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Hot Degenerates in the MCT Survey. III. A Sample of White Dwarf Stars in the Southern Hemisphere
Kepler, S. O.; Fontaine, G.; Bergeron, P. +7 more
We present optical spectra of 144 white dwarfs detected in the Montreal-Cambridge-Tololo colorimetric survey, including 120 DA, 12 DB, 4 DO, 1 DQ, and 7 DC stars. We also perform a model atmosphere analysis of all objects in our sample using the so-called spectroscopic technique, or the photometric technique in the case of DC white dwarfs. The mai…
TESS and HARPS reveal two sub-Neptunes around TOI 1062
Bouchy, F.; Fridlund, M.; Helled, R. +48 more
The Transiting Exoplanet Survey Satellite (TESS) mission was designed to perform an all-sky search of planets around bright and nearby stars. Here we report the discovery of two sub-Neptunes orbiting around TOI 1062 (TIC 299799658), a V = 10.25 G9V star observed in the TESS Sectors 1, 13, 27, and 28. We use precise radial velocity observations fro…
Long-term measurements of the erosion and accretion of dust deposits on comet 67P/Churyumov-Gerasimenko with the OSIRIS instrument
Sierks, H.; Fulle, M.; Güttler, C. +10 more
We monitor the seasonal erosion and accretion of dust deposits in the Imhotep, Hatmehit, and Ma'at regions of comet 67P/Churyumov-Gerasimenko with OSIRIS Narrow Angle Camera images. The vertical accuracy of such measurements is 0.2 m and the spatial scale of the images we used is lower than 0.60 m pixel-1. We calculate the height of 21 …
Precursory Signs of Large Forbush Decreases
Mavromichalaki, H.; Belov, A.; Eroshenko, E. +4 more
The study of space-weather effects and more specifically Forbush decreases of the cosmic-ray intensity depends on space and ground measurements. Very often Forbush decreases and geomagnetic storms are accompanied by pre-increases and/or pre-decreases manifested in cosmic-ray behavior, known as precursory signs. These cosmic-ray intensity variation…
Do Current X-Ray Observations Capture Most of the Black-hole Accretion at High Redshifts?
Papovich, Casey; Yang, Guang; Estrada-Carpenter, Vicente +4 more
The cosmic black hole accretion density (BHAD) is critical for our understanding of the formation and evolution of supermassive black holes (BHs). However, at high redshifts (z > 3), X-ray observations report BHADs significantly (~10 times) lower than those predicted by cosmological simulations. It is therefore paramount to constrain the high-z…
The 3.3 µm Infrared Emission Feature: Observational and Laboratory Constraints on Its Carrier
Tokunaga, Alan T.; Bernstein, Lawrence S.
We examine the self-consistency of laboratory and observational data for potential carriers of the 3.3 µm infrared emission feature (IEF), a member of the ubiquitous family of strong interstellar IEFs at 3.3, 3.4, 6.2, 7.7, 8.6, 11.2, and 12.7 µm. Previous studies have shown that most Galactic sources (reflection nebulae, H II regions,…
Modification of icy planetesimals by early thermal evolution and collisions: Constraints for formation time and initial size of comets and small KBOs
Jutzi, Martin; Golabek, Gregor J.
Comets and small Kuiper belt objects are considered to be among the most primitive objects in the solar system as comets like C/1995 O1 Hale-Bopp are rich in highly volatile ices like CO. It has been suggested that early in the solar system evolution the precursors of both groups, the so-called icy planetesimals, were modified by both short-lived …
Astrophysical properties of newly discovered Magellanic Cloud star clusters
Piatti, Andrés E.
New star cluster candidates projected toward the Large and Small Magellanic Clouds (LMC, SMC) have been recently discovered from relatively deep imaging surveys. Here, we conduct a sound analysis of 24 star cluster candidates located in the outer regions of the LMC and SMC using point spread function photometry produced by the Survey of the Magell…
Effects of solar flares and coronal mass ejections on Earth's horizontal magnetic field and solar wind parameters during the minimum solar cycle 24
Yoshikawa, A.; Syed Zafar, S. N. A.; Umar, R. +3 more
Previous studies have reported that coronal mass ejections (CMEs) and solar flares lead to the development of huge storms and high-speed streams. Our aim in this paper is to investigate the response of the geomagnetic index SYM/H to the solar wind parameters, such as solar wind speed V, dynamic pressure P, input energy IE and the interplanetary ma…
NGC 147 Corroborates the Break in the Stellar Mass-Stellar Metallicity Relation for Galaxies
Leethochawalit, Nicha; Kirby, Evan N.; Zhuang, Zhuyun +1 more
The stellar mass-stellar metallicity relation (MZR) is an essential approach to probing the chemical evolution of galaxies. It reflects the balance between galactic feedback and gravitational potential as a function of stellar mass. However, the current MZR of local dwarf satellite galaxies (M* ≲ 108 M⊙; measured f…