Search Publications
Pushing Automated Abundance Derivations into the Cool Dwarf Regime: A Test Using Three G and Two K Stars in Praesepe
Hawkins, Keith; Agüeros, Marcel A.; Schuler, Simon C. +2 more
We present the results of an abundance analysis of three G and two K dwarfs in the Praesepe open cluster based on high-resolution, moderate signal-to-noise-ratio spectra obtained with the ARC 3.5 m Telescope at Apache Point Observatory. Using a principal component analysis and the BACCHUS automated spectral analysis code, we determined stellar par…
Slitless Solar Imaging Spectroscopy
Kamalabadi, Farzad; Davila, Joseph M.; Oktem, Figen S.
Spectrometers provide our most detailed diagnostics of the solar coronal plasma, and spectral data is routinely used to measure the temperature, density, and flow velocity in coronal features. However, spectrographs suffer from a limited instantaneous field of view (IFOV). Conversely, imaging instruments can provide a relatively large IFOV, but ex…
Quiet-Sun Explosive Events Observed in He II λ304 with MOSES-06
Kankelborg, Charles C.; Rust, Thomas
In this paper the unique data from the Multi-Order Solar Extreme-Ultraviolet Spectrograph (MOSES) are used to investigate transition region explosive events in the He II λ304 spectral line. Particular attention is paid to two example events: one blueshifted jet and one bidirectional jet. Observations suggest that these events consist exclusively o…
Chandra Observations of the AS0295 Cluster
Hughes, John P.; Pascut, Aurelia
We present deep (205 ks) Chandra observations of the AS0295 binary merging cluster (z = 0.30). In the X-ray image, the secondary component is clearly visible as a surface brightness peak, while the primary cluster has a flatter distribution. We found cool gas (∼6 keV) associated with the secondary, while the central temperature of the primary does…
X-Ray Spectral Evolution of PSR J2032+4127 during the 2017 Periastron Passage
Kong, A. K. H.; Tam, P. H. T.; Cui, Y. +3 more
We report X-ray data analysis results obtained from Chandra, XMM-Newton, Nuclear Spectroscopic Telescope Array Mission (NuSTAR), and Swift observations of PSR J2032+4127 taken before, during, and after the periastron on 2017 November 13. We found the first clear evidence of a change in the X-ray spectral index over the passage period, thanks to a …
Infrequent Occurrence of Significant Linear Polarization in Hα Solar Flares
Hanaoka, Yoichiro; Kawate, Tomoko
We performed statistical and event studies of linear polarization in the Hα line during solar flares. The statistical study revealed that, among 71 Hα flares analyzed, including 64 GOES flares, only one event shows significant linear polarization signals. Such an infrequent occurrence of significant linear polarization in solar flares is consisten…
A Dual Black Hole Associated with Obscured and Unobscured AGNs: CXO J101527.2+625911
Kim, D. -C.; Momjian, E.; Kim, Minjin +6 more
We report the results of an investigation to determine the nature of the offset active galactic nucleus (AGN) found in the source CXO J101527.2+625911. Hubble Space Telescope and Chandra X-ray observatory data have suggested that the offset AGN, which has an angular separation of only 0.″26 from the center of the host galaxy, is a recoiled superma…
X-Rays from e ± Pair Halos
Ruffolo, D.; Luangtip, W.; Eungwanichayapant, A. +1 more
It was previously suggested that e ± pair halos could be observed in γ-rays. Searching for pair halos is a challenging topic in γ-ray astronomy that has not yet yielded a convincing detection for an individual object. Here we propose that X-ray observations could reveal the existence of e ± pair halos. To support our suggesti…
No Pulsar Wind Nebula in the Southern Blowout Region of the Cygnus Loop
Gotthelf, E. V.; Halpern, J. P.
We report on optical observations of the Katsuda et al. candidate X-ray pulsar and pulsar wind nebula in the Cygnus Loop supernova remnant. We determine that the point source suggested to be a pulsar is actually the nucleus of a Seyfert 1 galaxy at redshift z = 0.2080, while the diffuse X-ray source, which is displaced by 2.‧6 from the point sourc…
The Modulating Optical Depth of the Photoelectric Absorption Edge with a Pulse Phase in Accretion-powered X-Ray Pulsars
Kitamoto, Shunji; Yoshida, Yuki
We report the first discovery of a pulse phase modulating optical depths at the iron K-edge in accretion-powered X-ray pulsars from Suzaku observations. A significant modulating optical depth of the iron K-edge is detected for Vela X-1 and GX 1+4. Similar trends are seen in GX 301-2 and OAO 1657-415, though with poor statistical significance. The …