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The Key Role of Cold Ionospheric Ions As a Source of Hot Magnetospheric Plasma and As a Driver of the Dynamics of Substorms and Storms
Glocer, A.; Moore, T. E.; Giles, B. L. +3 more
The solar wind has been seen as the major source of hot magnetospheric plasma since the early 1960's. More recent theoretical and observational studies have shown that the cold (few eV) polar wind and warmer polar cusp plasma that flow continuously upward from the ionosphere can be a very significant source of ions in the magnetosphere and can bec…
Making an Onboard Reference Map From MRO/CTX Imagery for Mars 2020 Lander Vision System
Johnson, Andrew; Cheng, Yang; Ansar, Adnan
The Mars 2020 rover, Perseverance, landed in Jezero crater (18.4663°N, 77.4298°E) on February 18, 2021 to collect samples from Mars that could be returned to Earth by a future Mars Sample Return campaign. While providing a rich sampling opportunity, Jezero also contains numerous landing hazards including scarps, canyons, mesas, dune fields, rock f…
A differential RR Lyrae line-of-sight distance between M31 and M33
Sarajedini, Ata
We present a purely differential line-of-sight distance between M31 and M33 using ab-type RR Lyrae variables observed in each galaxy by the Hubble Space Telescope Advanced Camera for Surveys in the F606W filter. Using 1481 RR Lyraes in 13 M31 fields and 181 RR Lyraes in 6 M33 fields, and placing all of these stars on a uniform photometric scale wi…
High-α-Metal-Rich stars in the LAMOST-MRS survey and its connection with the galactic bulge
Zhao, Gang; Zhao, Jing-Kun; Wang, Rui +6 more
We report the detection of a large sample of high-α-metal-rich stars on the low giant branch with 2.6 < log g < 3.3 dex in the LAMOST-MRS survey. This special group corresponds to an intermediate-age population of 5 - 9 Gyr based on the [Fe/H]-[C/N] diagram and age-[C/N] calibration. A comparison group is selected to have a solar α ratio at …
Change-point Detection and Image Segmentation for Time Series of Astrophysical Images
Zezas, Andreas; Xu, Cong; Kashyap, Vinay L. +2 more
Many astrophysical phenomena are time-varying, in the sense that their intensity, energy spectrum, and/or the spatial distribution of the emission suddenly change. This paper develops a method for modeling a time series of images. Under the assumption that the arrival times of the photons follow a Poisson process, the data are binned into 4D grids…
FUV and NIR size of the HI selected low surface brightness galaxies
Cheng, Cheng; Li, Zi-Jian; Huang, Jia-Sheng +10 more
How low surface brightness galaxies (LSBGs) form stars and assemble stellar mass is one of the most important questions related to understanding the LSBG population. We select a sample of 381 HI bright LSBGs with both far ultraviolet (FUV) and near infrared (NIR) observations to investigate the star formation rate (SFR) and stellar mass scales, an…
A survey of IRAS young stellar object candidates. Searching for large-scale Herbig-Haro objects
Estalella, Robert; Riera, Angels; López, Rosario +1 more
Context. Jets and outflows are associated with young stellar objects across the stellar mass spectrum, from brown dwarf protostars to massive Ae/Be stars. Frequently the jet morphology is spatially discontinuous because of the temporal variability of the ejection from the driving source. Images covering a wide field of view around the jet-driving …
Anomalous Hydrogen Recombination Line Ratios in Ultraluminous Infrared Galaxies
Nakagawa, Takao; Baba, Shunsuke; Isobe, Naoki +5 more
We conducted systematic observations of the H I Brα (4.05 µm) and Brβ (2.63 µm) lines in 52 nearby (z < 0.3) ultraluminous infrared galaxies (ULIRGs) with AKARI. Among 33 ULIRGs wherein the lines are detected, 3 galaxies show anomalous Brβ/Brα line ratios (~1.0), which are significantly higher than those for case B (0.565). Our obse…
Significant H I and Metal Differences around the z = 0.83 Lens Galaxy toward the Doubly Lensed Quasar SBS 0909+532
Kulkarni, Varsha P.; Lopez, Sebastian; Cashman, Frances H.
We report a large difference in neutral hydrogen (H I) and metal column densities between the two sight lines probing opposite sides of the lensing galaxy at zlens = 0.83 toward the doubly lensed quasar SBS 0909+532. Using archival HST-STIS and Keck HIRES spectra of the lensed quasar images, we measure log NH I = 18.77 ± 0.12…
Spatial distribution of the aromatic and aliphatic carbonaceous nanograin features in the protoplanetary disk around HD 100546
Pantin, E.; Ysard, N.; Habart, E. +4 more
Context. Carbonaceous nanograins are present at the surface of protoplanetary disks around Herbig Ae/Be stars, where most of the ultraviolet energy from the central star is dissipated. Efficiently coupled to the gas, they are unavoidable to understand the physics and chemistry of these disks. Furthermore, nanograins are able to trace the outer fla…