# Exploring the internal rotation of the extremely low-mass He-core white dwarf GD 278 with TESS asteroseismology

**Authors:** Leila M. Calcaferro, Alejandro H. Córsico, Leandro G. Althaus, Isaac D. Lopez, J. J. Hermes  
**arXiv:** [2303.15962](https://arxiv.org/abs/2303.15962)  
**Date:** 2023-03-28  
**Summary page:** https://www.summarizepaper.com/en/paper/2303.15962v1/

## Key points

- Calcaferro et al. explore the internal rotation of GD 278, an extremely low-mass white dwarf that exhibits rotational splittings within its periodogram.
- The authors use asteroseismology to assess the theoretical frequency splittings expected for different rotation profiles and compare them to the observed frequency splittings of GD 278.
- They employ an asteroseismological model representative of the pulsations of this star, obtained by using the LPCODE stellar evolution code.
- Additionally, they derive a rotation profile resulting from detailed evolutionary calculations carried out with the MESA stellar evolution code and use it to infer the expected theoretical frequency splittings.
- Assuming linear profiles for GD 278's rotation leads to values of angular velocity at its surface and center that are only slightly differential but still compatible with rigid rotation.
- Both simple linear rotation profiles and those derived from evolutionary calculations produce values in very good agreement with each other regarding angular velocity at both surface and center.
- The resulting theoretical frequency splittings are also generally compatible with observed frequency splittings for both cases.
- The authors suggest a marginally differential behavior for GD 278's internal rotation which is very compatible with the rigid case considering uncertainties involved.
- This finding is consistent with previous observations made for white dwarfs and pre-white dwarfs.
- Overall, this study provides valuable insights into understanding the internal structure and dynamics of extremely low-mass white dwarfs like GD 278 through asteroseismology techniques.

## Summary

In their recent study, Calcaferro et al. explore the internal rotation of GD 278, an extremely low-mass white dwarf that exhibits rotational splittings within its periodogram. The authors use asteroseismology to assess the theoretical frequency splittings expected for different rotation profiles and compare them to the observed frequency splittings of GD 278. To achieve this, they employ an asteroseismological model representative of the pulsations of this star, obtained by using the LPCODE stellar evolution code. Additionally, they derive a rotation profile resulting from detailed evolutionary calculations carried out with the MESA stellar evolution code and use it to infer the expected theoretical frequency splittings. The authors find that assuming linear profiles for GD 278's rotation leads to values of angular velocity at its surface and center that are only slightly differential but still compatible with rigid rotation. Moreover, both simple linear rotation profiles and those derived from evolutionary calculations produce values in very good agreement with each other regarding angular velocity at both surface and center. The resulting theoretical frequency splittings are also generally compatible with observed frequency splittings for both cases. The results obtained from different approaches followed in this work agree, giving robustness to their findings as they were obtained employing two independent stellar evolution codes. The authors suggest a marginally differential behavior for GD 278's internal rotation which is very compatible with the rigid case considering uncertainties involved. This finding is consistent with previous observations made for white dwarfs and pre-white dwarfs. Overall, this study provides valuable insights into understanding the internal structure and dynamics of extremely low-mass white dwarfs like GD 278 through asteroseismology techniques.