Search Publications
The relation between the turbulent Mach number and observed fractal dimensions of turbulent clouds
Klessen, Ralf S.; Federrath, Christoph; Schneider, Nicola +1 more
Supersonic turbulence is a key player in controlling the structure and star formation potential of molecular clouds (MCs). The three-dimensional (3D) turbulent Mach number, M, allows us to predict the rate of star formation. However, determining Mach numbers in observations is challenging because it requires accurate measurements of the velocity d…
A Discrete Set of Possible Transit Ephemerides for Two Long-period Gas Giants Orbiting HIP 41378
Omohundro, Mark; Vanderburg, Andrew; Hellier, Coel +22 more
In 2015, K2 observations of the bright (V = 8.9, K = 7.7) star HIP 41378 revealed a rich system of at least five transiting exoplanets, ranging in size from super-Earths to gas giants. The 2015 K2 observations only spanned 74.8 days, and the outer three long-period planets in the system were only detected with a single transit, so their orbital pe…
NuSTAR Measurement of Coronal Temperature in Two Luminous, High-redshift Quasars
Brandt, W. N.; Bianchi, S.; Cappi, M. +13 more
X-ray emission from the active galactic nucleus (AGN) is believed to be produced via Comptonization of optical/ultraviolet seed photons emitted by the accretion disk, upscattered by hot electrons in a corona surrounding the black hole. A critical compactness versus temperature threshold is predicted above which any increase in the source luminosit…
On the Nature of the Bright Core of Solar Coronal Mass Ejections
Chen, Y.; Song, H. Q.; Cheng, X. +5 more
Coronal mass ejections (CMEs) often exhibit the classic three-part structure in a coronagraph, i.e., the bright front, dark cavity, and bright core, which are traditionally considered as the manifestations of coronal plasma pileup, magnetic flux rope (MFR), and filament, respectively. However, a recent survey based on 42 CMEs all possessing the th…
The Pristine survey - VII. A cleaner view of the Galactic outer halo using blue horizontal branch stars
McConnachie, Alan W.; Martin, Nicolas; Venn, Kim A. +11 more
We use the Pristine survey CaHK narrow-band photometry, combined with the Sloan Digital Sky Survey (SDSS)ugr photometry, to provide a cleaner sample of blue horizontal branch stars in the Galactic halo out to large distances. We demonstrate a completeness of 91 per cent and a purity of 93 per cent with respect to available spectroscopic classifica…
PG 1610+062: a runaway B star challenging classical ejection mechanisms
Geier, S.; Heber, U.; Irrgang, A. +2 more
Hypervelocity stars are rare objects, mostly main-sequence (MS) B stars, traveling so fast that they will eventually escape from the Milky Way. Recently, it has been shown that the popular Hills mechanism, in which a binary system is disrupted via a close encounter with the supermassive black hole at the Galactic center, may not be their only ejec…
Evaluating the evidence of multipolar surface magnetic field in PSR J0108-1431
Arumugasamy, Prakash; Mitra, Dipanjan
PSR J0108-1431 is an old pulsar where the X-ray emission is expected to have a thermal component from the polar cap and a non-thermal component from the magnetosphere. Although the phase-integrated spectra are fit best with a single non-thermal component modelled with a power law (PL) of photon index Γ = 2.9, the X-ray pulse profiles do show the p…
GALEX absolute calibration and extinction coefficients based on white dwarfs
Genest-Beaulieu, C.; Bergeron, P.; Gianninas, A. +3 more
We use 1837 DA white dwarfs with high signal-to-noise ratio spectra and Gaia parallaxes to verify the absolute calibration and extinction coefficients for the Galaxy Evolution Explorer (GALEX). We use white dwarfs within 100 pc to verify the linearity correction to the GALEX data. We find that the linearity correction is valid for magnitudes brigh…
Face changing companion of the redback millisecond pulsar PSR J1048+2339
Takata, J.; Kong, A. K. H.; Hui, C. Y. +3 more
We present optical observations of the redback millisecond pulsar PSR J1048+2339, which is a 4.66 ms radio pulsar in a compact binary with an orbital period of six hours. We obtained high-quality light curves of PSR J1048+2339 with the Lulin 1 m Telescope. The system shows two distinct six-hour orbital modulations, in which an ellipsoidal modulati…
Super-Earths in the TW Hya disc
Pinte, Christophe; Price, Daniel J.; Mentiplay, Daniel
We test the hypothesis that the sub-millimetre thermal emission and scattered light gaps seen in recent observations of TW Hya are caused by planet-disc interactions. We perform global three-dimensional dusty smoothed particle hydrodynamics simulations, comparing synthetic observations of our models with dust thermal emission, CO emission, and sca…