# Measuring the absolute total intrinsic redshifts (surface gravity plus the convective blueshift) of the main sequence stars and red giants using GAIA data

## TL;DR

This study uses GAIA data to measure intrinsic redshifts of stars, revealing the effects of surface gravity and convection, and showing differences between main sequence stars and red giants.

## Contribution

It provides the first direct measurements of total intrinsic redshifts for different star types using GAIA data, accounting for surface gravity and convective blueshift effects.

## Key findings

- Main sequence stars have similar intrinsic redshifts smaller than gravitational redshift.
- Red giants exhibit negative intrinsic redshifts, indicating dominant convective blueshift.
- Convective blueshift effects are significant in stellar redshift measurements.

## Abstract

We analyze the GAIA release II data to demonstrate how one can measure the absolute total intrinsic redshifts of the main sequence stars and red giants. We remove the relative velocity components of the stars' motion with respect to the sun by doing the analysis in the local standard of rest (LSR) frame defined by the average stars' motion. We provide results for four different types of stars. F, G and K types of stars have about the same value of intrinsic redshift, which is however much smaller than the expected gravitational redshift. This indicates that the GAIA's data include convective blueshift effect of a several hundreds m/s magnitude. The red giants' intrinsic redshifts are negative, which implies that their convective blueshift is stronger than the gravitational redshift. This is expected since red giants are far less compact than other types.