Search Publications
AstroSat Study of the Globular Cluster NGC 2298: Probable Evolutionary Scenarios of Hot Horizontal Branch Stars
Sahu, Snehalata; Chung, Chul; Subramaniam, Annapurni +3 more
We present the far-UV (FUV) photometry of images acquired with UVIT on AstroSat to probe the horizontal branch (HB) population of the Galactic globular cluster NGC 2298. UV-optical color-magnitude diagrams (CMDs) are constructed for member stars in combination with Hubble Space Telescope UV Globular Cluster Survey data for the central region and G…
Constraining the Origin of the Puzzling Source HESS J1640-465 and the PeVatron Candidate HESS J1641-463 Using Fermi-Large Area Telescope Observations
Grondin, M. -H.; Lemoine-Goumard, M.; Clark, C. J. +6 more
There are only a few very-high-energy sources in our Galaxy that might accelerate particles up to the knee of the cosmic-ray spectrum. To understand the mechanisms of particle acceleration in these PeVatron candidates, Fermi-Large Area Telescope (LAT) and High-Energy Stereoscopic System (H.E.S.S.) observations are essential to characterize their γ…
X-Ray Evidence Against the Hypothesis that the Hyperluminous z = 6.3 Quasar J0100+2802 is Lensed
Connor, Thomas; Stern, Daniel; Bañados, Eduardo +1 more
The z = 6.327 quasar SDSS J010013.02+280225.8 (hereafter J0100+2802) is believed to be powered by a black hole more massive than 1010 M ⊙, making it the most massive black hole known in the first billion years of the universe. However, recent high-resolution ALMA imaging shows four structures at the location of this quasar, p…
Associated Molecular and Atomic Clouds with X-Ray Shell of Superbubble 30 Doradus C in the LMC
Filipović, M. D.; Aharonian, F.; Rowell, G. +20 more
30 Doradus C is a superbubble that emits the brightest non-thermal X- and TeV gamma-rays in the Local Group. To explore the detailed connection between the high-energy radiation and the interstellar medium, we have carried out new CO and HI observations using the Atacama Large Millimeter/Submillimeter Array (ALMA), Atacama Submillimeter Telescope …
Candidate z ∼ 2.5 Lyman Continuum Sources in the GOODS Fields
Barger, A. J.; Cowie, L. L.; Jones, L. H.
We use the wealth of deep archival optical spectroscopy on the GOODS-South field from Keck, the VLT, and other facilities to select candidate high-redshift Lyman continuum (LyC) leakers in the Hubble Deep UV Legacy Survey (HDUV) data set. We select sources at $2.35\lt z\lt 3.05$ , where the HST/WFC3 F275W filter probes only the redshifted LyC. We …
Extinction in the Large Magellanic Cloud Bar around NGC 1854, NGC 1856, and NGC 1858
Milone, Antonino P.; Panagia, Nino; De Marchi, Guido
We report on the extinction properties in the fields around the clusters NGC 1854, NGC 1856, and NGC 1858 in the bar of the Large Magellanic Cloud. The color-magnitude diagrams of the stars in all these regions show an elongated red giant clump that reveals a variable amount of extinction across these fields, ranging from A V ≃ 0.2 to…
M-subdwarf Research. II. Atmospheric Parameters and Kinematics
Qin, Li; Luo, A. -Li; Hou, Wen +12 more
We applied the revised M subdwarf classification criteria discussed in Zhang et al. to Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) DR7 and combined the result with the M subdwarf sample from Savcheva et al. to construct a new M subdwarf sample for further study. The atmospheric parameters for each object were derived from fi…
Forward Modeling of Simulated Transverse Oscillations in Coronal Loops and the Influence of Background Emission
Van Doorsselaere, Tom; Antolin, Patrick; Li, Bo +1 more
We simulate transverse oscillations in radiatively cooling coronal loops and forward-model their spectroscopic and imaging signatures, paying attention to the influence of background emission. The transverse oscillations are driven at one footpoint by a periodic velocity driver. A standing kink wave is subsequently formed and the loop cross sectio…
The Quasi-biennial-oscillation-type Signals in the Subsurface Flow Fields during Solar Cycles 23 and 24
Howe, Rachel; Inceoglu, Fadil; Loto'aniu, Paul T. M.
We studied the presence and spatiotemporal evolution of quasi-biennial oscillations (QBOs) in the rotation-rate residuals at target depths of 0.90R⊙, 0.95R⊙, and 0.99R⊙ and at low- (0°-30°), mid- (30°-50°), and high-latitudinal (50°-70°) bands. To achieve these objectives we used data from the Michelson Doppler Ima…
Dynamical Evolution of an Active-region Filament Driven by Magnetic Reconnection
Hou, Yijun; Li, Ting; Zhang, Jun +1 more
Studying solar filament dynamical evolutions is an important approach to reveal the driving mechanism of solar eruptions, which seriously impact on the Sun-Earth system and could cause disastrous space weather. To better understand the evolution process of solar filaments, here we investigate an active-region filament by employing observations fro…