# Discovery of a magnetic field in $\rho$ Pup

## TL;DR

This paper reports the detection of a very weak magnetic field in the pulsating star $
ho$ Pup, marking it as only the second known magnetic $
ho$ Scuti star and suggesting a link to ultra-weak magnetic Am stars.

## Contribution

The study presents the first high-precision spectropolarimetric detection of a magnetic field in $
ho$ Pup, expanding the understanding of magnetism in pulsating Am stars.

## Key findings

- Magnetic field detected with longitudinal strength below 1 G
- $
ho$ Pup is the second magnetic $
ho$ Scuti star
- Possible connection to ultra-weak magnetic Am stars

## Abstract

$\rho$ Pup is a $\delta$ Scuti F2 pulsator, known to host a main radial mode as well as non-radial pulsations, with chemical peculiarities typical of evolved Am stars. We present high-precision spectropolarimetric observations of this star, obtained with ESPaDOnS at the Canada France Hawaii Telescope (CFHT) in the frame of the BRITE spectropolarimetric survey. A magnetic field is clearly detected in $\rho$ Pup, with a longitudinal field strength below 1 G. This makes $\rho$ Pup the second known magnetic $\delta$ Scuti discovered, after HD 188774, and a possible cool evolved counterpart of the recently discovered ultra-weakly magnetic Am family.