J/AJ/170/331 Eclipse depths & times for 7 systems from KELT & TESS (Baum+, 2025)
Eclipse depth variations in seven eclipsing binaries as observed by KELT and
TESS.
Baum A.C., Pepper J., Davenport J.R.A., Howell S.B.
<Astron. J., 170, 331 (2025)>
=2025AJ....170..331B 2025AJ....170..331B
ADC_Keywords: Binaries, eclipsing; Photometry; Optical;
Stars, double and multiple
Keywords: Binary stars ; Eclipsing binary stars
Abstract:
A set of eclipsing binary systems exhibit a changing inclination over
time due to the gravitational influence of a third stellar companion.
These changing inclinations manifest in photometric observations over
time as eclipse depth variations. To detect changing eclipse depths,
it is advantageous to have a long time baseline of observations, which
can be attained by combining data from multiple surveys. We collect
ground-based photometry from the Kilodegree Extremely Little Telescope
and space-based photometry from the Transiting Exoplanet Survey
Satellite (TESS) for seven known changing-inclination eclipsing
binaries: HS Hya, RW Per, IU Aur, AH Cep, SV Gem, V685 Cen, and SS
Lac. We measure eclipse depth variations and eclipse timing variations
in six systems; SS Lac no longer eclipses. As of observations
presented here from TESS Sector 35, eclipses are no longer visible in
HS Hya (as noted in J. R. A. Davenport et al. 2021). SV Gem,
previously believed to have stopped eclipsing, exhibits eclipse-like
features across all years of observation, as well as evidence of the
negative "O'Connell Effect." We also present high-resolution speckle
imaging from Gemini-North, Gemini-South, and the NESSI instrument on
the WIYN telescope for RW Per, AH Cep, SV Gem, and SS Lac, none of
which revealed a third companion. Speckle imaging of IU Aur from NESSI
revealed the presence of a third companion at an angular separation of
0.14"; we report the details of this detection.
Description:
The Kilodegree Extremely Little Telescope (KELT) is a small-aperture
robotic photometric telescope that operated from 2004 to 2020 to
search for transiting exoplanets. KELT-North observed from Winer
Observatory in Arizona, USA, and KELT-South from the South African
Astronomical Observatory in South Africa. The mounted filters results
in a bandpass similar to a broad R-band filter. All targets considered
here, with the exceptions of HS Hya and V685 Cen, were observed by
KELT-North. Each EB was observed anywhere between 1500 and 10,000
times over a baseline of 3-9yr.
All of the EBs examined here were also observed by the Transiting
Exoplanet Survey Satellite (TESS). During the TESS primary mission
(2018 April-2020 July), selected targets were observed with a 2min
cadence, and full-frame images (FFIs) were taken every 30min. In its
2yr-long 1st extended mission, which was completed in 2022 September,
TESS observed selected targets with 2min cadence and an additional
subgroup with 20s cadence; FFIs were obtained every 10min. In its
current 2nd extended mission, which is planned to last 3yr, it is
observing selected targets with 2min and 20s cadence, and FFIs are
obtained with 200s cadence. The data we present for our targets span
the primary, 1st extended, and 2nd extended missions. The 600 to
1000nm TESS bandpass is centered on the IC band. Each of our EBs was
observed in three to nine sectors and covers a time baseline of 2-5yr,
with substantial gaps.
RW Per, IU Aur, AH Cep, SV Gem, and V685 Cen show evidence of eclipse
depth variations in their KELT light curves. SS Lac is a previously
established former EB and continues to show no eclipses in KELT or
TESS data.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 113 7 Eclipsing binary system observational properties
table4.dat 62 70 Eclipse depth and timing measurements
table6.dat 44 102 AH Cep TESS eclipse measurements
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See also:
B/wds : The Washington Visual Double Star Catalog (Mason+ 2001-)
II/264 : ASAS Variable Stars in Southern hemisphere (Pojmanski+, 2002-2005)
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)
J/A+A/403/675 : UBV light curves of IU Aur (Ozdemir+, 2003)
J/A+A/417/263 : Catalogue of Algol type binary stars (Budding+, 2004)
J/other/A+ARV/18.67 : Accurate masses and radii of normal stars (Torres+, 2010)
J/AcA/61/103 : VI light curves of LMC eclipsing binaries (Graczyk+, 2011)
J/MNRAS/448/946 : Kepler eclipse timing variation analyses (Borkovits+, 2015)
J/ApJ/809/77 : Transiting Exoplanet Survey Satellite (TESS) (Sullivan+, 2015)
J/MNRAS/455/4136 : Kepler triples (Borkovits+, 2016)
