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The Unexpected Optical and Ultraviolet Variability of the Standard Star α Sex (HD 87887)
Bowman, Dominic M.; Lebreton, Yveline; Monier, Richard +1 more
The analysis of the available Transiting Exoplanet Survey Satellite (TESS) light curves of α Sex (HD 87887) reveals low-frequency pulsations with a period of about 9.1 hr in this spectroscopic A0 III standard star. The IUE observations in 1992 December reveal large flux variations both in the far-UV and in the mid-UV, which are accompanied by vari…
Coronal spectroscopy: Probing sources of slow solar wind in active regions, and the early phases of solar flares
Harra, Louise K.
Coronal spectroscopy has pushed forward the understanding of physical processes in all phenomena on the Sun. In this review we concentrate specifically on plasma parameters measured in sources of the slow solar wind in active regions and the early phases of solar flares. These topics are a key part of the science goals of the Solar Orbiter mission…
Searching for open clusters in Gaia DR3 using a parallax-blind approach
Carballo-Bello, Julio A.; Gran, Felipe; Peña-Ramírez, Karla +1 more
Gaia data is providing a unique opportunity to explore the structure of the Milky Way by discovering more and more of one of its best tracers: open clusters. Innovative algorithms, supported by Gaia accurate proper motions, parallaxes, photometry, and radial velocities (whenever available), have identified hundreds of new clusters of stars across …
Disentangling the two sub-populations of early Herbig Be stars using VLT/X-shooter spectra
Arun, R.; Manoj, P.; Maheswar, G. +5 more
Context. Early Herbig Be (HBe) stars are massive, young stars accreting through the boundary layer mechanism. However, given the rapid (<2 Myr) evolution of early Herbig stars to the main-sequence phase, studying the evolution of the circumstellar medium around these stars can be a cumbersome exercise.
Aims: In this work, we study the samp…
Is the M81 Fast Radio Burst Host Globular Cluster Special?
Vesperini, Enrico; Kundu, Arunav; Strader, Jay +5 more
We use multiband archival Hubble Space Telescope (HST) observations to measure the photometric and structural parameters of the M81 globular cluster (GC) that hosts the fast radio burst FRB 20200120E. Our best-fitting King model has an effective radius r h = 3.06 pc with a moderate King model concentration of c = 53, and an inferred c…
Solar wind H+ fluxes at 1 AU for solar cycles 23 and 24
Sznajder, Maciej
The solar wind consists of electrons and ion species having kinetic energy ≲ 10 keVs. Ion stream is mainly composed of protons. Their flux magnitude is especially important for radiation hardness assurance scientists who qualify materials for future space missions. Materials irreversibly degrade as soon as are exposed to solar radiation. Hence, pr…
Parámetros estructurales de cúmulos abiertos y su comportamiento en presencia de compañeros cercanos
Baume, G.; Rodríguez, M. J.; Feinstein, C. +3 more
The study of a relevant and homogeneous sample of open clusters is presented with the aim of analysing the internal structure in clusters that are part of binary or multiple systems. In the applied procedure we used the astrometric and photomeric data provided by the Gaia survey (DR2) and the membership probabilities of its members obtained from c…
Application of the binary spectral model to high-resolution spectra. First estimation of the fundamental parameters for HD 20784
Kovalev, Mikhail; Straumit, Ilya
In this paper, we applied previously developed method of binary spectral model fitting to the high-resolution spectra of HD 20784. Simultaneously analysing all three available epochs, we found spectroscopic parameters for both components of the system. These parameters are consistent with stellar evolution model's predictions and analysis of the p…
The Wagging Plasma Tail of Comet C/2020 S3 (Erasmus)
Jewitt, David; Li, Jing; Kim, Yoonyoung
Long-period comet C/2020 S3 (Erasmus) reached perihelion at 0.398 au on UT 2020 December 12.67, making it a bright, near-Sun object. Images taken between 2020 mid-November and December using the HI-1 camera and COR2 coronagraph on board STEREO-A, as well as the LASCO/C3 coronagraph on board SoHO, show significant variations in the plasma tail posi…
First investigations of 14 neglected, late-type contact binaries
M, Raghu Prasad; Jagirdar, Rukmini; Devarapalli, Shanti Priya
In the current work we present the first investigations of 14 neglected, late-type, short period contact binaries using period variation, photometric and spectroscopic analysis performed on long term space and ground based observations. The binaries in study belong to spectral classes F to K. In this study the two contact binaries TIC 242100930 an…