Search Publications
Constraints on monopole-dipole potential from tests of gravity
Poddar, Tanmay Kumar; Pachhar, Debashis
An ultralight axion like particle (ALP) can mediate a macroscopic force with long-range monopole-dipole interactions between the Earth and the Sun, if the Earth is treated as a polarized source. Because of the geomagnetic field, there exists an estimated 1042 polarized electrons within the Earth. These electrons, in a polarized state, c…
First VLTI/GRAVITY Observations of HIP 65426 b: Evidence for a Low or Moderate Orbital Eccentricity
Lutz, D.; Genzel, R.; Sturm, E. +96 more
Giant exoplanets have been directly imaged over orders of magnitude of orbital separations, prompting theoretical and observational investigations of their formation pathways. In this paper, we present new VLTI/GRAVITY astrometric data of HIP 65426 b, a cold, giant exoplanet which is a particular challenge for most formation theories at a projecte…
Ca triplet metallicities and velocities for 12 globular clusters toward the galactic bulge
Minniti, D.; Saviane, I.; Geisler, D. +6 more
Context. Globular clusters (GCs) are excellent tracers of the formation and early evolution of the Milky Way. The bulge GCs (BGCs) are particularly important because they can reveal vital information about the oldest in situ component of the Milky Way.
Aims: Our aim is to derive the mean metallicities and radial velocities for 13 GCs that lie…
Bayesian sampling with BeAtlas, a grid of synthetic Be star spectra I. Recovering the fundamental parameters of α Eri and β CMi
Carciofi, A. C.; de Amorim, T. H.; Vieira, R. G. +14 more
Classical B emission (Be) stars are fast rotating, near-main-sequence B-type stars. The rotation and the presence of circumstellar discs profoundly modify the observables of active Be stars. Our goal is to infer stellar and disc parameters, as well as distance and interstellar extinction, using the currently most favoured physical models for these…
Multiwavelength Characterization of the High-mass X-Ray Binary Population of M33
Williams, Benjamin F.; Eracleous, Michael; Dalcanton, Julianne J. +12 more
We present multiwavelength characterization of 65 high-mass X-ray binary (HMXB) candidates in M33. We use the Chandra ACIS survey of M33 (ChASeM33) catalog to select hard X-ray point sources that are spatially coincident with UV-bright point-source optical counterparts in the Panchromatic Hubble Andromeda Treasury: Triangulum Extended Region catal…
Spectroscopic and photometric studies on four solar-type short-period contact binaries in the triple stellar systems
Michel, Raúl; Wang, Shuang; Yang, Yuangui +2 more
We reported new spectroscopy and photometry for four short-period binaries, which were acquired by several small telescopes in China from 2020 to 2022. From new spectrum and Large Sky Area Multiobject Fiber Spectroscopic Telescope data, we determined their spectral types of G8V for PZ UMa, G7 for MM Com, and V0685 Peg and G3 for V1055 Her. When co…
Bringing 2D Eclipse Mapping out of the Shadows with Leave-one-out Cross Validation
McGill, Peter; Challener, Ryan C.; Welbanks, Luis
Eclipse mapping is a technique for inferring 2D brightness maps of transiting exoplanets from the shape of an eclipse light curve. With JWST's unmatched precision, eclipse mapping is now possible for a large number of exoplanets. However, eclipse mapping has only been applied to two planets, and the nuances of fitting eclipse maps are not yet full…
A New Physical Picture for Active Galactic Nuclei Lacking Optical Emission Lines
Ellison, Sara L.; Faber, S. M.; Salim, Samir +2 more
In this work, we use ~500 low-redshift (z ~ 0.1) X-ray active galactic nuclei (AGNs) observed by XMM-Newton and the Sloan Digital Sky Survey (SDSS) to investigate the prevalence and nature of AGNs that apparently lack optical emission lines ("optically dull AGNs"). Although one quarter of spectra appear absorption-line dominated in visual assessme…
Mass Distribution for Single-lined Hot Subdwarf Stars in LAMOST
Németh, Péter; Yang, Yong; Zhao, Jingkun +4 more
Masses for 664 single-lined hot subdwarf stars identified in LAMOST were calculated by comparing synthetic fluxes from spectral energy distribution with observed fluxes from a Virtual Observatory service. Three groups of hot subdwarf stars were selected from the whole sample according to their parallax precision to study the mass distributions. We…
SKYSURF-4: Panchromatic Hubble Space Telescope All-Sky Surface-brightness Measurement Methods and Results
Koekemoer, Anton M.; Casertano, Stefano; Driver, Simon P. +22 more
The diffuse, unresolved sky provides most of the photons that the Hubble Space Telescope (HST) receives, yet remains poorly understood. The HST Archival Legacy program SKYSURF aims to measure the 0.2-1.6 µm sky surface brightness (sky-SB) from over 140,000 HST images. We describe a sky-SB measurement algorithm designed for SKYSURF that is ab…