New Variable Stars Around the Cepheid Variable Tu Cas

From the short-period variability survey (SPVS) in Bohyunsan Optical Astronomy Observatory, we obtained time-series BV CCD images in the region of an open cluster M38 (NGC 1912) for 23 nights from February 1, 2007 to December 7, 2008. We found 18 δ Scuti stars and 2 γ Doradus stars. Among them, only 3 δ Scuti stars were known ones. From the color-magnitude diagram (CMD) of M38, most of them have been located in the instability strip. The two γ Doradus stars have been located within γ Doradus strip of M38. But, only four δ Scuti stars were located within radius 10 from the center of M38. To confirm of their membership for M38, we need more study, such as, proper motion by spectroscopic observation.

“…관측한 CCD 영상자료는 IRAF/CCDRED (Stetson 1987, Massey & Davis 1992 (Jeon et al 2005b(Jeon et al , 2007. (Jeon 2008(Jeon , 2009.…”

Section: 서론 산개성단 M38 (Ngc 1912)은 Webdaunclassified

New Variable Stars in the Region of the Open Cluster M38 (Ngc 1912) I: Δ Scuti and Γ Doradus Type Stars

2009

“…보현산천문대의 단주기 변광성 탐사연구(SPVS; Jeon et al 2005a)는 그동안의 시험관측을 통하여 V =9에서 14등급 사이의 단주기변광성, 특히 δ Scuti 형 변광성의 탐사에 유용함을 확인하였다 (Jeon et al 2004a(Jeon et al , 2004b(Jeon et al , 2005b. SPVS는 우리 은하의 산개성단에 대한 단주기 변광성을 체계적으로 탐사하는데 주된 목적을 두 고 있다.…”

Section: 서론unclassified

“…관측된 CCD 영상자료는 IRAF/CCDRED (Stetson 1987, Massey & Davis 1992 Jeon et al 2005bJeon et al , 2007. Jeon et al 2007;Lee et al 2007 Jin et al 2004).…”

Section: 산개성단 M50 (Ngc 2323)은 적경mentioning

confidence: 99%

Variable Stars in the Region of an Open Cluster M50

2008

From the short-period variability survey (SPVS), we obtained time-series BV CCD images in the region of an open cluster M50 (NGC 2323) for 10 nights from 2008 February 9 to 27. The observation was performed using a small refracting telescope (ϕ=155mm, f =1050mm) in Bohyunsan Optical Astronomy Observatory (BOAO). M50 is included in the observing field of ASAS (The All Sky Automated Survey). In the region of M50, we found 8 new variable stars including two δ Scuti stars with short-periods and very small amplitudes. There are known nine variable stars by the catalogues of ASAS and GCVS in the region. We confirmed the variability of the known variable stars for six and non-variability for three.

“…관측한 CCD 영상자료 는 IRAF/CCDRED (Stetson, 1987;Massey & Davis, 1992)를 이용하여 영점보정, 암잡음보정, 플랫보정의 전처리 과정을 수행하였다. 전처리 과정과 측광 과정 은 이전의 연구와 같다 (Jeon et al, 2005b(Jeon et al, , 2007. (Jeon, 2008(Jeon, , 2009 (Zacharias et al, 2012).…”

unclassified

Variable Stars in the Region of Cyg Ob3 Association Centered on the Open Cluster NGC 6871 I: Δ Scuti Type Stars

Jeon¹,

Lee²,

Park³

et al. 2012

Self Cite

As a part of the short-period variability survey (SPVS) at Bohyunsan Optical Astronomy Observatory, we obtained time-series BV CCD images in the region of Cyg OB3 association centered on the open cluster NGC 6871. The observations were performed for 18 nights from September 5, 2008 to September 1, 2009. We found 15 short-period variable stars in the region. They are δ Scuti type stars belonging to the local spiral arm, Orion spur. Among them, only two stars were previously known, and the rest are newly discovered ones. In this paper, we have performed a multiple-frequency analysis to determine frequencies of the 15 δ Scuti type stars, using the discrete Fourier transform and linear least-square fitting methods. One of the newly discovered variable stars is a double-mode δ Scuti type star with the fundamental and the first overtone modes, and two are high amplitude δ Scuti stars.