Planet berbulu raksasa yang mengorbit bintang katai merah yang keren

Teleskop Kitt Peak dari Observatorium Nasional membantu menentukan ini[{” attribute=””>Jupiter-like Planet is the lowest-density gas giant ever detected around a red dwarf.

A gas giant exoplanet with the density of a marshmallow has been detected in orbit around a cool red dwarf star. A suite of astronomical instruments was used to make the observations, including the NASA-funded NEID radial-velocity instrument on the WIYN 3.5-meter Telescope at Kitt Peak National Observatory, a Program of NSF’s NOIRLab. Named TOI-3757 b, the exoplanet is the fluffiest gas giant planet ever discovered around this type of star.

Using the WIYN 3.5-meter Telescope at Kitt Peak National Observatory in Arizona, astronomers have observed an unusual Jupiter-like planet in orbit around a cool red dwarf star. Located in the constellation of Auriga the Charioteer around 580 light-years from Earth, this planet, identified as TOI-3757 b, is the lowest-density planet ever detected around a red dwarf star and is estimated to have an average density akin to that of a marshmallow.

Red dwarf stars are the smallest and dimmest members of so-called main-sequence stars — stars that convert hydrogen into helium in their cores at a steady rate. Although they are “cool” compared to stars like our Sun, red dwarf stars can be extremely active and erupt with powerful flares. This can strip orbiting planets of their atmospheres, making this star system a seemingly inhospitable location to form such a gossamer planet.

Shubham Kanodia, seorang peneliti di Carnegie Institution for Science’s Earth and Planetary Laboratory dan penulis pertama pada makalah yang diterbitkan di Jurnal Astrologike. Sejauh ini hanya terlihat oleh sampel kecil survei Doppler, yang biasanya menemukan planet raksasa yang jauh dari bintang katai merah tersebut. Sampai sekarang kami belum memiliki sampel planet yang cukup besar untuk menemukan planet gas terdekat dengan cara yang kuat.”

Masih ada misteri yang tidak dapat dijelaskan seputar TOI-3757 b, terutama bagaimana planet gas raksasa dapat terbentuk di sekitar bintang katai merah, terutama planet berdensitas rendah. Namun, tim Kanodia percaya bahwa mereka mungkin memiliki solusi untuk misteri ini.

Dari Bumi dari Observatorium Nasional Kit Peak (KPNO), sebuah program NSF NOIRLab, teleskop 3,5 meter Wisconsin-Indiana-Yale-Noirlab (WIYN) tampaknya mengamati Bima Sakti saat keluar dari cakrawala. Silau atmosfer kemerahan, fenomena alam, juga mewarnai cakrawala. KPNO terletak di Gurun Arizona Sonora di Tohono O’odham Nation dan pandangan yang jelas dari bagian bidang Bima Sakti ini menunjukkan kondisi yang menguntungkan di lingkungan ini yang diperlukan untuk melihat benda langit yang redup. Kondisi ini, yang meliputi tingkat polusi cahaya yang rendah, langit yang lebih gelap 20 derajat, dan kondisi cuaca kering, telah memungkinkan para peneliti di konsorsium WIYN untuk terus mengamati galaksi, nebula, dan planet ekstrasurya serta banyak target astronomi lainnya menggunakan WIYN 3.5. teleskop -meter dan saudaranya, teleskop WIYN 0,9 meter. . Kredit: KPNO/NOIRLab/NSF/AURA/R. Sparks

Mereka menyarankan bahwa kepadatan yang sangat rendah dari TOI-3757 b bisa menjadi hasil dari dua faktor. Yang pertama berkaitan dengan inti berbatu planet ini; Raksasa gas diperkirakan mulai sebagai inti batu besar dengan massa sekitar sepuluh kali massa Bumi, di mana mereka dengan cepat menarik sejumlah besar gas di dekatnya untuk membentuk raksasa gas yang kita lihat sekarang. TOI-3757b memiliki kelimpahan elemen berat yang lebih rendah daripada katai M lainnya dengan raksasa gas, dan ini mungkin mengakibatkan pembentukan inti berbatu lebih lambat, menunda timbulnya akumulasi gas dan dengan demikian mempengaruhi kepadatan keseluruhan planet.

Faktor kedua mungkin orbit planet, yang sementara dianggap sedikit elips. Ada kalanya ia lebih dekat ke bintangnya daripada waktu lainnya, yang mengakibatkan pemanasan berlebih yang signifikan yang dapat menyebabkan atmosfer planet membengkak.

Satelit Transit NASA untuk Survei Exoplanet ([{” attribute=””>TESS) initially spotted the planet. Kanodia’s team then made follow-up observations using ground-based instruments, including NEID and NESSI (NN-EXPLORE Exoplanet Stellar Speckle Imager), both housed at the WIYN 3.5-meter Telescope; the Habitable-zone Planet Finder (HPF) on the Hobby-Eberly Telescope; and the Red Buttes Observatory (RBO) in Wyoming.

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 Saturn (the lowest-density planet in the Solar System), about one quarter the density of water (meaning it would float if placed in a giant bathtub filled with water), or in fact, similar in density to a marshmallow.

“Potential future observations of the atmosphere of this planet using NASA’s new James Webb Space Telescope could help shed light on its puffy nature,” says Jessica Libby-Roberts, a postdoctoral researcher at Pennsylvania State University and the second author on this paper.

“Finding more such systems with giant planets — which were once theorized to be extremely rare around red dwarfs — is part of our goal to understand how planets form,” says Kanodia.

The discovery highlights the importance of NEID in its ability to confirm some of the candidate exoplanets currently being discovered by NASA’s TESS mission, providing important targets for the new James Webb Space Telescope (JWST) to follow up on and begin characterizing their atmospheres. This will in turn inform astronomers what the planets are made of and how they formed and, for potentially habitable rocky worlds, whether they might be able to support life.

Reference: “TOI-3757 b: A low-density gas giant orbiting a solar-metallicity M dwarf” by Shubham Kanodia, Jessica Libby-Roberts, Caleb I. Cañas, Joe P. Ninan, Suvrath Mahadevan, Gudmundur Stefansson, Andrea S. J. Lin, Sinclaire Jones, Andrew Monson, Brock A. Parker, Henry A. Kobulnicky, Tera N. Swaby, Luke Powers, Corey Beard, Chad F. Bender, Cullen H. Blake, William D. Cochran, Jiayin Dong, Scott A. Diddams, Connor Fredrick, Arvind F. Gupta, Samuel Halverson, Fred Hearty, Sarah E. Logsdon, Andrew J. Metcalf, Michael W. McElwain, Caroline Morley, Jayadev Rajagopal, Lawrence W. Ramsey, Paul Robertson, Arpita Roy, Christian Schwab, Ryan C. Terrien, John Wisniewski and Jason T. Wright, 5 August 2022, The Astronomical Journal.
DOI: 10.3847/1538-3881/ac7c20