Search Publications
Geometric Corroboration of the Earliest Lensed Galaxy at z ≃ 10.8 from Robust Free-form Modelling
Broadhurst, Tom; Zitrin, Adi; Coe, Dan +4 more
A multiply lensed galaxy, MACS0647-JD, with a probable photometric redshift of z≃ {10.7}-0.4+0.6 is claimed to constitute one of the very earliest known galaxies, formed well before reionization was completed. However, spectral evidence that MACS0647-JD lies at high redshift has proven infeasible and so here we seek an indepe…
Ground-based monitoring of comet 67P/Churyumov-Gerasimenko gas activity throughout the Rosetta mission
Snodgrass, C.; Gillon, M.; Jehin, E. +5 more
Simultaneously to the ESA Rosetta mission, a world-wide ground-based campaign provided measurements of the large scale activity of comet 67P/Churyumov-Gerasimenko through measurement of optically active gas species and imaging of the overall dust coma. We present more than 2 yr of observations performed with the FORS2 low-resolution spectrograph a…
Spatially resolved near infrared observations of Enceladus' tiger stripe eruptions from Cassini VIMS
Nicholson, Philip D.; Hedman, Matthew M.; Clark, Roger N. +1 more
Particle properties of individual fissure eruptions within Enceladus' plume have been analyzed using high spatial resolution Visible and Infrared Mapping Spectrometer (VIMS) observations from the Cassini mission. To first order, the spectra of the materials emerging from Cairo, Baghdad and Damascus sulci are very similar, with a strong absorption …
Investigation of the Microtek Scanmaker 1000XL Plus Scanner of the Institute of Astrophysics of the Academy of Sciences of the Republic of Tajikistan
Andruk, V.; Yuldoshev, Q.; Mullo-Abdolov, A. +3 more
This work was done to estimate the accuracy of the processing method of photographic plates and the detailed study of the Microtek ScanMaker 1000XL Plus scanner, which plans to be used for the digitizing of about 1600 photographic plates of the Astrophysics Institute of the Academy of Sciences of the Republic of Tajikistan (Dushanbe) recorded for …
Fifteen years in the high-energy life of the solar-type star HD 81809. XMM-Newton observations of a stellar activity cycle
Schmitt, J. H. M. M.; Orlando, S.; Micela, G. +5 more
Context. The modulation of the activity level of solar-like stars is commonly revealed by cyclic variations in their chromospheric indicators, such as the Ca II H&K S-index, similarly to what is observed in our Sun. However, while the variation of solar activity is also reflected in the cyclical modulation of its coronal X-ray emission, simila…
Testing multimass dynamical models of star clusters with real data: mass segregation in three Galactic globular clusters
Dalessandro, E.; Beccari, G.; Pallanca, C. +1 more
We present the results of the analysis of deep photometric data for a sample of three Galactic globular clusters (NGC5466, NGC6218 and NGC 6981) with the aim of estimating their degree of mass segregation and testing the predictions of analytic dynamical models. The adopted data set, composed of both Hubble Space Telescope and ground-based data, r…
Transient Spiral Arms from Far Out-of-equilibrium Gravitational Evolution
Sylos Labini, Francesco; Benhaiem, David; Joyce, Michael
We describe how a simple class of out-of-equilibrium, rotating, and asymmetrical mass distributions evolve under their self-gravity to produce a quasi-planar spiral structure surrounding a virialized core, qualitatively resembling a spiral galaxy. The spiral structure is transient, but can survive tens of dynamical times, and further reproduces qu…
Evidence for Binarity and Possible Disk Obscuration in Kepler Observations of the Pulsating RV Tau Variable DF Cygni
Stassun, Keivan G.; Somers, Garrett; Vega, Laura D. +2 more
The Kepler light curve of DF Cyg is unparalleled in precision and cadence for any RV Tau star to date, spanning a baseline of ∼4 years and clearly displaying the signature pulsating behavior of alternating deep and shallow minima as well as the long-term trend indicative of an RVb-type variable. We measure DF Cyg’s formal period (the time interval…
Spontaneous hot flow anomalies at Mars and Venus
Zhang, Tielong; Futaana, Yoshifumi; Persson, Moa +8 more
We report the first observations of Spontaneous Hot Flow Anomalies (SHFAs) at Venus and Mars, demonstrating their existence in the foreshocks of other planets beyond Earth. Using data from the ESA Venus Express and the NASA Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft, we present magnetic and plasma observations from events at both pl…
Stars with fast Galactic rotation observed in Gaia TGAS: a signature driven by the Perseus arm?
Grand, Robert J. J.; Siebert, Arnaud; Famaey, Benoit +3 more
We report on the detection of a small overdensity of stars in velocity space with systematically higher Galactocentric rotation velocity than the Sun by about 20 km s-1 in the Gaia Data Release 1 Tycho-Gaia astrometric solution data. We find these fast Galactic rotators more clearly outside of the Solar radius, compared to inside of the…