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تسجيل مستخدم جديدA new LMC K-band distance from precision measurements of nearby red clump stars
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High-precision (sigma < 0.01) new JHK observations of 226 of the brightest and nearest red clump stars in the solar neighbourhood are used to determine distance moduli for the LMC. The resulting K- and H-band values of 18.47pm0.02 and 18.49pm0.06 imply that any correction to the K-band Cepheid PL relation due to metallicity differences between Cepheids in the LMC and in the solar neighborhood must be quite small.
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The Hipparcos I-band calibration of horizontal-branch red clump giants as standard candles has lead to controversial results for the distance to the Large Magellanic Cloud (LMC). In an attempt to properly ascertain the corrections for interstellar ex
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mathrm{eff}}$ and log $g$ as red giant branch stars. Recently, it was shown that the asteroseismic parameters, $rm{Delta}$P and $rm{Delta u}$, which are used to accurately select red clump stars, can be derived from spectra using the change in the surface carbon to nitrogen ratio ([C/N]) caused by mixing during the red giant branch. This change in [C/N] can also impact the spectral energy distribution. In this study, we predict the $rm{Delta}$P, $rm{Delta u}$, T$_{mathrm{eff}}$ and log $g$ using 2MASS, AllWISE, gaia, and Pan-STARRS data in order to select a clean sample of red clump stars. We achieve a contamination rate of $sim$20%, equivalent to what is achieved when selecting from T$_{mathrm{eff}}$ and log $g$ derived from low resolution spectra. Finally, we present two red clump samples. One sample has a contamination rate of $sim$ 20% and $sim$ 405,000 red clump stars. The other has a contamination of $sim$ 33% and $sim$ 2.6 million red clump stars which includes $sim$ 75,000 stars at distances $>$ 10 kpc. For |b|>30 degrees we find $sim$ 15,000 stars with contamination rate of $sim$ 9%. The scientific potential of this catalog for studying the structure and formation history of the Galaxy is vast given that it includes millions of precise distances to stars in the inner bulge and distant halo where astrometric distances are imprecise.
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