Search Publications
Unexpected Short-period Variability in Dwarf Carbon Stars from the Zwicky Transient Facility
Roulston, Benjamin R.; Green, Paul J.; Hermes, J. J. +1 more
Dwarf carbon (dC) stars, main-sequence stars showing carbon molecular bands, are enriched by mass transfer from a previous asymptotic-giant-branch (AGB) companion, which has since evolved to a white dwarf. While previous studies have found radial-velocity variations for large samples of dCs, there are still relatively few dC orbital periods in the…
A study of open clusters Frolov 1 and NGC 7510 using CCD UBV photometry and Gaia DR2 astrometry
Bilir, Selçuk; Yontan, Talar; Paunzen, Ernst +6 more
We present reddening, photometric metallicity, age, and distance estimates for the Frolov 1 and NGC 7510 open clusters based on charge‑coupled device (CCD)UBVphotometric andGaiadata. Photometric observations were collected using the 1‑m telescope of the TÜBİTAK National Observatory.Gaiadata release 2 (DR2) proper motion data in the direction of tw…
Ionospheric plasma energization at Mars during the September 2017 ICME event
Bhardwaj, Anil; Thampi, R. Satheesh; Thampi, Smitha V. +2 more
During September 2017, the solar active region (AR) 12673 produced several flares and Coronal Mass Ejections (CMEs). On 10 September 2017, a stronger and wider CME was erupted from AR 12673, which was Mars-directed (max. vsw = ~840 km s-1 near 1.5 au). This ICME caused a major space weather event at Mars on 12-13 September. W…
The Formation and Lifetime of Outflows in a Solar Active Region
Polito, Vanessa; Warren, Harry P.; Barczynski, Krzysztof +4 more
Active regions are thought to be one contributor to the slow solar wind. Upflows in EUV coronal spectral lines are routinely observed at their boundaries, and provide the most direct way for upflowing material to escape into the heliosphere. The mechanisms that form and drive these upflows, however, remain to be fully characterized. It is unclear …
The role of astronomical silicates during a cometary outburst
Wesołowski, Marcin
This paper presents a new approach to analyzing the change of cometary brightness. In our considerations, we assume that astronomical silicates (dust agglomerates) and gas are present in the coma. This assumption is a consequence of the analysis of the result observed during the Rosetta mission to comet 67P/Churyumov-Gerasimenko (abbreviated 67P/C…
The Dragonfly Wide Field Survey. II. Accurate Total Luminosities and Colors of Nearby Massive Galaxies and Implications for the Galaxy Stellar-mass Function
van Dokkum, Pieter; Conroy, Charlie; Abraham, Roberto +8 more
Stellar-mass estimates of massive galaxies are susceptible to systematic errors in their photometry, due to their extended light profiles. In this study, we use data from the Dragonfly Wide Field Survey to accurately measure the total luminosities and colors of nearby massive galaxies. The low surface brightness limits of the survey (µg…
G 112-43/44: A metal-poor binary star with a unique chemical composition and Helmi stream kinematics
Nissen, P. E.; Schuster, W. J.; Silva-Cabrera, J. S.
Context. Correlations between high-precision elemental abundance ratios and the kinematics of halo stars provide interesting information about the formation and early evolution of the Galaxy.
Aims: Element abundances of G 112-43/44, a metal-poor wide-orbit binary star with extreme kinematics, are revisited.
Methods: High-precision studie…
Multiwavelength observations of a metric type-II event
Hillaris, A.; Patsourakos, S.; Nindos, A. +1 more
We have studied a complex metric radio event that originated in a compact flare, observed with the ARTEMIS-JLS radiospectrograph on February 12, 2010. The event was associated with a surge observed at 195 and 304 Å and with a coronal mass ejection observed by instruments on board STEREO A and B near the eastern and western limbs respectively. On t…
Spectral state transitions in Circinus ULX5
Markowitz, Alex; Mondal, Samaresh; De Marco, Barbara +2 more
Context. We performed timing and spectral analyses of multi-epoch Suzaku, XMM-Newton, and NuSTAR observations of the ultraluminous X-ray source (ULX) Circinus ULX5 with the aim of putting constraints on the mass of the central object and the accretion mode operating in this source.
Aims: We investigate whether the source contains a stellar ma…
X-ray emitting structures in the Vela SNR: ejecta anisotropies and progenitor stellar wind residuals
Miceli, M.; Bocchino, F.; Orlando, S. +6 more
Context. The Vela supernova remnant (SNR) shows several ejecta fragments (or shrapnel) protruding beyond the forward shock, which are most likely relics of anisotropies that developed during the supernova (SN) explosion. Recent studies have revealed high Si abundance in two shrapnel (shrapnel A and G), located in opposite directions with respect t…