The First Stellar Parallaxes Revisited. (arXiv:2009.11913v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Reid_M/0/1/0/all/0/1">Mark J. Reid</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Menten_K/0/1/0/all/0/1">Karl M. Menten</a> (2) ((1) Center for Astrophysics | Harvard & Smithsonian, (2) Max-Planck-Institut fuer Radioastronomie)
We have re-analyzed the data used by Bessel, von Struve, and Henderson in the
1830s to measure the first parallax distances to stars. We can generally
reproduce their results, although we find that von Struve and Henderson have
underestimated some of their measurement errors, leading to optimistic parallax
uncertainties. We find that temperature corrections for Bessel’s measured
positions are larger than anticipated, explaining some systematics apparent in
his data. It has long been a mystery as to why von Struve first announced a
parallax for Vega of 0.125 arcsec, only later with more data to revise it to
double that value. We resolve this mystery by finding that von Struve’s early
result used two dimensions of position data, which independently give
significantly different parallaxes, but when combined only fortuitously give
the correct result. With later data, von Struve excluded the “problematic”
dimension, leading to the larger parallax value. Allowing for likely
temperature corrections, and using his data from both dimensions, reduces von
Struve’s parallax for Vega to a value consistent with the correct value.
We have re-analyzed the data used by Bessel, von Struve, and Henderson in the
1830s to measure the first parallax distances to stars. We can generally
reproduce their results, although we find that von Struve and Henderson have
underestimated some of their measurement errors, leading to optimistic parallax
uncertainties. We find that temperature corrections for Bessel’s measured
positions are larger than anticipated, explaining some systematics apparent in
his data. It has long been a mystery as to why von Struve first announced a
parallax for Vega of 0.125 arcsec, only later with more data to revise it to
double that value. We resolve this mystery by finding that von Struve’s early
result used two dimensions of position data, which independently give
significantly different parallaxes, but when combined only fortuitously give
the correct result. With later data, von Struve excluded the “problematic”
dimension, leading to the larger parallax value. Allowing for likely
temperature corrections, and using his data from both dimensions, reduces von
Struve’s parallax for Vega to a value consistent with the correct value.
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