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

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

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

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

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

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.

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).

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.

Data analysis Check DSS images.

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

Phase Dispersion Minimization （ PDM ） [Code is written by Marc W. Buie, Lowell Observatory] Phase Dispersion Minimization （ PDM ） [Code is written by Marc W. Buie, Lowell Observatory] Semi-regular Θ 95%Θ 95%

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

Light curves of ASAS and MACHO Light curves of ASAS and MACHO

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)

Period-Ks band magnitude relation. Period-Ks band magnitude relation. m bol =m k +3 (Josselin et al. 2000) m bol =m k +3 (Josselin et al. 2000) Distance modulus is adopted (Macri et al. 2006). Distance modulus is adopted (Macri et al. 2006).

M λ = a log P + b

A V = (0.81± 0.34)*LogP-(1.54±0.96)

Semi-regulars overlay on all candidates RSGs. Semi-regulars overlay on all candidates RSGs.

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

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