Search Publications
Measuring Velocities in the Early Stage of an Eruption: Using “Overlappogram” Data from Hinode EIS
Warren, Harry; Harra, Louise K.; Doschek, George A. +4 more
In order to understand the onset phase of a solar eruption, plasma parameter measurements in the early phases are key to constraining models. There are two current instrument types that allow us to make such measurements: narrow-band imagers and spectrometers. In the former case, even narrow-band filters contain multiple emission lines, creating s…
Discovery of Periodic Dips in the Brightest Hard X-Ray Source of M31 with EXTraS
Tiengo, Andrea; Haberl, Frank; Belfiore, Andrea +9 more
We performed a search for eclipsing and dipping sources in the archive of the EXTraS project—a systematic characterization of the temporal behavior of XMM-Newton point sources. We discovered dips in the X-ray light curve of 3XMM J004232.1+411314, which has been recently associated with the hard X-ray source dominating the emission of M31. A system…
Flare Ribbons Approach Observed by the Interface Region Imaging Spectrograph and the Solar Dynamics Observatory
Hou, Yijun; Li, Ting; Zhang, Jun
We report flare ribbons approach (FRA) during a multiple-ribbon M-class flare on 2015 November 4 in NOAA AR 12443, obtained by the Interface Region Imaging Spectrograph and the Solar Dynamics Observatory. The flare consisted of a pair of main ribbons and two pairs of secondary ribbons. The two pairs of secondary ribbons were formed later than the …
Removing Visual Bias in Filament Identification: A New Goodness-of-fit Measure
Green, C. -E.; Dawson, J. R.; Cunningham, M. R. +3 more
Different combinations of input parameters to filament identification algorithms, such as disperse and filfinder, produce numerous different output skeletons. The skeletons are a one-pixel-wide representation of the filamentary structure in the original input image. However, these output skeletons may not necessarily be a good representation of th…
M32 Analogs? A Population of Massive Ultra-compact Dwarf and Compact Elliptical Galaxies in Intermediate-redshift Clusters
Bell, Eric F.; Zhang, Yuanyuan
We report the discovery of relatively massive, M32-like ultra compact dwarf (UCD) and compact elliptical (CE) galaxy candidates in 0.2< z< 0.6 massive galaxy clusters imaged by the Cluster Lensing And Supernova survey with Hubble (CLASH) survey. Examining the nearly unresolved objects in the survey, we identify a sample of compact objects co…
Chandra Detection of Intracluster X-Ray sources in Virgo
Liu, Chengze; Peng, Eric W.; Li, Zhiyuan +1 more
We present a survey of X-ray point sources in the nearest and dynamically young galaxy cluster, Virgo, using archival Chandra observations that sample the vicinity of 80 early-type member galaxies. The X-ray source populations at the outskirts of these galaxies are of particular interest. We detect a total of 1046 point sources (excluding galactic…
ALMA Observations of SMM11 Reveal an Extremely Young Protostar in Serpens Main Cluster
Ohashi, Nagayoshi; Tomisaka, Kohji; Yen, Hsi-Wei +8 more
We report the discovery of an extremely young protostar, SMM11, located in the associated submillimeter condensation in the Serpens Main cluster using the Atacama Large Millimeter/submillimeter Array (ALMA) during its Cycle 3 at 1.3 mm and an angular resolution of ∼ 0\buildrel{\prime\prime}\over{.} 5∼ 210 {AU}. SMM11 is a Class 0 protostar without…
Probing Subsurface Flows in NOAA Active Region 12192: Comparison with NOAA 10486
Hill, F.; Tripathy, S. C.; Jain, Kiran
NOAA Active Region (AR) 12192 is the biggest AR observed in solar cycle 24 so far. This was a long-lived AR that survived for four Carrington rotations (CRs) and exhibited several unusual phenomena. We measure the horizontal subsurface flows in this AR in multiple rotations using the ring-diagram technique of local helioseismology and the Global O…
A Spitzer Spectral Atlas of Low-mass Active Galactic Nuclei
Ho, Luis C.; Barth, Aaron J.; Greene, Jenny E. +1 more
We present Spitzer low-resolution Infrared Spectrograph (IRS) spectra (5 µm ≲ λ ≲ 40 µm) of a sample of 41 Type 1 and Type 2 active galactic nuclei (AGNs) with estimated black hole masses of {M}{BH} ≲ {10}6 {M}⊙ , in order to probe the validity of unification models in this mass regime. We find that the…
Testing the Universality of the Stellar IMF with Chandra and HST
Lehmer, B. D.; Hornschemeier, A. E.; Maccarone, T. +8 more
The stellar initial mass function (IMF), which is often assumed to be universal across unresolved stellar populations, has recently been suggested to be “bottom-heavy” for massive ellipticals. In these galaxies, the prevalence of gravity-sensitive absorption lines (e.g., Na I and Ca II) in their near-IR spectra implies an excess of low-mass (m≲ 0.…