1,461 research outputs found
High resolution near-IR spectra of NGC 6624 and NGC 6569
We present the first abundances analysis based on high-resolution infrared
(IR) echelle spectra of NGC 6569 and NGC 6624, two moderately reddened globular
clusters located in the outer bulge of the Galaxy. We find
[Fe/H]=-0.790.02 dex and [Fe/H]=-0.690.02 dex for NGC 6569 and NGC
6624, respectively and an average -elements enhancement of
+0.430.02 dex and +0.390.02 dex, consistent with previous
measurements on other metal-rich Bulge clusters. We measure accurate radial
velocities of and
and velocity dispersions of and for NGC 6569 and NGC 6624, respectively. Finally, we find very low
isotopics ratio (7 in NGC 6624 and 5 in NGC
6569), confirming the presence extra-mixing mechanisms during the red giant
branch evolution phase.Comment: 7 pages, 3 figures, accepted for publication on MNRA
Detailed abundances for M giants in two inner bulge fields from Infrared Spectroscopy
We report abundance analysis for 30 M giant stars in two inner Galactic bulge
fields at (l,b)=(0,-1.75) deg and at (l,b)=(1,-2.65) deg, based on R=25,000
infrared spectroscopy from 1.5-1.8um using NIRSPEC at the Keck II telescope. We
find iron abundances of =-0.16 +/- 0.03 dex with a 1-sigma dispersion
of 0.12 +/- 0.02 and =-0.21 +/- 0.02 dex, with a 1-sigma dispersion of
0.09+/- 0.016 for the (l,b)=(0,-1.75) and (l,b)=(1,-2.65) deg fields,
respectively. In agreement with all prior studies, we find enhanced [alpha/Fe]
of +0.3 dex. We confirm the lack of any major vertical abundance or composition
gradient in the innermost ~600 pc between Baade's window and 150 pc from the
Galactic plane. We also confirm that the known enhancement of alpha elements
observed between 500 and 1000 pc from the nucleus is also present over the
volume of the inner bulge and may therefore be presumed to be a general
characteristic of bulge/bar stars within 1 kpc of the Galactic Center.Comment: Accepted for publication in the Astrophysical Journal. 27 pages
manuscript format, 6 figure
Near-Infrared photometry and spectroscopy of NGC 6539 and UKS 1: two intermediate metallicity Bulge Globular Clusters
Using the SofI imager at ESO/NTT and NIRSPEC spectrograph at KeckII, we have
obtained J,K images and echelle spectra covering the range 1.5 - 1.8 micron for
the intermediate metallicity Bulge globular clusters NGC6539 and UKS1. We find
[Fe/H]=-0.76 and -0.78, respectively, and an average alpha-enhancement of +0.44
dex and +0.31 dex, consistent with previous measurements of metal rich Bulge
clusters, and favoring the scenario of rapid chemical enrichment. We also
measure very low 12C/13C=4.5 +/-1 isotopic ratios in both clusters, suggesting
that extra-mixing mechanisms due to cool bottom processing are at work during
the evolution along the Red Giant Branch. Finally, we measure accurate radial
velocities of =+31 +/-4Km/s and =+57 +/-6Km/s and velocity dispersion
of about 8 Km/s and 11 Km/s for NGC6539 and UKS1, respectively.Comment: 10 pages, 7 figures, accepted for publication at MNRA
High resolution infrared spectra of NGC 6440 and NGC 6441: two massive Bulge Globular Clusters
Using the NIRSPEC spectrograph at Keck II, we have obtained infrared echelle
spectra covering the 1.5-1.8 micron range for giant stars in the massive bulge
globular clusters NGC6440 and NGC6441. We report the first high dispersion
abundance for NGC6440, [Fe/H]=-0.56+/-0.02 and we find [Fe/H]=-0.50+/-0.02 for
the blue HB cluster NGC6441. We measure an average -enhancement of
~+0.3 dex in both clusters, consistent with previous measurements of other
metal rich bulge clusters, and favoring the scenario of a rapid bulge formation
and chemical enrichment. We also measure very low 12C/13C isotopic ratios
(~5+/- 1), suggesting that extra-mixing mechanisms are at work during evolution
along the Red Giant Branch also in the high metallicity regime. We also measure
Al abundances, finding average [Al/Fe]=0.45+/-0.02 and [Al/Fe]=0.52+/-0.02 in
NGC6440 and NGC6441, respectively, and some Mg-Al anti-correlation in NGC6441.
We also measure radial velocities vr=-76+/-3 km/s and vr=+14+/-3 km/s and
velocity dispersions sigma=9+/-2 km/s and sigma=10+/-2 km/s, in NGC6440 and
NGC6441, respectively.Comment: 8 pages, 7 figure
Locally conformally K\"ahler structures on four-dimensional solvable Lie algebras
We classify and investigate locally conformally K\"ahler structures on
four-dimensional solvable Lie algebras up to linear equivalence. As an
application we can produce many examples in higher dimension, here including
lcK structures on Oeljeklaus-Toma manifolds, and we also give a geometric
interpretation of some of the -dimensional structures in our classification.Comment: Minor modifications added to the second version. To appear in Complex
Manifold
Exploiting Recurring Patterns to Improve Scalability of Parking Availability Prediction Systems
Parking Guidance and Information (PGI) systems aim at supporting drivers in finding suitable parking spaces, also by predicting the availability at driver’s Estimated Time of Arrival (ETA), leveraging information about the general parking availability situation. To do these predictions, most of the proposals in the literature dealing with on-street parking need to train a model for each road segment, with significant scalability issues when deploying a city-wide PGI. By investigating a real dataset we found that on-street parking dynamics show a high temporal auto-correlation. In this paper we present a new processing pipeline that exploits these recurring trends to improve the scalability. The proposal includes two steps to reduce both the number of required models and training examples. The effectiveness of the proposed pipeline has been empirically assessed on a real dataset of on-street parking availability from San Francisco (USA). Results show that the proposal is able to provide parking predictions whose accuracy is comparable to state-of-the-art solutions based on one model per road segment, while requiring only a fraction of training costs, thus being more likely scalable to city-wide scenarios
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