THREE-SITE PHOTOMETRIC MONITORING OF THE $\delta$ SCT-TYPE PULSATING STAR V1162 ORIONIS : PERIOD CHANGE AND ITS IMPLICATIONS FOR PRE-MAIN SEQUENCE EVOLUTION

다국어 초록 (Multilingual Abstract)

We present photometric results of the $\delta$ Sct star V1162 Ori, which is extensively monitored for a total of 49 nights from mid-December 2014 to early-March 2015. The observations are made with three KMTNet (Korea Microlensing Telescope Network) 1.6 m telescopes installed in Chile, South Africa, and Australia. Multiple frequency analysis is applied to the data and resulted in clear detection of seven frequencies without an alias problem\,: five known frequencies and two new ones with small amplitudes of 1.2-1.7 mmag. The amplitudes of all but one frequency are significantly different from previous results, confirming the existence of long-term amplitude changes. We examine the variations in pulsation timings of V1162 Ori for about 30 years by using the times of maximum light obtained from our data and collected from the literatures. The $O-C$ (Observed minus Calculated) timing diagram shows a combination of a downward parabolic variation with a period decreasing rate of (1/P)dP/dt = $-$4.22 $\times$ 10$^{-6}$ year$^{-1}$ and a cyclic change with a period of about 2780 days. The most probable explanation for this cyclic variation is the light-travel-time effect caused by an unknown binary companion, which has a minimum mass of 0.69 M$_\odot$. V1162 Ori is the first $\delta$ Sct-type pulsating star of which the observed fast period decrease can be interpreted as an evolutionary effect of a pre-main sequence star, considering its membership of the Orion OB 1c association.

참고문헌 (Reference)

1 Fitch, W. S, "ℓ = 0, 1, 2, and 3 Pulsation Constants for Evolutionary Models of δ Scuti Stars" 249 : 218-, 1981

2 Rodrıguez, E., "δ Scuti and Related Stars : Analysis of the R00 Catalogue" 366 : 178-, 2001

3 Breger, M, "δ Scuti Stars(Review), in Delta Scuti and Related Stars" 210 : 3-, 2000

4 Gaia Collaboration, "VizieR Online Data Catalogue : Gaia DR1"

5 Kim, S. -L., "Variable Stars in a Field of the Old Open Cluster M67 : Photometric Precision of the BOAO 1. 8 m Telescope" 29 : 43-, 1996

6 Khokhuntod, P., "V1162 Orion: Updated Amplitude and Period Variation"

7 Arentoft, A., "V1162 Ori : A Multiperiodic δ Scuti Star with Variable Period and Amplitude" 374 : 1056-, 2001

8 Lee, J. W., "The sdB+M Eclipsing System HW Virginis and Its Circumbinary Planets" 137 : 3181-, 2009

9 Kaiser, N., "The Pan-STARRS Wide-Field Optical/NIR Imaging Survey" 2010

10 McNamara, D. H, "The High-Amplitude δ Scuti Stars, in Delta Scuti and Related Stars" 210 : 373-, 2000

11 Sota, A., "The Galactic O-Star Spectroscopic Survey. I. Classification System and Bright Northern Stars in the Blue-Violet at R~2500" 193 : 24-, 2011

12 Gould, A., "The Extreme Microlensing Event OGLE-2007-BLG-224: Terrestrial Parallax Observation of a Thick-Disk Brown Dwarf" 698 : L147-, 2009

13 Solano, E., "Spectroscopic Survey of δ Scuti Stars I. Rotation Velocities and Effective Temperatures" 122 : 131-, 1997

14 Nieva, M. -F., "Present-Day Cosmic Abundances. A Comprehensive Study of Nearby Early B-type Stars and Implications for Stellar and Galactic Evolution and Interstellar Dust Models" 539 : A143-, 2012

15 Wils, P., "Photometry of High-Amplitude Delta Scuti Stars in 2014" (6150) : 2015

16 Wils, P., "Photometry of High-Amplitude Delta Scuti Stars in 2013" (6122) : 2014

17 Wils, P., "Photometry of High-Amplitude Delta Scuti Stars in 2012" (6049) : 2013

18 Wils, P., "Photometry of High-Amplitude Delta Scuti Stars" (6015) : 2012

19 Hintz, E. G., "Photometric Studies of δ Scuti Stars. II. V1162 Orionis" 110 : 689-, 1998

20 Arentoft, A., "Period and Amplitude Changes in the δ Scuti Star V 1162 Orionis" 354 : 589-, 2000

21 Breger, M., "Period Changes of δ Scuti Stars and Stellar Evolution" 332 : 958-, 1998

22 Marques, J. P., "On the Effect of Overshooting as Predicted by the Modelling of the Pre-main-Sequence Evolution of a 2M⊙ Star" 371 : 293-, 2006

23 Breger, M., "Nonradial and Radial Period Changes in the δ Scuti Star 4 CVn I. 700+ Nights of Photometry" 592 : A97-, 2016

24 Smith, M. A, "Nonradial Pulsations in the Zero-Age Main-Sequence Star Upsilon Orionis(09. 5 V)" 248 : 214-, 1981

25 Breger, M., "Nonradial Pulsation of the Delta Scuti Star BU Cancri in the Praesepe Cluster" 271 : 482-, 1993

26 Wils, P., "Maxima of High-Amplitude Delta Scuti Stars" (5977) : 2011

27 Wils, P., "Maxima of High-Amplitude Delta Scuti Stars" (5928) : 2010

28 Gilliland, R. L., "Limits to CCD Ensemble Photometry Precision and Prospects for Astero-seismology" 104 : 582-, 1992

29 김승리, "KMTNET: A NETWORK OF 1.6 M WIDE-FIELD OPTICAL TELESCOPES INSTALLED AT THREE SOUTHERN OBSERVATORIES" 한국천문학회 49 (49): 37-44, 2016

30 Arentoft, A., "Irregular Amplitude Variations and Another Abrupt Period Change in the δ Scuti Star V1162 Ori" 378 : L33-, 2001

31 Bally, J, "Handbook of Star Forming Regions Vol. I: The Northern Sky" ASP Monograph Publications 459-, 2008

32 Poretti, E., "Fourier Decomposition of the Light Curves of Pulsating Variables : The Delta Scuti stars BD−7◦1108, KU Centauri and V567 Ophiuchi" 228 : 350-, 1990

33 Breger, M., "Detection of 75+ Pulsation Frequencies in the δ Scuti Star FG Virginis" 435 : 955-, 2005

34 Breger, M, "Delta Scuti and Related Stars" 91 : 5-, 1979

35 Lampens, P, "BD−7◦1108, A New Delta Scuti Vari-able" (2794) : 1985

36 Siess, L., "An Internet Server for Pre-Main Sequence Tracks of Low-and Intermediate-Mass Stars" 366 : 178-, 2000

37 Kim, S. -L., "Algol-Type Eclipsing Binaries with δ Scuti-Type Pulsating Components : IV Cas" 122 : 1311-, 2010

38 Henden, A. A., "AAVSO Photometric All Sky Survey (APASS)" 2016

39 Silvotti, R., "A Giant Planet Orbiting the Extreme Horizontal Branch Star V 391 Pegasi" 449 : 189-, 2007

40 Montgomery, M. H., "A Deviation of the Errors for Least Square Fitting to Time Series Data" 13 : 28-, 1999