Characterization of the Zonal Wind Flow in the Upper Atmosphere of Titan with the VLT

We present Li, Na, Al, and Fe abundances of 199 lower red giant branch star members of the stellar system Omega Centauri, using high-resolution spectra acquired with FLAMES at the Very Large Telescope. The A(Li) distribution is peaked at A(Li) ∼ 1 dex with a prominent tail towards lower values. The peak of the distribution well agrees with the lithium abundances measured in lower red giant branch stars in globular clusters and Galactic field stars. Stars with A(Li) ∼ 1 dex are found at metallicities lower than [Fe/H] ∼ –1.3 dex but they disappear at higher metallicities. On the other hand, Li-poor stars are found at all metallicities. The most metal-poor stars exhibit a clear Li–Na anti-correlation, where about 30% of the sample have A(Li) lower than ∼0.8 dex, while these stars represent a small fraction of normal globular clusters. Most of the stars with [Fe/H] > –1.6 dex are Li poor and Na rich. The Li depletion measured in these stars is not observed in globular clusters with similar metallicities and we demonstrate that it is not caused by the proposed helium enhancements and/or young ages. Hence, these stars formed from a gas already depleted in lithium. Finally, we note that Omega Centauri includes all the populations (Li-normal/Na-normal, Li-normal/Na-rich, and Li-poor/Na-rich stars) observed, to a lesser extent, in mono-metallic GCs.

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Weak metal lines in optical high-resolution Very Large Telescope and Keck spectra of “cool” PG 1159 stars

Astronomy and Astrophysics ◽

10.1051/0004-6361/201424051 ◽

2014 ◽

Vol 569 ◽

pp. A99 ◽

Cited By ~ 6

Author(s):

K. Werner ◽

T. Rauch

Keyword(s):

High Resolution ◽

Large Telescope ◽

Very Large Telescope

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Interstellar Matter with Very Large Telescopes

International Astronomical Union Colloquium ◽

10.1017/s0252921100108772 ◽

1984 ◽

Vol 79 ◽

pp. 675-678

Author(s):

J. Lequeux

Keyword(s):

High Resolution ◽

Absorption Lines ◽

High Resolution Spectroscopy ◽

Interstellar Matter ◽

Large Telescope ◽

Interstellar Absorption ◽

Near Ir ◽

Very Large Telescope ◽

Large Telescopes ◽

Diffuse Matter

Interstellar matter is certainly one of the fields where a very large telescope (VLT) will prove to be most fruitful. This includes (somewhat paradoxically, but this will be explained later) the study of extended emissions. I will now examine in turn the different domains of interest for a VLT.I. Neutral diffuse matterOptical and near IR observations will mainly contribute to this domain through high-resolution spectroscopy of interstellar absorption lines in the spectra of stars. These lines are resonant lines of atoms (NaI, KI, etc.) or ions (CaII, TiII, etc.) as well as of some molecules (CH+, CH, CN, CS+, C2 in the near IR). Clearly this kind of study is always photon - limited; a VLT will collect more photons than present telescopes, thus increase the possibilities considerably.

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Speckle Interferometry, Speckle Masking, Speckle Spectroscopy and Speckle Frame Selection

International Astronomical Union Colloquium ◽

10.1017/s0252921100108498 ◽

1984 ◽

Vol 79 ◽

pp. 337-345 ◽

Cited By ~ 1

Author(s):

Gerd Weigelt

Keyword(s):

High Resolution ◽

Speckle Interferometry ◽

Large Telescope ◽

Speckle Imaging ◽

Frame Selection ◽

Very Large Telescope

AbstractHigh-resolution speckle imaging is one of the most fascinating possibilities of a Very Large Telescope (VLT). Various speckle methods can yield a resolution of about 0.01" with a 8-m to 10-m VLT. As exiting as the resolution is the limiting magnitude of the speckle methods. The limiting magnitude is extremely seeingdependent. The following limiting magnitudes are possible with speckle interferometry, speckle masking and speckle spectroscopy:4" seeing: limiting magnitude 152" seeing: limiting magnitude 17.51" seeing: limiting magnitude 20 (!)

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Surface properties of icy transneptunian objects from the second ESO large program

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310001729 ◽

2009 ◽

Vol 5 (S263) ◽

pp. 186-191

Author(s):

Francesca E. DeMeo ◽

Maria Antonietta Barucci ◽

Alvaro Alvarez-Candal ◽

Catherine de Bergh ◽

Sonia Fornasier ◽

...

