Archeology of an Ancient Star

Fuhrmann, K.; Chini, R.; Haas, Mary E.; Hackstein, M.; Ramolla, M.; Bernkopf, Jan

doi:10.1088/0004-637x/761/2/159

Cited by 48 publications

(49 citation statements)

References 18 publications

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“…Determination of the age of the system from spectroscopic parameters and isochrone fitting has produced age estimates greater than the asteroseismic results (e.g. 9.1 ± 0.8 Gyr from Laws et al (2003) or 8.0 ± 1.4 Gyr from Fuhrmann, Pfeiffer & Bernkopf (1998)) but more recently Delgado Mena et al (2014) give an age for 16 Cyg B of 6.23 Gyr that is consistent with the seismic result. Perrin & Spite (1981a) give B − V values for the A and B components, 0.64 and 0.66 respectively.…”

Section: Introductionmentioning

confidence: 73%

Asteroseismic inference on rotation, gyrochronology and planetary system dynamics of 16 Cygni

Davies

Chaplin

Farr

et al. 2014

Monthly Notices of the Royal Astronomical Society

114

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The solar analogs 16 Cyg A and 16 Cyg B are excellent asteroseismic targets in the Kepler field of view and together with a red dwarf and a Jovian planet form an interesting system. For these more evolved Sun-like stars we cannot detect surface rotation with the current Kepler data but instead use the technique of asteroseimology to determine rotational properties of both 16 Cyg A and B. We find the rotation periods to be 23.8 • , for A and B respectively. Together with these results we use the published mass and age to suggest that, under the assumption of a solar-like rotation profile, 16 Cyg A could be used when calibrating gyrochronology relations. In addition, we discuss the known 16 Cyg B star-planet eccentricity and measured low obliquity which is consistent with Kozai cycling and tidal theory.

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Section: Introductionmentioning

confidence: 73%

Asteroseismic inference on rotation, gyrochronology and planetary system dynamics of 16 Cygni

Davies

Chaplin

Farr

et al. 2014

Monthly Notices of the Royal Astronomical Society

114

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“…Our upper limit for the Li abundance (A(Li) ≤ 0.9 dex) is also about 20 times smaller than the Li abundance expected for an age of 1 Gyr (Tucci Maia et al 2015), showing that the star is not young. Thus, the high projected rotational velocity is most likely the consequence of angular momentum transfer during the accretion stage from the former AGB star (Fuhrmann & Bernkopf 1999), which "rejuvenated" HIP 10725, enhancing both rotation and chromospheric activity.…”

Section: Discussionmentioning

confidence: 99%

“…Chromospheric activity in blue stragglers tends to be incompatible with their isochrone-derived ages; they present significant rotational velocities, thus appearing to be younger (Fuhrmann & Bernkopf 1999). Severe Li depletion is also observed; this is a sign of old age (Monroe et al 2013;Meléndez et al 2014a) that also contradicts the young age scenario.…”

Section: Introductionmentioning

confidence: 93%

HIP 10725: The first solar twin/analogue field blue straggler

Schirbel

Meléndez

Karakas

et al. 2015

A&A

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Context. Blue stragglers are easy to identify in globular clusters, but are much harder to identify in the field. Here we present the serendipitous discovery of one field blue straggler, HIP 10725, that closely matches the Sun in mass and age, but with a metallicity slightly lower than solar. Aims. We characterise the solar twin/analogue HIP 10725 to assess whether this star is a blue straggler. Methods. We employed spectra with high resolution (R ∼ 10 5 ) and high signal-to-noise ratio (330) obtained with UVES at the VLT to perform a differential abundance analysis of the solar analogue HIP 10725. Radial velocities obtained by other instruments were also used to check for binarity. We also studied its chromospheric activity, age, and rotational velocity. Results. HIP 10725 is severely depleted in beryllium ([Be/H] ≤ −1.2 dex) for its stellar parameters and age. The abundances relative to solar of the elements with Z ≤ 30 show a correlation with condensation temperature, and the neutron capture elements produced by the s-process are greatly enhanced, while the r-process elements seem normal. We found its projected rotational velocity (v sin i = 3.3 ± 0.1 km s −1 ) to be significantly higher than solar and incompatible with its isochrone-derived age. Radial velocity monitoring shows that the star has a binary companion. Conclusions. Based on the high s-process element enhancements and low beryllium abundance, we suggest that HIP 10725 has been polluted by mass transfer from an AGB star that probably had an initial mass of about 2 M . The radial velocity variations suggest the presence of an unseen binary companion, probably the remnant of a former AGB star. Isochrones predict a solar-age star, but this disagrees with the high projected rotational velocity and high chromospheric activity. We conclude that HIP 10725 is a field blue straggler, rejuvenated by the mass-transfer process of its former AGB companion.

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“…As we already discussed in Haywood et al (2013), these objects have no peculiarities. We did not note at that time, however, the dedicated study of Fuhrmann et al (2012) on HIP 38908 (HR 3138). Fuhrmann et al (2012) found a similar "young" age for this object: we derive an age of 5.4 +1.4 −2.3 Gyr, while Fuhrmann et al (2012) give 5.6 +2.2 −1.8 Gyr.…”

Section: Datamentioning

confidence: 99%

“…We did not note at that time, however, the dedicated study of Fuhrmann et al (2012) on HIP 38908 (HR 3138). Fuhrmann et al (2012) found a similar "young" age for this object: we derive an age of 5.4 +1.4 −2.3 Gyr, while Fuhrmann et al (2012) give 5.6 +2.2 −1.8 Gyr. They commented further on the fact that radial velocity excludes the possibility that HR 3138 is a blue straggler with a white dwarf.…”

Section: Datamentioning

confidence: 99%

Clues to the formation of the Milky Way’s thick disk

Haywood

Matteo

Snaith

et al. 2015

A&A

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We analyze the chemical properties of a set of solar vicinity stars, and show that the small dispersion in abundances of α-elements at all ages provides evidence that the star formation history (SFH) has been uniform throughout the thick disk. In the context of longtimescale infall models, we suggest that this result points either to a limited dependence of the gas accretion on the Galactic radius in the inner disk (R < 10 kpc) or to a decoupling of the accretion history and SFH due to other processes governing the interstellar medium in the early disk, suggesting that infall cannot be a determining parameter of the chemical evolution at these epochs. We argue that these results and other recent observational constraints -namely the lack of radial metallicity gradient and the non-evolving scale length of the thick disk -are better explained if the early disk is viewed as a pre-assembled gaseous system, with most of the gas settled before significant star formation took place -formally the equivalent of a closed-box model. In either case, these results point to a weak or non-existent inside-out formation history in the thick disk or in the first 3-5 Gyr of the formation of the Galaxy. We argue, however, that the growing importance of an external disk whose chemical properties are distinct from those of the inner disk would give the impression of an inside-out growth process when seen through snapshots at different epochs. The progressive, continuous process usually invoked may not have actually existed in the Milky Way.

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Archeology of an Ancient Star

Cited by 48 publications

References 18 publications

Asteroseismic inference on rotation, gyrochronology and planetary system dynamics of 16 Cygni

Asteroseismic inference on rotation, gyrochronology and planetary system dynamics of 16 Cygni

HIP 10725: The first solar twin/analogue field blue straggler

Clues to the formation of the Milky Way’s thick disk

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