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1

New Galactic Multi-Mode Cepheids from the ASAS-SN Survey

Jurcsik J., Hajdu G., Catelani M.

Acta Astronomica

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2018

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Vol. 68, No. 4

341--350

EN

A systematic search for multi-mode Cepheids using the database of the ASAS-SN survey has led to the detection of thirteen new double-mode and two triple-mode Cepheids in the Galactic disk. These discoveries have increased the number of Galactic disk multi-mode Cepheids by 33%. One of the new triple-mode variables pulsates simultaneously in the fundamental and in the first and the second radial overtone modes and the other in the first three radial overtone modes. Overtone triple-mode Cepheids were identified only in the Galactic bulge and in the Large and Small Magellanic Clouds previously.

2

On the Distribution of the Modulation Frequencies of RR Lyrae Stars

Jurcsik J., Szeidl B., Nagy A., Sódor Á.

Acta Astronomica

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2005

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Vol. 55, No. 3

303--314

EN

For the first time connection between the pulsation and modulation properties of RR Lyr stars has been detected. Based on the available data it is found that the possible range of the modulation frequencies, i.e., the possible maximum value of the modulation frequency depends on the pulsation frequency. Short period variables (P<0.4 d) can have modulation period as short as some days, while longer period variables (P>0.6 d) always exhibit modulation with Pmod>20 d. We interpret this tendency with the equality of the modulation period with the surface rotation period, because similar distribution of the rotational periods is expected if an upper limit of the total angular momentum of stars leaving the RGB exists. The distribution of the projected rotational velocities of red and blue horizontal branch stars at different temperatures shows a similar behavior as vrot derived for RR Lyr stars from their modulation periods. This common behavior gives reason to identify the modulation period with the rotational period of the modulated RR Lyr stars.

3

Identification and Astrometry of Variable Stars in M3

Bakos G. Á., Benkö J. M., Jurcsik J.

Acta Astronomica

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2000

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Vol. 50, No. 2

221--248

EN

The space distribution of orbital poles for 252 visual binaries is analyzed to check a possible tendency towards parallelism. It is confirmed that orbital planes do not show any trend to be parallel to the Galactic plane. No strong evidence is found for a preferential orientation of the orbital planes for subgroups of binaries with similar periods and eccentricities. Asymmetry in the distribution of orbital poles is seen only for a subgroup of 19 binaries lying closer than 10 pc. Small differences in the distribution of orbital poles are also detected for subgroups with different location on HR diagram.