Keyword(s):

Solar System ◽

Surface Properties ◽

New Technology ◽

Outer Solar System ◽

Large Telescope ◽

Very Large Telescope ◽

Large Program ◽

Transneptunian Objects ◽

Photometric Color

AbstractAn analysis is well underway for the data from the second Large Program (PI M. A. Barucci) dedicated to investigating the surface properties of Centaurs and Transneptunian objects through spectroscopic, photometric color, lightcurve, and polarimetric observations using the European Southern Observatory (ESO) Very Large Telescope (VLT) and New Technology Telescope (NTT). 45 objects were observed between 2006 and 2008, allowing a broad characterization of at least the largest and brightest objects among this population. In this report, we summarize all our findings, but focus on the analysis of the presence of ices such as methane, ethane, nitrogen, ammonia hydrate, methanol, and particularly H2O which is so abundant throughout the outer solar system.

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High-Resolution Spectroscopy from 3050 to 10000 Å of the Hubble Deep Field South QSO J2233−606 with UVES at the ESO Very Large Telescope

The Astronomical Journal ◽

10.1086/301575 ◽

2000 ◽

Vol 120 (4) ◽

pp. 1648-1653 ◽

Cited By ~ 18

Author(s):

S. Cristiani ◽

V. D’Odorico

Keyword(s):

High Resolution ◽

High Resolution Spectroscopy ◽

Large Telescope ◽

Very Large Telescope ◽

Hubble Deep Field

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Detection and characterization of two VLM binaries: LP 1033-31 and LP 877-72

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2173 ◽

2020 ◽

Vol 498 (1) ◽

pp. 737-749

Author(s):

Subhajeet Karmakar ◽

A S Rajpurohit ◽

F Allard ◽

D Homeier

Keyword(s):

Adaptive Optics ◽

Spectral Type ◽

Near Infrared ◽

Binding Energies ◽

Secondary Component ◽

Large Telescope ◽

Very Large Telescope ◽

Adaptive Optics Imaging ◽

M Dwarf

ABSTRACT Using the high-resolution near-infrared adaptive optics imaging from the NaCo instrument at the Very Large Telescope, we report the discovery of a new binary companion to the M-dwarf LP 1033-31 and also confirm the binarity of LP 877-72. We have characterized both the stellar systems and estimated the properties of their individual components. We have found that LP 1033-31 AB with the spectral type of M4.5+M4.5 has a projected separation of 6.7 ± 1.3 AU. Whereas with the spectral type of M1+M4, the projected separation of LP 877-72 AB is estimated to be 45.8 ± 0.3 AU. The binary companions of LP 1033-31 AB are found to have similar masses, radii, effective temperatures, and log g with the estimated values of 0.20 ± 0.04 $\rm {M}_{\odot }$, 0.22 ± 0.03 $\rm {R}_{\odot }$, and 3200 K, 5.06 ± 0.04. However, the primary of LP 877-72 AB is found to be twice as massive as the secondary with the derived mass of 0.520 ± 0.006 $\rm {M}_{\odot }$. The radius and log g for the primary of LP 877-72 AB are found to be 1.8 and 0.95 times that of the secondary component with the estimated values of 0.492 ± 0.011 $\rm {R}_{\odot }$ and 4.768 ± 0.005, respectively. With an effective temperature of 3750 ± 15 K, the primary of LP 877-72 AB is also estimated to be ∼400 K hotter than the secondary component. We have also estimated the orbital period of LP 1033-31 and LP 877-72 to be ∼28 and ∼349 yr, respectively. The binding energies for both systems are found to be >1043 erg, which signifies that both systems are stable.

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Characterization of the ground layer of turbulence at Paranal using a robotic SLODAR system

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz3498 ◽

2019 ◽

Vol 492 (1) ◽

pp. 934-949

Author(s):

T Butterley ◽

R W Wilson ◽

M Sarazin ◽

C M Dubbeldam ◽

J Osborn ◽

...

Keyword(s):

Vertical Profile ◽

Ground Level ◽

Ground Layer ◽

Weak Turbulence ◽

Large Telescope ◽

Active Optics ◽

Very Large Telescope ◽

Statistical Results ◽

Good Agreement

ABSTRACT We describe the implementation of a robotic SLODAR instrument at the Cerro Paranal observatory. The instrument measures the vertical profile of the optical atmospheric turbulence strength, in 8 resolution elements, to a maximum altitude ranging between 100 and 500 m. We present statistical results of measurements of the turbulence profile on a total of 875 nights between 2014 and 2018. The vertical profile of the ground layer of turbulence is very varied, but in the median case most of the turbulence strength in the ground layer is concentrated within the first 50 m altitude, with relatively weak turbulence at higher altitudes up to 500 m. We find good agreement between measurements of the seeing angle from the SLODAR and from the Paranal DIMM seeing monitor, and also for seeing values extracted from the Shack–Hartmann active optics sensor of Very Large Telescope (VLT) Unit Telescope 1 (UT1), adjusting for the height of each instrument above ground level. The SLODAR data suggest that a median improvement in the seeing angle from 0.689 to 0.481 arcsec at wavelength 500 nm would be obtained by fully correcting the ground-layer turbulence between the height of the UTs (taken as 10 m) and altitude 500 m.

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