J/ApJ/836/177 : RVs and R-band obs. of the EB* V541 Cyg (Torres+, 2017)
J/A+A/609/A46 : Light curves 0f 6 MC eclipsing binaries (Jurysek+, 2018)
J/AJ/156/259 : Robo-AO detected close binaries in Gaia DR2 (Ziegler+, 2018)
J/MNRAS/493/5005 : TICs 167692429 and 220397947 triple stars (Borkovits+, 2020)
J/AJ/162/189 : 125 years light curve of HS Hydrae with DASCH (Davenport+, 2021)
J/ApJS/262/10 : Kepler eclipsing binaries with Gaia data (Knote+, 2022)
J/ApJS/258/16 : TESS Eclipsing Binary stars. I. Sectors 1-26 (Prsa+, 2022)
J/AJ/165/81 : CHIRON RV of V907 Sco system components (Zasche+, 2023)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- System System
10- 18 I9 --- TIC [2940839/468682885] TESS Input Catalog
(IV/39) identifier
20- 21 I2 h RAh Hour of right ascension (ICRS) from Gaia DR3
(I/355)
23- 24 I2 min RAm Minute of right ascension (ICRS) from Gaia
DR3 (I/355)
26- 34 F9.6 s RAs Second of right ascension (ICRS) from Gaia
DR3 (I/355)
36 A1 --- DE- Sign of declination (ICRS) from Gaia DR3
(I/355)
37- 38 I2 deg DEd Degree of declination (ICRS) from Gaia DR3
(I/355)
40- 41 I2 arcmin DEm Arcminute of declination (ICRS) from Gaia
DR3 (I/355)
43- 51 F9.6 arcsec DEs Arcsecond of declination (ICRS) from Gaia
DR3 (I/355)
53- 57 F5.2 mag Vmag [6.88/10.57] Out-of-eclipse V-band magnitude
from Simbad
59- 63 F5.2 mag Tmag [6.67/10.18] Out-of-eclipse T-band magnitude
from TIC (IV/39)
65- 69 I5 K Teff1 [6500/32000] Effective temperature
71- 74 I4 K e_Teff1 [50/1000]? Teff1 uncertainty
76- 80 I5 K Teff2 [4000/28600]? Effective temperature
82- 85 I4 K e_Teff2 [50/1000]? Teff2 uncertainty
87- 91 F5.2 --- RUWE [0.97/10.16] Renormalised unit weight error
from Gaia DR3
93- 96 F4.2 mas AEN [0.16/2.18] Astrometric excess noise from
Gaia DR3
98- 103 F6.1 --- sAEN [30.9/3180.1] AEN significance
105- 109 F5.3 --- CROWDSAP [0.91/1]? Approximate fraction of flux
within the TESS aperture originating from
the target star; from TIC
111- 113 A3 --- Ref Reference of the effective temperatures (1)
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Note (1): If we find no published effective temperature, we consult Gaia values.
Reference as follows:
a = Torres+1997, 1997AJ....114.2764T 1997AJ....114.2764T
b = Olson+1992, 1992AJ....103..256O 1992AJ....103..256O
c = Ozdemir+2003, J/A+A/403/675
d = Holmgren+1990, 1990A&A...236..409H 1990A&A...236..409H
e = Gaia DR2, I/345
f = Chochol+2003, 2003CoSka..33..107C 2003CoSka..33..107C
g = Mayer+2004, 2004IBVS.5563....1M 2004IBVS.5563....1M
h = Milone+2000, 2000AJ....119.1405M 2000AJ....119.1405M
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- System System
10- 13 I4 yr Year [2006/2025] Observed Year (1)
15- 17 A3 --- Sector TESS Sector (1)
19 A1 --- Instr Mission (2)
21- 33 F13.5 d Tmed [2454057/2460762] Median observation time
during the indicated year, BJD at TDB
35- 40 F6.4 mag Depth [2e-4/0.69] Eclipse Depth (3)
42- 47 F6.4 mag e_Depth [1e-4/0.06] Uncertainty in Depth
49- 55 F7.4 --- Phase [-0.021/0.015] Phase of primary eclipse minimum
(4)
57- 62 F6.4 --- e_Phase [0/0.009] Uncertainty in Phase
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Note (1): For KELT, each year of observation is listed. For TESS, we
note the year and Sector from which values are measured.
Note (2): Mission as follows:
K = Kilodegree Extremely Little Telescope (KELT), with KELT-North at Winer
Observatory in Arizona, USA, and KELT-South at the South African
Astronomical Observatory in South Africa. All targets considered here,
with the exceptions of HS Hya and V685 Cen, were observed by KELT-North.
40 occurrences
T = Transiting Exoplanet Survey Satellite (TESS) Science Processing
Operations Center (SPOC); 30 occurrences
Note (3): From gaussian fitting.
Note (4): Measured phase of primary eclipse minimum from Gaussian
fit. Calculated phase of primary minimum is 0. Years with scarce
observations failing to capture clear eclipses are left blank.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 yr Year [2019/2024] Observed Year
6- 8 A3 --- Sector TESS Sector
10- 16 F7.4 mag Depth [-0.017/-0.01] Eclipse Depth (1)
18- 23 F6.4 mag e_Depth [3e-4/5e-4] Uncertainty in Depth
25- 37 F13.5 d Tmin [2458765/2460610] Measured time of primary
eclipse minimum, BJD at TBD (1)
39- 44 F6.4 d e_Tmin [2e-4/1.4e-3] Uncertainty in tmin
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Note (1): Depth and Tmin from gaussian fit.
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History:
From electronic version of the journal
License: CC-BY-4.0
(End) Prepared by [AAS], Robin Leichtnam [CDS] 01-Sep-2026