ann24034 — Announcement

NEID Earth Twin Survey Delivers On Its Goal to Push the Limits of Exoplanet Discovery

Extremely precise NEID spectrograph on the WIYN 3.5-meter Telescope surpasses three decades of previous measurements with confirmation of new ‘super-Earth’

21 November 2024

For four years the NEID (rhymes with fluid) spectrograph, mounted on the WIYN 3.5-meter Telescope at U.S. National Science Foundation Kitt Peak National Observatory (KPNO), a Program of NSF NOIRLab, has been delivering on one of its main science goals — to confirm exoplanet candidates from other exoplanet missions and characterize both newly confirmed and known planets.

But NEID is also carrying out a larger program called the NEID Earth Twin Survey (NETS). NETS is aimed at pushing exoplanet detection beyond the limits of pre-NEID instruments with the specific goal of searching around bright, nearby stars for low-mass exoplanets that weren’t detectable before. NEID is now delivering on this goal as the first instrument to confirm and characterize exoplanet HD 86728 b. The team, led by postdoctoral researcher and NOIRLab astronomer Arvind Gupta, presents these results in a paper to appear in AAS Journals.

NEID is optimized to observe an incredibly subtle effect that occurs between a star and its planet(s) as they orbit. The gravitational force between a planet and its star is mutual, so the star’s position shifts very slightly as the planet travels around it. This wobble can be measured as the star’s so-called radial velocity [1]. NEID is designed to achieve radial velocity measurements smaller than 3.5 kilometers per hour (2 miles per hour), which is roughly the speed at which you might leisurely stroll around your neighborhood. The ability to measure such astoundingly subtle motion makes NEID one of the best instruments available for detecting exoplanets beyond a certain threshold.

Despite the extensive observing history of its host star, with hundreds of measurements spanning over three decades, HD 86728 b has evaded detection thanks to its small mass and the limits of technology. In 2021 it was classified as a planetary candidate based on a tentative detection, though the observations were inconclusive. NEID was able to make the first conclusive detection of HD 86728 b in only 137 nights, demonstrating how its unmatched sensitivity is accelerating astronomers’ ability to find Earth-like planets.

The team found that HD 86728 b has an orbital period of 31 days and is about nine times the mass of Earth, classifying it as a super-Earth. They also found that it appears to be the only planet orbiting its star, though it’s possible that other exoplanets have gone undetected if they have smaller sizes and longer orbits. The team is planning follow-up observations to continue their search [2].

HD 86728 b is the first planetary discovery to result from NETS, and the first exoplanet that NEID has discovered independent of other missions and surveys. This result serves as a significant demonstration of the remarkable capabilities of NEID and speaks to its future discovery potential.

Notes

[1] This method of detection was the cornerstone for the 2019 Nobel Prize in Physics for the first ever detection of an exoplanet.

[2] If confirmed to be a true loner, HD 86728 b would be in the small (less than 12%) minority of exoplanets with similar sizes and periods with no known siblings.

More information

NSF NOIRLab (U.S. National Science Foundation National Optical-Infrared Astronomy Research Laboratory), the U.S. center for ground-based optical-infrared astronomy, operates the International Gemini Observatory (a facility of NSF, NRC–Canada, ANID–Chile, MCTIC–Brazil, MINCyT–Argentina, and KASI–Republic of Korea), NSF Kitt Peak National Observatory (KPNO), NSF Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and NSF–DOE Vera C. Rubin Observatory (operated in cooperation with the Department of Energy’s SLAC National Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona. The astronomical community is honored to have the opportunity to conduct astronomical research on I’oligam Du’ag (Kitt Peak) in Arizona, on Maunakea in Hawai‘i, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence that these sites have to the Tohono O’odham Nation, to the Native Hawaiian community, and to the local communities in Chile, respectively.