Search Publications
Limits to Ionization-parameter Mapping as a Diagnostic of HII Region Optical Depth
Oey, M. S.; Sawant, Amit N.; Micheva, Genoveva +2 more
We employ ionization-parameter mapping (IPM) to infer the optical depth of H II regions in the northern half of M33. We construct [O III]λ5007/[O II]λ3727 and [O III]λ5007/[S II]λ6724 ratio maps from narrowband images continuum-subtracted in this way, from which we classify the H II regions by optical depth to ionizing radiation, based on their io…
GTC/CanariCam Deep Mid-infrared Imaging Survey of Northern Stars within 5 pc
Rebolo, Rafael; Caballero, José A.; Pinfield, David J. +7 more
In this work we present the results of a direct imaging survey for brown dwarf companions around the nearest stars at the mid-infrared 10 micron range (λ c = 8.7 µm, Δλ = 1.1 µm) using the CanariCam instrument on the 10.4 m Gran Telescopio Canarias (GTC). We imaged the 25 nearest stellar systems within 5 pc of the Sun at d…
Blueshifted Hydrogen Emission and Shock Wave of RR Lyrae Variables in SDSS and LAMOST
Deng, Licai; Liu, Chao; Zhang, Huawei +4 more
Hydrogen emissions of RR Lyrae variables are the imprints of shock waves traveling through their atmospheres. We develop a pattern recognition algorithm, which is then applied to single-epoch spectra of the Sloan Digital Sky Survey and the Large Sky Area Multi-Object Fiber Spectroscopic Telescope survey. These two spectroscopic surveys covered ~10…
Multi-scale Radio and X-Ray Structure of the High-redshift Quasar PMN J0909+0354
Paragi, Zsolt; Frey, Sándor; Perger, Krisztina +3 more
The high-redshift quasar PMN J0909+0354 (z = 3.288) is known to have a parsec-scale compact jet structure, based on global 5 GHz very long baseline interferometry (VLBI) observations performed in 1992. Its kiloparsec-scale structure was studied with the Karl G. Jansky Very Large Array (VLA) in the radio and the Chandra space telescope in X-rays. A…
Swift/XRT Deep Galactic Plane Survey Discovery of a New Intermediate Polar Cataclysmic Variable, Swift J183920.1-045350
Göğüş, Ersin; Buckley, David; Kouveliotou, Chryssa +20 more
We report on the Swift/XRT Deep Galactic Plane Survey discovery and multiwavelength follow-up observations of a new intermediate polar (IP) cataclysmic variable, Swift J183920.1-045350. A 449.7 s spin period is found in XMM-Newton and NuSTAR data, accompanied by a 459.9 s optical period that is most likely the synodic, or beat period, produced fro…
Nearly 30,000 Late-type Main-sequence Stars with Stellar Age from LAMOST DR5
Zhao, Gang; Zhao, Jingkun; Ye, Xianhao +3 more
We construct a sample of nearly 30,000 main-sequence stars with 4500 K < Teff < 5000 K and stellar ages estimated by the chromospheric activity-age relation. This sample is used to determine the age distribution in the R-Z plane of the Galaxy, where R is the projected Galactocentric distance in the disk midplane and Z is the heigh…
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…
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…
A Multi-wavelength Analysis of Small-scale Brightenings Observed by IRIS
Morgan, Huw; Humphries, Llŷr Dafydd
Small-scale brightenings in solar atmospheric observations are a manifestation of heating and/or energy transport events. We present statistical characteristics of brightenings from a new detection method applied to 1330, 1400, and 2796 Å IRIS slit-jaw image time series. A total of 2377 events were recorded that coexist in all three channels, givi…