. +2 more
The time variation of a planetary magnetic field can reveal important aspects of a planet's interior structure. Searching for time variation in planetary magnetic fields other than Earth has proved challenging owing to the small number of spacecraft missions flown to date, but such a detection may be possible given a sufficiently long baseline for…