Search Publications
K2-265 b: a transiting rocky super-Earth
Bouchy, F.; Deleuil, M.; Kirk, J. +34 more
We report the discovery of the super-Earth K2-265 b detected with K2 photometry. The planet orbits a bright (Vmag = 11.1) star of spectral type G8V with a period of 2.37 days. We obtained high-precision follow-up radial velocity measurements from HARPS, and the joint Bayesian analysis showed that K2-265 b has a radius of 1.71 ± 0.11 R
Dynamics of Intense Currents in the Solar Wind
Zelenyi, Lev M.; Angelopoulos, Vassilis; Artemyev, Anton V. +3 more
Transient currents in the solar wind are carried by various magnetic field discontinuities that contribute significantly to the magnetic field fluctuation spectrum. Internal instabilities and dynamics of these discontinuities are believed to be responsible for magnetic field energy dissipation and corresponding charged particle acceleration and he…
Constraining the geometry of the nuclear wind in PDS 456 using a novel emission model
Piro, L.; Fiore, F.; Piconcelli, E. +4 more
Context. Outflows from active galactic nuclei (AGN) are often invoked to explain the co-evolution of AGN and their host galaxies, and the scaling relations between the central black hole mass and the bulge velocity dispersion. Nuclear winds are often seen in the X-ray spectra through Fe K shell transitions and some of them are called ultra fast ou…
The 155-day X-ray cycle of the very massive Wolf-Rayet star Melnick 34 in the Large Magellanic Cloud
Crowther, P. A.; Pollock, A. M. T.; Townsley, Leisa K. +2 more
The Wolf-Rayet star Mk 34 was observed more than 50 times as part of the deep T-ReX Chandra ACIS-I X-ray imaging survey of the Tarantula Nebula in the Large Magellanic Cloud conducted between 2014 May and 2016 January. Its brightness showed one bright maximum and repeated faint minima which help define an X-ray recurrence time of 155.1 ± 0.1 d tha…
LHS 1610A: A Nearby Mid-M Dwarf with a Companion That Is Likely a Brown Dwarf
Latham, David W.; Berlind, Perry; Calkins, Michael L. +7 more
We present the spectroscopic orbit of LHS 1610A, a newly discovered single-lined spectroscopic binary with a trigonometric distance placing it at 9.9 ± 0.2 pc. We obtained spectra with the TRES instrument on the 1.5 m Tillinghast Reflector at the Fred Lawrence Whipple Observatory located on Mt. Hopkins in AZ. We demonstrate the use of the TiO mole…
A high-velocity component to the complex absorption in IRAS 13349+2438
Guainazzi, M.; Schartel, N.; Santos-Lleó, M. +4 more
We present an analysis of XMM-Newton spectra of the low-redshift quasar IRAS 13349+2438. The Reflection Grating Spectrometer spectrum shows a large number of absorption lines from two zones of warm absorption, with velocities of ∼-600 km s-1, as noted by previous authors. Additionally, we find robust evidence from multiple Lyα absorptio…
Revised Exoplanet Radii and Habitability Using Gaia Data Release 2
Wittenmyer, Robert A.; Horner, Jonathan; Wright, Duncan J. +4 more
Accurate stellar properties are crucial for determining exoplanet characteristics. Gaia DR2 presents revised distances, luminosities, and radii for 1.6 billion stars. Here, we report the calculation of revised radii and densities for 320 non-Kepler exoplanets using this data and present updated calculations of the incident flux received by 690 kno…
Understanding the HMI Pseudocontinuum in White-light Solar Flares
Kleint, Lucia; Kašparová, Jana; Jurčák, Jan +1 more
We analyze observations of the X9.3 solar flare (SOL2017-09-06T11:53) observed by SDO/HMI and Hinode/Solar Optical Telescope. Our aim is to learn about the nature of the HMI pseudocontinuum I c used as a proxy for the white-light continuum. From model atmospheres retrieved by an inversion code applied to the Stokes profiles observed by …
Metal abundances in hot white dwarfs with signatures of a superionized wind
Rauch, T.; Werner, K.; Kruk, J. W.
About a dozen hot white dwarfs with effective temperatures Teff = 65 000-120 000 K exhibit unusual absorption features in their optical spectra. These objects were tentatively identified as Rydberg lines of ultra-high excited metals in ionization stages v-x, indicating line formation in a dense environment with temperatures near 10…
Hubble Space Telescope Observations of Variations in Ganymede's Oxygen Atmosphere and Aurora
Milan, S. E.; Nichols, J. D.; Clarke, J. T. +7 more
We present high-sensitivity Hubble Space Telescope (HST) Cosmic Origins Spectrograph and HST Space Telescope Imaging Spectrograph measurements of atmospheric OI 130.4-nm and OI] 135.6-nm emissions at Ganymede, which exhibit significant spatial and temporal variability. These observations represent the first observations of Ganymede using HST Cosmi…