Search Publications
A Differential Abundance Analysis of Very Metal-poor Stars
McWilliam, Andrew; Chaboyer, Brian; O'Malley, Erin M. +1 more
We have performed a differential line-by-line chemical abundance analysis, ultimately relative to the Sun, of nine very metal-poor main-sequence (MS) halo stars, near [Fe/H] = -2 dex. Our abundances range from -2.66≤slant [{Fe}/{{H}}]≤slant -1.40 dex with conservative uncertainties of 0.07 dex. We find an average [α/Fe] = 0.34 ± 0.09 dex, typical …
Modelling of the outburst on 2015 July 29 observed with OSIRIS cameras in the Southern hemisphere of comet 67P/Churyumov-Gerasimenko
Jorda, L.; Lamy, P. L.; Lara, L. M. +60 more
Images of the nucleus and the coma (gas and dust) of comet 67P/Churyumov- Gerasimenko have been acquired by the OSIRIS (Optical, Spectroscopic and Infrared Remote Imaging System) cameras since 2014 March using both the wide-angle camera and the narrow-angle camera (NAC). We use images from the NAC camera to study a bright outburst observed in the …
MACS J0553.4-3342: a young merging galaxy cluster caught through the eyes of Chandra and HST
Raychaudhury, Somak; Navale, Nilam R.; Pandge, M. B. +6 more
We present a detailed analysis of a young merging galaxy cluster MACS J0553.4-3342 (z=0.43) from Chandra X-ray and Hubble Space Telescope archival data. X-ray observations confirm that the X-ray emitting intra-cluster medium (ICM) in this system is among the hottest (average T = 12.1 ± 0.6 keV) and most luminous known. Comparison of X-ray and opti…
Stringent limits on the masses of the supermassive black holes in seven nearby galaxies
Morelli, L.; Beifiori, A.; Dalla Bontà, E. +6 more
We present new stringent limits on the mass M• of the central supermassive black hole for a sample of seven nearby galaxies. Our M• estimates are based on the dynamic modeling of the central width of the nebular emission lines measured over sub-arcsecond apertures with the Hubble Space Telescope. The central stellar velocity …
Metallicity calibration and photometric parallax estimation: II. SDSS photometry
Bilir, S.; Ak, T.; Karaali, S. +4 more
We used the updated [Fe/H] abundances of 168 F-G type dwarfs and calibrated them to a third order polynomial in terms of reduced ultraviolet excess,
Statistical study of low-frequency magnetic field fluctuations near Venus during the solar cycle
Zhang, T. L.; Wang, G. Q.; Xiao, S. D.
We statistically investigate the solar cycle dependence of the magnetic field fluctuations in the frequency range 30-300 MHz based on Venus Express data. We present the spatial distributions of fluctuation properties during three typical periods of the solar cycle, and a comparative study is also performed. With the increase of solar activity, the…
Spectral moments for the analysis of frequency shift, broadening, and wavevector anisotropy in a turbulent flow
Narita, Y.
Turbulence represents essentially random fluctuations that evolve both spatially and temporally, and appear in various geophysical and space science applications. A spectral moment method is proposed to characterize the turbulence energy spectra in the wavevector and frequency domain in the lowest-order sense. The frequency shift velocity and the …
The JCMT Gould Belt Survey: A First Look at SCUBA-2 Observations of the Lupus I Molecular Cloud
White, G. J.; Di Francesco, J.; Marsh, K. +50 more
This paper presents observations of the Lupus I molecular cloud at 450 and 850 µm with Submillimetre Common User Bolometer Array (SCUBA-2) as part of the James Clerk Maxwell Telescope Gould Belt Survey (JCMT GBS). Nine compact sources, assumed to be the discs of young stellar objects (YSOs), 12 extended protostellar, pre-stellar and starless…
On the ancient field blue straggler HR 5455
Fuhrmann, Klaus; Chini, Rolf
We report the discovery of HR 5455 as an ancient field blue straggler that upon Roche lobe overflow from its evolved companion, now a white dwarf, has been rejuvenated to a MBS = 1.32 ± 0.05 M⊙ bright F6V source with a purported age of τ ≃ 1.7 Gyr. The unequivocal evidence for HR 5455 being instead a τ ≃ 12 Gyr old Population…
The nearby spiral density-wave structure of the Galaxy
Hou, Li-Gang; Jiang, Ing-Guey; Griv, Evgeny
Accurate measurements of distances and line-of-sight velocities of 19291 intermediate-old giant stars in the near-infrared with typical uncertainties in the distances and velocities of 5 per cent and 0.1 km s-1 have recently been carried out to examine the Galactic disc with the APOGEE survey. In the framework of the Lin-Shu density-wav…