Multiple populations along the asymptotic giant branch of the globular cluster M4

ABSTRACT We report the discovery of the only very nitrogen-enhanced metal-poor star known in a Galactic globular cluster. This star, in the very metal-poor cluster ESO280−SC06 , has $[\textrm{N}/\textrm{Fe}]\, \gt +2.5$, while the other stars in the cluster show no obvious enhancement in nitrogen. Around 80 NEMP stars are known in the field, and their abundance patterns are believed to reflect mass transfer from a binary companion in the asymptotic giant branch phase. The dense environment of globular clusters is detrimental to the long term survival of binary systems, resulting in a low observed binary fraction among red giants and the near absence of NEMP stars. We also identify the first known horizontal branch members of ESO280−SC06 , which allow for a much better constraint on its distance. We calculate an updated orbit for the cluster based on our revised distance of 20.6 ± 0.5 kpc, and find no significant change to its orbital properties.

Download Full-text

‘Status update’ for the AGB scenario for the formation of multiple populations

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319006641 ◽

2019 ◽

Vol 14 (S351) ◽

pp. 289-292

Author(s):

Francesca D’Antona

Keyword(s):

First Generation ◽

Second Generation ◽

Asymptotic Giant Branch ◽

Multiple Populations ◽

Cooling Flow

AbstractThe Asymptotic Giant Branch (AGB) scenario for the formation of multiple populations has been quantitatively studied in the course of the last twenty years, examining the aspects both of nucleosynthesis and of the dynamics of formation of new stars in a cooling flow at the center of the first generation cluster, and of the following N–body evolution. The large complexity of these studies finds many validations in the properties of multiple populations. Here I shortly summarize recent accomplishments in the study of the evolution of massive AGBs and super–AGBs including the explanation of anomalous high lithium abundances in ‘extreme’ second generation stars in ω Cen and NGC 2808.

Download Full-text

Searching for multiple populations in Ruprecht 106

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab443 ◽

2021 ◽

Author(s):

H Frelijj ◽

S Villanova ◽

C Muñoz ◽

J G Fernández-Trincado

Keyword(s):

Globular Cluster ◽

Stellar Population ◽

Atmospheric Parameters ◽

Photometric Analysis ◽

Dynamical Study ◽

Multiple Populations ◽

Red Giant ◽

Definition Of ◽

Energy Plane ◽

Giant Branch Stars

Abstract More than a decade has passed since the definition of Globular Cluster (GC) changed, and now we know that they host Multiple Populations (MPs). But few GCs do not share that behaviour and Ruprecht 106 is one of these clusters. We analyzed thirteen member red giant branch stars using spectra in the wavelength range 6120-6405 Å obtained through the GIRAFFE Spectrograph, mounted at UT2 telescope at Paranal, as well as the whole cluster using C, V, R and I photometry obtained through the Swope telescope at Las Campanas. Atmospheric parameters were determined from the photometry to determine Fe and Na abundances. A photometric analysis searching for MPs was also carried out. Both analyses confirm that Ruprecht 106 is indeed one on the few GCs to host Simple Stellar Population, in agreement with previous studies. Finally, a dynamical study concerning its orbits was carried out to analyse the possible extragalactic origin of the Cluster. The orbital integration indicates that this GC belongs to the inner halo, while an Energy plane shows that it cannot be accurately associated with any known extragalactic progenitor.

Download Full-text

The Rapidly Rotating, Hydrogen-deficient, Hot Post-Asymptotic Giant Branch Star ZNG 1 in the Globular Cluster M5

The Astrophysical Journal ◽

10.1086/381389 ◽

2003 ◽

Vol 600 (1) ◽

pp. L43-L46 ◽

Cited By ~ 10

Author(s):

W. Van Dyke Dixon ◽

Thomas M. Brown ◽

Wayne B. Landsman

Keyword(s):

Globular Cluster ◽

Asymptotic Giant Branch ◽

Asymptotic Giant Branch Star ◽

Branch Star

Download Full-text

Hydrodynamic simulations of second generation star formation in a young globular cluster

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319006732 ◽

2019 ◽

Vol 14 (S351) ◽

pp. 269-272

Author(s):

Francesco Calura

Keyword(s):

Star Formation ◽

Globular Cluster ◽

Second Generation ◽

Three Dimensional ◽

Asymptotic Giant Branch ◽

Central Density ◽

Agb Stars ◽

Hydrodynamic Simulations ◽

Numerical Studies

AbstractI will present results obtained by means of three-dimensional hydrodynamic simulations of the formation of second generation (SG) stars in a young globular cluster (GC). Our setup includes the mass return from Asymptotic Giant branch (AGB) stars, the accretion of pristine gas as well as star formation of SG stars, three ingredients which have never been simultaneously taken into account in previous 3D numerical studies of GC formation. The cluster is set in motion with respect to a distribution of gas and allowed to accrete mass from it. Formation of SG stars occurs out of the gas shed by AGB stars and from the gas accreted during the motion of the cluster. We consider two models characterised by different densities of the external gas. In both cases, we find that a very compact SG subsystem with central density > 105M⊙/pc3 forms in the innermost regions of the cluster.

Download Full-text