Hunting for Planets Around Quiet Stars express
The TESS telescope, like a patient sentinel, stares at the same stars for months, waiting for a planet to momentarily block its star's light. But the sentinel has blind spots: some dim red dwarfs only came into its field of view for a short time, so their planets could have gone unnoticed. Now astronomers have selected 121 such stars that have only recently accumulated enough observations and given them their first thorough check.
Each star is like a lamp that sometimes has something passing in front of the bulb, slightly dimming the light. The scientists looked for such flickers with periods from half a day to a hundred days. To do this, they ran the data through several filters: first an automated signal search, then a check for interference from neighboring stars, and finally a comparison with data from the Gaia space telescope, which knows the exact position of every star. Out of hundreds of thousands of red dwarfs, they selected 121, and among them they found 20 suspicious flickers in 16 systems.
The remaining signals are weaker for now: they could be noise, but they could also be confirmed if TESS looks at these stars a few more times. One star showed a single flicker — possibly a planet with a very long year passed in front of it just once during the entire observation period.
Now astronomers have a list of addresses where to point more powerful telescopes. Every confirmed planet around such a dim star is a chance to find a world like Earth: red dwarfs live for hundreds of billions of years, and their planets have had plenty of time to become habitable.
Original abstract
as written by the authors arXiv:2603.10247
M-dwarf stars are the most favorable hosts for detecting small transiting planets, yet mid-to-late M-dwarfs that acquired sufficient TESS multi-sector coverage only through recent Cycle 6+ observations represent a newly accessible discovery space. This paper presents a systematic transit survey of 121 M3-M6 dwarfs (Teff = 2700-3400 K) selected as "newly enabled" targets -- stars with <=2 archival TESS sectors that only recently crossed the multi-sector detection threshold, covering P = 0.5-100 d. The sample was selected from 498,312 TIC M-dwarfs via a 9-step funnel. The pipeline combines TLS with a signal validation cascade, TRICERATOPS vetting, Gaia DR3 verification, and three empirical signal reliability tests. Pipeline validation achieved 100% recovery (16/16 planets) on 10 known systems with zero false positives. The survey identifies 20 transit-like signals across 16 systems, none with prior TOI designations. The reliability framework classifies 2 as Tier 1 (High Robustness), 7 as Tier 2 (Moderate), and 10 as Tier 3 (Noise-Susceptible); one monotransit is excluded. No candidate SDE significantly exceeds its host star's noise floor. The global false alarm rate is 17.4% (21/121; Wilson 95% CI: [11.6%, 25.1%]).The 2 Tier 1 candidates are priorities for RV confirmation. The 10 Tier 3 candidates require additional TESS sectors to establish signal persistence; 9 systems need high-resolution imaging.
Red dwarfs of class M are the most common stars in the Galaxy: for every star like the Sun, there are about six of these little ones. Yet they are so dim that not a single one is visible to the naked eye.
In the series 'The Expanse', Ceres station and other human settlements are located precisely around red dwarfs — because such stars live the longest and provide a stable, albeit faint, light.