The absolute motion of the peculiar cluster NGC 6791

Bedin, L. R.; Piotto, G.; Carraro, G.; King, Ivan R.; Anderson, Jay

doi:10.1051/0004-6361:20066085

Cited by 50 publications

(63 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At r > 1000 ′′ , two tails running at opposite directions are clearly visible, with the one in the southern direction extending up to distances larger than 2500 ′′ from the cluster center. It is important to note that both the external tidal arms and the innermost elongation of the cluster run almost parallel to the absolute proper motion vector (Bedin et al 2006) and to the direction of the Galactic center (GalC; Figure 3). This behaviour is in agreement with a real tidal nature for the observed distortions.…”

Section: The Matched Filter Analysismentioning

confidence: 98%

Evidence of tidal distortions and mass-loss from the old open cluster NGC 6791

Dalessandro

Miocchi

Carraro³

et al. 2015

Monthly Notices of the Royal Astronomical Society

Self Cite

View full text Add to dashboard Cite

We present the first evidence of clear signatures of tidal distortions in the density distribution of the fascinating open cluster NGC 6791. We used deep and wide-field data obtained with the Canada-France-Hawaii-Telescope covering a 2 • ×2 • area around the cluster. The two-dimensional density map obtained with the optimal matched filter technique shows a clear elongation and an irregular distribution starting from ∼ 300 ′′ from the cluster center. At larger distances, two tails extending in opposite directions beyond the tidal radius are also visible. These features are aligned to both the absolute proper motion and to the Galactic center directions. Moreover, other overdensities appear to be stretched in a direction perpendicular to the Galactic plane.Accordingly to the behaviour observed in the density map, we find that both the surface brightness and the star count density profiles reveal a departure from a King model starting from ∼ 600 ′′ from the center.These observational evidence suggest that NGC 6791 is currently experiencing mass loss likely due to gravitational shocking and interactions with the tidal field. We use this evidence to argue that NGC 6791 should have lost a significant fraction of its original mass. A larger initial mass would in fact explain why the cluster survived so long. Using available recipes based on analytic studies and N -body simulations, we derived the expected mass loss due to stellar evolution and tidal interactions and estimated the initial cluster mass to be M ini = (1.5-4) × 10 5 M ⊙ .

show abstract

Section: The Matched Filter Analysismentioning

confidence: 98%

Evidence of tidal distortions and mass-loss from the old open cluster NGC 6791

Dalessandro

Miocchi

Carraro³

et al. 2015

Monthly Notices of the Royal Astronomical Society

Self Cite

View full text Add to dashboard Cite

show abstract

“…Bensby et al: 714 dwarf stars in the Solar neighbourhood Galactic orbits were then calculated with the grinton integrator (Carraro et al 2002;Bedin et al 2006) which uses the Milky Way potential model by Allen & Santillan (1991). The model is time-independent, axisymmetric, fully analytic, and consists of a spherical central bulge, a disk, a massive spherical halo, and has a total mass of 9 × 10 11 solar masses.…”

