Search Publications
Sunspot Light Walls Suppressed by Nearby Brightenings
Hou, Yijun; Yang, Shuhong; Zhang, Jun +3 more
Light walls, as ensembles of oscillating bright structures rooted in sunspot light bridges, have not been well studied, although they are important for understanding sunspot properties. Using the Interface Region Imaging Spectrograph and Solar Dynamics Observatory observations, here we study the evolution of two oscillating light walls each within…
Observational signatures of past mass-exchange episodes in massive binaries: the case of LSS 3074
Gosset, E.; Rauw, G.; Manfroid, J. +4 more
Context. The role of mass and momentum exchanges in close massive binaries is very important in the subsequent evolution of the components. Such exchanges produce several observational signatures such as asynchronous rotation and altered chemical compositions, that remain after the stars detach again.
Aims: We investigated these effects for t…
Probing the Metal Enrichment of the Intergalactic Medium at z = 5-6 Using the Hubble Space Telescope
Fan, Xiaohui; Cai, Zheng; Finlator, Kristian +2 more
We test the galactic outflow model by probing associated galaxies of four strong intergalactic C IV absorbers at z = 5-6 using the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) ramp narrowband filters. The four strong C IV absorbers reside at z = 5.74, 5.52, 4.95, and 4.87, with column densities ranging from N C IV = 1…
Far-ultraviolet observation of the globular cluster NGC 6397
Knigge, C.; Shara, M.; Dieball, A. +2 more
We present an observational far-ultraviolet (FUV) and near-ultraviolet (NUV) study of the core region of the globular cluster (GC) NGC 6397. The observations were obtained with the Space Telescope Imaging Spectrograph (STIS, FUV) and the Wide Field Camera 3 (NUV) on board the Hubble Space Telescope. Here, we focus on the UV-bright stellar populati…
Direct probe of the inner accretion flow around the supermassive black hole in NGC 2617
Costantini, E.; Miniutti, G.; Motta, S. E. +12 more
Aims: NGC 2617 is a nearby (z 0.01) active galaxy that recently switched from being a Seyfert 1.8 to be a Seyfert 1.0. At the same time, it underwent a strong increase of X-ray flux by one order of magnitude with respect to archival measurements. We characterise the X-ray spectral and timing properties of NGC 2617 with the aim of studying the…
Variability of the symbiotic X-ray binary GX 1+4. Enhanced activity near periastron passage
Iłkiewicz, Krystian; Mikołajewska, Joanna; Monard, Berto
Context. GX 1+4 belongs to a rare class of X-ray binaries with red giant donors, symbiotic X-ray binaries. It has a history of complicated variability on multiple timescales in the optical light and X-rays. The nature of this variability remains poorly understood.
Aims: We aim to study variability of GX 1+4 on long timescale in X-ray and opti…
Star-forming Environments throughout the M101 Group
Mihos, J. Christopher; Harding, Paul; Watkins, Aaron E.
We present a multiwavelength study of star formation within the nearby M101 Group, including new deep Hα imaging of M101 and its two companions. We perform a statistical analysis of the Hα-to-FUV flux ratios in H II regions located in three different environments: M101's inner disk, M101's outer disk, and M101's lower-mass companion galaxy NGC 547…
Interplanetary Magnetic Flux Ropes as Agents Connecting Solar Eruptions and Geomagnetic Activities
Marubashi, K.; Cho, K. -S.; Ishibashi, H.
We investigate the solar wind structure for 11 cases that were selected for the campaign study promoted by the International Study of Earth-affecting Solar Transients (ISEST) MiniMax24 Working Group 4. We can identify clear flux rope signatures in nine cases. The geometries of the nine interplanetary magnetic flux ropes (IFRs) are examined with a …
A moderately precise dynamical age for the Homunculus of Eta Carinae based on 13 years of HST imaging
Smith, Nathan
The Hubble Space Telescope archive contains a large collection of images of η Carinae, and this paper analyses those most suitable for measuring its expanding Homunculus Nebula. Multiple intensity tracings through the Homunculus reveal the fractional increase in the overall size of the nebula; this avoids registration uncertainty, mitigates bright…
Understanding the nature of the intriguing source X Persei: a deep look with a Suzaku observation
Maitra, Chandreyee; Paul, Biswajit; Pradhan, Pragati +1 more
We present detailed broad-band timing and spectral analysis of the persistent, low luminosity and slowly spinning pulsar X Persei using a deep Suzaku observation of the source. The spectrum is unusually hard with a cyclotron resonance scattering feature (CRSF), the presence of which has been debated. By comparing the spectral models relevant for a…