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arXiv · 2401.03959

Projected rotational velocities for LAMOST stars with effective temperature lower than 9000 K

Fang Zuo·A-Li Luo·Bing Du·Yinbi Li·Hugh R. A. Jones·Yi-han Song·Xiao Kong·Yan-xin Guo
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Abstract

In Data Release 9 of LAMOST, we present measurements of v sin i for a total of 121,698 stars measured using the Medium Resolution Spectrograph (MRS) and 80,108 stars using the Low Resolution Spectrograph (LRS). These values were obtained through a chi^2 minimisation process, comparing LAMOST spectra with corresponding grids of synthetically broadened spectra. Due to the resolution and the spectral range of LAMOST, v sin i measurements are limited to stars with effective temperature (Teff) ranging from 5000 K to 8500 K for MRS and 7000 K to 9000 K for LRS. The detectable v sin i for MRS is set between 27 km/s and 350 km/s , and for LRS between 110 km/s and 350 km/s, This limitation is because the convolved reference spectra become less informative beyond 350 km/s. The intrinsic precisions of v sin i , determined from multi-epoch observations, is approximately 4.0 km/s for MRS and 10.0 km/s for LRS at signal-to-noise ratio (S/N) greater than 50. Our v sin i values show consistence with those from APOGEE17, displaying a scatter of 8.79 km/s. They are also in agreement with measurements from the Gaia DR3 and SUN catalogs. An observed trend in LAMOST MRS data is the decrease in v sin i with dropping Teff, particularly transiting around 7000 K for dwarfs and 6500 K for giants, primarily observed in stars with near-solar abundances.

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Fang Zuo, A-Li Luo, Bing Du, Yinbi Li, Hugh R. A. Jones, Yi-han Song, Xiao Kong, Yan-xin Guo. 2024-01-08. Projected rotational velocities for LAMOST stars with effective temperature lower than 9000 K. https://arxiv.org/abs/2401.03959

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