Search Publications
Multipoint Study of Successive Coronal Mass Ejections Driving Moderate Disturbances at 1 au
Poedts, Stefaan; Scolini, Camilla; West, Matthew J. +10 more
We analyze in this work the propagation and geoeffectiveness of four successive coronal mass ejections (CMEs) that erupted from the Sun during 2013 May 21-23 and were detected in interplanetary space by the Wind and/or STEREO-A spacecraft. All these CMEs featured critical aspects for understanding so-called “problem space weather storms” at Earth.…
Metal-poor Stars Observed with the Automated Planet Finder Telescope. I. Discovery of Five Carbon-enhanced Metal-poor Stars from LAMOST
Zhao, Gang; Placco, Vinicius M.; Li, Haining +6 more
We report on the discovery of five carbon-enhanced metal-poor (CEMP) stars in the metallicity range of -3.3 < [Fe/H] < -2.4. These stars were selected from the LAMOST DR3 low-resolution (R ∼ 2000) spectroscopic database as metal-poor candidates and followed up with high-resolution spectroscopy (R ∼ 110,000) with the Lick/APF. Stellar paramet…
Spectral Evidence for Heating at Large Column Mass in Umbral Solar Flare Kernels. I. IRIS Near-UV Spectra of the X1 Solar Flare of 2014 October 25
Kowalski, Adam F.; De Pontieu, Bart; Kerr, Graham S. +5 more
The GOES X1 flare SOL2014-10-25T17:08:00 was a three-ribbon solar flare observed with the Interface Region Imaging Spectrograph (IRIS) in the near-UV (NUV) and far-UV. One of the flare ribbons crossed a sunspot umbra, producing a dramatic, ∼1000% increase in the NUV continuum radiation. We comprehensively analyze the UV spectral data of the umbral…
Clocking the assembly of double-barred galaxies with the MUSE TIMER project
Leaman, Ryan; Fragkoudi, Francesca; van de Ven, Glenn +11 more
The formation of two stellar bars within a galaxy has proved challenging for numerical studies. It is not yet clear whether the inner bar is born via a star formation process promoted by gas inflow along the outer bar or whether it is dynamically assembled from instabilities in a small-scale stellar disc. Observational constraints to these scenari…
Light Curves and Rotational Properties of the Pristine Cold Classical Kuiper Belt Objects
Thirouin, Audrey; Sheppard, Scott S.
We present a survey of the rotational and physical properties of the dynamically low inclination Cold Classical (CC) trans-Neptunian objects (TNOs). The CCs are primordial planetesimals and contain information about our solar system and planet formation over the first 100 million years after the Sun’s formation. We obtained partial/complete light …
Dust observations with antenna measurements and its prospects for observations with Parker Solar Probe and Solar Orbiter
Issautier, Karine; Meyer-Vernet, Nicole; Mann, Ingrid +10 more
The electric and magnetic field instrument suite FIELDS on board the NASA Parker Solar Probe and the radio and plasma waves instrument RPW on the ESA Solar Orbiter mission that explore the inner heliosphere are sensitive to signals generated by dust impacts. Dust impacts have been observed using electric field antennas on spacecraft since the 1980…
HAZMAT. V. The Ultraviolet and X-Ray Evolution of K Stars
Barman, Travis; Meadows, Victoria S.; Richey-Yowell, Tyler +3 more
Knowing the high-energy radiation environment of a star over a planet’s formation and evolutionary period is critical in determining if that planet is potentially habitable and if any biosignatures could be detected, as UV radiation can severely change or destroy a planet’s atmosphere. Current efforts for finding a potentially habitable planet are…
Discovery of a 21 Myr old stellar population in the Orion complex⋆
Lewis, Geraint F.; Buder, Sven; Ness, Melissa K. +12 more
Context. The Orion complex is arguably the most studied star-forming region in the Galaxy. While stars are still being born in the Orion nebula, the oldest part was believed to be no more than 13 Myr old.
Aims: In order to study the full hierarchy of star formation across the Orion complex, we perform a clustering analysis of the Ori OB1a reg…
Search for extra-tidal RR Lyrae stars in Milky Way globular clusters from Gaia DR2
Minniti, Dante; Singh, Harinder P.; Kundu, Richa
We used extra-tidal RR Lyrae stars to study the dynamics of Galactic globular clusters and know how effects like dynamical friction and tidal disruption affect these clusters. The Gaia DR2 catalogue for RR Lyrae stars (Clementini et al. 2018) is used along with the proper motions and tidal radii data for the globular clusters compiled from literat…
Stellar accelerations and the galactic gravitational field
Easther, Richard; Silverwood, Hamish
Typical stars in the Milky Way galaxy have velocities of hundreds of kilometres per second and experience gravitational accelerations of ∼10-10 m s-2, resulting in velocity changes of a few centimetres per second over a decade. Measurements of these accelerations would permit direct tests of the applicability of Newtonian dyn…