scholarly journals Investigation of a sample of carbon-enhanced metal-poor stars observed with FORS and GMOS

2018 ◽  
Vol 614 ◽  
pp. A68 ◽  
Author(s):  
E. Caffau ◽  
A. J. Gallagher ◽  
P. Bonifacio ◽  
M. Spite ◽  
S. Duffau ◽  
...  
Keyword(s):  
Large Telescope ◽  
Low Resolution ◽  
Dwarf Stars ◽  
Population Statistics ◽  
European Southern Observatory ◽  
Carbon Abundance ◽  
Very Large Telescope ◽  
The Galaxy ◽  
Sizeable Fraction ◽  
Low Dispersion

Aims. Carbon-enhanced metal-poor (CEMP) stars represent a sizeable fraction of all known metal-poor stars in the Galaxy. Their formation and composition remains a significant topic of investigation within the stellar astrophysics community. Methods. We analysed a sample of low-resolution spectra of 30 dwarf stars, obtained using the visual and near UV FOcal Reducer and low dispersion Spectrograph for the Very Large Telescope (FORS/VLT) of the European Southern Observatory (ESO) and the Gemini Multi-Object Spectrographs (GMOS) at the GEMINI telescope, to derive their metallicity and carbon abundance. Results. We derived C and Ca from all spectra, and Fe and Ba from the majority of the stars. Conclusions. We have extended the population statistics of CEMP stars and have confirmed that in general, stars with a high C abundance belonging to the high C band show a high Ba-content (CEMP-s or -r/s), while stars with a normal C abundance or that are C-rich, but belong to the low C band, are normal in Ba (CEMP-no).

scholarly journals Optical linear polarization measurements of quasars obtained with the Very Large Telescope at Paranal Observatory

2018 ◽  
Vol 620 ◽  
pp. A68 ◽  
Author(s):  
D. Hutsemékers ◽  
B. Borguet ◽  
D. Sluse ◽  
V. Pelgrims
Keyword(s):  
Linear Polarization ◽  
Large Telescope ◽  
Polarization Measurements ◽  
Very Large Telescope ◽  
Low Dispersion

We report 87 previously unpublished optical linear polarization measurements of 86 quasars obtained in May and October 2008, and from April to July 2015 with the FOcal Reducer and low-dispersion Spectrographs FORS1 and FORS2 attached to the Very Large Telescope at the Paranal Observatory. Of the 86 quasars, 37 have p ≥ 0.6%, 9 have p ≥ 2%, and 1 has p ≥ 10%.

Spectroscopic anatomy of a meteor trail cross section with the European Southern Observatory Very Large Telescope

2004 ◽  
Vol 39 (4) ◽  
pp. 609-616 ◽  
Author(s):  
Peter Jenniskens ◽  
Emmanuel Jehin ◽  
Remi A. Cabanac ◽  
Christophe O. Laux ◽  
Iain D. Boyd
Keyword(s):  
Cross Section ◽  
Large Telescope ◽  
European Southern Observatory ◽  
Very Large Telescope ◽  
Meteor Trail

scholarly journals Chemical analysis of very metal-poor turn-off stars from SDSS-DR12

2018 ◽  
Vol 619 ◽  
pp. A10 ◽  
Author(s):  
P. François ◽  
E. Caffau ◽  
S. Wanajo ◽  
D. Aguado ◽  
M. Spite ◽  
...  
Keyword(s):  
Chemical Composition ◽  
First Generation ◽  
High Ratio ◽  
Sloan Digital Sky Survey ◽  
Carbon Abundance ◽  
Very Large Telescope ◽  
Medium Resolution ◽  
Sky Survey ◽  
The Galaxy ◽  
Very High

Context. The most metal-poor stars are the relics of the early chemical evolution of the Galaxy. Their chemical composition is an important tool to constrain the nucleosynthesis in the first generation of stars. The aim is to observe a sample of extremely metal-poor star (EMP stars) candidates selected from the Sloan Digital Sky Survey Data Release 12 (SDSS DR12) and determine their chemical composition. Aims. We obtain medium resolution spectra of a sample of six stars using the X-shooter spectrograph at the Very Large Telescope (VLT) and we used ATLAS models to compute the abundances. Methods. Five stars of the sample have a metallicity [Fe/H] between −2.5 dex and −3.2 dex. We confirm the recent discovery of SDSS J002314.00+030758.0 as a star with an extremely low [Fe/H] ratio. Assuming the α-enhancement [Ca/Fe] = +0.4 dex, we obtain [Fe/H] = −6.1 dex. Results. We could also determine its magnesium abundance and found that this star exhibits a very high ratio [Mg/Fe]≤ +3.60 dex assuming [Fe/H] = −6.13 dex. We determined the carbon abundance and found A(C) = 6.4 dex. From this carbon abundance, this stars belongs to the lower band of the A(C)–[Fe/H] diagram.

scholarly journals Unusual polarimetric properties for interstellar comet 2I/Borisov

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
S. Bagnulo ◽  
A. Cellino ◽  
L. Kolokolova ◽  
R. Nežič ◽  
T. Santana-Ros ◽  
...  
Keyword(s):  
Solar System ◽  
Physical Characteristics ◽  
Dust Particles ◽  
The Sun ◽  
Large Telescope ◽  
European Southern Observatory ◽  
Long Period ◽  
Very Large Telescope ◽  
Cometary Activity

AbstractSo far, only two interstellar objects have been observed within our Solar System. While the first one, 1I/‘Oumuamua, had asteroidal characteristics, the second one, 2I/Borisov, showed clear evidence of cometary activity. We performed polarimetric observations of comet 2I/Borisov using the European Southern Observatory Very Large Telescope to derive the physical characteristics of its coma dust particles. Here we show that the polarization of 2I/Borisov is higher than what is typically measured for Solar System comets. This feature distinguishes 2I/Borisov from dynamically evolved objects such as Jupiter-family and all short- and long-period comets in our Solar System. The only object with similar polarimetric properties as 2I/Borisov is comet C/1995 O1 (Hale-Bopp), an object that is believed to have approached the Sun only once before its apparition in 1997. Unlike Hale-Bopp and many other comets, though, comet 2I/Borisov shows a polarimetrically homogeneous coma, suggesting that it is an even more pristine object.

scholarly journals Keck and European Southern Observatory Very Large Telescope View of the Symmetry of the Ejecta of the XRF/SN 2006aj

2007 ◽  
Vol 661 (2) ◽  
pp. 892-898 ◽  
Author(s):  
Paolo A. Mazzali ◽  
Ryan J. Foley ◽  
Jinsong Deng ◽  
Ferdinando Patat ◽  
Elena Pian ◽  
...  
Keyword(s):  
Large Telescope ◽  
European Southern Observatory ◽  
Very Large Telescope
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