Complete radial velocity time series for HD 86728. NEID data are shown as light blue (Run 1) and dark blue (Run 2) circles. Credit: Gupta et al., 2024.
An international team of astronomers announces the discovery of a new extrasolar world orbiting a nearby star known as HD 86728. It is the first exoplanet detection made by the NEID Earth Twin Survey (NETS). The discovery was detailed in a research paper published September 18 on the preprint server arXiv.
NEID is a fiber-powered, environmentally stabilized near-infrared optical spectrograph mounted on the WIYN1 3.5-m telescope at Kitt Peak National Observatory in Arizona. The NETS survey uses NEID to search for low-mass exoplanets orbiting nearby bright stars.
A team of astronomers led by Arvind F. Gupta of the U.S. National Science Foundation’s National Optical-Infrared Astronomy Research Laboratory in Tucson, Arizona, has identified the first exoplanet from NETS. The newly discovered planet orbits HD 86728, a bright star of spectral type G3Va, located about 48.6 light-years away.
“In this work, we present the first three years of NETS observations of the HD 86728 system and confirm the detection of the exoplanet HD 86728 b… HD 86728 was observed with NEID on 137 different nights during the first three years of the NETS program,” the researchers wrote in the paper.
According to the study, the newly discovered exoplanet HD 86728 b orbits its host star in a circular orbit every 31.15 days, at a distance of about 0.19 AU. The projected mass of this planet was estimated to be about 9.16 Earth masses.
Astronomers have noted that the vast majority of exoplanets with masses and orbital periods similar to HD 86728 b are found in multi-planet systems. Therefore, if it only hosts HD 86728 b, this planet would be in the small minority (less than 12%) with no known sister. However, further observations are needed to rule out the presence of additional planets orbiting HD 86728.
As for the host star, HD 86728, it has a radius of about 1.24 solar radii, while its mass is comparable to that of the Sun. The star has an effective temperature of about 5,610 K and its metallicity is 0.2 dex.
In conclusion, the authors of the paper emphasized that the detection of HD 86728 b proves how important extremely precise radial velocity spectrographs are for the search for low-mass extraterrestrial worlds.
“NEID and other extremely precise spectrographs will continue to reduce the sensitivity threshold of quiet stars, enabling the detection of lower-mass, longer-period exoplanets as we move toward discovering Earth analogues with radial velocity measurements,” the scientists wrote.
More information:
Arvind F. Gupta et al., The NEID Earth Twin Survey. I. Confirmation of a 31-day planet orbiting HD 86728, arXiv (2024). DOI: 10.48550/arxiv.2409.12315
Journal information:
arXiv
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