We present a general overview and the first results of the SUMO project (a SUrvey of Multiple pOpulations in Globular Clusters). The objective of this survey is the study of multiple stellar ...populations in the largest sample of globular clusters homogeneously analysed to date. To this aim we obtained high signal-to-noise (S/N > 50) photometry for main sequence stars with mass down to ∼0.5 M in a large sample of clusters using both archival and proprietary U, B, V and I data from ground-based telescopes.
In this paper, we focus on the occurrence of multiple stellar populations in 23 clusters. We define a new photometric index, c
U, B, I
= (U − B) − (B − I), which turns out to be very effective for identifying multiple sequences along the red giant branch (RGB). We found that in the V-c
U, B, I
diagram all clusters presented in this paper show broadened or multimodal RGBs, with the presence of two or more components. We found a direct connection with the chemical properties of different sequences, which display different abundances of light elements (O, Na, C, N and Al). The c
U, B, I
index is also a powerful tool for identifying distinct sequences of stars along the horizontal branch and, for the first time in the case of NGC 104 (47 Tuc), along the asymptotic giant branch. Our results demonstrate that (i) the presence of more than two stellar populations is a common feature amongst globular clusters, as already highlighted in previous work; (ii) multiple sequences with different chemical contents can be easily identified by using standard Johnson photometry obtained with ground-based facilities; (iii) in the study of globular cluster multiple stellar populations the c
U, B, I
index is an alternative to spectroscopy, and has the advantage of larger statistics.
Abstract
Open clusters have long been used to study the chemodynamical evolution of the Galactic disc. This requires a homogeneously analysed sample covering a wide range of ages and distances. In ...this paper, we present the Open Clusters Chemical Abundances from Spanish Observatories (OCCASO) second data release. This comprises a sample of high-resolution (R > 65 000) and high signal-to-noise spectra of 115 red clump stars in 18 open clusters. We derive atmospheric parameters (T
eff, log g, ξ), and Fe/H abundances using two analysis techniques: equivalent widths and spectral synthesis. A detailed comparison and a critical review of the results of the two methods are made. Both methods are carefully tested between them, with the Gaia FGK benchmark stars, and with an extensive sample of literature values. We perform a membership study using radial velocities and the resulting abundances. Finally, we compare our results with a chemodynamical model of the Milky Way thin disc concluding that the oldest open clusters are consistent with the models only when dynamical effects are taken into account.
Open clusters (OCs) are crucial for studying the formation and evolution of the Galactic disc. However, the lack of a large number of OCs analysed homogeneously hampers the investigations about ...chemical patterns and the existence of Galactocentric radial and vertical gradients, or an age–metallicity relation. To overcome this, we have designed the Open Cluster Chemical Abundances from Spanish Observatories (OCCASO) survey. We aim to provide homogeneous radial velocities, physical parameters and individual chemical abundances of six or more red clump stars for a sample of 25 old and intermediate-age OCs visible from the Northern hemisphere. To do so, we use high-resolution spectroscopic facilities (R ≥ 62 000) available at Spanish observatories. We present the motivation, design and current status of the survey, together with the first data release of radial velocities for 77 stars in 12 OCs, which represents about 50 per cent of the survey. We include clusters never studied with high-resolution spectroscopy before (NGC 1907, NGC 6991, NGC 7762), and clusters in common with other large spectroscopic surveys like the Gaia-ESO Survey (NGC 6705) and Apache Point Observatory Galactic Evolution Experiment (NGC 2682 and NGC 6819). We perform internal comparisons between instruments to evaluate and correct internal systematics of the results, and compare our radial velocities with previous determinations in the literature, when available. Finally, radial velocities for each cluster are used to perform a preliminary kinematic study in relation with the Galactic disc.
TASTE Nascimbeni, V; Cunial, A; Murabito, S ...
Astronomy and astrophysics (Berlin),
1/2013, Letnik:
549
Journal Article
Recenzirano
The TASTE project is searching for low-mass planets with the transit timing variation (TTV) technique by gathering high-precision, short-cadence light curves for a selected sample of transiting ...exoplanets. It has been claimed that the "hot Jupiter" WASP-3b could be perturbed by a second planet. Presenting eleven new light curves (secured at the IAC80 and UDEM telescopes) and re-analyzing thirty-eight archival light curves in a homogeneous way, we show that new data do not confirm the previously claimed TTV signal. However, we bring evidence that measurements are not consistent with a constant orbital period, though no significant periodicity can be detected. Additional dynamical modeling and follow-up observations are planned to constrain the properties of the perturber or to put upper limits to it. We provide a refined ephemeris for WASP-3b and improved orbital/physical parameters. A contact eclipsing binary, serendipitously discovered among field stars, is reported here for the first time.
Orbital obliquity is thought to be a fundamental parameter in tracing the physical mechanisms that cause the migration of giant planets from the snow line down to roughly 102 au from their host ...stars. We are carrying out a large programme to estimate the spin-orbit alignment of a sample of transiting planetary systems to study what the possible configurations of orbital obliquity are and whether they correlate with other stellar or planetary properties. We determine the true and the projected obliquity of HAT-P-36 and WASP-11/HATP-10 systems, respectively, which are both composed of a relatively cool star and a hot Jupiter planet. We used the new spectroscopic and photometric data to revise the main physical parameters and measure the sky-projected misalignment angle of the two systems. In the case of HAT-P-36, we were also able to estimate an upper limit of its real obliquity, which turned out to be psi < 63 degrees.
