J/A+A/702/A17 Pre-main-sequence eclip. binary MML 48 (Gomez Maqueo Chew+, 2025)
Discovery of the pre-main-sequence eclipsing binary MML 48.
Gomez Maqueo Chew Y., Hebb L., Stempels H.C., Walter F.M., James D.J.,
Feiden G.A., Petrucci R., Lister T., Baraffe I., Brodheim M., Faedi F.,
Anderson D.R., Street R.A., Hellier C., Stassun K.G.
<Astron. Astrophys. 702, A17 (2025)>
=2025A&A...702A..17G 2025A&A...702A..17G (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, eclipsing ; Binaries, spectroscopic ;
Radial velocities ; Photometry ; Optical
Keywords: binaries: eclipsing - binaries: spectroscopic -
stars: fundamental parameters - stars: low-mass -
stars: individual: MML 48 - stars: pre-main sequence
Abstract:
We present the discovery of the eclipsing binary MML 48, which is a
member of Upper Centaurus Lupus, has an associated age of 16 Myr, and
is composed of two young, low-mass stars.
We used space- and ground-based observations to characterize the
system with both time-series photometry and spectroscopy. Given the
extreme mass ratio between the stars, qEB=0.209±0.014, we modeled
a single-lined spectroscopic and eclipsing binary system. Results. The
orbital period, 2.0171068±0.0000004d, is measured from the highest
precision light curves. We derive a primary mass of 1.2±0.07M☉
using stellar models, and with radial velocities we measured a
secondary mass of 0.2509±0.0078M☉ . The radii are large, as
expected for pre-main-sequence stars, and are measured as
1.574±0.026±0.050R☉ and 0.587±0.0095±0.050R☉ , for
the primary and secondary stars, respectively.
MML 48 joins the short list of known low-mass, pre-main-sequence
eclipsing binaries (EBs), being one of only five systems with
intermediate ages (15-25Myr), and the system with the most extreme
mass ratio. The primary star is currently at the "fusion bump",
undergoing an over-production of energy in the core due to the
build-up of 3He before reaching its equilibrium abundance set by the
proton-proton (p-p) I chain. MML 48 A is the first young star in an
eclipsing system that has been found during its fusion bump. MML 48 is
thus an important benchmark for low-mass stellar evolution at a time
when the stars are rapidly changing, which allows for a tight
constraint on the corresponding isochrone given the uneven mass ratio.
Description:
The EB MML 48 was observed in the field of view of the Wide Angle
Search for Planets (WASP) transiting planet survey from 2006-2014.
Two secondary eclipses of MML 48 were observed on 3 July, 2013 and 5
July, 2013 in order to constrain the eccentricity of the orbit and the
size and brightness of the secondary star through the timing and depth
of the eclipse. These data were obtained with the Spectral Camera on
the 2-m Faulkes Telescope South (FTS) through the Las Cumbres
Observatory Global Telescope Network (LCOGT). We observed the target
with ten-second exposure times repeatedly for approximately 4.3 hours
in the PanSTARRS zs f
To obtain simultaneous multiband photometry suitable for detailed EB
analysis, MML 48 was observed for six consecutive nights from 16-22
March, 2019 with the optical CCD camera on the Cerro Tololo
Inter-American Observatory/Small and Moderate Aperture Research
Telescope System (CTIO/SMARTS) 0.9 m telescope.
The EB MML 48 was observed in the Johnson VRI bands during four
consecutive nights (27-30 June, 2018) with the 2.15-m "Jorge
Sahade" telescope at Complejo Astronomico El Leoncito (CASLEO) in
Argentina (PI: Petrucci; DDT).
The EB MML 48 (TIC 129116176) was observed as part of a TESS Guest
Investigator (GI) program (PI: Ricker; ID: G011280-G011154) in
two-minute cadence in Sector 11 in 2019. Additionally, in Cycle 3 of
the TESS GI program MML 48 was observed in Sector 38 (2021) in
two-minute cadence (PI: Hebb; ID: G03143). In 2023, it was again
observed in two-minute cadence in Sector 65.
During the nights of 7 June, 2012 June, 2 July, 2012, 5 July, 2012,
and 5 September, 2012, MML 48 was observed with the Goodman High
Throughput Spectrograph on the 4.1m SOuthern Astrophysical Research
(SOAR) telescope at Cerro Pachon.
We obtained two 900 s exposures of MML 48 on the consecutive nights of
19-20 September, 2012 using the FEROS spectrograph (R∼48000) on the
2.2m MPG/ESO telescope at La Silla (PI: Faedi; ID: 089.C-0471).
Eleven spectra of MML 48 were taken in fiber mode (R∼24700) with the
CHIRON echelle spectrograph 2013) on the CTIO/SMARTS 1.5m telescope.
Ten spectra were taken between 16 and 21 March, 2019 to be coincident
with the follow-up time-series photometry taken on the
CTIO/SMARTS-0.9m, and an additional single spectrum was obtained on 28
May, 2019.
Objects:
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RA (2000) DE Designation(s)
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14 41 34.99 -47 00 28.7 MML 48 = TIC 129116176
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 50 26092 Light-curve data for MML 48
table2.dat 36 18 Radial-velocity measurements for primary
EB component
table3.dat 36 54 Time of minimum for full primary eclipses of
MML 48
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 13 F13.7 d Time Barycentric Julian Date (TDB) (BJD-2450000)
15- 23 E9.7 mag mag Differential magnitude in Filter
25- 32 F8.6 mag e_mag Error in differential magnitude in Filter
34- 45 A12 --- Tel Telescope name
47- 50 A4 --- Filter Filter used (BVRI Ic zs TESS WASP)
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 14 F14.9 d Time Barycentric Julian Date (TDB) (BJD-2450000)
16- 25 F10.6 km/s RV Radial velocity
27- 29 F3.1 km/s e_RV Error in radial velocity
31- 36 A6 --- Inst Instrument name (CHIRON, FEROS or SOAR)
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Dataset Telescope used and year of observations
13- 16 A4 --- Filter Filter used (BV Ic TESS WASP)
18- 28 F11.5 d Epoch Time of primary eclipse (TDB) (BJD-2450000)
30- 36 E7.6 d e_Epoch Error in the time of the primary eclipse (TDB)
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Acknowledgements:
Yilen Gomez Maqueo Chew, ygmc(at)astro.unam.mx
(End) Patricia Vannier [CDS] 12-Sep-2025