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Spatial and temporal distribution of sinuous ridges in southeastern Terra Sabaea and the northern region of Hellas Planitia, Mars☆
Williams, Rebecca M. E.; Anderson, Ryan B.; Gullikson, Amber L.
Sinuous ridges are an important yet understudied component of Mars' hydrologic history. We have produced a map of sinuous ridges, valleys and channels, and tectonic ridges across southeastern Terra Sabaea and into northern Hellas Planitia (10°-45° S, 35°-80° E) using a CTX mosaic. Although we mapped different types of ridges and negative relief fe…
Evidence of an upper ionospheric electric field perturbation correlated with a gamma ray burst
Ubertini, Pietro; Bazzano, Angela; Zannoni, Ugo +68 more
Earth's atmosphere, whose ionization stability plays a fundamental role for the evolution and endurance of life, is exposed to the effect of cosmic explosions producing high energy Gamma-ray-bursts. Being able to abruptly increase the atmospheric ionization, they might deplete stratospheric ozone on a global scale. During the last decades, an aver…
Not So Fast, Not So Furious: Just Magnetic
Villaver, Eva; Landstreet, John D.; Bagnulo, Stefano
WD 0810-353 is a white dwarf within the 20 pc volume around the Sun. Using Gaia astrometric distance and proper motions, and a radial velocity derived from Gaia spectroscopy, it has been predicted that this star will pass within 1 pc of the solar system in about 30 kyr. However, WD 0810-353 has been also shown to host a magnetic field with a stren…
Rapidly Evolving Transients in Archival ZTF Public Alerts
Filippenko, Alexei V.; Yang, Yi; Li, Wenxiong +8 more
We search the archival Zwicky Transient Facility public survey for rapidly evolving transient (RET) candidates based on well-defined criteria between 2018 May and 2021 December. The search yielded 19 bona fide RET candidates, corresponding to a discovery rate of ~5.2 events per year. Even with a Galactic latitude cut of 20°, eight of the 19 events…
Confinedness of an X3.1-class Solar Flare Occurred in NOAA 12192: Analysis from Multi-instrument Observations
Guglielmino, S. L.; Zuccarello, F.; Ferrente, F. +1 more
The nonassociation of coronal mass ejections with high energetic flares is sparse. For this reason, the magnetic conditions required for the confinedness of major flares is a topic of active research. Using multi-instrument observations, we investigated the evolution and effects of confinedness in an X3.1 flare, which occurred in active region (AR…
The Maunakea Spectroscopic Explorer: Thousands of fibers, infinite possibilities
Sobeck, Jennifer; Barden, Samuel C.; Sheinis, Andrew
The Maunakea Spectroscopic Explorer (MSE) is a massively multiplexed spectroscopic survey facility that will replace the Canada–France–Hawai'i Telescope over the next two decades. This 12.5‑m telescope, with its 1.5 square degree field of view, will observe 18,000–20,000 astronomical targets in every pointing from 0.36 to 1.80 m at low/moderate re…
Optimizing machine learning methods to discover strong gravitational lenses in the deep lens survey
Jones, Tucker; Keerthi Vasan, G. C.; Sheng, Stephen +2 more
Machine learning models can greatly improve the search for strong gravitational lenses in imaging surveys by reducing the amount of human inspection required. In this work, we test the performance of supervised, semi-supervised, and unsupervised learning algorithms trained with the ResNetV2 neural network architecture on their ability to efficient…
The EUV Reflectance of Mercury's Surface Measured by BepiColombo/PHEBUS
Korablev, O.; Chaufray, J. -Y.; Leblanc, F. +10 more
On 9 and 10 October 2021, Probing the Hermean Exosphere by Ultraviolet Spectroscopy aboard BepiColombo observed the disk-integrated reflected light from the Sun by Mercury in the spectral range 90-160 nm at a phase angle of 70°. These observations are used to derive the EUV reflectance of the surface of Mercury in this wavelength range for the fir…
Revisiting the orbital motion of WR 138
Nazé, Yaël; Gosset, Eric; Rauw, Gregor
The optical spectrum of WR 138 exhibits emission lines typical of a WN6o star and absorption lines from a rapidly-rotating OB star. Using a large set of spectroscopic data, we establish a new orbital solution of the WN6o star based on the radial velocities of highly-ionized nitrogen lines. We show that the WN6o star moves on a 4.3 yr orbit with a …
Recent Progress in Finding Binary Systems with the B[e] Phenomenon
Raj, Ashish; Chojnowski, S. Drew; Manset, Nadine +9 more
This paper describes recent studies of the FS CMa-type objects, a group of stars showing the B[e] phenomenon defined in 2007. The objects exhibit strong emission-line spectra with both permitted and forbidden lines suggesting the presence of a B-type star as well as strong IR excesses due to radiation of circumstellar dust. These properties are ha…