XO-2 is the first confirmed wide stellar binary system where the almost twin components XO-2N and XO-2S have planets, and it is a peculiar laboratory in which to investigate the diversity of ...planetary systems. This stimulated a detailed characterization study of the stellar and planetary components based on new observations. We collected high-resolution spectra with the HARPS-N spectrograph and multi-band light curves. Spectral analysis led to an accurate determination of the stellar atmospheric parameters and characterization of the stellar activity, and high-precision radial velocities of XO-2N were measured. We collected 14 transit light curves of XO-2Nb used to improve the transit parameters. Photometry provided accurate magnitude differences between the stars and a measure of their rotation periods. The iron abundance of XO-2N was found to be +0.054 dex greater, within more than 3sigma, than that of XO-2S. The existence of a long-term variation in the radial velocities of XO-2N is confirmed, and we detected a turnover with respect to previous measurements.
Open clusters have long been used to study the chemodynamical evolution of the Galactic disc. This requires a homogeneously analysed sample covering a wide range of ages and distances. In this paper, ...we present the Open Clusters Chemical Abundances from Spanish Observatories (OCCASO) second data release. This comprises a sample of high-resolution (R > 65 000) and high signal-to-noise spectra of 115 red clump stars in 18 open clusters. We derive atmospheric parameters (Teff, log g, ξ), and Fe/H abundances using two analysis techniques: equivalent widths and spectral synthesis. A detailed comparison and a critical review of the results of the two methods are made. Both methods are carefully tested between them, with the Gaia FGK benchmark stars, and with an extensive sample of literature values. We perform a membership study using radial velocities and the resulting abundances. Finally, we compare our results with a chemodynamical model of the Milky Way thin disc concluding that the oldest open clusters are consistent with the models only when dynamical effects are taken into account.
Context. One-opposition near-Earth asteroids (NEAs) are growing in number, and they must be recovered to prevent loss and mismatch risk, and to improve their orbits, as they are likely to be too ...faint for detection in shallow surveys at future apparitions. Aims. We aimed to recover more than half of the one-opposition NEAs recommended for observations by the Minor Planet Center (MPC) using the Isaac Newton Telescope (INT) in soft-override mode and some fractions of available D-nights. During about 130 h in total between 2013 and 2016, we targeted 368 NEAs, among which 56 potentially hazardous asteroids (PHAs), observing 437 INT Wide Field Camera (WFC) fields and recovering 280 NEAs (76% of all targets). Methods. Engaging a core team of about ten students and amateurs, we used the THELI, Astrometrica, and the Find_Orb software to identify all moving objects using the blink and track-and-stack method for the faintest targets and plotting the positional uncertainty ellipse from NEODyS. Results. Most targets and recovered objects had apparent magnitudes centered around V ~ 22.8 mag, with some becoming as faint as V ~ 24 mag. One hundred and three objects (representing 28% of all targets) were recovered by EURONEAR alone by Aug. 2017. Orbital arcs were prolonged typically from a few weeks to a few years; our oldest recoveries reach 16 years. The O−C residuals for our 1854 NEA astrometric positions show that most measurements cluster closely around the origin. In addition to the recovered NEAs, 22 000 positions of about 3500 known minor planets and another 10 000 observations of about 1500 unknown objects (mostly main-belt objects) were promptly reported to the MPC by our team. Four new NEAs were discovered serendipitously in the analyzed fields and were promptly secured with the INT and other telescopes, while two more NEAs were lost due to extremely fast motion and lack of rapid follow-up time. They increase the counting to nine NEAs discovered by the EURONEAR in 2014 and 2015. Conclusions. Targeted projects to recover one-opposition NEAs are efficient in override access, especially using at least two-meter class and preferably larger field telescopes located in good sites, which appear even more efficient than the existing surveys.
Open clusters (OCs) are crucial for studying the formation and evolution of the Galactic disc. However, the lack of a large number of OCs analysed homogeneously hampers the investigations about ...chemical patterns and the existence of Galactocentric radial and vertical gradients, or an age-metallicity relation. To overcome this, we have designed the Open Cluster Chemical Abundances from Spanish Observatories (OCCASO) survey. We aim to provide homogeneous radial velocities, physical parameters and individual chemical abundances of six or more red clump stars for a sample of 25 old and intermediate-age OCs visible from the Northern hemisphere. To do so, we use high-resolution spectroscopic facilities (R >= 62 000) available at Spanish observatories. We present the motivation, design and current status of the survey, together with the first data release of radial velocities for 77 stars in 12 OCs, which represents about 50 per cent of the survey. We include clusters never studied with high-resolution spectroscopy before (NGC 1907, NGC 6991, NGC 7762), and clusters in common with other large spectroscopic surveys like the Gaia-ESO Survey (NGC 6705) and Apache Point Observatory Galactic Evolution Experiment (NGC 2682 and NGC 6819). We perform internal comparisons between instruments to evaluate and correct internal systematics of the results, and compare our radial velocities with previous determinations in the literature, when available. Finally, radial velocities for each cluster are used to perform a preliminary kinematic study in relation with the Galactic disc.
The GAPS programme with HARPS-N at TNG Damasso, M.; Esposito, M.; Nascimbeni, V. ...
Astronomy and astrophysics (Berlin),
9/2015, Letnik:
581
Journal Article
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