J/A+A/710/A311 LHS 3844 Radial velocities (Nagel+, 2026)
Mass determination of the ultra-short-period planet LHS 3844 b.
First K-band radial velocity measurements with CRIRES+.
Nagel E., Koehler J., Zechmeister M., Rains A.D., Seemann U., Hatzes A.,
Reiners A., Piskunov N., Boldt-Christmas L., Bristow P., Chaturvedi P.,
Cont D., Czesla S., Dorn R.J., Guenther E., Jung Y., Kochukhov O.,
Lesjak F., Lucertini F., Marquart T., Nortmann L., Rengel M., Rodler F.,
Smoker J.V.
<Astron. Astrophys. 710, A311 (2026)>
=2026A&A...710A.311N 2026A&A...710A.311N (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Radial velocities
Keywords: methods: data analysis - methods: observational -
techniques: radial velocities - techniques: spectroscopic -
planets and satellites: general - stars: individual: LHS 3844
Abstract:
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
Rb=1.286R{earth} and an orbital period of Pb=0.462929709d,
placing it in the class of ultra-short-period (USP) planets. The host
star LHS 3844 is an old (7.8±1.6Gyr), slowly rotating (Prot=130.0d)
M5.0 dwarf with M=0.151M_☉ 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 detect
periodic RV variations with a semi-amplitude Kb=6.95m/s, implying a
planetary mass of mb=2.37±0.25M{earth} and a bulk density of
rhob=6.15g/cm3, consistent with a predominantly rocky composition.
We further find excess RV variability that may be attributed to
stellar jitter or to an additional planetary signal, for which we
identify a tentative super-Earth candidate with a period of ∼6.88d.
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 (ESM) 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.
Description:
Radial velocity measurements of LHS 3844 obtained with CRIRES+
ESPRESSO. CRIRES+ observations were carried out using the gas-cell
calibration technique in the K-band. Radial velocities were extracted
using the viper pipeline. Radial velocities obtained with ESPRESSO
were derived using the template-matching code serval. A description of
the instruments, data reduction, and RV extraction procedures is given
in Sect. 2.3 of the paper.
Objects:
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RA (2000) DE Designation(s)
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22 41 58.12 -69 10 08.3 LHS 3844 = L 119-213
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
rvcrires.dat 26 60 CRIRES+ radial velocity time-series of LHS 3844
(table B1)
rvespres.dat 26 23 ESPRESSO radial velocity time-series of LHS 3844
(table B2)
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Byte-by-byte Description of file: rvcrires.dat rvespres.dat
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Bytes Format Units Label Explanations
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1- 11 F11.3 d BJD Barycentric Julian Date
14- 19 F6.2 m/s RV Radial velocity
22- 26 F5.2 m/s e_RV Radial velocity uncertainty
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Acknowledgements:
Evangelos Nagel, evangelos.nagel(at)uni-goettingen.de
License: CC-BY-4.0 [see https://spdx.org/licenses/]
(End) Patricia Vannier [CDS] 25-Mar-2026