Search Publications
TPHO: A Time-dependent Photoionization Model for AGN Outflows
Mehdipour, Missagh; Kaastra, Jelle; Kara, Erin +3 more
Outflows in active galactic nuclei (AGN) are considered a promising candidate for driving AGN feedback at large scales. However, without information on the density of these outflows we cannot determine how much kinetic power they are imparting to the surrounding medium. Monitoring the response of the ionization state of the absorbing outflows to c…
Total reflection of a flare-driven quasi-periodic extreme ultraviolet wave train at a coronal hole boundary
Shen, Yuandeng; Zhou, Chengrui; Zhou, Xinping +3 more
Context. A flare-driven quasi-periodic extreme ultraviolet wave train totally reflected at a coronal hole boundary was well imaged on both temporal and spatial scales by AIA/SDO.
Aims: We aim to investigate the driving mechanisms of the quasi-periodic wave train and demonstrate the total reflection effect at the coronal hole boundary.
Me…
Photospheric Prompt Emission From Long Gamma Ray Burst Simulations. II. Spectropolarimetry
Lazzati, Davide; Parsotan, Tyler
Although gamma ray bursts (GRBs) have been detected for many decades, the lack of knowledge regarding the radiation mechanism that produces the energetic flash of radiation, or prompt emission, from these events has prevented the full use of GRBs as probes of high-energy astrophysical processes. While there are multiple models that attempt to desc…
Validation of TESS exoplanet candidates orbiting solar analogues in the all-sky PLATO input catalogue
Piotto, Giampaolo; Wilson, Thomas G.; Collier Cameron, Andrew +6 more
The Transiting Exoplanet Survey Satellite (TESS) is focusing on relatively bright stars and has found thousands of planet candidates. However, mainly because of the low spatial resolution of its cameras (≈ 21 arcsec/pixel), TESS is expected to detect several false positives (FPs); hence, vetting needs to be done. Here, we present a follow-up progr…
Discovery of a Double Sequence of Blue Straggler Stars in the Core-collapsed Globular Cluster NGC 6256
Cadelano, Mario; Pallanca, Cristina; Dalessandro, Emanuele +3 more
We used a combination of high-resolution optical images acquired with the Hubble Space Telescope and near-IR wide-field data to investigate the stellar density profile and the population of blue straggler stars (BSSs) in the Galactic globular cluster NGC 6256, with the aim of probing its current stage of internal dynamical evolution. We found that…
An Absolute Calibration of the Near-infrared Period-Luminosity Relations of Type II Cepheids in the Milky Way and in the Large Magellanic Cloud
Breuval, Louise; Gieren, Wolfgang; Pietrzyński, Grzegorz +29 more
We present time-series photometry of 21 nearby type II Cepheids in the near-infrared J, H, and K s passbands. We use this photometry, together with the Third Gaia Early Data Release parallaxes, to determine for the first time period-luminosity relations (PLRs) for type II Cepheids from field representatives of these old pulsating star…
The SEDIGISM survey: The influence of spiral arms on the molecular gas distribution of the inner Milky Way
König, C.; Menten, K. M.; Henning, T. +23 more
The morphology of the Milky Way is still a matter of debate. In order to shed light on uncertainties surrounding the structure of the Galaxy, in this paper, we study the imprint of spiral arms on the distribution and properties of its molecular gas. To do so, we take full advantage of the SEDIGISM (Structure, Excitation, and Dynamics of the Inner …
Burton's Curse: The Impact of Bulk Flows on the Galactic Longitude-Velocity Diagram and the Illusion of a Continuous Perseus Arm
Peek, J. E. G.; Tchernyshyov, Kirill; Miville-Deschenes, Marc-Antoine
In this work, we demonstrate that the Perseus Arm is not a continuous structure of molecular gas in the second quadrant. We first show that the observed, distanced-resolved velocity structure of the Galaxy in the outer disk is capable of creating illusory spiral arms, as was first proposed by Burton. Second, we measure the distances to a collectio…
More Evidence for Variable Helium Absorption from HD 189733b
Redfield, Seth; Knutson, Heather A.; France, Kevin +5 more
We present a new Keck/NIRSPEC observation of metastable helium absorption from the upper atmosphere of HD 189733b, a hot Jupiter orbiting a nearby moderately active star. We measure an average helium transit depth of 0.420% ± 0.013% integrated over the [-20, 20] km s-1 velocity range. Comparing this measurement to eight previously publi…
The period-age relation of long-period variables
Mowlavi, N.; Trabucchi, M.
Context. Pieces of empirical evidence suggest the existence of a period-age relation for long-period variables (LPVs). Yet, this property has hardly been studied on theoretical grounds thus far.
Aims: We aim to examine the period-age relation using the results from recent nonlinear pulsation calculations.
Methods: We combined isochrone m…