The Chinese SONG proposal: scientific

concerns

Jianning Fu(Beijing Normal University)

and Chinese SONG team

Beijing ─ March 29, 2010

The third workshop of SONG

Contents

Scientific goal of Chinese SONG proposal

Criteria of target selection Process and results of target

selection Test observations Summary and discussion

1. Scientific goal of Chinese SONG proposal

The SONG project

Optical path ofthe SONG 1-m

telescope

Scientific goals of the SONG project

1 ） Make high-precision time-series radial-velocity observations for individual stars brighter than 6th magnitude, to do asterseismological study.

2 ） Make high-precision high-speed photometric observations for selected fields of the bulge of the Milky Way, to search for exoplanets by means of the micro-lensing effects.

Scientific goal of the Chinese SONG proposal

The Chinese-initiated scientific goal：1) For the selected bright target stars of SONG:

Make Johnson BVR simultaneous photometrical observations for the 15′×15′ fields around the

target stars, when radial-velocity observations are being made for the target stars2) For the bright stars selected by Chinese SONG team:

Select bright stars in the fields of open clusters Aim：

1) to search for and study in detail the variable objects2) to make asteroseismology for the pulsating stars

Modifications of the optical

paths1) Move the lucky image

module to the secondary Nasmyth focus;

2) Place a mirror before the primary Nasmyth focus,to reflect light of a 15′×15′ FOV to a Wide-Field-Imager Module (WFIM);

3) Make a hole of 12-mm diameter (92× 92 FOV) at the center of the reflection mirror, to allow the light of the bright target star to go to M4 then to the Coudé train.

1) Two Dichroic beam-splitters lead light to three CCD cameras equipped with Johnson B、 V 、 R filters after a focal reducer;

2) Time-series data of the objects in the 15′×15′ FOV are collected simultaneously with the Coudé train.

WFIM composition

(Light from the telescope)

WFIM

2. Criteria of target selection

Targets selected by Chinese SONG team：Stars brighter than 7 magnitudes in V in the fields of open clusters

Using long-term networked observation data of SONG, one may do,1 ） asteroseismology of pulsating stars in

the open clusters;2 ） exoplanet detection in the open

clusters by transit events;3 ） study of binary stars in open clusters.

Potential target stars of SONG

Number of targets: 813

(From the talk of JCD in Beijing in Dec. 2009) B - V

V

For bright stars:Field and parameter search

limits:V magnitude: Min -2, Max

7B-V: Min 0.4, Max 1.3

For open clusters:close enough to the potential

bright stars

3. Process and results of target selection

Step 1: for bright stars

6477 candidate stars found in Hipparcos Main Catalogue

(epoch J 1991.25)with the Multi-parameter

search tool;

http://www.rssd.esa.int/index.php?project=HIPPARCOS&page=multisearch2

RA DISTRIBUTION

DEC DISTRIBUTION

V MAG DISTRIBUTION

B-V DISTRIBUTION

Step 2: for open clusters

Download catalog of open clusters from:Dias W. S., Alessi B. S., Moitinho A. and Lépine J. R. D., 2002, A&A, 389, 871

http://www.astro.iag.usp.br/~wilton/

Number of clusters: 1787 Clusters with Diameter: 1782 (99.72%) Clusters with Distance: 1114 (62.34%) Clusters with Reddening: 1093 (61.16%) Clusters with Age: 982 (54.95%) Clusters with Distance, Reddening. and Age: 969 (54.22%) Clusters with Proper Motion (PM): 890 (49.80%) Clusters with Radial Velocity (RV): 502 (28.09%) Clusters with PM + RV: 482 (26.97%) Clusters with Distance, Age, PM and RV: 430 (24.06%) Clusters with Abundance: 178 ( 9.96%)

RA DISTRIBUTION

DEC DISTRIBUTION

APPARENT DIAMETER DISTRIBUTION

Apparent Diameter (Degree)

Step 3: bright stars in open cluster fields

Take the bright stars at the center of the fields, and the edges of the open clusters (OC) located just at the edges of the fields, as the critical situation of targets

Separation in RA ≤ (Diameter of OC + Diameter of the field)/2

Separation in DEC ≤ (Diameter of OC + Diameter of the field)/2

SELECTED CANDIDATES

254 PAIRS

BRIGHT STARS ： 243 (3.75%)OPEN CLUSTERS ： 121 (6.77%)

RA DISTRIBUTION OF OPEN CLUSTERS

DEC DISTRIBUTION OF OPEN CLUSTERS

APPARENT DIAMETER OF OPEN CLUSTERS

Apparent Diameter (arc minute)

