Search Publications
RR Lyrae Stars in Stellar Streams with Gaia: The Escapers
Grebel, Eva K.; Simunovic, Mirko; Abbas, Mohamad
We attempt to identify RR Lyrae (RRL) stars in stellar streams that might have escaped from seven globular clusters (GCs) based on proper motions, distances, color-magnitude diagrams, and other properties extracted from the Gaia Early Data Release 3 (EDR3) database. Specifically, we cross-match two large RRL stars catalogs (from Gaia DR2 and Catal…
Properties of Plasmoids Observed in Saturn's Dayside and Nightside Magnetodisc
Coates, A. J.; Wei, Y.; Ye, S. -Y. +7 more
Plasmoid is a key structure for transferring magnetic flux and plasma in planetary magnetospheres. At Earth, plasmoids are key media which transfer energy and mass in the "Dungey Cycle." For giant planets, plasmoids are primarily generated by the dynamic processes associated with "Vasyliunas cycle." It is generally believed that planetary magnetot…
Variations of Peak He/H Ratios in Solar Energetic (E > 4 MeV) Particle Events and Comparisons with Solar Wind He/H Ratios
Brown, D.; Kahler, S. W.
We determine solar energetic particle (SEP) event He/H peak intensity ratios AHe observed in the four energy channels of the SOHO EPHIN detector covering 4-53 MeV nuc-1. Those SEP AHe values range over two orders of magnitude for 43 large western hemisphere SEP events through the period 1997-2017. AHe of…
Fe XII and Fe XIII Line Widths in the Polar Off-limb Solar Corona up to 1.5 R⊙
Landi, Enrico; Zhu, Yingjie; Szente, Judit
The nonthermal broadening of spectral lines formed in the solar corona is often used to seek evidence of Alfvén waves propagating in the corona. To have a better understanding of the variation of line widths at different altitudes, we measured the line widths of the strong Fe XII 192.4, 193.5, and 195.1 Å and Fe XIII 202.0 Å in an off-limb souther…
Bright single-mode RR Lyrae stars: Matching Gaia EDR3 with pulsation and evolutionary models
Kovacs, Geza; Karamiqucham, Behrooz
We combine observed metallicity, optical, and infrared magnitudes with evolutionary and pulsation models to derive average luminosities for 156 single-mode RR Lyrae stars. These luminosities are compared with those obtained from the Gaia EDR3 parallaxes and are found to be in excellent agreement with the high accuracy subsample (62 stars, with rel…
On the derivation of thermospheric temperatures from dayglow emissions on Mars
González-Galindo, Francisco; López-Valverde, Miguel Ángel; Forget, François +2 more
The Cameron bands and the UV doublet are two of the most prominent emission systems in the UV in Mars dayside. Their altitude variation has been exploited in the past to derive thermospheric temperatures from measurements obtained by the Mariner 6, 7, and 9 missions, the SPICAM instrument on board Mars Express, and the IUVS instrument on board MAV…
The Field of Shock-Generated Alfven Oscillations Near the Plasmapause
Zong, Q. -G.; Leonovich, A. S.; Kozlov, D. A. +1 more
A theoretical interpretation is given for magnetohydrodynamic (MHD) oscillations observed by the GOES and Cluster satellites on November 7, 2004 near the plasmapause (Zong et al., 2009, 2012, https://doi.org/10.1029/2009ja014393, https://doi.org/10.10…
Shape, colour, and distance in weak gravitational flexion
Goldberg, David M.; Fabritius, Joseph M., II; Arena, Evan J.
Canonically, elliptical galaxies might be expected to have a perfect rotational symmetry, making them ideal targets for flexion studies - however, this assumption has not been tested. We have undertaken an analysis of low- and high-redshift galaxy catalogues of known morphological type with a new gravitational lensing code, Lenser. Using colour me…
New constraints on the chemical composition and outgassing of 67P/Churyumov-Gerasimenko
Thomas, N.; Rubin, M.; Mousis, O. +4 more
Strong heterogeneities in the composition of the volatile species have been detected in the coma of comet 67P/Churyumov-Gerasimenko (67P/C-G) by the ROSINA instrument onboard the ESA's Rosetta spacecraft. However, it is not clear if these heterogeneities are indicative of heterogeneities in the near-surface nucleus composition or if the coma compo…
Compact planetary nebulae MaC 2-1 and Sp 4-1: photoionization models and dust characteristics
Mondal, Soumen; Das, Ramkrishna; Bandyopadhyay, Rahul
We study the characteristics of the planetary nebulae (PNe) MaC 2-1 and Sp 4-1. We use our optical spectra taken with the 2 m Himalayan Chandra Telescope, Spitzer mid-infrared (mid-IR) spectra, HST images, and IR photometric data. These PNe have not previously been individually studied in detail. Both are in the low- to moderate-excitation class. …