Ming Yang & B. W. Jiang Beijing Normal University

1. Ming Yang & B. W. Jiang Beijing Normal University Red Super Giants in LMC: The Period-luminosity Relations

2. Outlines Introduction Sample selection Data analysis Period-luminosity relations Concerned with SONG

3. Introduction • Evolved, moderately massive (10-25M☉), He-burning, very large radii (200-1500 R☉), low surface temperature (3000-4000 K), heavy dusty envelope, radiation transpot to infrared band(Levesque et al. 2005). • Long been known for low optical variations. • Because of their great brightness, these stars might be a useful group of extra galactic distance indicators (Wood & Bessell 1985).

4. Sample selection • Samples: • Total: 191 stars • ASAS: 169 stars • MACHO: 15 stars • Time span: about 3000 days. • Feast et al. (1980) : 14 stars • Pierce et al. (2000) : 15 stars • Kastner et al. (2008): 25 stars • Massey et al. (2003): 137 stars

5. Identification • “Luminous” and “Red” – Color-magnitude diagram and Two-color diagram • 2MASS Point Source catalog • SAGE Winter ’08 IRAC Catalog • SAGE Winter ’08 MIPS 24 m Catalog • Search radius: 1 arcsec

6. For comparison, we add a background that is the 1268 massive stars (M > 8M⊙) in the LMC by Bonanos et al. (2009) which are collected from literatures and have been identified by the same criteria in the SAGE infrared data as we used. • It indicates that the RSGs locate in a distinctive region in CMD and TCD from the other massive stars in the LMC.

7. CMD and TCD • The boundary of carbon-rich star, J - Ks = 1.6 defined by Hughes & Wood (1990) • Most of the M-supergiants are concentrated in 0.5≤ (J - K)≤1.5 (Josselin et al. 2000) • The region only defined by the data, not the theoretical calculation (including 95% targets).

8. Outliers which at least appear in two diagrams should not be considered in the next step of investigation due to their different properties compare with other candidates. • There are some massive sources from Bonanos et al. (2009) which locate in the same regions as RSGs but are not included in the sample.

9. Data analysis • Check DSS images.

10. A least-squares (Savitzky-Golay) polynomial smoothing filter is applied for the ASAS data. • The points whose airmass larger than 2.0 are dismissed (MACHO).

12. Phase Dispersion Minimization（PDM） [Code is written by Marc W. Buie, Lowell Observatory] • Semi-regular • Θ< 0.6 → Probability of correct period > 95%

13. Fourier analysis (Period04; Lenz 2004) • Only adopt the frequency • which correponding to the • highest peak in Fourier • spctrum.

14. Light curves of ASAS and MACHO

15. Period-luminosity relations • Semi-regular RSGs: • 3 targets from Feast et al. (1980) • 4 targets from Pierce et al.(2000) • 14 targets from Kastner et al. (2008) • 14 targets from Massey & Olsen (2003)

16. Period-Ks band magnitude relation. • mbol=mk+3 (Josselin et al. 2000) • Distance modulus 18.41 is adopted(Macri et al. 2006).

19. Mλ = a log P + b

20. AV = (0.81± 0.34)*LogP-(1.54±0.96)

21. Semi-regulars overlay on all candidates RSGs.

22. Concerned with SONG • Long-term observation for years????? (only need three or four days once) • Suitable magnitude range? ( Vmin≈14 mag, Vmax=10 mag) • High precision (no doubt)

23. END Thanks