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Abstract Barnard’s Star is an old, single M dwarf star that comprises the second-closest extrasolar system. It has a long history of claimed planet detections from both radial velocities and astrometry. However, none of these claimed detections have so far withstood further scrutiny. Continuing this story, extreme precision radial velocity measurements from the ESPRESSO instrument have recently been used to identify four new sub-Earth-mass planet candidates around Barnard’s Star. We present here 112 radial velocities of Barnard’s Star from the MAROON-X instrument that were obtained independently to search for planets around this compelling object. The data have a typical precision of 30 cm s−1and are contemporaneous with the published ESPRESSO measurements (2021–2023). The MAROON-X data on their own confirm planet b (P= 3.154 days) and planet candidates c and d (P= 4.124 and 2.340 days, respectively). Furthermore, adding the MAROON-X data to the ESPRESSO data strengthens the evidence for planet candidate e (P= 6.739 days), thus leading to its confirmation. The signals from all four planets are <50 cm s−1, the minimum masses of the planets range from 0.19 to 0.34M⊕, and the system is among the most compact known among late M dwarfs hosting low-mass planets. The current data rule out planets with masses >0.57M⊕(with a 99% detection probability) in Barnard's Star’s habitable zone (P= 10–42 days).
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This content will become publicly available on April 8, 2026
Calibrating the Instrumental Drift in MAROON-X Using an Ensemble Analysis
Abstract MAROON-X is a state-of-the-art extreme-precision radial velocity spectrograph deployed on the 8.1 m Gemini-N telescope on Maunakea, Hawai’i. Using a stabilized Fabry–Pérot etalon for wavelength and drift calibration, MAROON-X has achieved a short-term precision of ∼30 cm s−1. However, due to a long-term drift in the etalon (2.2 cm s−1per day) and various interruptions of the instrument baseline over the first few years of operation, MAROON-X experiences radial velocity (RV) offsets between observing runs several times larger than the short-term precision during any individual run, which hinders the detection of longer-period signals. In this study, we analyze RV measurements of 11 targets that either exhibit small RV scatter or have signals that can be precisely constrained using Keplerian or Gaussian process models. Leveraging this ensemble, we calibrate MAROON-X’s run offsets for data collected between 2020 September and early 2024 January to a precision of ∼0.5 m s−1. When applying these calibrated offsets to HD 3651, a quiet star, we obtain residual velocities with an rms of <70 cm s−1in both the red and blue channels of MAROON-X over a baseline of 29 months. We also demonstrate the sensitivity of MAROON-X data calibrated with these offsets through a series of injection-recovery tests. Based on our findings, MAROON-X is capable of detecting sub m s−1signals out to periods of more than 1000 days.
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- Award ID(s):
- 2108465
- PAR ID:
- 10647707
- Publisher / Repository:
- AAS
- Date Published:
- Journal Name:
- The Astronomical Journal
- Volume:
- 169
- Issue:
- 5
- ISSN:
- 0004-6256
- Page Range / eLocation ID:
- 253
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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