Search Publications
X-ray intraday variability and power spectral density profiles of the blazar 3C 273 with XMM-Newton during 2000-2021
Gupta, Alok C.; Wiita, Paul J.; Ward, Martin +3 more
We present X-ray intraday variability and power spectral density (PSD) analyses of the longest 23 pointed XMM-Newton observations of the blazar 3C 273 that were taken during 2000-2021. These good time intervals contain between 5 and 24.6 h of data. Variability has been estimated in three energy bands: 0.2-2 keV (soft), 2-10 keV (hard), and 0.2-10 …
ULX pulsar Swift J0243.6+6124 observations with NuSTAR: dominance of reflected emission in the super-Eddington state
Gilfanov, M. R.; Tsygankov, S. S.; Filippova, E. V. +1 more
We report the discovery of the bright reflected emission component in the super-Eddington state of the ultraluminous X-ray pulsar Swift J0243.6+6124, based on the NuSTAR observations of the source during its 2017 outburst. The flux of the reflected emission is weakly variable over the pulsar phase while the direct emission shows significantly larg…
Chemical Composition of Bright Stars in the Northern Hemisphere: Star-Planet Connection
Grundahl, F.; Kjeldsen, H.; von Essen, C. +12 more
In fulfilling the aims of the planetary and asteroseismic research missions, such as that of the NASA Transiting Exoplanet Survey Satellite (TESS) space telescope, accurate stellar atmospheric parameters and a detailed chemical composition are required as inputs. We have observed high-resolution spectra for all 848 bright (V < 8 mag) stars that…
A Revised Understanding of the Structure of the Venusian Magnetotail From a High-Altitude Intercept With a Tail Ray by Parker Solar Probe
Collinson, Glyn A.; Ramstad, Robin; Frahm, Rudy +5 more
One of the major discoveries of NASA's 1979-1991 Pioneer Venus Orbiter is that the nightside ionosphere becomes filamentary at high altitude, forming comet-like tail rays. Pioneer Venus Orbiter could not establish how much farther into the wake of Venus tail rays extend, nor understand how they form. Here we present plasma and fields data from the…
Dependence of Energetic Storm Particle Heavy Ion Peak Intensities and Spectra on Source CME Longitude and Speed
Jian, L. K.; Desai, M. I.; Dayeh, M. A. +4 more
We examine variations in energetic storm particle (ESP) heavy ion peak intensities and energy spectra at CME-driven interplanetary shocks. We focus on their dependence with heliolongitude relative to the source region of their associated CMEs, and with CME speed, for events observed in Solar Cycle 24 at the STEREO-A, STEREO-B, and/or ACE spacecraf…
Zodiacal exoplanets in time (ZEIT) XII: a directly imaged planetary-mass companion to a young Taurus M dwarf star
Kuzuhara, M.; Tamura, M.; Kudo, T. +21 more
We report the discovery of a resolved (0.9 arcsec) substellar companion to a member of the 1-5 Myr Taurus star-forming region. The host star (2M0437) is a single mid-M type (Teff ≈ 3100 K) dwarf with a position, space motion, and colour-magnitude that support Taurus membership, and possible affiliation with a ~2.5-Myr-old subgroup. A co…
Investigating dust properties in AGB wind-ISM interaction regions
De Beck, E.; Mecina, M.; Maercker, M. +1 more
Aims: In this paper, we aim to constrain the dust mass and grain sizes in the interaction regions between the stellar winds and the interstellar medium (ISM) around asymptotic giant branch (AGB) stars. By describing the dust in these regions, we aim to shed light on the role of evolved low-mass stars in the origin of dust in galaxies.
Me…
Supersonic Expansion of the Bipolar H II Region Sh2-106: A 3500 Year Old Explosion?
Ginsburg, Adam; Bally, John; Chia, Zen +4 more
Multi-epoch narrowband Hubble Space Telescope images of the bipolar H II region Sh2-106 reveal highly supersonic nebular proper motions that increase with projected distance from the massive young stellar object S106 IR, reaching over ~30 mas yr-1 (~150 km s-1 at D = 1.09 kpc) at a projected separation of ~1.'4 (0.44 pc) from…
Unveiling the disc structure in ultraluminous X-ray source NGC 55 ULX-1
Fabian, A. C.; Pinto, C.; Di Salvo, T. +11 more
Ultraluminous X-ray sources (ULXs) are the most extreme among X-ray binaries in which the compact object, a neutron star or a black hole, accretes matter from the companion star, and exceeds a luminosity of $10^{39} \ \rm erg \, s^{-1}$ in the X-ray energy band alone. Despite two decades of studies, it is still not clear whether ULX spectral trans…
Dielectric Constant Estimation of Lunar Surface Using Mini-RF and Chandrayaan-2 SAR Data
Kumar, Raj; Das, Anup; Putrevu, Deepak +4 more