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Testing of the Taylor Frozen-in-flow Hypothesis at Electron Scales in the Solar Wind Turbulence
Sahraoui, F.; Huang, S. Y.
In single-spacecraft observations the Taylor frozen-in-flow hypothesis is usually used to infer wavenumber spectra of turbulence from the frequency ones. While this hypothesis can be valid at MHD scales in the solar wind because of the small phase speeds of the fluctuations in comparison with the solar wind flow speed, its validity at electron sca…
System initial mass function of the 25 Ori group from planetary-mass objects to intermediate/high-mass stars
Petr-Gotzens, Monika G.; Suárez, Genaro; Briceño, César +4 more
The stellar initial mass function (IMF) is an essential input for many astrophysical studies but only in a few cases has it been determined over the whole cluster mass range, limiting the conclusions about its nature. The 25 Orionis group (25 Ori) is an excellent laboratory for investigating the IMF across the entire mass range of the population, …
Identifying Young Stellar Objects in the Outer Galaxy: l = 224° Region in Canis Major
Boyer, Martha L.; Szczerba, Ryszard; Elia, Davide +14 more
We study a very young star-forming region in the outer Galaxy that is the most concentrated source of outflows in the Spitzer Space Telescope GLIMPSE360 survey. This region, dubbed CMa-l224, is located in the Canis Major OB1 association. CMa-l224 is relatively faint in the mid-infrared, but it shines brightly at the far-infrared wavelengths as rev…
Diagnosing 0.1-10 au Scale Morphology of the FU Ori Disk Using ALMA and VLTI/GRAVITY
Henning, Thomas; Mérand, Antoine; Takami, Michihiro +11 more
We report new Atacama Large Millimeter/submillimeter Array Band 3 (86-100 GHz; ∼80 mas angular resolution) and Band 4 (146-160 GHz; ∼50 mas angular resolution) observations of the dust continuum emission toward the archetypal and ongoing accretion burst young stellar object FU Ori, which simultaneously covered its companion, FU Ori S. In addition,…
WASP-South hot Jupiters: WASP-178b, WASP-184b, WASP-185b, and WASP-192b
Bouchy, F.; Queloz, D.; Hellier, Coel +19 more
We report on four new transiting hot Jupiters discovered by the WASP-South survey. WASP-178b transits a V = 9.9, A1V star with Teff = 9350 ± 150 K, the second-hottest transit host known. It has a highly bloated radius of 1.81 ± 0.09 RJup, in line with the known correlation between high irradiation and large size. With an esti…
Stealth Coronal Mass Ejections from Active Regions
Long, David M.; O'Kane, Jennifer; Green, Lucie +1 more
Stealth coronal mass ejections (CMEs) are eruptions from the Sun that have no obvious low coronal signature. These CMEs are characteristically slower events but can still be geoeffective and affect space weather at Earth. Therefore, understanding the science underpinning these eruptions will greatly improve our ability to detect and, eventually, f…
C-Complex Asteroids: UV-Visible Spectral Characteristics and Implications for Space Weathering Effects
Vilas, Faith; Hendrix, Amanda R.
Space weathering effects on the rocky S-class asteroids are well understood. However, on the low-albedo C-complex asteroids, such as spacecraft targets Bennu and Ryugu, the situation is more complicated, especially due to a lack of spectral features throughout the visible-near infrared spectral region. Here we show, through a combination of observ…
Uncertainties in direct dark matter detection in light of Gaia's escape velocity measurements
Valluri, Monica; Freese, Katherine; Wu, Youjia +2 more
Direct detection experiments have set increasingly stringent limits on the cross section for spin-independent dark matter-nucleon interactions. In obtaining such limits, experiments primarily assume the standard halo model (SHM) as the distribution of dark matter in our Milky Way. Three astrophysical parameters are required to define the SHM: the …
IRIS Observations of Magnetic Interactions in the Solar Atmosphere between Preexisting and Emerging Magnetic Fields. II. UV Emission Properties
Young, Peter R.; Guglielmino, Salvo L.; Zuccarello, Francesca
Multiwavelength ultraviolet (UV) observations by the Interface Region Imaging Spectrograph satellite in active region NOAA 12529 have recently pointed out the presence of long-lasting brightenings, akin to UV bursts, and simultaneous plasma ejections occurring in the upper chromosphere and transition region during secondary flux emergence. These s…
Probing the weak wind phenomenon in Galactic O-type giants
Bouret, J. -C.; Pereira, C. B.; Marcolino, W. L. F. +1 more
Aims: Analyses of Galactic late O dwarfs (O8-O9.5V stars) raised the "weak wind problem": spectroscopic mass-loss rates (Ṁ) are up to two orders of magnitude lower than the theoretical values. We investigated the stellar and wind properties of Galactic late O giants (O8-O9.5III stars). These stars have luminosities log (L⋆ / L…