Submitting Campus

Daytona Beach

Department

Physical Sciences

Document Type

Article

Publication/Presentation Date

9-2-2025

Abstract/Description

Hot subdwarf B (sdB) stars are post-main-sequence stars of high temperature and gravity. Approximately 30% of sdBs exhibit stable pressure and/or gravity-mode pulsations, which can be used via the timing method to test for companion stars and determine their orbital solutions. We used short cadence data from the Transiting Exoplanet Survey Satellite (TESS) to search for previously undiscovered companions to sdBs. In this paper, we focus on searching for companions with orbital periods shorter than 13.5 days which are detectable within one sector of TESS data (about 27 days). The timing method requires that we derive pulsation frequencies in subsets of data significantly shorter than the periods we are searching for, which we set at 0.5–1.5 day. We investigated ten sdB stars with previously detected p-mode pulsations for which at least one p-mode pulsation remains detectable with a signal-to-noise ratio > 4 within data subsets of duration 0.5–1.5 day. We find that two (TIC 202354658 and TIC 69298924) of these ten sdB stars likely have white-dwarf companions and set limits on companion masses for the other eight sdB stars.

Publication Title

The Astronomical Journal

DOI

10.3847/1538-3881/adf73c

Publisher

IOP Science

Grant or Award Name

We acknowledge research support from the National Science Foundation (NSF) under grant No. AST-2108975. T.O. acknowledges research support from the National 2600 2800 3000 3200 3400 3600 50 0 50 time delay (sec) f5 f2 50 0 50 time delay (sec) 2620 2640 2660 2680 2700 2720 5 10 15 25 0 25 time delay (sec) 3340 3360 3380 3400 3420 3440 5 10 15 20 50 0 50 time delay (sec) 2885 2890 2895 2900 2905 2910 5 10 15 20 40 20 0 20 40 3535 3540 3545 3550 3555 3560 5 10 15 20 25 0 25 3610 3615 3620 3625 3630 3635 5 10 15 BJD - 2457000 amplitude (ppt) amplitude (ppt) amplitude (ppt) All sectors (Sectors 48-85) Sectors 48-51 Sectors 75-78 Sector 58 Sector 82 Sector 85 Figure 6. Pulsation timing analysis of TIC 202354658 using f5 (the largest amplitude pulsation—shown in “•”) and f2 (the second largest amplitude pulsation— shown in “■”). (Row1) Pulsation timing analysis of all available sectors, Sectors 48–51, 58, 75–78, 82, and 85. (Row2–4: top) The pulsation timing analysis of each sector. The solid curve shows the best-fit sinusoid. (Row2–4: bottom) The pulsation amplitude variations of each sector. (The data used to create this figure are available in the online article.) 8 The Astronomical Journal, 170:199 (9pp), 2025 October Otani et al. Aeronautics and Space Administration (NASA) under grant No. 80NSSC24K0494.

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