Search for Variable Stars in Two Old Open Clusters: NGC 2506 and NGC 2420

• Autorzy: Kim, S.-L. , Chum, M.-Y. , Park, B.-G. , Kim, S. C. , Lee, S. H. , Lee, M. G. , Ann, H. B. , Sung, H. , Jeon, Y.-B. , Yuk, I.-S.
• Języki publikacji: EN

Abstrakty

EN

We present results of photometric observations of two old open clusters: NGC 2506 and NGC 2420. V-band time-series and UBVI absolute CCD photometric observations were carried out to search for variable stars and to investigate their physical properties. From the UBVI photometry of NGC 2506, we obtain interstellar reddening of E(B-V)=0.04±0.03 mag, distance modulus (V-M_V)₀=12.5±0.1 mag, and age log(t/yr)=9.25. From monitoring of 590 stars with 304 CCD frames taken for ten nights, three δ Sct stars and one eclipsing binary star are discovered in NGC 2506. For the other cluster, NGC 2420, we have examined light variations of 505 stars using 347 time-series data obtained for five nights, finding no variable star. It should be noted that we have found no γ Dor star among main-sequence stars near F0 in these two old open clusters, which is consistent with the suggestion that γ Dor-type phenomenon occurs in stars younger than log(t/yr)=8.4. On the other hand, it has been known that color-magnitude diagrams of these two clusters show well-established binary sequences, implying high incidence of binary systems: ≥20% for NGC 2506 and ≈50% for NGC 2420. However, only one eclipsing binary star was found in these two clusters.

Słowa kluczowe

EN

stars: variables: general; open clusters and associations: individual: NGC 2506; open clusters and associations: individual: NGC 2420

• Czasopismo: Acta Astronomica
• Rocznik: 2001
• Tom: Vol. 51, No. 1
• Strony: 49--63
• Opis fizyczny: Bibliogr. 35 poz., tab., wykr.

Twórcy

autor

Kim, S.-L.

• Korea Astronomy Observatory, Taejon, 305-348, Korea ,

autor

Chum, M.-Y.

• Korea Astronomy Observatory, Taejon, 305-348, Korea

autor

Park, B.-G.

• Korea Astronomy Observatory, Taejon, 305-348, Korea

autor

Kim, S. C.

• Astronomy Program, SEES, Seoul Nat. Univ., Seoul, 151-742, Korea

autor

Lee, S. H.

• Dep. of Earth Sciences, Pusan Nat. Univ., Pusan, 609-735, Korea

autor

Lee, M. G.

• Astronomy Program, SEES, Seoul Nat. Univ., Seoul, 151-742, Korea

autor

Ann, H. B.

• Dep. of Earth Sciences, Pusan Nat. Univ., Pusan, 609-735, Korea

autor

Sung, H.

• Korea Astronomy Observatory, Taejon, 305-348, Korea

autor

Jeon, Y.-B.

• Korea Astronomy Observatory, Taejon, 305-348, Korea

autor

Yuk, I.-S.

• Korea Astronomy Observatory, Taejon, 305-348, Korea

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