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A trail of the invisible: blue globular clusters trace the radial density distribution of the dark matter - case study of NGC 4278
Forbes, Duncan A.; Dolfi, Arianna; Kluge, Matthias +2 more
We present new, deep optical observations of the early-type galaxy NGC 4278, which is located in a small loose group. We find that the galaxy lacks fine substructure, that is, it appears relaxed, out to a radius of ~70 kpc. Our g- and i-band surface brightness profiles are uniform down to our deepest levels of ~28 mag arcsec-2. This spa…
The Early Light Curve of the Type Ia Supernova 2021hpr in NGC 3147: Progenitor Constraints with the Companion Interaction Model
Wheeler, J. Craig; Im, Myungshin; Kim, Dohyeong +19 more
The progenitor system of Type Ia supernovae (SNe Ia) is expected to be a close binary system consisting of a carbon/oxygen white dwarf (WD) and a nondegenerate star or another WD. Here, we present results from high-cadence monitoring observations of SN 2021hpr in a spiral galaxy, NGC 3147, and constraints on the progenitor system based on its earl…
Image enhancement with wavelet-optimized whitening
Auchère, F.; Buchlin, É.; Soubrié, E. +1 more
Context. Due to its physical nature, the solar corona exhibits large spatial variations of intensity that make it difficult to simultaneously visualize the features present at all levels and scales. Many general-purpose and specialized filters have been proposed to enhance coronal images. However, most of them require the ad hoc tweaking of parame…
The high optical brightness of the BlueWalker 3 satellite
Bannister, Michele T.; Bassa, Cees; Damke, Guillermo +37 more
Large constellations of bright artificial satellites in low Earth orbit pose significant challenges to ground-based astronomy1. Current orbiting constellation satellites have brightnesses between apparent magnitudes 4 and 6, whereas in the near-infrared Ks band, they can reach magnitude 2 (ref. 2). Satellite operators, astron…
The Polytropic Behavior of Solar Wind Protons as Observed by the Ulysses Spacecraft during Solar Minimum
Livadiotis, George; Nicolaou, Georgios; McComas, David J.
We analyze proton bulk parameters derived from Ulysses observations and investigate the polytropic behavior of solar wind protons over a wide range of heliocentric distances and latitudes. The large-scale variations of the proton density and temperature over heliocentric distance indicate that plasma protons are governed by subadiabatic processes …
Spiral structure and massive star formation in the hub-filament-system G326.27-0.49
Güsten, Rolf; Wyrowski, F.; Veena, V. S. +2 more
Hub-filament systems (HFSs) are potential sites of formation of star clusters and high mass stars. To understand the HFSs and to provide observational constraints on current theories that attempt to explain star formation globally, we report a study of the region associated with G326.27-0.49 using infrared data of dust continuum and newly obtained…
A Gaia Data Release 3 View on the Tip of the Red Giant Branch Luminosity
Casertano, Stefano; Li, Siyang; Riess, Adam G.
The tip of the red giant branch (TRGB) is a standard candle that can be used to help refine the determination of the Hubble constant. Gaia Data Release 3 (DR3) provides synthetic photometry constructed from low-resolution BP/RP spectra for Milky Way field stars that can be used to directly calibrate the luminosity of the TRGB in the Johnson-Cousin…
New Velocity Measurements of NGC 5128 Globular Clusters Out to 130 kpc: Outer Halo Kinematics, Substructure, and Dynamics
Forbes, Duncan A.; Caldwell, Nelson; Strader, Jay +11 more
We present new radial velocity measurements from the Magellan and the Anglo-Australian Telescopes for 175 previously known and 121 newly confirmed globular clusters (GCs) around NGC 5128, the nearest accessible massive early-type galaxy at D = 3.8 Mpc. Remarkably, 28 of these newly confirmed GCs are at projected radii $\gt 50^{\prime} $ (≳54 kpc),…
A Recipe for Unbiased Background Modeling in Deep Wide-field Astronomical Images
van Dokkum, Pieter; Abraham, Roberto; Pasha, Imad +9 more
Unbiased sky background modeling is crucial for the analysis of deep wide-field images, but it remains a major challenge in low surface brightness astronomy. Traditional image processing algorithms are often designed to produce artificially flat backgrounds, erasing astrophysically meaningful structures. In this paper, we present three ideas that …
Reference frames in general relativity and the galactic rotation curves
Frutos-Alfaro, F.; Costa, L. Filipe O.; Natário, José +1 more
The physical interpretation of the exact solutions of the Einstein field equations is, in general, a challenging task, part of the difficulties lying in the significance of the coordinate system. We discuss the extension of the International Astronomical Union (IAU) reference system to the exact theory. It is seen that such an extension, retaining…