Search Publications
K2-19b and c are in a 3:2 Commensurability but out of Resonance: A Challenge to Planet Assembly by Convergent Migration
Espinoza, Néstor; Bayliss, Daniel; Fulton, Benjamin J. +11 more
K2-19b and c were among the first planets discovered by NASA’s K2 mission and together stand in stark contrast with the physical and orbital properties of the solar system planets. The planets are between the size of Uranus and Saturn at 7.0 ± 0.2 {R}\oplus and 4.1 ± 0.2 {R}\oplus , respectively, and reside a mere 0.1% outsi…
Dark dust and single-cloud sightlines in the ISM
Krełowski, J.; Siebenmorgen, R.; Bagnulo, S. +2 more
The precise characteristics of clouds and the nature of dust in the diffuse interstellar medium can only be extracted by inspecting the rare cases of single-cloud sightlines. In our nomenclature such objects are identified by interstellar lines, such as K I, that show at a resolving power of λ/Δλ ~ 75 000 one dominating Doppler component that acco…
Forecasting Chemical Abundance Precision for Extragalactic Stellar Archaeology
Ting, Yuan-Sen; Weisz, Daniel R.; Sandford, Nathan R.
Increasingly powerful and multiplexed spectroscopic facilities promise detailed chemical abundance patterns for millions of resolved stars in galaxies beyond the Milky Way (MW). Here, we employ the Cramér-Rao lower bound (CRLB) to forecast the precision to which stellar abundances for metal-poor, low-mass stars outside the MW can be measured for 4…
Source of Energetic Protons in the 2014 September 1 Sustained Gamma-ray Emission Event
Gopalswamy, N.; Yashiro, S.; Mäkelä, P. +3 more
We report on the source of >300 MeV protons during the SOL2014-09-01 sustained gamma-ray emission (SGRE) event based on multi-wavelength data from a wide array of space- and ground-based instruments. Based on the eruption geometry we provide concrete explanation for the spatially and temporally extended γ -ray emission from the eruption. We sho…
On the Ratios of Si IV Lines (λ1394/λ1403) in an Emerging Flux Region
Isobe, Hiroaki; Tripathi, Durgesh; Nived, V. N. +1 more
The resonance lines of Si IV formed at λ1394 and 1403 Å are the most critical for the diagnostics of the solar transition region in the observations of the Interface Region Imaging Spectrograph (IRIS). Studying the intensity ratios of these lines (1394 Å/1403 Å), which under optically thin conditions is predicted to be two, helps us to diagnose th…
Galactic Rotation Parameters Based on Stars from Active Star-Forming Regions with Data from the Gaia DR2 Catalogue
Bobylev, V. V.; Bajkova, A. T.; Krisanova, O. I.
We have studied a sample of more than 25 000 young stars with proper motions and trigonometric parallaxes from the Gaia DR2 catalogue. The relative errors of their parallaxes do not exceed 10$%$. The selection of stars belonging to active star-forming regions was made by Marton et al. based on data from the Gaia DR2 catalogue by invoking infrared …
The Extreme CNO-enhanced Composition of the Primitive Iron-poor Dwarf Star J0815+4729
Burgasser, Adam J.; Aguado, David S.; Allende Prieto, Carlos +2 more
We present an analysis of high-resolution Keck/HIRES spectroscopic observations of J0815+4729, an extremely carbon-enhanced, iron-poor dwarf star. These high-quality data allow us to derive a metallicity of [Fe/H] = -5.49 ± 0.14 from the three strongest Fe I lines and to measure a high [Ca/Fe] = 0.75 ± 0.14. The large carbon abundance of A(C) = 7.…
The interacting nature of dwarf galaxies hosting superluminous supernovae
Schulze, Steve; Leloudas, Giorgos; Man, Allison W. S. +3 more
Context. Type I superluminous supernovae (SLSNe I) are rare, powerful explosions whose mechanism and progenitors remain elusive. Several studies have shown a preference for SLSNe I to occur in low-metallicity, actively star-forming dwarf galaxies.
Aims: We investigate whether the host galaxies of SLSNe I show increased evidence for interactio…
Near-infrared variability in dusty white dwarfs: tracing the accretion of planetary material
Xu, Siyi; von Hippel, Ted; Su, Kate Y. L. +4 more
The inwards scattering of planetesimals towards white dwarfs is expected to be a stochastic process with variability on human time-scales. The planetesimals tidally disrupt at the Roche radius, producing dusty debris detectable as excess infrared emission. When sufficiently close to the white dwarf, this debris sublimates and accretes on to the wh…
SDSS J1004+4112: the case for a galaxy cluster dominated by primordial black holes
Hawkins, M. R. S.
Aims: This paper is aimed at providing a plausible explanation for the large amplitude microlensing events observed in the cluster-lensed quasar system, SDSS J1004+4112. The microlensed quasar images appear to lie well clear of the stellar population of the cluster, raising the possibility that the cluster dark matter is composed of compact b…