Informace o publikaci

Testing a scaling relation between coherent radio emission and physical parameters of hot magnetic stars


DAS Barnali CHANDRA Poonam SHULTZ Matt E. LETO Paolo MIKULÁŠEK Zdeněk PETIT Véronique WADE Gregg A.

Rok publikování 2022
Druh Článek v odborném periodiku
Časopis / Zdroj Monthly Notices of the Royal Astronomical Society
Fakulta / Pracoviště MU

Přírodovědecká fakulta

Klíčová slova masers; polarization; stars: early-type; stars: individual: HD35502; HD36526; HD37479; HD61556; HD182180; stars: magnetic field
Popis 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 14 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 T-eff less than or similar to 16 kK (likely an artefact of the small sample size), rendering the proposed connection between ECME luminosity and T-eff 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 T-eff for late-B and A-type stars, but T-eff 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.

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