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A new generation of observatories is enabling detailed study of exoplanetary atmospheres and the diversity of alien climates, allowing us to seek evidence for extraterrestrial biological and geological processes. Now is therefore the time to identify the most unique planets to be characterized with these instruments. In this context, we report on the discovery and validation of TOI-715 b, a |$R_{\rm b}=1.55\pm 0.06\rm R_{\oplus }$| planet orbiting its nearby (42 pc) M4 host (TOI-715/TIC 271971130) with a period |$P_{\rm b} = 19.288004_{-0.000024}^{+0.000027}$| d. TOI-715 b was first identified by TESS and validated using ground-based photometry, high-resolution imaging and statistical validation. The planet's orbital period combined with the stellar effective temperature |$T_{\rm eff}=3075\pm 75~\rm K$| give this planet an installation |$S_{\rm b} = 0.67_{-0.20}^{+0.15}~\rm S_\oplus$|⁠ , placing it within the most conservative definitions of the habitable zone for rocky planets. TOI-715 b's radius falls exactly between two measured locations of the M-dwarf radius valley; characterizing its mass and composition will help understand the true nature of the radius valley for low-mass stars. We demonstrate TOI-715 b is amenable for characterization using precise radial velocities and transmission spectroscopy. Additionally, we reveal a second candidate planet in the system, TIC 271971130.02, with a potential orbital period of |$P_{02} = 25.60712_{-0.00036}^{+0.00031}$| d and a radius of |$R_{02} = 1.066\pm 0.092\, \rm R_{\oplus }$|⁠ , just inside the outer boundary of the habitable zone, and near a 4:3 orbital period commensurability. Should this second planet be confirmed, it would represent the smallest habitable zone planet discovered by TESS to date. [ABSTRACT FROM AUTHOR]

In the last decade, a dozen close-in giant planets have been discovered orbiting stars with spectral types ranging from M0 to M4, a mystery since known formation pathways do not predict the existence of such systems. Here, we confirm TOI-4860 b, a Jupiter-sized planet orbiting an M4.5 host, a star at the transition between fully and partially convective interiors. First identified with TESS data, we validate the transiting companion's planetary nature through multicolour photometry from the TRAPPIST-South/North, SPECULOOS, and MuSCAT3 facilities. Our analysis yields a radius of |$0.76\pm 0.02~\rm R_{Jup}$| for the planet, a mass of |$0.34~\rm M_\odot$| for the star, and an orbital period of |$1.52~\rm d$|⁠. Using the newly commissioned SPIRIT InGaAs camera at the SPECULOOS-South Observatory, we collect infrared photometry in zYJ that spans the time of secondary eclipse. These observations do not detect a secondary eclipse, placing an upper limit on the brightness of the companion. The planetary nature of the companion is further confirmed through high-resolution spectroscopy obtained with the IRD spectrograph at Subaru Telescope, from which we measure a mass of |$0.67\pm 0.14~\rm M_{Jup}$|⁠. Based on its overall density, TOI-4860 b appears to be rich in heavy elements, like its host star. [ABSTRACT FROM AUTHOR]

We present the discovery of TYC9191-519-1b (TOI-150b, TIC 271893367) and HD271181b (TOI-163b, TIC 179317684), two hot Jupiters initially detected using 30-min cadence Transiting Exoplanet Survey Satellite (TESS) photometry from Sector 1 and thoroughly characterized through follow-up photometry (CHAT, Hazelwood, LCO/CTIO, El Sauce, TRAPPIST-S), high-resolution spectroscopy (FEROS, CORALIE), and speckle imaging (Gemini/DSSI), confirming the planetary nature of the two signals. A simultaneous joint fit of photometry and radial velocity using a new fitting package juliet reveals that TOI-150b is a |$1.254\pm 0.016\ \rm {R}_ \rm{J}$|⁠ , massive (⁠|$2.61^{+0.19}_{-0.12}\ \rm {M}_ \rm{J}$|⁠) hot Jupiter in a 5.857-d orbit, while TOI-163b is an inflated (⁠|$R_ \rm{P}$| = |$1.478^{+0.022}_{-0.029} \,\mathrm{ R}_ \rm{J}$|⁠ , |$M_ \rm{P}$| = |$1.219\pm 0.11 \, \rm{M}_ \rm{J}$|⁠) hot Jupiter on a P = 4.231-d orbit; both planets orbit F-type stars. A particularly interesting result is that TOI-150b shows an eccentric orbit (⁠|$e=0.262^{+0.045}_{-0.037}$|⁠), which is quite uncommon among hot Jupiters. We estimate that this is consistent, however, with the circularization time-scale, which is slightly larger than the age of the system. These two hot Jupiters are both prime candidates for further characterization – in particular, both are excellent candidates for determining spin-orbit alignments via the Rossiter–McLaughlin (RM) effect and for characterizing atmospheric thermal structures using secondary eclipse observations considering they are both located closely to the James Webb Space Telescope (JWST) Continuous Viewing Zone (CVZ). [ABSTRACT FROM AUTHOR]