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Observations of the SX Phoenicis Star XX Cygni. X.H. Yang Beijing Normal University 2010.4.1. Contents. Introduction of the SX Phe stars New observations Data reduction Light curves Analysis Conclusions. Introduction. δ Scuti Stars: 1.The SX Phoneicis stars

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observations of the sx phoenicis star xx cygni

Observations of the SX Phoenicis Star XX Cygni

X.H. Yang

Beijing Normal University

2010.4.1

contents
Contents
  • Introduction of the SX Phe stars
  • New observations
  • Data reduction
  • Light curves
  • Analysis
  • Conclusions
introduction
Introduction

δ Scuti Stars:

1.The SX Phoneicis stars

2.High-amplitude δ Scuti Stars (HADS)

Period changes:

Period increasing and period decreasing were detected in different

δ Scuti Stars

  • The SX Phoenicis stars:
    • Found in the field stars
    • Found in the blue straggler populations of globular clusters
  • short-period
  • Single- or multiple-mode pulsations
slide4
Importance of studying SX Phe stars

1.Studying stellar evolution

2. Potential targets for Asterseismology

slide5
XX Cygni:

20h03m15.6 58°57\'17.0"

Spectral type: A5-F5,

V=11.m7, P≈0.d1349, △V=0.m84

Mass:1 Msun [Fe/H]=-0.49 dex

Teff: 7530 K Radial Velocity=-108 km/s

slide6
Discovered by Ceraski (1904)
  • Constant period, marked by occasional discontinuous period changes (Szeidl & Mahdy 1981)
  • Single-mode pulsation (Hintz & Joner1997)
  • Both amplitude and period changes (Zhou et al. 2001)
  • If the small secondary peak(maximum) is real,it is transient (Blake 2002)
slide7
The secondary peak or maximum

From BLAKE

Period Changes in SX Phoenicis Stars. II. XX Cygni

new observations
New observations
  • Telescope used in observations

1. The 85-cm telescope located at the Xinglong Station of NAOC

Focal ratio: 3.27 ; Focal length: 2780mm

CCD camera: CCD,PI1024 BFT

Filters: Standard Johnson-Cousin-Bessel UBVRI

Field of view: 16’.5×16’.5

2.The 60-cm telescope located in Kunming (Yunnan Astronomical Observatory)

data reduction
Data Reduction

Data reduction was performed using the APPHOT program in IRAF:

1.Bias and Dark correction, Flat fielding

2.Multiple aperture photometry

3.Determination of the best aperture

slide14

Field of view:

16’.5*16’.5

Xinglong

light curves
Light Curves

2007

07.15-08.30

Xinglong 85cm

Error:

0.004-0.02

slide16
2008.08.31

Xinglong

Error:

0.003

slide17
2009

07.09

-10.17

Xinglong

Error:

0.003-0.02

Kunming

60cm

Kunming

analysis
Analysis

Observed new times of maximum: 37

slide19
Fourier analysis:

Software: Period04

Data set: 2007.08

8 nights of observations

conclusions
Conclusions

No secondary peaks were found in our data.

  • Next work:
    • O-C analysis
    • Period change analysis
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