Section: Space Velocities and Galactic Orbitsmentioning

confidence: 99%

Exploring the Milky Way stellar disk

Bensby

Feltzing

Oey

2014

A&A

1,035

227

1,612

View full text Add to dashboard Cite

Aims. The aim of this paper is to explore and map the age and abundance structure of the stars in the nearby Galactic disk. Methods. We have conducted a high-resolution spectroscopic study of 714 F and G dwarf and subgiant stars in the Solar neighbourhood. The star sample has been kinematically selected to trace the Galactic thin and thick disks to their extremes, the metal-rich stellar halo, sub-structures in velocity space such as the Hercules stream and the Arcturus moving group, as well as stars that cannot (kinematically) be associated with either the thin disk or the thick disk. The determination of stellar parameters and elemental abundances is based on a standard 1-D LTE analysis using equivalent width measurements in high-resolution (R = 40 000 − 110 000) and high signal-to-noise (S /N = 150 − 300) spectra obtained with FEROS on the ESO 1.5-m and 2.2-m telescopes, SOFIN and FIES on the Nordic Optical Telescope, UVES on the ESO Very Large Telescope, HARPS on the ESO 3.6-m telescope, and MIKE on the Magellan Clay telescope. NLTE corrections for individual Fe i lines were employed in every step of the analysis. Results. We present stellar parameters, stellar ages, kinematical parameters, orbital parameters, and detailed elemental abundances for O, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Zn, Y, and Ba for 714 nearby F and G dwarf stars. Our data show that there is an old and α-enhanced disk population, and a younger and less α-enhanced disk population. While they overlap greatly in metallicity between −0.7 < [Fe/H] +0.1, they show a bimodal distribution in [α/Fe]. This bimodality becomes even clearer if stars where stellar parameters and abundances show larger uncertainties (T eff 5400 K) are discarded, showing that it is important to constrain the data set to a narrow range in the stellar parameters if small differences between stellar populations are to be revealed. We furthermore find that the α-enhanced population has orbital parameters placing the stellar birthplaces in the inner Galactic disk while the low-α stars mainly come from the outer Galactic disk, fully consistent with the recent claims of a short scale-length for the α-enhanced Galactic thick disk. We have also investigated the properties of the Hercules stream and the Arcturus moving group and find that neither of them present chemical or age signatures that could point to that they are disrupted clusters or extragalactic accretion remnants from ancient merger events. Instead, they are most likely dynamical features originating within the Galaxy. We furthermore have discovered that a standard 1-D, LTE analysis, utilising ionisation and excitation balance of Fe i and Fe ii lines produces a flat lower main sequence. As the exact cause for this effect is unclear we chose to apply an empirical correction. Turn-off, and more evolved, stars, appears to be un-affected.

show abstract

“…The GRINTON integrator was used for this purpose (Carraro et al 2002;Bedin et al 2006). This code integrates the orbits back in time for several Galactic revolutions and returns the minimum and maximum distances from the Galactic centre (R min , R max ), maximum height from the Galactic plane (Z max ) and the eccentricity e of the orbit.…”

Section: Galactic Orbits and Membership Assignmentmentioning

confidence: 99%

Heavy elements in old very metal-rich stars

Trevisan

Barbuy

2014

A&A

View full text Add to dashboard Cite

Context. We studied a sample of high proper motion, old and metal-rich dwarf stars, selected from the NLTT catalogue. The low pericentric distances and eccentric orbits of these solar neighbourhood stars indicate that they might have originated in the inner parts of the Galaxy. Aims. Chemical tagging can probe the formation history of stellar populations. To identify the origin of a sample of 71 very metal-rich dwarf stars, we derive the abundances of the neutron-capture elements Y, Ba, La, and Eu. Methods. The spectroscopic analysis is based on optical high-resolution échelle spectra obtained with the FEROS spectrograph at the ESO 1.52 m Telescope at La Silla, Chile. The abundances of Y, Ba, La, and Eu were derived through LTE analysis, employing the MARCS model atmospheres.Results. The abundances of Y, Ba, La, and Eu vs. Fe and Mg as the reference elements indicate similarities between our sample of old metal-rich dwarf stars and the thin disk. On the other hand, the abundance ratios using O as the reference element, as well as their kinematics, suggest that our sample is clearly distinct from the thin-disk stars. They could be old inner thin-disk stars, as suggested previously, or bulge stars. In either cases, they would have migrated from the inner parts of the Galaxy to the solar neighbourhood.

show abstract

The absolute motion of the peculiar cluster NGC 6791

Cited by 50 publications

References 11 publications

Evidence of tidal distortions and mass-loss from the old open cluster NGC 6791

Evidence of tidal distortions and mass-loss from the old open cluster NGC 6791

Exploring the Milky Way stellar disk

Heavy elements in old very metal-rich stars

Contact Info

Product

Resources

About