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Timing and spectral analysis of 2S 1417-624 during its 2018 outburst
Serim, M. M.; Şahiner, Ş.; Baykal, A. +4 more
We investigate timing and spectral characteristics of the transient X-ray pulsar 2S 1417-624 during its 2018 outburst with NICER follow up observations. We describe the spectra with high-energy cut-off and partial covering fraction absorption (PCFA) model and present flux-dependent spectral changes of the source during the 2018 outburst. Utilizing…
Sizing from the smallest scales: the mass of the Milky Way
Cooper, M. C.; Simon, J. D.; Ji, A. P. +6 more
As the Milky Way and its satellite system become more entrenched in near field cosmology efforts, the need for an accurate mass estimate of the Milky Way's dark matter halo is increasingly critical. With the second and early third data releases of stellar proper motions from Gaia, several groups calculated full 6D phase-space information for the p…
A Panchromatic Study of Massive Stars in the Extremely Metal-poor Local Group Dwarf Galaxy Leo A
McQuinn, Kristen B. W.; Williams, Benjamin F.; Choi, Yumi +17 more
We characterize massive stars (M > 8 M ⊙) in the nearby (D ∼ 0.8 Mpc) extremely metal-poor (Z ∼ 5% Z ⊙) galaxy Leo A using Hubble Space Telescope ultraviolet (UV), optical, and near-infrared (NIR) imaging along with Keck/Low-Resolution Imaging Spectrograph and MMT/Binospec optical spectroscopy for 18 main-sequence OB stars…
Occurrence and statistics of IRIS bursts
Kleint, Lucia; Panos, Brandon
Small reconnection events in the lower solar atmosphere can lead to its heating, but whether such heating can propagate into higher atmospheric layers and potentially contribute to coronal heating is an open question. We carry out a large statistical analysis of all IRIS observations from 2013 and 2014. We identified "IRIS burst" (IB) spectra usin…
Crosspolar performance of an elliptical corrugated-horn antenna
Silk, Joseph; Wu, Yi-Peng; Pinetti, Elena +1 more
The ultra-slow-roll (USR) inflation represents a class of single-field models with sharp deceleration of the rolling dynamics on small scales, leading to a significantly enhanced power spectrum of the curvature perturbations and primordial black hole (PBH) formation. Such a sharp transition of the inflationary background can trigger the coherent m…
Asteroseismology of the double-radial mode δ Scuti star BP Pegasi
Daszyńska-Daszkiewicz, J.; Pamyatnykh, A. A.; Walczak, P. +1 more
Using the All-Sky Automated Survey data, we determine the pulsational frequencies of the high-amplitude δ Scuti star BP Pegasi. The analysis revealed only the two known, independent frequencies that we use to perform the seismic analysis of the star. On the basis of multicolour Strömgren photometry, we independently find that both frequencies can …
Zeta-Payne: A Fully Automated Spectrum Analysis Algorithm for the Milky Way Mapper Program of the SDSS-V Survey
Xiang, Maosheng; Ting, Yuan-Sen; Kollmeier, Juna A. +13 more
The Sloan Digital Sky Survey (SDSS) has recently initiated its fifth survey generation (SDSS-V), with a central focus on stellar spectroscopy. In particular, SDSS-V's Milky Way Mapper program will deliver multiepoch optical and near-infrared spectra for more than 5 × 106 stars across the entire sky, covering a large range in stellar mas…
A Multiepoch X-Ray Study of the Nearby Seyfert 2 Galaxy NGC 7479: Linking Column Density Variability to the Torus Geometry
Ajello, M.; Marchesi, S.; Torres-Albà, N. +3 more
Active galactic nuclei are powered by accreting supermassive black holes, surrounded by a torus of obscuring material. Recent studies have shown how the torus structure, formerly thought to be homogeneous, appears to be "patchy": the detection of variability in the line-of-sight hydrogen column density, in fact, matches the description of an obscu…
Globular Cluster UVIT Legacy Survey (GlobULeS) - I. FUV-optical colour-magnitude diagrams for eight globular clusters
Dalessandro, Emanuele; Hutchings, John; Stetson, Peter B. +22 more
We present the first results of eight globular clusters (GCs) from the AstroSat/UVIT Legacy Survey programme GlobULeS based on the observations carried out in two far-ultraviolet (FUV) filters (F148W and F169M). The FUV-optical and FUV-FUV colour-magnitude diagrams (CMDs) of GCs with the proper motion membership were constructed by combining the U…
An Improved Magnetohydrodynamic Simulation of the 2006 December 13 Coronal Mass Ejection of NOAA Active Region 10930
Fan, Yuhong
We present a magnetohydrodynamic simulation of the coronal mass ejection on 2006 December 13 in the emerging δ-sunspot NOAA Active Region 10930, improving upon a previous simulation by Fan as follows. (1) Incorporate an ambient solar wind instead of using a static potential magnetic field extrapolation as the initial state. (2) In addition to impo…