Search Publications
Formation of coarse sediment lags in ice-sediment mixtures: A geomorphic signature of sublimation on regolith surfaces
Levy, Joseph S.; Aylward, Daniel S.; Schmidt, Logan M.
In many high-latitude locations on Mars, boulder sized clasts are present at the ground surface atop finer-grained sediments. These areas are concentrated in the latitude dependent mantle (LDM), an ice-rich surface unit that is globally distributed polewards of ∼30° latitude. Here, we test the hypothesis that sublimation of buried ice can drive gr…
Observational constraints on the magnetic field of the bright transient Be/X-ray pulsar SXP 4.78
Tsygankov, Sergey S.; Lutovinov, Alexander A.; Poutanen, Juri +4 more
We report results of the spectral and timing analysis of the Be/X-ray pulsar SXP 4.78 using the data obtained during its recent outburst with NuSTAR, Swift, Chandra, and NICER observatories. Using an overall evolution of the system luminosity, spectral analysis, and variability power spectrum we obtain constraints on the neutron star magnetic fiel…
Hubble Space Telescope Far-UV Spectroscopy of the Short Orbital Period Recurrent Nova CI Aql: Implications for White Dwarf Mass Evolution
Williams, Robert E.; Wilson, R. E.; Sion, Edward M. +3 more
An Hubble Space Telescope Cosmic Object Spectrograph Far UV spectrum (1170 Å to 1800 Å) was obtained for the short orbital period recurrent novae (T Pyxidis subclass), CI Aquilae. CI Aql is the only classical Cataclysmic variable (CV) known to have two eclipses of a sensible depth per orbit cycle and also to have pre- and post-outburst light curve…
MHD simulation of the solar wind flow around the coma of comet Churyumov-Gerasimenko during Rosetta's flyby
Baranov, V. B.; Alexashov, D. B.; Lebedev, M. G.
The magnetohydrodynamic (MHD) model of the interaction between the solar wind and a cometary ionosphere is applied to investigate certain peculiar features of the solar wind flow around comet Churyumov-Gerasimenko during Rosetta's flyby at this comet. The model accounts for photoionization of the neutral component of the cometary outflow and the r…
A method to analyse velocity structure
Arnold, Becky; Goodwin, Simon P.
We present a new method of analysing and quantifying velocity structure in star-forming regions suitable for the rapidly increasing quantity and quality of stellar position-velocity data. The method can be applied to data in any number of dimensions, does not require the centre or characteristic size (e.g. radius) of the region to be determined, a…
Correcting Parker Solar Probe Electron Measurements for Spacecraft Magnetic and Electric Fields
Whittlesey, Phyllis; Kasper, Justin; Larson, Davin +2 more
The spacecraft body of the Parker Solar Probe may interfere with electron measurements in two ways. The first is the presence of several permanent magnets near the Solar Probe Analyzers (SPAN) instruments. The second is the widely varying spacecraft potential. We estimate the effect of these interferences by performing particle tracing simulations…
An enigmatic hump around 30 keV in Suzaku spectra of Aquila X-1 in the hard state
Makishima, Kazuo; Tamagawa, Toru; Nakano, Toshio +4 more
The typical accreting neutron star, Aquila X-1, was observed with Suzaku seven times in the decay phase of an outburst in 2007 September-October. Among them, the second to the fourth observations were performed 10 to 22 days after the outburst peak, when the source was in the hard state with a luminosity of 2 × 1036 erg s-1. …
Discovery and Identification of MAXI J1621-501 as a Type I X-Ray Burster with a Super-orbital Period
Göğüş, Ersin; Bahramian, Arash; Chakrabarty, Deepto +26 more
MAXI J1621-501 is the first Swift/XRT Deep Galactic Plane Survey transient that was followed up with a multitude of space missions (NuSTAR, Swift, Chandra, NICER, INTEGRAL, and MAXI) and ground-based observatories (Gemini, IRSF, and ATCA). The source was discovered with MAXI on 2017 October 19 as a new, unidentified transient. Further observations…
Early science with the Large Millimetre Telescope: new mm-wave detections of circumstellar discs in IC 348 from LMT/AzTEC
Gutermuth, Robert A.; Lane, James; Wilson, Grant W. +2 more
We present the most complete sample of mm measurements of protoplanetary discs in the star-forming region IC 348 to date. New observations from the Large Millimetre Telescope and the 1.1 mm camera AzTEC are combined with literature results in order to characterize the disc population as relating to both stellar properties within the IC 348 region …
Search for Evolutionary Changes in the Periods of Cepheids: BY Cas
Berdnikov, L. N.
For the low-amplitude Cepheid BY Cas we have constructed an O - C diagram spanning a time interval 123 years. The O - C diagram has the shape of a parabola, which has made it possible to determine for the first time the quadratic light elements and to calculate the rate of evolutionary increase in the period, dP/dt = +0.985 (±0.091) s yr-1