Search Publications
High-resolution Spectroscopic Abundances of Red Giant Branch Stars in NGC 6584 and NGC 7099
Chaboyer, Brian; O'Malley, Erin M.
We obtain high-resolution spectra of red giant branch stars in NGC 6584 and NGC 7099 to perform a detailed abundance analysis. We confirm cluster membership for these stars based on consistent radial velocities measured in this study and small pixel offsets between the observations of Sarajedini et al. and Piotto et al. We find mean metallicities …
Synchronized observations of bright points from the solar photosphere to the corona
Tavabi, Ehsan
One of the most important features in the solar atmosphere is the magnetic network and its relationship to the transition region (TR) and coronal brightness. It is important to understand how energy is transported into the corona and how it travels along the magnetic field lines between the deep photosphere and chromosphere through the TR and coro…
LBT/MODS spectroscopy of globular clusters in the irregular galaxy NGC 4449
Tosi, M.; Cusano, F.; Mignoli, M. +10 more
We present intermediate-resolution (R ∼ 1000) spectra in the ∼3500-10 000 Å range of 14 globular clusters in the Magellanic irregular galaxy NGC 4449 acquired with the Multi-Object Double Spectrograph on the Large Binocular Telescope. We derived Lick indices in the optical and the Ca II triplet index in the near-infrared in order to infer the clus…
K2 observations of the rapidly oscillating Ap star 33 Lib (HD 137949): new frequencies and unique non-linear interactions
Bowman, D. M.; Kurtz, D. W.; Cunha, M. S. +2 more
We present the analysis of K2 short cadence data of the rapidly oscillating Ap (roAp) star, 33 Librae (HD 137949). The precision afforded to the K2 data allow us to identify at least 11 pulsation modes in this star, compared to the three previously reported. Reoccurring separations between these modes lead us to suggest a large frequency separatio…
An Upper Limit on Nickel Overabundance in the Supercritical Accretion Disk Wind of SS 433 from X-ray Spectroscopy
Medvedev, P. S.; Tsygankov, S. S.; Sazonov, S. Yu. +2 more
We analyze a long (with a total exposure time of 120 ks) X-ray observation of the unique Galactic microquasar SS 433 carried out by the XMM-Newton space observatory with the goal of searching for the fluorescent line of neutral (or weakly ionized) nickel at energy 7.5 keV. We consider two models for the formation of fluorescent lines in the spectr…
A distant sample of halo wide binaries from SDSS
Gould, Andrew; Coronado, Johanna; Chanamé, Julio +1 more
Samples of reliably identified halo wide binaries are scarce. If reasonably free from selection effects and with a small degree of contamination by chance alignments, these wide binaries become a powerful dynamical tool, having provided one of the very few experiments capable of constraining the nature of dark matter in the Milky Way halo. Current…
Super lithium-rich K giant with low 12C to 13C ratio
Zhao, G.; Pan, K.; Gao, Q. +5 more
Context. The lithium abundances in a few percent of giants exceed the value predicted by the standard stellar evolution models, and the mechanisms of Li enhancement are still under debate. The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) survey has obtained over six million spectra in the past five years, and thus provides a …
Agnostic stacking of intergalactic doublet absorption: measuring the Ne VIII population
Shull, J. Michael; Danforth, Charles W.; Mathur, Smita +2 more
We present a blind search for doublet intergalactic metal absorption with a method dubbed `agnostic stacking'. Using a forward-modelling framework, we combine this with direct detections in the literature to measure the overall metal population. We apply this novel approach to the search for Ne VIII absorption in a set of 26 high-quality COS spect…
Probing the Massive Star-forming Environment: A Multiwavelength Investigation of the Filamentary IRDC G333.73+0.37
Vig, S.; Mookerjea, B.; Ishwara-Chandra, C. H. +3 more
We present a multiwavelength study of the filamentary infrared dark cloud (IRDC) G333.73+0.37. The region contains two distinct mid-infrared sources S1 and S2 connected by dark lanes of gas and dust. Cold dust emission from the IRDC is detected at seven wavelength bands, and we have identified 10 high-density clumps in the region. The physical pro…
G7.7-3.7: A Young Supernova Remnant Probably Associated with the Guest Star in 386 CE (SN 386)
Vink, Jacco; Zhou, Ping; Li, Geng +1 more
Although the Galactic supernova rate is about two per century, only few supernova remnants (SNRs) are associated with historical records. There are a few ancient Chinese records of “guest stars” that are probably sightings of supernovae for which the associated SNRs are not established. Here we present an X-ray study of the SNR G7.7-3.7, as observ…