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Multiwavelength investigation of the candidate Galactic PeVatron MGRO J1908+06
Mereghetti, S.; Sidoli, L.; La Palombara, N. +3 more
The candidate PeVatron MGRO J1908+06, which shows a hard spectrum beyond 100 TeV, is one of the most peculiar γ-ray sources in the Galactic plane. Its complex morphology and some possible counterparts spatially related with the very high energy (VHE) emission region, preclude to distinguish between a hadronic and leptonic nature of the γ-ray emiss…
S2D2: Small-scale Significant substructure DBSCAN Detection. I. NESTs detection in 2D star-forming regions
Hacar, Álvaro; Buckner, Anne S. M.; González, Marta +13 more
Context. The spatial and dynamical structure of star-forming regions can offer insights into stellar formation patterns. The amount of data from current and upcoming surveys calls for robust and objective procedures for detecting structures in order to statistically analyse the various regions and compare them.
Aims: We aim to provide the com…
Lower-luminosity Obscured AGN Host Galaxies Are Not Predominantly in Major-merging Systems at Cosmic Noon
Kirkpatrick, Allison; Kocevski, Dale D.; Heckman, Timothy +15 more
For over 60 yr, the scientific community has studied actively growing central supermassive black holes (active galactic nuclei, AGNs), but fundamental questions on their genesis remain unanswered. Numerical simulations and theoretical arguments show that black hole growth occurs during short-lived periods (~107-108 yr) of pow…
New Infrared Spectral Indices of Luminous Cold Stars: From Early K to M Types
Menten, Karl M.; Zhu, Qingfeng; Kudritzki, Rolf-Peter +4 more
We present infrared spectral indices (1.0-2.3 µm) of Galactic late-type giants and red supergiants (RSGs). We used existing and new spectra obtained at resolution power R = 2000 with SpeX on the IRTF telescope. While a large CO equivalent width (EW), at 2.29 µm ([CO, 2.29] ≳ 45 Å) is a typical signature of RSGs later than spectral type…
On the Decay of Sunspot Groups and Their Internal Parts in Detail
Muraközy, Judit
The decay of sunspot groups is a relatively unknown field since most studies have focused mainly on the decay of sunspots or sunspot groups, but only on small samples. As an extension of the recent work of Muraközy (2020), which is based on a large verified sample, this study investigates not only the long-term behavior of the decay of sunspot gro…
Transport Characteristics of the Near-Surface Layer of the Nucleus of Comet 67P/Churyumov-Gerasimenko
Blum, J.; Agarwal, J.; Rezac, L. +4 more
The paper considers the free molecular flow of gas through the dusty porous surface layer of a comet nucleus. The study is based on computer models of generation of a porous medium and Knudsen gas diffusion. We consider various types of homogeneous and heterogeneous layers constructed from nonintersecting spheres, including layers that contain mic…
Solar wind temperature-velocity relationship over the last five solar cycles and Forbush decreases associated with different types of interplanetary disturbance
Melkumyan, A. A.; Belov, A. V.; Abunina, M. A. +4 more
The behaviour of the solar wind (SW) proton temperature and velocity and their relationship during Forbush decreases (FDs) associated with various types of solar source - coronal mass ejections (CMEs) and coronal holes (CHs) - have been studied. Analysis of cosmic ray variations, SW temperature, velocity, density, plasma beta, and magnetic field (…
Confirmation of ξ1 CMa's ultra-slow rotation: magnetic polarity reversal and a dramatic change in magnetospheric UV emission lines
Wade, G. A.; Fullerton, A. W.; Shultz, M. E. +5 more
The magnetic β Cep pulsator ξ1 CMa has the longest rotational period of any known magnetic B-type star. It is also the only magnetic B-type star with magnetospheric emission that is known to be modulated by both rotation and pulsation. We report here the first unambiguous detection of a negative longitudinal magnetic field in ξ1
Switchback-like structures observed by Solar Orbiter
Fedorov, A.; Lavraud, B.; Andre, N. +19 more
Context. Rapid polarity reversals of the radial heliospheric magnetic field were discovered by Ulysses and they are now frequently observed as a common near-Sun phenomenon by NASA's Parker Solar Probe (PSP). Other solar wind missions, including ESA-NASA Solar Orbiter (SolO), also observe similar phenomena. The nature of these fluctuations is uncle…
The Orbit and Density of the Jupiter Trojan Satellite System Eurybates-Queta
Buie, Marc W.; Noll, Keith S.; Levison, Harold F. +8 more
We report observations of the Jupiter Trojan asteroid (3548) Eurybates and its satellite Queta with the Hubble Space Telescope and use these observations to perform an orbital fit to the system. Queta orbits Eurybates with a semimajor axis of 2350 ± 11 km at a period of 82.46 ± 0.06 days and an eccentricity of 0.125 ± 0.009. From this orbit we der…