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Chemical abundance analysis of red giant branch stars in the globular cluster E3
Monaco, L.; Mucciarelli, A.; Villanova, S. +2 more
Context. Globular clusters are known to host multiple stellar populations, which are a signature of their formation process. The globular cluster E3 is one of the few low-mass globulars that is thought not to host multiple populations.
Aims: We investigate red giant branch stars in E3 with the aim of providing a first detailed chemical invent…
Biermann-Battery-Mediated Magnetic Reconnection in 3D Colliding Plasmas
Fox, W.; Bhattacharjee, A.; Germaschewski, K. +5 more
Recent experiments have demonstrated magnetic reconnection between colliding plasma plumes, where the reconnecting magnetic fields were self-generated in the plasma by the Biermann-battery effect. Using fully kinetic 3D simulations, we show the full evolution of the magnetic fields and plasma in these experiments, including self-consistent magneti…
Dependence of Coronal Loop Temperature on Loop Length and Magnetic Field Strength
Velli, M.; Ugarte-Urra, I.; Dahlburg, R. B. +2 more
The temperature characteristics of solar coronal loops over a wide range of lengths and magnetic field strengths are investigated by means of numerical simulations. A very high correlation between magnetic field strength (B 0) and maximum temperature (T max) is found. Shorter loops rooted at stronger fields are those that rea…
Kinematics of the Horsehead Nebula and IC 434 Ionization Front in CO and C+
Bally, John; Stanke, Thomas; Zinnecker, Hans +5 more
Stratospheric Observatory for Infrared Astronomy [C II] 157 µm, APEX 860 µm J = 3-2 CO, and archival James Clerk Maxwell Telescope J = 2-1 CO and 13CO observations of the Horsehead Nebula are presented. The photon-dominated region (PDR) between the Orion B molecular cloud and the adjacent IC 434 H II region is used to study …
Ensemble Properties of the White Dwarf Population of the Old, Solar Metallicity Open Star Cluster Messier 67
Kilic, Mukremin; Bellini, A.; Bolte, Michael +4 more
White dwarfs (WDs) are excellent forensic tools for studying end-of-life issues surrounding low- and intermediate-mass stars, and the old, solar metallicity open star cluster Messier 67 is a proven laboratory for the study of stellar evolution for solar-type stars. In this paper, we present a detailed spectroscopic study of brighter (M g
Search for thermal X-ray features from the Crab nebula with the Hitomi soft X-ray spectrometer
Done, Chris; Safi-Harb, Samar; Hamaguchi, Kenji +192 more
The Crab nebula originated from a core-collapse supernova (SN) explosion observed in 1054 AD. When viewed as a supernova remnant (SNR), it has an anomalously low observed ejecta mass and kinetic energy for an Fe-core-collapse SN. Intensive searches have been made for a massive shell that solves this discrepancy, but none has been detected. An alte…
Hitomi X-ray studies of giant radio pulses from the Crab pulsar
Done, Chris; Safi-Harb, Samar; Hamaguchi, Kenji +201 more
To search for giant X-ray pulses correlated with the giant radio pulses (GRPs) from the Crab pulsar, we performed a simultaneous observation of the Crab pulsar with the X-ray satellite Hitomi in the 2-300 keV band and the Kashima NICT radio telescope in the 1.4-1.7 GHz band with a net exposure of about 2 ks on 2016 March 25, just before the loss o…
Measuring Model-independent Masses and Radii of Single-lined Eclipsing Binaries: Analytic Precision Estimates
Stassun, Keivan G.; Stevens, Daniel J.; Gaudi, B. Scott
We derive analytic estimates for the ability with which one can obtain precise, empirical stellar masses and radii via single-lined eclipsing binaries (EBs) in the era of Gaia and TESS. Including stars that host transiting substellar companions, such single-lined EBs already number in the hundreds from ground-based transit surveys and will compris…
Energy conversion in cometary atmospheres. Hybrid modeling of 67P/Churyumov-Gerasimenko
Kallio, E.; Gunell, H.; Nilsson, H. +6 more
Aims: We wish to investigate the energy conversion between particles and electromagnetic fields and determine the location where it occurs in the plasma environment of comets.
Methods: We used a hybrid plasma model that included photoionization, and we considered two cases of the solar extreme ultraviolet flux. Other parameters correspon…
Yet another UFO in the X-ray spectrum of a high-z lensed QSO
Cappi, M.; Ponti, G.; Vignali, C. +6 more
Aim. Ultra-fast outflows (UFO) appear to be common in local active galactic nuclei (AGN) and may be powerful enough (Ėkin ≥ 1% of Lbol) to effectively quench the star formation in their host galaxies. To test feedback models based on AGN outflows, it is mandatory to investigate UFOs near the peak of AGN activity, that is, at …