Search Publications
Jeans that fit: weighing the mass of the Milky Way analogues in the ΛCDM universe
Sharma, Sanjib; Driver, Simon P.; Robotham, Aaron S. G. +2 more
The spherical Jeans equation is a widely used tool for dynamical study of gravitating systems in astronomy. Here, we test its efficacy in robustly weighing the mass of Milky Way analogues, given they need not be in equilibrium or even spherical. Utilizing Milky Way stellar haloes simulated in accordance with Λ cold dark matter (ΛCDM) cosmology by …
First astrometric reduction of Cassini Imaging Science Subsystem images using an automatic procedure: application to Enceladus images 2013-2017
Cooper, N. J.; Lainey, V.; Vienne, A. +3 more
We provide new astrometric observations of Enceladus from images taken using the Cassini Imaging Science Subsystem (ISS) Narrow-Angle Camera. Astrometric reduction was performed using a new fully automatic camera repointing technique built within the CAVIAR software package. The new automatic procedure is based on the k-d tree technique and has be…
Mapping the Kinematically Decoupled Core in NGC 1407 with MUSE
Coccato, Lodovico; Johnston, Evelyn J.; Hau, George K. T. +1 more
Studies of the kinematics of NGC 1407 have revealed complex kinematical structure, consisting of the outer galaxy, an embedded disc within a radius of ∼60 arcsec, and a kinematically decoupled core (KDC) with a radius of less than 30 arcsec. However, the size of the KDC and the amplitude of the kinematic misalignment it induces have not yet been d…
An off-axis galaxy cluster merger: Abell 0141
Caglar, Turgay
We present structural analysis results of Abell 0141 (z = 0.23) based on X-ray data. The X-ray luminosity map demonstrates that Abell 0141 (A0141) is a bimodal galaxy cluster, which is separated on the sky by ∼0.65 Mpc with an elongation along the north-south direction. The optical galaxy density map also demonstrates this bimodality. We estimate …
Survival function analysis of planet size distribution with Gaia Data Release 2 updates
Vanderburg, Andrew; Zeng, Li; Sasselov, Dimitar D. +1 more
Applying the survival function analysis to the planet radius distribution of the Kepler confirmed/candidate planets, we have identified two natural divisions of planet radius at 4 Earth radii (R⊕) and 10 R⊕. These divisions place constraints on planet formation and interior structure model. The division at 4 R⊕ sep…
Periodic optical variability and debris accretion in white dwarfs: a test for a causal connection*
Maoz, Dan; Loeb, Abraham; Hallakoun, Na'ama +9 more
Recent Kepler photometry has revealed that about half of white dwarfs (WDs) have periodic, low-level (∼10-4 - 10-3), optical variations. Hubble Space Telescope (HST) ultraviolet spectroscopy has shown that up to about one half of WDs are actively accreting rocky planetary debris, as evidenced by the presence of photospheric m…
Pre-discovery transits of the exoplanets WASP-18b and WASP-33b from Hipparcos
McDonald, I.; Kerins, E.
We recover transits of WASP-18b and WASP-33b from Hipparcos (1989-1993) photometry. Marginal detections of HAT-P-56b and HAT-P-2b may be also present in the data. New ephemerides are fitted to WASP-18b and WASP-33b. A tentative (∼1.3σ) orbital decay is measured for WASP-18b, but the implied tidal quality factor (Q΄ ∼ 5 × 105)…
A distance estimate to the Cygnus Loop based on the distances to two stars located within the remnant
Neustadt, Jack M. M.; Milisavljevic, Dan; Fesen, Robert A. +1 more
Underlying nearly every quantitative discussion of the Cygnus Loop supernova remnant is uncertainty about its distance. Here, we present optical images and spectra of nebulosities around two stars whose mass-loss material appears to have interacted with the remnant's expanding shock front and thus can be used to estimate the Cygnus Loop's distance…
NuSTAR rules out a cyclotron line in the accreting magnetar candidate 4U2206+54
Reig, P.; Torrejón, J. M.; Postnov, K. +3 more
Based on our new NuSTAR X-ray telescope data, we rule out any cyclotron line up to 60 keV in the spectra of the high-mass X-ray binary 4U2206+54. In particular, we do not find any evidence of the previously claimed line around 30 keV, independently of the source flux, along the spin pulse. The spin period has increased significantly, since the las…
Exploring the spectral variability of the Seyfert 1.5 galaxy Markarian 530 with Suzaku
Gallo, L. C.; Gonzalez, A. G.; Ehler, H. J. S.
A 2012 Suzaku observation of the Seyfert 1.5 galaxy Markarian 530 was analysed and found to exhibit two distinct modes of variability, which were found to be independent from one another. First, the spectrum undergoes a smooth transition from a soft to hard spectrum. Secondly, the spectrum displays more rapid variability seemingly confined to a ve…