Search Publications
The HST Large Programme on NGC 6752 - V. Differences in luminosity and mass function among stellar populations
Vesperini, Enrico; Anderson, Jay; Salaris, Maurizio +8 more
We exploit the astro-photometric dataset of the multi-epoch infrared parallel field of a Hubble Space Telescope Large Programme aimed at studying the faintest stars of the globular cluster NGC 6752 to determine the luminosity and mass functions of the multiple stellar populations of this cluster. Thanks to the measurement of proper motions and dee…
JWST imaging of the closest globular clusters—I. Possible infrared excess among white dwarfs in NGC 6397
Salaris, M.; Apai, D.; Anderson, J. +9 more
We present James Webb Space Telescope observations of the globular cluster NGC 6397 and use them to extend to infrared wavelengths the characterization of the cluster's entire white dwarf (WD) cooling sequence (CS). The data allows us to probe fundamental astrophysical WD properties and to search for evidence in their colors for (or against) the e…
HST astrometry of the closest brown dwarfs-II. Improved parameters and constraints on a third body
Apai, D.; Pourbaix, D.; Bedin, L. R. +5 more
Located at less than two pc away, Luhman 16 AB (WISE J104915.57-531906.1) is the closest pair of brown dwarfs and the third closest "stellar" system to Earth. An exoplanet candidate in the Luhman 16 binary system was reported in 2017 based on a weak astrometric signature in the analysis of 12 HST epochs. An additional epoch collected in 2018 and r…
Photometry and astrometry with JWST‑II: NIRCam distortion correction
Bedin, L. R.; Nardiello, D.; Griggio, M.
In preparation to make the most of our own planned James Webb Space Telescope investigations, we take advantage of publicly available calibration and early‑science observations to independently derive and test a geometric‑distortion solution for NIRCam detectors. Our solution is able to correct the distortion to better than 0.2 mas. Current data i…
Decomposition of the central structure of NGC 2273 in the NIR: A case study
Quirrenbach, A.; Gredel, R.; Thompson, D. +11 more
The Seyfert 2 galaxy NGC 2273 is a prime target to explore how active nuclei can be fed. It has a star‑forming innermost nuclear ring with a radius of 0.33kpc from where material may be funneled to the supermassive black hole in its center. In this article, we discuss high‑resolution adaptive optics aided JHKs images of NGC 2273 taken with the Lar…
Possible optical counterparts of ULXs in NGC 1672
Sonbas, Eda; Allak, Sinan; Akyuz, Aysun +1 more
In this study, we use archival data from Hubble Space Telescope (HST), Chandra, XMM‑Newton, and Swift‑XRT, to probe the nature of 9 (X1‑X9) candidate ultraluminous X‑ray sources (ULXs) in NGC 1672. Our study focuses on using the precise source positions obtained via improved astrometry based on Chandra and HST observations to search for and identi…
Large-scale asymmetry in galaxy spin directions: Analysis of galaxies with spectra in DES, SDSS, and DESI Legacy Survey
Shamir, Lior
Multiple previous studies using several different probes have shown considerable evidence for the existence of cosmological-scale anisotropy and a Hubble-scale axis. One of the probes that show such evidence is the distribution of the directions toward which galaxies spin. The advantage of the analysis of the distribution of galaxy spin directions…
Stark broadening effect in hot DA white dwarfs: Ultraviolet lines of Fe V
Hamdi, Rafik; Ben Nessib, Nabil; Sahal-Bréchot, Sylvie +1 more
Stark widths and shifts have been calculated for 17 ultraviolet lines of Fe V of astrophysical interest. The calculations have been made using semiclassical perturbation approach. The work is motivated by the importance of ultraviolet lines for the study of hot white dwarf atmospheres specially for investigations of the variation of fine structure…
Gaia search for stellar companions of TESS Objects of Interest II
Mugrauer, Markus; Michel, Kai-Uwe
We present the latest results of our ongoing multiplicity study of (Community) TESS Objects of Interest, using astro- and photometric data from the ESA-Gaia mission, to detect stellar companions of these stars and to characterize their properties. In total, 107 binary, 5 hierarchical triple star systems, as well as one quadruple system were detect…
Jet‑triggered star formation in young radio galaxies
Baum, Stefi; Morganti, Raffaella; Tremblay, Grant +7 more
Emission in the ultraviolet continuum is a salient signature of the hot, massive and consequently short-lived, stellar population that traces recent or ongoing star formation. With the aim of mapping star forming regions and morphologically separating the generic star formation from that associated with the galaxy-scale jet activity, we obtained h…