Search Publications
The X-ray emission in young radio active galactic nuclei
Chen, Liang; Liao, Mai; Gu, Minfeng +1 more
In this work, we investigated the X-ray emission for a sample of young radio active galactic nuclei (AGNs) by combining data from Chandra/XMM-Newton with data for other wavebands. We find strong correlations between the X-ray luminosity LX at 2-10 keV and the radio luminosities LR at 5 GHz for the VLBI radio-core, VLA radio-c…
Orbits of Five Triple Stars
Latham, David W.; Tokovinin, Andrei
Joint analysis of radial velocities and position measurements of five hierarchical stellar systems is undertaken to determine elements of their inner and outer orbits and, whenever possible, their mutual inclinations. The inner and outer periods are 12.9 and 345 yr for HD 12376 (ADS 1613), 1.14 and ∼1500 yr for HD 19971 (ADS 2390), 8.3 and 475 yr …
MEGARA-IFU detection of extended He II λ4686 nebular emission in the central region of NGC 1569 and its ionization budget
Terlevich, E.; Terlevich, R.; Charlot, S. +21 more
We here report the detection of extended He II λ4686 nebular emission in the central region of NGC 1569 using the integral field spectrograph MEGARA at the 10.4 m Gran Telescopio Canarias. The observations cover a field of view (FoV) of 12.5 arcsec × 11.3 arcsec at a seeing-limited spatial resolution of ∼15 pc and at a spectral resolution of R = 6…
Magnetic activity and evolution of the four Hyades K giants
Schmitt, J. H. M. M.; Schröder, K. -P.; Mittag, M. +2 more
We determine the exact physical parameters of the four Hyades cluster K giants, using their parallaxes and atmospheric modelling of our red-channel TIGRE high-resolution spectra. Performing a comparison with well-tested evolutionary tracks, we derive exact masses and evolutionary stages. At an age of 588 (±60) Myr and with a metallicity of Z = 0.0…
The 2016 January eruption of recurrent Nova LMC 1968
Soszyński, I.; Udalski, A.; Szymański, M. K. +23 more
We present a comprehensive review of all observations of the eclipsing recurrent Nova LMC 1968 in the Large Magellanic Cloud which was previously observed in eruption in 1968, 1990, 2002, 2010, and most recently in 2016. We derive a probable recurrence time of 6.2 ± 1.2 yr and provide the ephemerides of the eclipse. In the ultraviolet-optical-IR p…
Uncovering the orbit of the hercules dwarf galaxy
Strader, Jay; Erkal, Denis; Sand, David J. +6 more
We present new chemo-kinematics of the Hercules dwarf galaxy based on Keck II-DEIMOS spectroscopy. Our 21 confirmed members, including 9 newly confirmed members, have a systemic velocity of VHerc = 46.4 ± 1.3 km s-1 and a velocity dispersion $\sigma _{V,\mathrm{Herc}}=4.4^{+1.4}_{-1.2}$ km s-1, consistent with prev…
Application of a Modified Spheromak Model to Simulations of Coronal Mass Ejection in the Inner Heliosphere
Pogorelov, Nikolai V.; Arge, Charles N.; Singh, Talwinder +1 more
The magnetic fields of interplanetary coronal mass ejections (ICMEs), which originate close to the Sun in the form of a flux rope, determine their geoeffectiveness. Therefore, robust flux rope-based models of CMEs are required to perform magnetohydrodynamic (MHD) simulations aimed at space weather predictions. We propose a modified spheromak model…
Evidence of Dust Grain Evolution from Extinction Mapping in the IC 63 Photodissociation Region
Williams, Benjamin F.; Gordon, Karl D.; Baes, Maarten +5 more
Photodissociation regions (PDRs) are parts of the ISM consisting of predominantly neutral gas, located at the interface between H II regions and molecular clouds. The physical conditions within these regions show variations on very short spatial scales, and therefore PDRs constitute ideal laboratories for investigating the properties and evolution…
PHL 417: a zirconium-rich pulsating hot subdwarf (V366 Aquarid) discovered in K2 data
Hermes, J. J.; Saio, H.; Reed, M. D. +6 more
The Kepler spacecraft observed the hot subdwarf star PHL 417 during its extended K2 mission, and the high-precision photometric light curve reveals the presence of 17 pulsation modes with periods between 38 and 105 min. From follow-up ground-based spectroscopy, we find that the object has a relatively high temperature of 35 600 K, a surface gravit…
On the Granulation and Irregular Variation of Red Supergiants
Jiang, Bi-Wei; Ren, Yi
The mechanisms and characteristics of the irregular variations of red supergiants (RSGs) are studied based on the RSG samples in the Small Magellanic Cloud (SMC), Large Magellanic Cloud (LMC), and M31. With the time-series data from the All-Sky Automated Survey for SuperNovae and Intermediate Palomar Transient Factory survey, we use the continuous…