Search Publications
Leaves on trees: identifying halo stars with extreme gradient boosted trees
Helmi, Amina; Veljanoski, Jovan; Breddels, Maarten +1 more
Context. Extended stellar haloes are a natural by-product of the hierarchical formation of massive galaxies like the Milky Way. If merging is a non-negligible factor in the growth of our Galaxy, evidence of such events should be encoded in its stellar halo. The reliable identification of genuine halo stars is a challenging task, however.
Aims…
Empirical Modeling of the Geomagnetosphere for SIR and CME-Driven Magnetic Storms
Tsyganenko, N. A.; Andreeva, V. A.
During geomagnetic disturbances, the solar wind arrives in the form of characteristic sequences lasting from tens of hours to days. The most important magnetic storm drivers are the coronal mass ejections (CMEs) and the slow-fast stream interaction regions (SIRs). Previous data-based magnetic field models did not distinguish between these types of…
Finding the Critical Decay Index in Solar Prominence Eruptions
Ravindra, B.; Doddamani, V. H.; Vemareddy, P. +1 more
The background field is assumed to play a prime role in erupting structures like prominences. In the flux rope models, the critical decay index (n c ) is a measure of the rate at which background field intensity decreases with height over the flux rope or erupting structure. In the real observations, the critical height of the backgrou…
Young open cluster IC 4996 and its vicinity: multicolor photometry and Gaia DR2 astrometry
Munari, U.; Straižys, V.; Raudeliūnas, S. +9 more
The open cluster IC 4996 in Cygnus and its vicinity are investigated by applying a two-dimensional photometric classification of stars measured in the Vilnius seven-color photometric system. Cluster members are identified by applying distances based on the Gaia DR2 parallaxes and the point vector diagram of the Gaia DR2 proper motions. For some B-…
OGLE-2018-BLG-0022: A Nearby M-dwarf Binary
Saha, A.; Lowry, S.; Mao, S. +32 more
We report observations of the binary microlensing event OGLE-2018-BLG-0022, provided by the Robotic Observations of Microlensing Events (ROME)/Reactive Event Assessment (REA) Survey, which indicate that the lens is a low-mass binary star consisting of M3 (0.375 ± 0.020 M ⊙) and M7 (0.098 ± 0.005 M ⊙) components. The lens is u…
ODEA: Orbital Dynamics in a complex Evolving Architecture. Application to the planetary system HD 106906
De Rosa, R. J.; Lagrange, A. -M.; Beust, H. +3 more
Context. Mixed-variable symplectic integrators are widely used in orbital dynamics. However, they have been developed for Solar system-type architectures, and can not handle evolving hierarchy, in particular in systems with two or more stellar components. Such configuration may have occurred in the history of HD 106906, a tight pair of F-type star…
Lack of close-in, massive planets of main-sequence A-type stars from Kepler
Skarka, Marek; Grziwa, Sascha; Guenther, Eike W. +5 more
Some theories of planet formation and evolution predict that intermediate-mass stars host more hot Jupiters than Sun-like stars, others reach the conclusion that such objects are very rare. By determining the frequencies of those planets we can test those theories.
Ionization age of iron ejecta in the Galactic Type Ia supernova remnant G306.3-0.9
Uchida, Hiroyuki; Bamba, Aya; Tsuru, Takeshi Go +5 more
We present a 190 ks observation of the Galactic supernova remnant (SNR) G306.3-0.9 with Suzaku. To study ejecta properties of this possible Type Ia SNR, the absolute energy-scale at the Fe-K band was calibrated to a level of uncertainty less than 10 eV by a cross-calibration with the Hitomi microcalorimeter using the Perseus cluster spectra. This …
Colorado Ultraviolet Transit Experiment data simulator
France, Kevin; Rüdisser, Hannah T.; Koskinen, Tommi +5 more
The Colorado Ultraviolet Transit Experiment (CUTE) is a 6U NASA CubeSat carrying on board a low-resolution (R ∼ 2000 to 3000), near-UV (2500 to 3300 Å) spectrograph. It has a rectangular primary Cassegrain telescope to maximize the collecting area. CUTE, which is planned for launch in spring 2020, is designed to monitor transiting extra-solar plan…
Evidence of Interacting Elongated Filaments in the Star-forming Site AFGL 5142
Dewangan, L. K.; Ojha, D. K.; Baug, T. +1 more
To probe the ongoing physical mechanism, we studied a wide-scale environment around AFGL 5142 (area ∼25 pc × 20 pc) using a multiwavelength approach. The Herschel column density (N(H2)) map reveals a massive inverted Y-like structure (mass ∼6280 M ⊙), which hosts a pair of elongated filaments (lengths >10 pc). The Herschel…