日本天文学会2008年秋季年会

中小口径望遠鏡による天文学・A28c

2008.9.11-13

GA

岡山理科大学High Resolution Spectroscopyof Binaries Using GAOES

Gunma Astronomical Observatory

http://www.astron.pref.gunma.jp/

High Resolution Spectroscopy of Double-lined Detached Eclipsing Binaries
Using the Gunma Astronomical Observatory Echelle SpectrographHakim L. Malasan1, Osamu Hashimoto2, A.T. Purijatmiko1 , Hikaru Taguchi2 , GAOES team
1 : Institut Teknologi Bandung, 2 : Gunma Astronomical Observatory
On the basis of collaboration between Gunma Astronomical Observatory in Japan and Institut Teknologi Bandung in Indonesia, high-resolution
spectroscopy of stellar objects using the newly designed Gunma Astronomical Observatory Echelle Spectrometer (GAOES) installed at a 1.5 metertelescope has been actively carried out since 2004. GAOES has several advantageousnesses against conventional echelle spectrographs, i.e. its
compactness, higher throughput and stability that enable one to conduct high-resolution spectroscopy (R ~ 70,000) on relatively faint objects. Doublelined eclipsing binaries are, so far, the only objects for which fundamental and simultaneous determinations of absolute physical parameters can bededuced. In the case of detached eclipsing binaries of this type, mutual interaction can be neglected and analyses of observables can yield in simultaneous
absolute dimensions for the two single stars. Further, evolutionary models should be able to predict the same age for both components for a certain
chemical composition.We have made high-resolution optical spectroscopic observations using GAOES of several double-lined detached eclipsingbinaries, i.e. CD Tau, EE Peg, Beta Aur and IQ Per in 2006. Among them, CD Tau has been monitored since 2004 up to now. With the introduction of
new camera system of GAOES, significant improvement on the obtained S/N data lead us to better spectra for analysis on line profiles and radialvelocities.

Interest in Double-lined
Detached Eclipsing Binaries

Problems

A “typical” Astrophysical Laboratory• Photometry

Double-lined
eclipsing binaries• Spectroscopy

Detached double-lined
eclipsing binaries
Constraints for theevolutionary models• Light curves• Rad.velocity curve

Current evolutionary models unable to describe
observed properties of low-mass
eclipsing binaries (0.7−1.1 M )(Popper 1997, Clausen et al 1999):* Radius too small (log g too large)* Effective temperature too highMasses, radii-No mass transfer,no mutual interaction

Possible explanations (Clausen et al 1999):-Components independently evolvefrom a common origin both in time
& chemical composition* Observational problems* Lack of chemical composition determination* Inaccuracies of the physics of the models
i.e. mixing length parameter→ similar isochrone fitsto eclipsing binary pair’s
physical parameters

About CD-Tauri◆HD 34335, HIP 24663:
An eclipsing binary & a double-line spectroscopic binary◆α = 5h 17m 31.2s, δ = +20° 07′ 54.6″ (J2000.0)◆Vsystem,max = 6.75m◆Spectral Classes : F6V (primary)+ F6V (secondary)Purpose(Ribas et al. 2000)

High-resolution spectroscopy
exploratory work
* To apply standard reduction technique(IRAF-based) to the echellograms* To obtain heliocentric radial velocities
for primary and secondary components* Detailed profile analyses: Deblending,equivalent widths, abundance

Observation of CD-Tauri
Date :20041021, 20041023, 20041027
20050210, 20051127, 20061222
20061230, 20061231, 20070101
20070104, 20080130, 20080131
20080201

Radial velocity curves
 Popper (1971) : Poor quality
 Ribas et al. (1999): CORAVEL@ 1 m Obs. De Geneve telescope

Telescope : GAO-150cm Relfector

Min I (HJD)=2441619.4075+3.435137dE

Instrument : GAOESLight curves(photoelectric photometry)
 Srivastava (1976): UBV
 Wood (1976): Strömgren
 Gulmen et al (1980): BV

Radial velocity curve solution(Lehman-Filhés method for
double lines radial velocity)

Setting
S/N KA =96.8 kms−1 , KB =102.1 kms−1
 q = MB/MA = 0.948
 a = 13.52 R
 γ = −29.3 kms−1: 30-130

Strategic advantages for GAOESLight curves solution(Wilson-Devinney code)

Physical Properties
MA=1.44±0.02 M
RA =1.79±0.02 R
log gA=4.09±0.01
TeffA =6200±50 K

 e=0
 i=87.7°
 rA=0.1330 r B=0.1172
 LB/LA (B)=0.770 L B/L A (V)=0.772
 TeffB/TeffA =0.999

M B=1.37±0.02 M 
RB=1.58±0.02 R
log g B=4.17±0.01
TeffB =6200±50K

Results for CD-Tauri
Hα absorption lines
21 Oct. 2004 26:39 (JST): 1” slit (R~70,000)

Exposure : 30-60 min x 2-4 times

10 Feb 2005 22:15 (JST)11 Feb 2005 23:06 (JST)High-resolution :Tough against light pollution
Wide slit :Tough against poor seeing
Independent Operation ( as a public observatory ) :Plenty observation time on a small number of specific subjects

Current Programs (up to 2010)
New radial velocity curve

StarV

Period(days)

Remarks

CD Tau6.3

3.4

Almost full orbital
phase coverage(2004-2009)

Beta Aur

1.9

3.9

2006 - 2009

EE Peg7.9

2.6

2007 - 2010

IQ Per7.7

1.7

2007 - 2010