TOI-1743 b: A Transiting Super-Earth

• TOI-1743 b is a transiting super-Earth exoplanet orbiting an M4V dwarf, characterized by precise transit detections from TESS and ground-based photometry.
• It has a measured radius of 1.83 R⊕ and lies within the radius valley, marking the transition between rocky and volatile-rich planets.
• Robust validation through photometry, high-resolution imaging, and spectroscopic reconnaissance confirms its planetary nature and suitability for further atmospheric studies.

TOI-1743 b is a transiting super-Earth exoplanet orbiting an early M-dwarf (spectral type M4V), discovered by the Transiting Exoplanet Survey Satellite (TESS). Identified as one of several planets in a cohort of super-Earth to Neptune-sized planets around M dwarfs, TOI-1743 b features well-constrained physical and orbital parameters and occupies a significant position within the so-called radius valley—a region in parameter space that is integral to studies of planetary formation and atmospheric evolution.

1. Discovery and Photometric Detection

TOI-1743 b was detected by the TESS mission as a periodic transit signature in high-cadence (2-minute) light curves spanning up to 39 observational sectors. The shape, depth, and recurrence of the signal indicated a transiting planetary companion. The initial detection in TESS data was corroborated and refined via subsequent ground-based photometric campaigns, employing multiple facilities including TUG-T100, SAINT-EX, TRAPPIST-North, LCOGT, KeplerCam, and MuSCAT3. The joint approach allowed for increased temporal coverage, independent verification of ephemerides, and scrutiny of possible astrophysical false positives (Yalçınkaya et al., 5 Sep 2025).

2. Planetary Signal Validation

The validation process of TOI-1743 b combined several robust methodologies:

• Analysis of TESS Data Validation (DV) reports, including odd–even transit depth comparison, centroid motion checks, "ghost" contamination tests, and bootstrap resampling, all confirmed the integrity of the transit signal.
• High-resolution imaging (both optical speckle and adaptive optics) supplemented by archival images was conducted to exclude unresolved background or gravitationally bound stellar companions capable of producing a transit-like signal.
• A statistical validation was performed using TRICERATOPS, which delivered an exceptionally low false positive probability (FPP) of

$\mathrm{FPP} = (2.996 \pm 1.910) \times 10^{-5},$

strongly confirming the planetary nature.

• Spectroscopic reconnaissance with, for example, the Shane/Kast spectrograph, further supported stellar classification and simultaneously excluded close eclipsing binaries.

3. Physical and Orbital Characteristics

Table 1 summarizes the principal measured parameters for TOI-1743 b as determined through a joint analysis (via EXOFASTv2) of TESS and ground-based photometric datasets:

Parameter	Value	Uncertainty
Orbital period ($P$)	$4.266046$ days	$\pm 0.000002$ days
Planetary radius ($R_p$)	$1.83\;R_\oplus$	$+0.11/-0.10\;R_\oplus$
Equilibrium temperature ($T_{\rm eq}$)	$485\;\mathrm{K}$	$+14 / -13\;\mathrm{K}$
Transit depth $(R_p/R_\star)^2$	$\approx 0.0496$	(dimensionless)

These values place TOI-1743 b in the small-radius, short-period regime typical for rocky super-Earths orbiting M dwarfs. The transit depth quantifies the fraction of stellar flux occulted and is consistent with the derived stellar and planetary radii.

4. Context: The Radius Valley and Planetary Structure

TOI-1743 b occupies a locus in the radius–period parameter space known as the radius valley. This regime is characterized by a paucity of sub-Neptunes and is interpreted as marking the transition between planets with substantial hydrogen–helium envelopes and those that are primarily rocky (super-Earths). For low-mass stars, such as M dwarfs, this feature serves as an empirical constraint on atmospheric loss mechanisms (e.g., photoevaporation, core-powered mass loss).

With a measured radius of $1.83~R_\oplus$, TOI-1743 b aligns with the lower-radius, likely rocky population within the bimodal distribution. This status is of specific value for testing atmospheric evolution models and determining the boundary conditions governing volatile retention.

5. Prospects for Mass Measurement and Atmospheric Characterization

TOI-1743 b is suitable for both radial velocity (RV) follow-up and atmospheric studies, owing to the host star’s near-infrared brightness ($K_{mag} < 11$) and the planet’s orbital and physical characteristics. The expected RV semi-amplitude is

$K_\star \approx 3.7^{+1.4}_{-0.9}\; \mathrm{m/s},$

which is accessible via current near-infrared spectrographs. Consequently, precise mass determination is feasible.

The planet’s Transmission Spectroscopy Metric (TSM), approximately $60 \pm 25$, indicates favorable prospects for atmospheric exploration via platforms such as JWST. Atmospheric models suggest that if a significant volatile envelope exists, molecular absorption features (H$_2$O, CH$_4$, CO$_2$) should be detectable at typical spectroscopic signal-to-noise ratios. Achieving precise mass and radius measurements will reduce degeneracies in compositional modeling, further informing the paper of planetary evolution in the radius valley.

6. Implications for Planet Formation and Comparative Exoplanetology

TOI-1743 b, along with comparably validated super-Earths (e.g., TOI-5799 b and TOI-5799 c), provides a laboratory for empirical examination of planet formation pathways in M-dwarf systems. Its well-constrained parameters and position within the radius valley facilitate critical tests of atmospheric loss and retention mechanisms. Continuous follow-up—combining RV, transit timing, and transmission or emission spectroscopy—will refine estimates of composition, bulk density, and atmospheric scale height, contributing directly to the statistical framework surrounding the origins of short-period rocky planets.