SIMBAD references

2014ApJ...788..112V - Astrophys. J., 788, 112 (2014/June-3)

First detection of thermal radio emission from solar-type stars with the Karl G. Jansky very large array.

VILLADSEN J., HALLINAN G., BOURKE S., GUDEL M. and RUPEN M.

Abstract (from CDS):

We present the first detections of thermal radio emission from the atmospheres of solar-type stars τ Cet, η Cas A, and 40 Eri A. These stars all resemble the Sun in age and level of magnetic activity, as indicated by X-ray luminosity and chromospheric emission in Ca II H and K lines. We observed these stars with the Karl G. Jansky Very Large Array with sensitivities of a few µJy at combinations of 10.0, 15.0, and 34.5 GHz. τ Cet, η Cas A, and 40 Eri A are all detected at 34.5 GHz with signal-to-noise ratios of 6.5, 5.2, and 4.5, respectively. 15.0 GHz upper limits imply a rising spectral index greater than 1.0 for τ Cet and 1.6 for η Cas A, at the 95% confidence level. The measured 34.5 GHz flux densities correspond to stellar disk-averaged brightness temperatures of roughly 10,000 K, similar to the solar brightness temperature at the same frequency. We explain this emission as optically thick thermal free-free emission from the chromosphere, with possible contributions from coronal gyroresonance emission above active regions and coronal free-free emission. These and similar quality data on other nearby solar-type stars, when combined with Atacama Large Millimeter/Submillimeter Array observations, will enable the construction of temperature profiles of their chromospheres and lower transition regions.

Abstract Copyright:

Journal keyword(s): radio continuum: stars - stars: chromospheres - stars: individual: ({tau} Cet, {eta} Cas A, 40 Eri A) - stars: solar-type

Simbad objects: 14

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2019.10.15-02:14:21

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