Weak Magnetic Fields in Two Herbig Ae Systems: The SB2 AK Sco and the Presumed Binary HD 95881

TL;DR

This study detects weak magnetic fields in two Herbig Ae binary systems, AK Sco and HD 95881, using high-precision spectropolarimetry, revealing magnetic activity and spectral variability in these young stellar objects.

Contribution

First detection of weak magnetic fields in AK Sco and HD 95881 Herbig Ae binaries using SVD analysis with high-precision spectropolarimetry.

Findings

Magnetic fields of approximately -83 G and -93 to 105 G detected in the systems.

Spectral variability observed in AK Sco's accretion and photospheric lines.

First presentation of the double-lined spectrum of HD 95881.

Abstract

We report the detection of weak mean longitudinal magnetic fields in the Herbig Ae double-lined spectroscopic binary AK Sco and in the presumed spectroscopic Herbig Ae binary HD95881 using observations with the High Accuracy Radial velocity Planet Searcher polarimeter (HARPSpol) attached to the European Southern Observatory's (ESO's) 3.6m telescope. Employing a multi-line singular value decomposition (SVD) method, we detect a mean longitudinal magnetic field <B_z>=-83+-31G in the secondary component of AK Sco on one occasion. For HD95881, we measure <B_z>=-93+-25G and <B_z>=105+-29G at two different observing epochs. For all the detections the false alarm probability is smaller than 10^-5. For AK Sco system, we discover that accretion diagnostic Na I doublet lines and photospheric lines show intensity variations over the observing nights. The double-lined spectral appearance of HD95881 is presented here for the first time.