Search Publications
X-ray pulsar HD 49798: a contracting white dwarf with a debris disk?
Chen, Wen-Cong
HD 49798/RX J0648.0C4418 is a peculiar binary including a hot subdwarf of O spectral type and a compact companion in a 1.55 day orbit. Based on the steady spin period derivative Ṗ = (−2.17 ± 0.01) × 10−15 s s−1 , the compact object was thought to be a contracting young white dwarf (WD). However, the X-ray luminosity produced …
Solar Minimum Exospheric Neutral Density Near the Subsolar Magnetopause Estimated From the XMM Soft X-Ray Observations on 12 November 2008
Pagani, C.; Kuntz, K. D.; Koutroumpa, D. +3 more
The Earth's magnetosheath and cusps emit soft X-rays due to the charge exchange between highly charged solar wind ions and exospheric hydrogen atoms. The Lunar Environment Heliospheric X-ray Imager and Solar wind Magnetosphere Ionosphere Link Explorer missions are scheduled to image the Earth's dayside magnetosphere system in soft X-rays to invest…
Search for an Alien Message to a Nearby Star
Wright, Jason T.; Gillon, Michaël; Burdanov, Artem
If alien probes have colonized the whole galaxy, they could have formed an efficient galactic-scale communication network by establishing direct gravitationally lensed links between neighboring systems. Under this scenario, observing the positions opposite the nearest ecliptic stars represents a promising artifact SETI strategy that could make it …
Open clusters with proper motions fully separatedfrom the field stars using Gaia DR2
Tadross, A. L.; Badawy, W. A.; Hendy, Y. H. M. +3 more
The study of open star clusters makes us understand a lot about the composition and construction of the Milky Way Galaxy. Thanks to the Gaia DR2 database that helps us to get the genetic members of star clusters using their proper motions and parallaxes, estimating their physical properties in a very accurate way. This study aims to detect the rea…
On the validity of the spectroscopic age indicators [Y/Mg], [Y/Al], [Y/Si], [Y/Ca], and [Y/Ti] for giant stars
Abuchaim, Yuri; Kerber, Leandro; Katime Santrich, Orlando J. +1 more
The abundance ratios [Y/Mg], [Y/Al], [Y/Si], [Y/Ca], and [Y/Ti] have been suggested as chemical clocks for solar-metallicity dwarf stars in the field as well as for giant stars in open clusters. To verify this last hypothesis, we derive these abundances ratios of 50 giant stars belonging to seven open clusters. To calculate the abundances, we anal…
Companion mass limits for 17 binary systems obtained with binary differential imaging and MagAO/Clio
Weinberger, Alycia J.; Close, Laird M.; Males, Jared R. +4 more
Improving direct detection capability close to the star through improved star subtraction and post-processing techniques is vital for discovering new low-mass companions and characterizing known ones at longer wavelengths. We present results of 17 binary star systems observed with the Magellan adaptive optics system (MagAO) and the Clio infrared c…
The CGM-GRB Study. II. Outflow-Galaxy Connection at z 2-6
Cenko, S. Bradley; Veilleux, Sylvain; Perley, Daniel +4 more
We use a sample of 27 gamma-ray bursts (GRBs) at redshift z = 2-6 to probe the outflows in their respective host galaxies (log(M */M ⊙) ~ 9-11) and search for possible relations between the outflow properties and those of the host galaxies, such as M *, the star formation rate (SFR), and the specific SFR (sSFR). Fi…
A New Period Determination Method for Periodic Variable Stars
Li, Bin; Li, Xu-Zhi; Zhu, Qing-Feng +4 more
Variable stars play a key role in understanding the Milky Way and the universe. The era of astronomical big data presents new challenges for quick identification of interesting and important variable stars. Accurately estimating the periods is the most important step to distinguish different types of variable stars. Here, we propose a new method o…
Active region and flare ribbon properties associated with X-class flares and CMEs of solar cycle 24
Moon, Y. -J.; Shanmugaraju, A.; Lim, Daye +4 more
The solar eruptive events and their origin are important in the context of forecasting their occurrence and their effects on the space and the earth. In this paper, a set of 45 X-class flare-associated coronal mass ejections (CMEs) and their source region characteristics are analysed. The X-ray flares and white light CMEs were observed by GOES and…
A multiwavelength study of the flat-spectrum radio quasar NVSS J141922-083830 covering four flaring episodes
Stalin, C. S.; Kniazev, A.; Buckley, D. A. H. +9 more
We present multiwavelength observations and a model for flat-spectrum radio quasar (FSRQ) NVSS J141922-083830, originally classified as a blazar candidate of unknown type (BCU II object) in the Third Fermi-LAT AGN Catalog. Relatively bright flares (>3 magnitudes) were observed on 2015 February 21 (MJD 57074) and 2018 September 8 (MJD 58369) in …