A Volume Limited Survey of mCP Stars Within 100pc II: Rotational and Magnetic Properties. (arXiv:1811.05635v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Sikora_J/0/1/0/all/0/1">J. Sikora</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wade_G/0/1/0/all/0/1">G. A. Wade</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Power_J/0/1/0/all/0/1">J. Power</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Neiner_C/0/1/0/all/0/1">C. Neiner</a>
Various surveys focusing on the magnetic properties of intermediate-mass main
sequence (MS) stars have been previously carried out. One particularly puzzling
outcome of these surveys is the identification of a dichotomy between the
strong ($gtrsim100,{rm G}$), organized fields hosted by magnetic chemically
peculiar (mCP) stars and the ultra-weak ($lesssim1,{rm G}$) fields
associated with a small number of non-mCP MS stars. Despite attempts to detect
intermediate strength fields (i.e. those with strengths $gtrsim10,{rm G}$
and $lesssim100,{rm G}$), remarkably few examples have been found. Whether
this so-called “magnetic desert”, separating the stars hosting ultra-weak
fields from the mCP stars truly exists has not been definitively answered. In
2007, a volume-limited spectropolarimetric survey of mCP stars using the
MuSiCoS spectropolarimeter was initiated to test the existence of the magnetic
desert by attempting to reduce the biases inherent in previous surveys. Since
then, we have obtained a large number of ESPaDOnS and NARVAL Stokes $V$
measurements allowing this survey to be completed. Here we present the results
of our homogeneous analysis of the rotational periods (inferred from
photometric and magnetic variability) and magnetic properties (dipole field
strengths and obliquity angles) of the 52 confirmed mCP stars located within a
heliocentric distance of $100,{rm pc}$. No mCP stars exhibiting field
strengths $lesssim300,{rm G}$ are found within the sample, which is
consistent with the notion that the magnetic desert is a real property and not
the result of an observational bias. Additionally, we find evidence of magnetic
field decay, which confirms the results of previous studies.
Various surveys focusing on the magnetic properties of intermediate-mass main
sequence (MS) stars have been previously carried out. One particularly puzzling
outcome of these surveys is the identification of a dichotomy between the
strong ($gtrsim100,{rm G}$), organized fields hosted by magnetic chemically
peculiar (mCP) stars and the ultra-weak ($lesssim1,{rm G}$) fields
associated with a small number of non-mCP MS stars. Despite attempts to detect
intermediate strength fields (i.e. those with strengths $gtrsim10,{rm G}$
and $lesssim100,{rm G}$), remarkably few examples have been found. Whether
this so-called “magnetic desert”, separating the stars hosting ultra-weak
fields from the mCP stars truly exists has not been definitively answered. In
2007, a volume-limited spectropolarimetric survey of mCP stars using the
MuSiCoS spectropolarimeter was initiated to test the existence of the magnetic
desert by attempting to reduce the biases inherent in previous surveys. Since
then, we have obtained a large number of ESPaDOnS and NARVAL Stokes $V$
measurements allowing this survey to be completed. Here we present the results
of our homogeneous analysis of the rotational periods (inferred from
photometric and magnetic variability) and magnetic properties (dipole field
strengths and obliquity angles) of the 52 confirmed mCP stars located within a
heliocentric distance of $100,{rm pc}$. No mCP stars exhibiting field
strengths $lesssim300,{rm G}$ are found within the sample, which is
consistent with the notion that the magnetic desert is a real property and not
the result of an observational bias. Additionally, we find evidence of magnetic
field decay, which confirms the results of previous studies.
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