Search Publications
The Solar-cycle Variations of the Anisotropy of Taylor Scale and Correlation Scale in the Solar Wind Turbulence
Zhou, G.; He, H. -Q.
The field-aligned anisotropy of the solar wind turbulence, which is quantified by the ratio of the parallel to the perpendicular correlation (and Taylor) length scales, is determined by simultaneous two-point correlation measurements during the time period 2001-2017. Our results show that the correlation scale along the magnetic field is the large…
Gaia EDR3 parallaxes of type I X-ray bursters and their implications on the models of type I X-ray bursts: A generic approach to the Gaia parallax zero point and its uncertainty
Deller, Adam T.; Miller-Jones, James C. A.; Ding, Hao
Light curves of photospheric radius expansion (PRE) bursts, a subset of type I X-ray bursts, have been used as standard candles to estimate the `nominal PRE distances' for 63% of PRE bursters (bursters), assuming PRE burst emission is spherically symmetric. Model-independent geometric parallaxes of bursters provide a valuable chance to test models…
Radial Velocity Monitoring of the Young Star Hubble 4: Disentangling Star-spot Lifetimes from Orbital Motion
Anderson, Jay; Johns-Krull, Christopher M.; Prato, L. +1 more
We studied the weak-lined T Tauri star Hubble 4, a known long-period binary, and its star-spot phenomena. We used optical radial velocity (RV) data taken over a span of 14 yr (2004-2010, 2017-2019) at the McDonald Observatory 2.7 m Harlan J. Smith Telescope and single epoch imaging from the Hubble Space Telescope (HST)/Wide Field Camera 3 instrume…
Understanding the Angular Momentum Evolution of T Tauri and Herbig Ae/Be Stars
Osorio, Yeisson; Hernández, Jesús; Roman-Lopes, Alexandre +8 more
We investigate a sample of six Herbig Ae/Be stars belonging to the Orion OB1 association, as well as 73 low-mass objects, members of the σ Orionis cluster, in order to explore the angular momentum evolution at early stages of evolution, and its possible connection with main-sequence Ap/Bp magnetic stars. Using FIES and HECTOCHELLE spectra, we obta…
Imaging from STIX visibility amplitudes
Massa, Paolo; Krucker, Säm; Piana, Michele +5 more
Aims: This study is aimed at providing the first demonstration of STIX Fourier-transform X-ray imaging using semi-calibrated (amplitude-only) visibility data acquired during Solar Orbiter's cruise phase.
Methods: We used a parametric imaging approach whereby STIX visibility amplitudes are fitted by means of two non-linear optimization me…
A lighter core for Phobos?
Li, Fei; Pätzold, Martin; Yan, Jianguo +7 more
Context. The origin of the Martian moons Phobos and Deimos is still poorly understood, and is the focus of intense debate.
Aims: We demonstrate that a stratified internal structure of Phobos is compatible with the observed gravity coefficients.
Methods: We fit previously derived C20 and C22 Phobos gravity coefficien…
A Rotating Azimuthally Distributed Auroral Current System on Saturn Revealed by the Cassini Spacecraft
Coates, A. J.; Krupp, N.; Dougherty, M. K. +14 more
Stunning aurorae are mainly produced when accelerated electrons travel along magnetic field lines to collide with the atmosphere. The motion of electrons often corresponds to the evolution of a magnetic field-aligned current system. In the terrestrial magnetosphere, the current system is formed at the night-side sector, and thus produces an aurora…
GG Carinae: orbital parameters and accretion indicators from phase-resolved spectroscopy and photometry
Grant, David; Porter, Augustus; Blundell, Katherine +1 more
B[e] supergiants are a rare and unusual class of massive and luminous stars, characterized by opaque circumstellar envelopes. GG Carinae is a binary whose primary component is a B[e] supergiant and whose variability has remained unsatisfactorily explained. Using photometric data from ASAS, OMC, and ASAS-SN and spectroscopic data from the Global Je…
Environments of a sample of AzTEC submillimetre galaxies in the COSMOS field
Finoguenov, A.; Aravena, M.; Barrufet, L. +2 more
Aims: Submillimetre galaxies (SMGs) are bright sources at submillimetre wavelengths (F850 µm > 2-5 mJy). Made up of mostly of high-z galaxies (z > 1), SMGs are amongst the most luminous dusty galaxies in the Universe. These galaxies are thought to be the progenitors of the massive elliptical galaxies in the local Univer…
Changes in granulation scales over the solar cycle seen with SDO/HMI and Hinode/SOT
Malherbe, J. M.; Roudier, T.; Ballot, J. +1 more
Context. The Sun is the only star where the superficial turbulent convection can be observed at very high spatial resolution. The Solar Dynamics Observatory (SDO) has continuously observed the full Sun from space with multi-wavelength filters since July 2010. In particular, the Helioseismic and Magnetic Imager (HMI) instrument takes high-cadence f…