SIMBAD references

2017ApJ...840...67L - Astrophys. J., 840, 67-67 (2017/May-2)

On the origin of sub-subgiant stars. II. Binary mass transfer, envelope stripping, and magnetic activity.

LEINER E., MATHIEU R.D. and GELLER A.M.

Abstract (from CDS):

Sub-subgiant stars (SSGs) lie to the red of the main sequence and fainter than the red giant branch in cluster color-magnitude diagrams (CMDs), a region not easily populated by standard stellar evolution pathways. While there has been speculation on what mechanisms may create these unusual stars, no well-developed theory exists to explain their origins. Here we discuss three hypotheses of SSG formation: (1) mass transfer in a binary system, (2) stripping of a subgiant's envelope, perhaps during a dynamical encounter, and (3) reduced luminosity due to magnetic fields that lower convective efficiency and produce large starspots. Using the stellar evolution code MESA, we develop evolutionary tracks for each of these hypotheses, and compare the expected stellar and orbital properties of these models with six known SSGs in the two open clusters M67 and NGC 6791. All three of these mechanisms can create stars or binary systems in the SSG CMD domain. We also calculate the frequency with which each of these mechanisms may create SSG systems, and find that the magnetic field hypothesis is expected to create SSGs with the highest frequency in open clusters. Mass transfer and envelope stripping have lower expected formation frequencies, but may nevertheless create occasional SSGs in open clusters. They may also be important mechanisms to create SSGs in higher mass globular clusters.

Abstract Copyright: © 2017. The American Astronomical Society. All rights reserved.

Journal keyword(s): binaries: spectroscopic - galaxies: clusters: individual: (M67, NGC 6791) - stars: magnetic field - stars: mass-loss - starspots - starspots

CDS comments: Table 3: WOCS 12270 is not in SIMBAD.

Simbad objects: 14

goto Full paper

goto View the reference in ADS

To bookmark this query, right click on this link: simbad:2017ApJ...840...67L and select 'bookmark this link' or equivalent in the popup menu


2019.11.14-11:16:29

© Université de Strasbourg/CNRS

    • Contact