The project delivers the first comprehensive spectroscopic census of thousands of the Sun's lower-mass K dwarf counterparts within the local solar neighborhood. Carrazco-Gaxiola's team focused on more than 2,000 K dwarfs within 130 light-years of Earth, obtaining high-resolution measurements of the spectra, or detailed color distribution, emitted by each star.

The observations were collected with spectrographs mounted on two 60-inch telescopes, one in each hemisphere, to cover the full sky. The CHIRON spectrograph on the SMARTS 60-inch telescope at Cerro Tololo Inter-American Observatory in the Chilean Andes and the TRES spectrograph on the Tillinghast Telescope at Fred Lawrence Whipple Observatory in southern Arizona together enabled uniform monitoring of K dwarfs across both hemispheres.

"This survey marks the first comprehensive look at thousands of the Sun's lower-mass cousins," Carrazco-Gaxiola said. "These stars, known as 'K dwarfs,' are commonly found throughout space, and they provide a long-term, stable environment for their planetary companions."

"The CHIRON spectrograph on the SMARTS telescope in Chile and the TRES spectrograph on the Tillinghast Telescope in Arizona are such complementary instruments," said Allyson Bieryla, an astronomer at the Center for Astrophysics | Harvard and Smithsonian. "The power of having these two telescopes in opposite hemispheres is that it gives us access to all the K-dwarfs across the entire sky."

K dwarfs are slightly cooler and fainter than the Sun, but they outnumber Sun-like stars by roughly a factor of two in the solar neighborhood. Their extended lifetimes mean that any life that emerges on planets orbiting these stars could experience relatively stable stellar conditions over very long timescales.

Analysis of the high-resolution spectra provides estimates of each star's temperature, age, spin rate and motion through space. Specific color features in the spectra probe heated upper atmospheric layers energized by stellar magnetic fields, helping astronomers evaluate radiation environments around orbiting planets.

"This survey will be the foundation for studies of nearby stars for decades to come," said Distinguished University Professor of Physics and Astronomy Todd Henry, who serves as Carrazco-Gaxiola's adviser and is a senior author on the study. "These stars and their planets will be the destinations for spacecraft exploration in the far future of space travel."

Carrazco-Gaxiola's survey, titled "An All-Sky Spectroscopic Reconnaissance of More Than 2,100 K Dwarfs Within 40 Parsecs Using High-Resolution Spectra," is being presented at an American Astronomical Society press conference on Jan. 6. The AAS selected the presentation for a press briefing because of its broad scientific interest, and further information is available through the meeting press page here.

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