Search Publications
Discovery and analysis of three magnetic hot subdwarf stars: evidence for merger-induced magnetic fields
Geier, S.; Heber, U.; Pelisoli, Ingrid +6 more
Magnetic fields can play an important role in stellar evolution. Among white dwarfs, the most common stellar remnant, the fraction of magnetic systems is more than 20 per cent. The origin of magnetic fields in white dwarfs, which show strengths ranging from 40 kG to hundreds of MG, is still a topic of debate. In contrast, only one magnetic hot sub…
NEID Rossiter-McLaughlin Measurement of TOI-1268b: A Young Warm Saturn Aligned with Its Cool Host Star
Torres, Guillermo; Vanderburg, Andrew; Rampalli, Rayna +56 more
Close-in gas giants present a surprising range of stellar obliquity, the angle between a planet's orbital axis and its host star's spin axis. It is unclear whether the obliquities reflect the planets' dynamical history (e.g., aligned for in situ formation or disk migration versus misaligned for high-eccentricity tidal migration) or whether other m…
What Is Unusual About the Third Largest Geomagnetic Storm of Solar Cycle 24?
Gopalswamy, N.; Yashiro, S.; Mäkelä, P. +4 more
We report on the solar and interplanetary (IP) causes of the third largest geomagnetic storm (26 August 2018) in solar cycle 24. The underlying coronal mass ejection (CME) originating from a quiescent filament region becomes a 440 km/s magnetic cloud (MC) at 1 au after ∼5 days. The prolonged CME acceleration (for ∼24 hr) coincides with the time pr…
Ca II triplet spectroscopy of Small Magellanic Cloud red giants. V. Abundances and velocities for 12 massive clusters
Grebel, E. K.; Da Costa, G.; Geisler, D. +4 more
Aims: We aim to analyze the chemical evolution of the Small Magellanic Cloud, adding 12 additional clusters to our existing sample, based on accurate and homogeneously derived metallicities. We are particularly interested in seeing if there is any correlation between age and metallicity for the different structural components to which the clu…
A quarter century of spectroscopic monitoring of the nearby M dwarf Gl 514. A super-Earth on an eccentric orbit moving in and out of the habitable zone
Amado, P. J.; Caballero, J. A.; Reiners, A. +31 more
Context. Statistical analyses based on Kepler data show that most of the early-type M dwarfs host multi-planet systems consisting of Earth- to sub-Neptune-sized planets with orbital periods of up to ~250 days, and that at least one such planet is likely located within the habitable zone. M dwarfs are therefore primary targets to search for potenti…
The Nearby Evolved Stars Survey II: Constructing a volume-limited sample and first results from the James Clerk Maxwell Telescope
Kim, J.; Menten, K. M.; Marshall, J. P. +89 more
The Nearby Evolved Stars Survey (NESS) is a volume-complete sample of ~850 Galactic evolved stars within 3 kpc at (sub-)mm wavelengths, observed in the CO J = (2-1) and (3-2) rotational lines, and the sub-mm continuum, using the James Clark Maxwell Telescope and Atacama Pathfinder Experiment. NESS consists of five tiers, based on distances and dus…
SolO/EUI Observations of Ubiquitous Fine-scale Bright Dots in an Emerging Flux Region: Comparison with a Bifrost MHD Simulation
Tiwari, Sanjiv K.; De Pontieu, Bart; Berghmans, David +2 more
We report on the presence of numerous tiny bright dots in and around an emerging flux region (an X-ray/coronal bright point) observed with SolO's EUI/HRIEUV in 174 Å. These dots are roundish and have a diameter of 675 ± 300 km, a lifetime of 50 ± 35 s, and an intensity enhancement of 30% ± 10% above their immediate surroundings. About h…
Typhon: A Polar Stream from the Outer Halo Raining through the Solar Neighborhood
Martin, Nicolas; Famaey, Benoit; Viswanathan, Akshara +5 more
We report on the discovery in the Gaia DR3 astrometric and spectroscopic catalog of a new polar stream that is found as an overdensity in action space. This structure is unique as it has an extremely large apocenter distance, reaching beyond 100 kpc, and yet is detected as a coherent moving structure in the solar neighborhood with a width of ~4 kp…
γ Columbae as a recently stripped pulsating core of a massive star
Meynet, Georges; Przybilla, Norbert; Irrgang, Andreas
Stellar cores, that is, the central regions where densities and temperatures are high enough for nuclear fusion processes to take place, are usually covered by an opaque envelope. Only in very rare cases, stars may expose their cores, for example, when a tiny fraction of them evolve into Wolf-Rayet or helium hot subdwarf stars. However, for the va…
The Accretion Flow Geometry of MAXI J1820+070 through Broadband Noise Research with Insight Hard X-ray Modulation Telescope
Zhang, S.; Bu, Qing-Cui; Zhang, Liang +25 more
Here we present a detailed study of the broadband noise in the power density spectra of the black hole X-ray binary MAXI J1820+070 during the hard state of its 2018 outburst, using Hard X-ray Modulation Telescope observations. The broadband noise shows two main humps, which might separately correspond to variability from a variable disk and two Co…