Artist’s impression of a very thin gas giant planet orbiting a red dwarf star. Gas giant outer planet [right] Densely marshmallows orbiting a cool red dwarf star [left] by a NASA-funded NEID Radial Velocity Instrument on the 3.5-meter WIYN Telescope at Kitt Peak National Observatory, a program of NSF NOIRLab. The planet, called TOI-3757 b, is the thinnest gas giant planet ever discovered around this type of star. Credit: NOIRLab/NSF/AURA/J. da Silva/Spaceengine/M. Zamani
The Kitt Peak National Observatory helps determine that[{”attribute=””>Jupiter-likePlanetisthelowest-densitygasgianteverdetectedaroundareddwarf[{”attribute=””>Jupiter-likePlanetisthelowest-densitygasgianteverdetectedaroundareddwarf
A gas giant 
From the grounds of the Kate Peak National Observatory (KPNO), NSF’s NOIRLab program, the 3.5-meter Wisconsin-Indiana-Yale-Noirlab (WIYN) telescope appears to be gazing at the Milky Way as it streams from the horizon. Reddish glow, which is a normal phenomenon, also colors the horizon. KPNO is located in the Arizona Sonoran Desert in the Tohono O’odham Nation and this clear view of part of the plane of the Milky Way shows the favorable conditions in this environment needed to see faint celestial bodies. These conditions, which include low levels of light pollution, 20-degree darker skies and dry weather conditions, allowed researchers from the WIYN Consortium to follow observations of galaxies, nebulae and exoplanets as well as many other astronomical targets using the WIYN 3.5 meter telescope and its sister WIYN 0.9 meter telescope. . Credit: KPNO/NOIRLab/NSF/AURA/R. Sparks
They suggest that the extremely low density of TOI-3757 b could be the result of two factors. The first relates to the rocky core of the planet. Gas giants are thought to start out as massive rocky cores with a mass about ten times the mass of Earth, at which point they quickly pool large amounts of nearby gas together to form the gas giants we see today. TOI-3757b has a lower abundance of heavy elements than other M dwarfs with gas giants, and this may have caused the rocky core to form more slowly, delaying the onset of gas accumulation and thus affecting the planet’s overall density.
The second factor may be the planet’s orbit, which is tentatively considered to be slightly elliptical. There are times when it gets closer to its star than at other times, producing significant excess heat that can cause the planet’s atmosphere to swell.
NASA’s extraterrestrial orbital spacecraft ([{”attribute=””>TESS)initiallyspottedtheplanetKanodia’steamthenmadefollow-upobservationsusingground-basedinstrumentsincludingNEIDandNESSI(NN-EXPLOREExoplanetStellarSpeckleImager)bothhousedattheWIYN35-meterTelescope;theHabitable-ZonePlanetFinder(HPF)ontheHobby-EberlyTelescope;andtheRedButtesObservatory(RBO)[{”attribute=””>TESS)initiallyspottedtheplanetKanodia’steamthenmadefollow-upobservationsusingground-basedinstrumentsincludingNEIDandNESSI(NN-EXPLOREExoplanetStellarSpeckleImager)bothhousedattheWIYN35-meterTelescope;theHabitable-zonePlanetFinder(HPF)ontheHobby-EberlyTelescope;andtheRedButtesObservatory(RBO)inWyoming
TESS surveyed the crossing of this planet TOI-3757 b in front of its star, which allowed astronomers to calculate the planet’s diameter to be about 150,000 kilometers (100,000 miles) or about just slightly larger than that of Jupiter. The planet finishes one complete orbit around its host star in just 3.5 days, 25 times less than the closest planet in our Solar System — Mercury — which takes about 88 days to do so.
The astronomers then used NEID and HPF to measure the star’s apparent motion along the line of sight, also known as its radial velocity. These measurements provided the planet’s mass, which was calculated to be about one-quarter that of Jupiter, or about 85 times the mass of the Earth. Knowing the size and the mass allowed Kanodia’s team to calculate TOI-3757 b’s average density as being 0.27 grams per cubic centimeter (about 17 grams per cubic feet), which would make it less than half the density of