35 research outputs found
HD 35502: a hierarchical triple system with a magnetic B5IVpe primary
We present our analysis of HD~35502 based on high- and medium-resolution
spectropolarimetric observations. Our results indicate that the magnetic
B5IVsnp star is the primary component of a spectroscopic triple system and that
it has an effective temperature of , a mass of
, and a polar radius of . The
two secondary components are found to be essentially identical A-type stars for
which we derive effective temperatures (), masses
(), and radii (). We infer a
hierarchical orbital configuration for the system in which the secondary
components form a tight binary with an orbital period of
that orbits the primary component with a period of over .
Least-Squares Deconvolution (LSD) profiles reveal Zeeman signatures in Stokes
indicative of a longitudinal magnetic field produced by the B star ranging
from approximately to with a median uncertainty of
. These measurements, along with the line variability produced
by strong emission in H, are used to derive a rotational period of
. We find that the measured of the B star then implies an inclination angle of the star's
rotation axis to the line of sight of . Assuming the
Oblique Rotator Model, we derive the magnetic field strength of the B star's
dipolar component () and its obliquity
(). Furthermore, we demonstrate that the calculated Alfv\'{e}n
radius () and Kepler radius
() place HD~35502's central B star well within the
regime of centrifugal magnetosphere-hosting stars.Comment: 24 pages, 14 figures, Accepted for publication in MNRA
Testing a scaling relation between coherent radio emission and physical parameters of hot magnetic stars
Coherent radio emission via electron cyclotron maser emission (ECME) from hot
magnetic stars was discovered more than two decades ago, but the physical
conditions that make the generation of ECME favourable remain uncertain. Only
recently was an empirical relation, connecting ECME luminosity with the stellar
magnetic field and temperature, proposed to explain what makes a hot magnetic
star capable of producing ECME. This relation was, however, obtained with just
fourteen stars. Therefore, it is important to examine whether this relation is
robust. With the aim of testing the robustness, we conducted radio observations
of five hot magnetic stars. This led to the discovery of three more stars
producing ECME. We find that the proposed scaling relation remains valid after
the addition of the newly discovered stars. However we discovered that the
magnetic field and effective temperature correlate for kK (likely an artifact of the small sample size), rendering the proposed
connection between ECME luminosity and unreliable. By
examining the empirical relation in light of the scaling law for incoherent
radio emission, we arrive at the conclusion that both types of emission are
powered by the same magnetospheric phenomenon. Like the incoherent emission,
coherent radio emission is indifferent to for late-B and
A-type stars, but appears to become important for early-B type
stars, possibly due to higher absorption, or, higher plasma density at the
emission sites suppressing the production of the emission.Comment: 14 pages, 12 figures, accepted for publication in MNRA