كوكب صخري حول قزم أحمر سريع

الملخص الأصلي

كما كتبه المؤلفون، بالإنجليزية arXiv:2603.28238

We present the first planet mass measurement obtained with CRIRES+ radial velocity (RV) observations using the K-band gas cell. Our target, LHS 3844 b (TOI-136), is a transiting super-Earth with radius $$R_b=1.286^{+0.043}_{-0.044}R_\oplus$$ and an orbital period of $$P_b = 0.462929709^{+0.000000044}_{-0.000000042}$$d, placing it in the class of ultra-short-period (USP) planets. The host star LHS 3844 is an old ($$7.8\pm1.6$$Gyr), slowly rotating ($$P_{rot} = 130.0^{+16.9}_{-13.4}$$d) M5.0 dwarf with $$M_\star = 0.151\pm0.014M_\odot$$ at a distance of 15pc (V=15.2mag, K=9.2mag). Combining our CRIRES+ RVs with archival ESPRESSO spectra, and confirming the signal in each dataset independently, we detected periodic RV variations with a semi-amplitude $$K_b=6.95^{+0.55}_{-0.60}$$m/s, implying a planetary mass of $$m_b = 2.37\pm0.25M_\oplus$$ and a bulk density of $$\rho_b = 6.15^{+0.60}_{-0.61}$$gcm$$^{-3}$$, consistent with a predominantly rocky composition. We further found excess RV variability that may be attributed to stellar jitter or to an additional planetary signal, for which we identified a tentative super-Earth candidate with a period of $$\approx6.88$$d. Owing to its proximity to its M-dwarf host, LHS 3844 b experiences intense irradiation and is unlikely to retain a substantial H/He envelope. Interior modeling places an upper limit on the iron-core mass fraction, which is consistent with an Earth-like rocky composition. With an emission spectroscopy metric of 28, LHS 3844 b is a prime JWST target for atmospheric and surface characterization and the most promising surface-characterization target known. Phase-curve spectroscopy may reveal its surface mineralogy and enable the first robust detection of exoplanet surface spectral features. Our results demonstrate that near-infrared RVs obtained with CRIRES+ enable robust mass measurements of super-Earths orbiting late M dwarfs.