Search Publications
The tidal stream generated by the globular cluster NGC 3201
Miralda-Escudé, Jordi; Palau, Carles G.
We detect a tidal stream generated by the globular cluster NGC 3201 extending over ~140 deg on the sky, using the Gaia DR2 data, with the maximum-likelihood method we presented previously to study the M68 tidal stream. Most of the detected stream is the trailing one, which stretches in the southern Galactic hemisphere and passes within a close dis…
TESS Observations of Be Stars: General Characteristics and the Impulsive Magnetic Rotator Model
Balona, Luis A.; Ozuyar, Dogus
Evidence of rotational light modulation in 30%-40% of normal B stars is presented, suggesting the presence of starspots and photospheric activity. On this basis, we propose that mass loss in Be stars is a result of magnetic reconnection coupled with rapid but not necessarily near-critical rotation. The ejected matter is trapped at two diametricall…
Analytical Framework for Space Debris Collision Avoidance Maneuver Design
Di Lizia, Pierluigi; Colombo, Camilla; Gonzalo, Juan Luis
An analytical formulation for collision avoidance maneuvers involving a spacecraft and a space debris is presented, including solutions for the maximum deviation and minimum collision probability cases. Gauss' planetary equations and relative motion equations are used to map maneuvers at a given time to displacements at the predicted close approac…
ALMA and IRIS Observations of the Solar Chromosphere. II. Structure and Dynamics of Chromospheric Plages
Martínez-Sykora, Juan; De Pontieu, Bart; Chintzoglou, Georgios +7 more
We propose and employ a novel empirical method for determining chromospheric plage regions, which seems to better isolate a plage from its surrounding regions than other methods commonly used. We caution that isolating a plage from its immediate surroundings must be done with care in order to successfully mitigate statistical biases that, for inst…
Lessons learned from SPHERE for the astrometric strategy of the next generation of exoplanet imaging instruments
Henning, Thomas; Boccaletti, Anthony; Wahhaj, Zahed +14 more
Measuring the orbits of directly imaged exoplanets requires precise astrometry at the milliarcsec level over long periods of time due to their wide separation to the stars (≳10 au) and long orbital period (≳20 yr). To reach this challenging goal, a specific strategy was implemented for the instrument Spectro-Polarimetric High-contrast Exoplanet Re…
Radio pulsations from the γ-ray millisecond pulsar PSR J2039-5617
Belfiore, A.; Venter, C.; Possenti, A. +9 more
The predicted nature of the candidate redback pulsar 3FGL J2039.6-5618 was recently confirmed by the discovery of γ-ray millisecond pulsations (Clark et al., hereafter Paper I), which identify this γ-ray source as PSR J2039-5617. We observed this object with the Parkes radio telescope in 2016 and 2019. We detect radio pulsations at 1.4 and 3.1 GHz…
Compton-Thick AGN in the NuSTAR ERA VII. A joint NuSTAR, Chandra, and XMM-Newton Analysis of Two Nearby, Heavily Obscured Sources
Vignali, C.; Gilli, R.; Ajello, M. +11 more
We present the joint Chandra, XMM-Newton, and NuSTAR analysis of two nearby Seyfert galaxies, NGC 3081 and ESO 565-G019. These are the only two having Chandra data in a larger sample of 10 low-redshift (z ≤ 0.05), candidates Compton-thick (CT) Active Galactic Nuclei selected in the 15-150 keV band with Swift-BAT that were still lacking NuSTAR data…
A search for satellite galaxies of nearby star-forming galaxies with resolved stars in LBT-SONG
Kochanek, Christopher S.; Sand, David J.; Peter, Annika H. G. +2 more
We present results from a resolved stellar population search for dwarf satellite galaxies of six nearby (D < 5 Mpc), sub-Milky Way mass hosts using deep (m ~ 27 mag) optical imaging from the Large Binocular Telescope. We perform image simulations to quantify our detection efficiency for dwarfs over a large range in luminosity and size, and deve…
Beyond Simple AGN Unification with Chandra-observed 3CRR Sources at 0.5 < z < 1
Azadi, Mojegan; Wilkes, Belinda J.; McDowell, Jonathan C. +14 more
Low-frequency radio selection finds radio-bright galaxies regardless of the amount of obscuration by gas and dust. We report Chandra observations of a complete 178 MHz-selected, and so orientation-unbiased, sample of 44 0.5 < z < 1 3CRR sources. The sample is comprised of quasars and narrow-line radio galaxies (NLRGs) with similar radio lumi…
Exploring the Stellar Rotation of Early-type Stars in the LAMOST Medium-resolution Survey. I. Catalog
Deng, Licai; de Grijs, Richard; Liu, Chao +3 more
We derive stellar parameters and abundances ("stellar labels") of 40,034 late-B and A-type main-sequence stars extracted from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope Medium Resolution Survey (LAMOST-MRS). The primary selection of our early-type sample was obtained from LAMOST Data Release 7 based on spectral-line indices. We …