Search Publications
Beyond the Minisolar Maximum of Solar Cycle 24: Declining Solar Magnetic Fields and the Response of the Terrestrial Magnetosphere
Janardhan, P.; Ingale, M.; Bisoi, S. K.
The present study examines the response of the terrestrial magnetosphere to the long-term steady declining trends observed in solar magnetic fields and solar wind microturbulence levels since mid-1990s that has been continuing beyond the minisolar maximum of cycle 24. A detailed analysis of the response of the terrestrial magnetosphere has been ca…
UV to X-Ray Comptonization Delay in Mrk 493
Dewangan, Gulab C.; Pal, Main; Pawar, Pramod +1 more
The broadband X-ray emission from type 1 active galactic nuclei, dominated by a power-law continuum, is thought to arise from repeated inverse Compton scattering of seed optical/UV photons by energetic electrons in a hot corona. The seed optical/UV photons are assumed to arise from an accretion disk, but direct observational evidence has remained …
Measuring the expansion and age of the nova shell IPHASX J210204.7 + 471015
Guerrero, M. A.; Toalá, J. A.; Santamaría, E. +4 more
The parallax expansion and kinematics of a nova shell can be used to assess its age and distance, and to investigate the interaction of the ejecta with the circumstellar medium. These are key to understand the expansion and dispersal of the nova ejecta in the Galaxy. Multi-epoch images and high-dispersion spectroscopic observations of the recently…
First Evidence of Enhanced Recombination in Astrophysical Environments and the Implications for Plasma Diagnostics
Dupree, A. K.; Raymond, J.; García-Rojas, J. +6 more
We report the first unambiguous observational evidence of Rydberg Enhanced Recombination (RER), a potentially important recombination mechanism that has hitherto been unexplored in low-temperature photoionized plasmas. RER shares similarities with dielectronic recombination, with the difference that the electron is captured into a highly excited s…
Migrating Scarps as a Significant Driver for Cometary Surface Evolution
Soderblom, J. M.; Davidsson, B.; Oklay, N. +10 more
Rosetta observations of 67P/Churyumov-Gerasimenko (67P) reveal that most changes occur in the fallback-generated smooth terrains, vast deposits of granular material blanketing the comet's northern hemisphere. These changes express themselves both morphologically and spectrally across the nucleus, yet we lack a model that describes their formation …
TOPCAT and Gaia
Taylor, M. B.
TOPCAT, and its command line counterpart STILTS, are powerful tools for working with large source catalogs. ESA's Gaia mission, most recently with its second data release, is producing source catalogs of unprecedented quality for more than a billion sources. This paper presents some examples of how TOPCAT and STILTS can be used for analysis of Gai…
Study of Sunspot Penumbra to Umbra Area Ratio Using Kodaikanal White-light Digitised Data
Banerjee, Dipankar; Jha, Bibhuti Kumar; Mandal, Sudip
We study the long-term behaviour of the sunspot penumbra to umbra area ratio by analysing recently digitised Kodaikanal white-light data (1923 - 2011). We implement an automatic umbra extraction method and compute the ratio over eight solar cycles (Cycles 16 - 23). Although the average ratio does not show any variation with spot latitudes, cycle p…
IMF By Influence on Magnetospheric Convection in Earth's Magnetotail Plasma Sheet
Hamrin, M.; Tenfjord, P.; Laundal, K. M. +7 more
We use Geotail, Cluster, and Time History of Events and Macroscale Interactions during Substorms data over 15 years (1995-2009) to statistically investigate convective ion flows (V⊥xy<200 km/s) in the magnetotail plasma sheet under the influence of a clearly nonzero dawn-dusk interplanetary magnetic field (IMF By). We find…
A nitrogen-enhanced metal-poor star discovered in the globular cluster ESO280-SC06
Martell, Sarah L.; Simpson, Jeffrey D.
We report the discovery of the only very nitrogen-enhanced metal-poor star known in a Galactic globular cluster. This star, in the very metal-poor cluster ESO280-SC06 , has [N/Fe] > +2.5, while the other stars in the cluster show no obvious enhancement in nitrogen. Around 80 NEMP stars are known in the field, and their abundance patterns are be…
Recent Advancements and Remaining Challenges Associated With Inner Magnetosphere Cross-Energy/Population Interactions (IMCEPI)
Jordanova, Vania K.; Yu, Yiqun; Liemohn, Mike W. +2 more
The geospace inner magnetosphere, within about 10 Earth radii, contains various plasma populations with energy from a few electron volts to megaelectron volts and plays important roles in regulating the energy density of the magnetosphere, the magnetic field configuration, and wave dynamics. As an integrated part of the magnetosphere, the inner ma…