RA-DEC GRAPH OF OPEN CLUSTERS

RA DIATRIBUTION OF BRIGHT STARS

DEC DISTRIBUTION OF BRIGHT STARS

V MAG DISTRIBUTION

B-V DISTRIBUTION

RA-DEC GRAPH OF BRIGHT STARS

NUMBER OF BRIGHT STARS WITHIN THE OPEN CLUSTER

FIELDS

Separation in RA from the bright star to the open cluster center

Separation in Dec from the bright star to the open cluster center

No Name of Open Cluster RA (h) DEC (degree)Number of bright stars

1 'Platais 2' 1.23055556 32.02833 8

2'NGC 457' 1.32638889 58.28667 2

3'NGC 752' 1.96138889 37.785 2

4'NGC 869' 2.31666667 57.12833 2

5'NGC 884' 2.37305556 57.12583 2

6'Alessi 13' 3.36166667 -36.3 2

7'Melotte 20' 3.40527778 49.86167 3

8'Melotte 25' 4.44833333 15.86667 21

9'Melotte 31' 5.30277778 33.37361 2

10'Collinder 65' 5.435 16.70028 2

11'Collinder 70' 5.59166667 -1.1 3

12'Platais 5' 6.16 -22.1517 4

13'Platais 6' 6.25722222 3.845 4

14'Collinder 89' 6.3 23.63333 4

15'NGC 2451A' 7.72 -38.4 2

16'Collinder 173' 8.04694444 -46.3833 7

17'Ruprecht 64' 8.62222222 -40.15 2

18'NGC 2632' 8.67333333 19.66667 4

19'Platais 8' 9.15833333 -59.1283 30

20'Platais 9' 9.22972222 -43.74 9

21'Turner 5' 9.56416667 -36.615 3

22'Platais 10' 13.7244444 -59.1217 4

23'Collinder 285' 14.685 69.56667 20

24'Collinder 302' 16.4355556 -26.25 5

25'Alessi 24' 17.4002778 -62.8633 2

26'NGC 6475' 17.8975 -34.7933 3

27'Collinder 359' 18.0183333 2.9 4

28'IC 4725' 18.5297222 -19.1167 2

29'ASCC 100' 19.0269444 33.57 2

30'ASCC 123' 22.71 54.26 2

31'Alessi 22' 23.8019444 36.205 2

4. Test observations

March 2 and 6, 2010: Run IThe 80-cm telescope at Xinglong station

March 10 and 12, 2010: Run IIThe 100-cm telescope at Xinglong station

Attention:Light of the bright star masked at the center of the window of the CCD camer

The 80-cm telescope Mounting: equatorial Made by AstroOptik

company of Germany

Equipped with a PI CCD camera of1340×1300

Cooling: liquid nitrogen

FOV: 11.5′×11.5′

The 1-m telescope Mounting: altazimuth Made by EOS

company of Australia Equipped with a PI

CCD camera of 1340×1300

Cooling: electronic FOV: 12′×12′

Targets:HIP 29860:

RA=06:17:16; DEC=05:06:00; V=5.71; B-V=0.61;

Open cluster: Platais 6; RA=06:15:26; DEC=03:50:42; Diameter=4.2°;Sep in RA=27.6′; Sep in DEC=75.3′

HIP 69107:RA=14:08:46; DEC=59:20:16; V=6.47; B-

V=1.023; Open cluster: Collinder 285; RA=14:41:06; DEC=69:34:00; Diameter=23.33°;Sep in RA=8°5′; Sep in DEC=10°14′

Test observations: Run I2010.3.2/80cm/Hip 29860

238 frames in 3.86 h

Light curvesexample

Photometry precision

Test observations:2010.3.2/80cm/Hip 69107

108 frames in 4.13 h

Light curvesexample

Photometry precision

Date: 2010.3.10Telescope: 100cmTarget: Hip 29860Data: 136 frames for 3.68

hours

Test observations : Run II

Date: 2010.3.10Telescope: 100cmTarget: Hip 69107Data: 127 frames for 4.13

hours

Test observations

5. Summary and discussion

―the Coudé path for RV observations and the Nasmyth instruments for micro-lensing effect detection will never work simultaneously;―the M3 can rotate 180°;

―the 3-color 15′×15′ photometer allows the light of the bright star to go to the Coudé path;

the proposed modifications will not harm the original scientific work of SONG.

However, one may get scientific benefits with these modifications.

Long-term 3-color networked data will be collected for the objects in the fields.This kind of data will be unique andvery important in science.

We estimate the price of these modifications around 300,000 euros for each node.

Bright stars matching the requirements of SONG are found in the fields of open clusters.

In the test observations with the 80-cm telescope, no variable stars discovered.Possible reasons:

1) photometry precision relatively low and few data collected;

2) the ages of the open clusters should

be concerned in the target selection.

Test observations with the 100-cm telescope:

1) field rotation is visible;2) a specific photometry code is needed to do photometry for the objects in the rotating frames.

We plan to make more test observations for more bright stars in the selected open clusters with the ages concerned.

Discussion and collaboration are welcome.

Thanks for your attention!