Search Publications
Tracking the Source of Solar Type II Bursts through Comparisons of Simulations and Radio Data
Kasper, Justin C.; Hegedus, Alexander M.; Manchester, Ward B.
The most intense solar energetic particle events are produced by coronal mass ejections (CMEs) accompanied by intense type II radio bursts below 15 MHz. Understanding where these type II bursts are generated relative to an erupting CME would reveal important details of particle acceleration near the Sun, but the emission cannot be imaged on Earth …
Possible Detection of X-Ray Emitting Circumstellar Material in the Synchrotron-dominated Supernova Remnant RX J1713.7-3946
Acero, Fabio; Katsuda, Satoru; Terada, Yukikatsu +4 more
We report on a discovery of an X-ray emitting circumstellar material (CSM) knot inside the synchrotron dominant supernova remnant RX J1713.7-3946. This knot was previously thought to be a Wolf-Rayet star (WR 85), but we realized that it is in fact ~40″ away from WR 85, indicating no relation to WR 85. We performed high-resolution X-ray spectroscop…
The relationship between bipolar magnetic regions and their sunspots
Solanki, S. K.; Yeo, K. L.; Krivova, N. A. +1 more
Context. The relationship between bipolar magnetic regions (BMRs) and their sunspots is an important property of the solar magnetic field, but it is not well constrained. One consequence is that it is a challenge for surface flux transport models (SFTMs) based on sunspot observations to determine the details of BMR emergence, which they require as…
AX UMa, an ab-type RR Lyrae Star with a Rapidly Decreasing Pulsation Period, and Its Binarity
Qian, S. -B.; He, J. -J.; Zhu, L. -Y. +2 more
The pulsation periods of RR Lyrae stars usually vary with time, and they are often used as probes to study the mechanism behind the variation. After the early discovery that the pulsation period of the RR Lyrae star AX UMa decreased rapidly, in further research, we made multiband photometric observations of this star using the Sino-Thai 70 cm tele…
Disentangling the Physical Origin of Emission Line Ratio Offsets at High Redshift with Spatially Resolved Spectroscopy
Cooper, M. C.; Martin, Crystal L.; Treu, Tommaso +6 more
We present spatially resolved Hubble Space Telescope grism spectroscopy of 15 galaxies at z ~ 0.8 drawn from the DEEP2 survey. We analyze Hα+[N II], [S II], and [S III] emission on kiloparsec scales to explore which mechanisms are powering emission lines at high redshifts, testing which processes may be responsible for the well-known offset of hig…
The wide upper main sequence and main-sequence turnoff of the ∼ 800 Myr old star cluster NGC 1831
Bellini, Andrea; Goudfrooij, Paul; Correnti, Matteo +1 more
We present the analysis of the colour-magnitude diagram (CMD) morphology of the ~800 Myr old star cluster NGC 1831 in the Large Magellanic Cloud, exploiting deep, high-resolution photometry obtained using the Wide Field Camera 3 onboard the Hubble Space Telescope. We perform a simultaneous analysis of the wide upper main sequence and main-sequence…
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 …