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Evidence for a Rotational Component in the Circumgalactic Medium of Nearby Galaxies
Wakker, Bart P.; French, David M.
We present results of a study comparing the relative velocity of Lyα absorbers to the rotation velocity of nearby galaxy disks in the local universe (z ≤ 0.03). We have obtained rotation curves via long-slit spectroscopy of eight galaxies with the Southern African Large Telescope, and combine this data set with an additional 16 galaxies with data …
Hierarchical star formation in nearby galaxies
Baume, G.; Rodríguez, M. J.; Feinstein, C.
Aims: The purpose of this work is to study the properties of the spatial distribution of the young population in three nearby galaxies in order to better understand the first stages of star formation.
Methods: We used ACS/HST photometry and the "path-linkage criterion" in order to obtain a catalog of young stellar groups (YSGs) in the ga…
Probing the nuclear and circumnuclear properties of NGC 6300 using X-ray observations
Naik, Sachindra; Jana, Arghajit; Chatterjee, Arka +3 more
We present the results obtained from a detailed X-ray timing and spectral analysis of the Seyfert 2 galaxy NGC 6300 by using observations from the Suzaku observatory, theChandra X-ray Observatory and the Nuclear Spectroscopic Telescope Array(NuSTAR) mission between 2007 and 2016. We calculate the variance and the rms fractional variability of the …
ASKAP reveals giant radio halos in two merging SPT galaxy clusters
Johnston-Hollitt, Melanie; Akamatsu, Hiroki; Hodgson, Torrance +4 more
Early science observations from the Australian Square Kilometre Array Pathfinder (ASKAP) have revealed clear signals of diffuse radio emission associated with two clusters detected by the South Pole Telescope via their Sunyaev Zel'dovich signal: SPT CLJ0553-3342 (MACS J0553.4-3342) and SPT CLJ0638-5358 (Abell S0592) are both high-mass lensing clus…
Chemically Peculiar A and F Stars with Enhanced s-process and Iron-peak Elements: Stellar Radiative Acceleration at Work
Ting, Yuan-Sen; Rix, Hans-Walter; Zhang, Meng +6 more
We present ≳15,000 metal-rich ([Fe/H] > -0.2 dex) A and F stars whose surface abundances deviate strongly from solar abundance ratios and cannot plausibly reflect their birth material composition. These stars are identified by their high [Ba/Fe] abundance ratios ([Ba/Fe] > 1.0 dex) in the LAMOST DR5 spectra analyzed by Xiang et al. They are …
A Catalog of Bipolar Active Regions Violating the Hale Polarity Law, 1989 - 2018
Zhukova, Anastasiya; Sokoloff, Dmitry; Abramenko, Valentina +1 more
There is no list of bipolar active regions (ARs) with reverse polarity (anti-Hale regions), although statistical investigations of such ARs (bearing the imprint of deep subphotospheric processes) are important for understanding solar-cycle mechanisms. We studied 8606 ARs from 1 January 1989 to 31 December 2018 to detect anti-Hale regions and to co…
Chandra Monitoring of the J1809-1917 Pulsar Wind Nebula and Its Field
Pavlov, George G.; Kargaltsev, Oleg; Klingler, Noel +3 more
PSR J1809-1917 is a young (τ = 51 kyr) and energetic ( $\dot{E}=1.8\times {10}^{36}$ erg s-1) radio pulsar powering an X-ray pulsar wind nebula (PWN) that exhibits morphological variability. We report on the results of a new monitoring campaign by the Chandra X-ray Observatory (Chandra), carried out across six epochs with a ∼7 week cade…
A Rapidly Varying Red Supergiant X-Ray Binary in the Galactic Center
Gottlieb, Amy M.; Ackley, Kendall; DeWitt, Curtis +2 more
We analyzed multiwavelength observations of the previously identified Galactic center X-ray binary CXO 174528.79-290942.8 (XID 6592) and determine that the near-infrared counterpart is a red supergiant based on its spectrum and luminosity. Scutum X-1 is the only previously known X-ray binary with a red supergiant donor star and closely resembles X…
The Detection of Dust Gap-ring Structure in the Outer Region of the CR Cha Protoplanetary Disk
Dong, Ruobing; Kataoka, Akimasa; Sitko, Michael +13 more
We observe the dust continuum at 225 GHz and CO isotopologue (12CO, 13CO, and C18O) J = 2-1 emission lines toward the CR Cha protoplanetary disk using the Atacama Large Millimeter/submillimeter Array. The dust continuum image shows a dust gap-ring structure in the outer region of the dust disk. A faint dust ring is…
Placing limits on long-term variations in quiet-Sun irradiance and their contribution to total solar irradiance and solar radiative forcing of climate
Lockwood, Mike; Ball, William T.
Recent reconstructions of total solar irradiance (TSI) postulate that quiet-Sun variations could give significant changes to the solar power input to Earth's climate (radiative climate forcings of 0.7-1.1 W m-2 over 1700-2019) arising from changes in quiet-Sun magnetic fields that have not, as yet, been observed. Reconstructions without…