Search Publications
Studying the physical properties of tidal features - I. Extracting morphological substructure in CANDELS observations and VELA simulations
Bell, Eric F.; Ferguson, Henry C.; Hathi, Nimish P. +17 more
The role of major mergers in galaxy evolution remains a key open question. Existing empirical merger identification methods use non-parametric and subjective visual classifications that can pose systematic challenges to constraining merger histories. As a first step towards overcoming these challenges, we develop and share publicly a new PYTHON-ba…
The tale of the Milky Way globular cluster NGC 6362 - I. The orbit and its possible extended star debris features as revealed by Gaia DR2
Robin, Annie C.; Minniti, Dante; Fernández-Trincado, José G. +5 more
We report the identification of possible extended star debris candidates beyond the cluster tidal radius of NGC 6362 based on the second Gaia data release (Gaia DR2). We found 259 objects possibly associated with the cluster lying in the vicinity of the giant branch and 1-2 magnitudes fainter/brighter than the main-sequence turn-off in the cluster…
Spectroscopic and astrometric radial velocities: Hyades as a benchmark
Pasquini, L.; Ludwig, H. -G.; de Medeiros, J. R. +1 more
We study the accuracy of spectroscopic radial velocities (RVs) by comparing spectroscopic and astrometric RVs for stars of the Hyades open cluster. We obtained High-Accuracy Radial velocity Planet Searcher (HARPS) spectra for a large sample of Hyades stars and combined them with accurate astrometric RVs based on Hipparcos and Gaia data. After clea…
Resolving accretion flows in nearby active galactic nuclei with the Event Horizon Telescope
Nagar, Neil M.; Ramakrishnan, Venkatessh; Xie, Fu-Guo +5 more
The Event Horizon Telescope (EHT), now with its first ever image of the photon ring around the supermassive black hole of M87, provides a unique opportunity to probe the physics of supermassive black holes through Very Long Baseline Interferometry (VLBI), such as the existence of the event horizon, the accretion processes as well as jet formation …
GJ 357: a low-mass planetary system uncovered by precision radial velocities and dynamical simulations
Suárez, Juan C.; Tuomi, M.; Jenkins, J. S. +5 more
We report the detection of a new planetary system orbiting the nearby M2.5V star GJ 357, using precision radial velocities from three separate echelle spectrographs, High Accuracy Radial velocity Planet Searcher (HARPS), High Resolution Echelle Spectrograph (HiRES), and Ultraviolet and Visible Echelle Spectrograph (UVES). Three small planets have …
The central star of planetary nebula PHR 1315 - 6555 and its host Galactic open cluster AL 1
Lykou, F.; Zijlstra, A.; Parker, Q. A. +2 more
PHR 1315 - 6555 is a rare case of a Galactic planetary nebula that is a proven member of the open cluster AL 1. This membership allows its distance to be defined with precision, and thus accurate measurements of its physical characteristics along with the parameters of its central star (CS) can be obtained. In this work, we use the Hubble Space Te…
Multi-epoch X-ray spectral analysis of the narrow-line Seyfert 1 galaxy Mrk 478
Gallo, L. C.; Zoghbi, A.; Gonzalez, A. G. +2 more
A multi-epoch X-ray spectral and variability analysis is conducted for the narrow-line Seyfert 1 (NLS1) active galactic nucleus (AGN) Mrk 478. All available X-ray data from XMM-Newton and Suzaku satellites, spanning from 2001 to 2017, are modelled with a variety of physical models, including partial covering, soft Comptonization, and blurred refle…
On the Oosterhoff dichotomy in the Galactic bulge - II. Kinematical distribution
Smolec, R.; Grebel, E. K.; Catelan, M. +3 more
We present a kinematical study of RR Lyrae stars associated with two Oosterhoff groups in the Galactic bulge. We used data published in the first paper of the series, plus proper motions from the Gaia Data Release 2, and radial velocities from the literature. A 6D kinematical and spatial solution was obtained for 429 RR Lyrae stars. We use a model…
Space astrometry of the very massive ∼150 M⊙ candidate runaway star VFTS682
Lennon, D. J.; Renzo, M.; Platais, I. +12 more
How very massive stars form is still an open question in astrophysics. VFTS682 is among the most massive stars known, with an inferred initial mass of ≳150 M_⊙. It is located in 30 Doradus at a projected distance of 29 pc from the central cluster R136. Its apparent isolation led to two hypotheses: either it formed in relative isolation or it was e…
Synthetic 26Al emission from galactic-scale superbubble simulations
Diehl, R.; Rodgers-Lee, D.; Krause, M. G. H. +1 more
Emission from the radioactive trace element 26Al has been observed throughout the Milky Way with the COMPTEL and INTEGRAL satellites. In particular, the Doppler shifts measured with INTEGRAL connect 26Al with superbubbles, which may guide 26Al flows off spiral arms in the direction of Galactic rotation. In order to…