Solar-like oscillators

The Sun vibrates in hundreds of individual resonant frequencies that peak at a period of about 5 minutes. These are solar oscillations, which are both driven and damped by near-surface convection. Other stars with substantial surface convection zones pulsate for the same reason. Their pulsations are solar-like oscillations and the stars are themselves the solar-like oscillators.

The principal feature necessary for solar-like oscillations is a substantial near-surface convection zone, so solar-like oscillations can be observed in most dwarfs and subgiants cooler than about 6500 kelvin and basically all red giants. The amplitudes are generally small, though increase with luminosity, so it takes a lot of sensitive, uninterrupted data to see the oscillations in dwarfs and subgiants. TESS only detects solar-like oscillations in very bright (at least naked-eye visible!) main-sequence stars.

On the other hand, basically all red giants are solar-like oscillators. At very high luminosities (i.e., bright giants and beyond), the time scale of driving and damping becomes long and the stars are better characterised as semi-regular variables, but these long-period variables aren’t generally suited to TESS’s relatively short observations.

• Dwarfs and subgiants
  • δ Eridani
  • β Hydri
  • ζ Tucanae
• Red giants
  • γ Mensae
  • ν Octantis