We have studied the zero-point offset of Gaia early Data Release 3 (EDR3) parallaxes based on a sample 0.3 million giant stars built from LAMOST data with distance accuracy better than 8.5\%. The official parallax corrections largely reduce global in EDR3 parallaxes: offsets are $-$27.9 $\mu$as and $-$26.5 (before correction) $+$2.6 $+$2.9 (after for five- six-parameter solutions, respectively....

We present period-luminosity diagrams for nearby Miras and semiregulars, selecting stars with parallaxes better than 20 per cent and well-determined periods. Using K-band magnitudes, we find two well-defined P-L sequences, one corresponding to the standard Mira P-L relation and the second shifted to shorter periods by a factor of about 1.9. The second sequence only contains semiregular variable...

An “inventory” of different classification systems were made. Two different surveys for B9 to F2 type stars were chosen in oder to get an unbiased sample of “normal” stars. Jaschek & Valbousquet (1997) and Jaschek & Gómez (1998) already investigated the intrinsic consistency of the MK spectral classification systems. But interesting enough their results contradict in some important points. With...