Star cluster group

Discussions

2015

2015.06.23

Li: 星團 IMF

PADOVA isochrone test

Zhong: M35 Proper Motion

PM+Spatial --> high prob. mem. comp. with LAMOST RV. (need phot info. to support the results)

2015.06.18

Lin: 跟中央大學談的合作事項。

1. PTF 在星團中的變星 -- 饒兆聰，楊庭彰 (造父變星、RR Ly)

2. NGC752 科學文章 -- 陳文屏 (蒸發、潮汐的成員，動力自行成員、金屬豐度)

3. 星團中的 Brown Dwarfs -- 陳文屏

2015.06.08

Lin: 說明用密度找PS1星團，分析距離年齡的方法。

整理出star cluster catalog以及Be star catalog。

Zhong: LAMOST在星團中的觀測還不足。

Li: 學習Chi-square fitting方法。

Catalogs

variable stars

Star cluster sample from (186) Dias et al. 2002[1] and (320) Kharchenko et al. 2013. [2] with age > 10^9 years and 0 < Dec < 80 deg.

Be stars

NGC 6830

REPORTING OF NEWLY DISCOVERED BE STARS IN THE OPEN CLUSTER NGC6830 (in prep.)
ABSTRACT
We report 10 newly discovered Be stars in the open cluster NGC6830 with the Hα imaging photometry
of the Palomar Transient Factory Survey. Stellar membership of the candidates was verified with
photometric and kinematic memberships using 2MASS data and proper motions. The spectroscopic
observations were carried out for two objects by the new spectrograph SED-Machine that is mounted
on the Palomar 60 inch Telescope. Our preliminary results of the SED-Machine shows strong Hα
emission lines, which are further confirmed by the Hiyoyu spectrograph of Lulin One-meter Telescope.
Most of the Be stars (9/11) are located in the outer region of the cluster, suggesting gravitational 
disruption over time could result in this spatial distribution.

NGC 663

SEARCHING FOR Be STARS IN THE OPEN CLUSTER NGC 663[3]
ABSTRACT
We present Be star candidates in the open cluster NGC663, identified by Hα imaging 
photometry with the Palomar Transient Factory Survey, as a pilot program to investigate 
how the Be star phenomena, the emission spectra, extended circumstellar envelopes, 
and fast rotation, correlate with massive stellar evolution. Stellar membership of the 
candidates was verified by 2MASS magnitudes and colors and by proper motions (PMs).  
We discover four new Be stars and exclude one known Be star from being a member due 
to its inconsistent PMs. The fraction of Be stars to member stars [N(Be)/N(members)] in 
NGC663 is 3.5%. The spectral type of the 34 Be stars in NGC663 shows bimodal peaks 
at B0–B2 and B5–B7, which is consistent with the statistics in most star clusters. 
Additionally, we also discover 23 emission-line stars of different types, including 
non-member Be stars, dwarfs, and giants.

Brown dwarfs

Candidates in the LAMOST by 王有芬

     RA      Dec     u     g     r     i     z  i-z SpT(SDSS)
152.36670 28.32595 23.91 23.78 21.84 18.94 17.23 1.71 Img [4]
156.61830 29.91000 22.81 23.27 22.00 19.11 17.32 1.79 Img [5]
 13.59698 38.60359 26.13 25.50 22.14 19.16 17.34 1.82 Img [6]
 18.07205 45.60115 23.05 23.44 21.26 18.76 17.21 1.55 Img [7]
 24.01353 33.14750 25.15 23.44 21.63 18.79 16.97 1.82 Img [8]
142.77210 29.56904 23.76 22.55 20.99 18.31 16.80 1.49 Img [9]

bookmarks

Local Group Astrostatistics Conference http://dept.astro.lsa.umich.edu/lgastrostatistics/