The Pulsating Eclipsing Binary TIC 309658221 in a 7.59 Day Orbit. (arXiv:1904.07362v1 [astro-ph.SR])

<a href="http://arxiv.org/find/astro-ph/1/au:+Lee_J/0/1/0/all/0/1">Jae Woo Lee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kristiansen_M/0/1/0/all/0/1">Martti H. Kristiansen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hong_K/0/1/0/all/0/1">Kyeongsoo Hong</a>

We present a new eclipsing binary (EB) showing multiperiodic oscillations

using the first three sectors of {it TESS} photometry. The eclipse and

pulsation light curves of TIC 309658221 were modeled using an iterative method

to obtain a consistent photometric solution. The {it TESS} target is a

circular-orbit, detached binary system with a mass ratio of 0.349, an

inclination angle of 80.42 deg, and a temperature difference of 847 K between

the components. The primary component of the system lies near the red edge of

the $delta$ Sct instability region on the main-sequence band in the

Hertzsprung-Russell diagram. Multiple frequency analyses were applied to the

eclipse-subtracted residuals after removing the binary effects in the observed

data. These resulted in the detection of 26 frequencies, of which $f_1-f_6$

were independent pulsation frequencies. The 20 other frequencies could be

mainly caused by orbital harmonics ($f_8$ and $f_{11}$) or combination

frequencies. The period ratios and pulsation constants of the $f_1-f_6$

frequencies are in the ranges of $P_{rm pul}/P_{rm orb}$ = 0.010$-$0.013 and

Q = 0.027$-$0.036 days, respectively, which are typical of $delta$ Sct type.

The results reveal that TIC 309658221 is an eclipsing $delta$ Sct star with an

orbital period of 7.5952 days and pulsation frequencies of 9.94$-$13.01

day$^{-1}$. This work demonstrates that the 2-min cadence observations of {it

TESS} are very useful for the study of pulsating EBs with multiple frequencies

and low amplitudes.

We present a new eclipsing binary (EB) showing multiperiodic oscillations

using the first three sectors of {it TESS} photometry. The eclipse and

pulsation light curves of TIC 309658221 were modeled using an iterative method

to obtain a consistent photometric solution. The {it TESS} target is a

circular-orbit, detached binary system with a mass ratio of 0.349, an

inclination angle of 80.42 deg, and a temperature difference of 847 K between

the components. The primary component of the system lies near the red edge of

the $delta$ Sct instability region on the main-sequence band in the

Hertzsprung-Russell diagram. Multiple frequency analyses were applied to the

eclipse-subtracted residuals after removing the binary effects in the observed

data. These resulted in the detection of 26 frequencies, of which $f_1-f_6$

were independent pulsation frequencies. The 20 other frequencies could be

mainly caused by orbital harmonics ($f_8$ and $f_{11}$) or combination

frequencies. The period ratios and pulsation constants of the $f_1-f_6$

frequencies are in the ranges of $P_{rm pul}/P_{rm orb}$ = 0.010$-$0.013 and

Q = 0.027$-$0.036 days, respectively, which are typical of $delta$ Sct type.

The results reveal that TIC 309658221 is an eclipsing $delta$ Sct star with an

orbital period of 7.5952 days and pulsation frequencies of 9.94$-$13.01

day$^{-1}$. This work demonstrates that the 2-min cadence observations of {it

TESS} are very useful for the study of pulsating EBs with multiple frequencies

and low amplitudes.

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