HR 6819
HR 6819 (bl.a. også kendt som HD 167128 og QV Telescopii) er et system bestående af tre himmellegemer med solmassestørrelser i stjernebilledet Kikkerten.[1] To af legemerne er almindelige stjerner; det tredje legeme er et sort hul. HR 6819 er det eneste stjerneobjekt med et sort hul, som kan ses med det blotte øje. Af alle kendte sorte huller i 2020 er dette det nærmeste Solsystemet, med en afstand på ca. 1000 lysår.[2][3][4]
HR 6819 er i lang tid blevet opfattet som en dobbeltstjerne. Ved at betragte systemet via MPG/ESO-2,2-m-Teleskopet med FEROS-spektrografen på La-Silla-Observatoriet, kunne det ses, at en af de to synlige stjerner kredsede om et usynligt objekt med en periodetid på 40,3 døgn. Da dette usynlige objekt har en masse på mindst 4 solmasser, kan det kun være et sort hul. Dette sorte hul er ikke aktivt. Det sorte hul har ingen synlig vekselvirkning med omgivelserne (fx lave en akkretionsskive).[5][4]
Referencer
- ^ eso.org: Location of the HR 6819 in the constellation of Telescopium Citat: "...This map shows most of the stars visible to the unaided eye under good conditions and the system itself is marked with a red circle...", backup
- ^ 06 maj 2020, videnskab.dk: Astronomer finder usynligt sort hul, som er det tætteste på Jorden. Formentlig ligger der hundreder af millioner af sorte huller skjult i vores galakse, mener forskerne Citat: "...Astronomer fra Det Europæiske Sydobservatiorium (ESO) i Chile har spottet et sort hul 1.000 lysår fra Jorden, hvilket er det tætteste på Jorden, man hidtil kender til...Omkring det nyopdagede sorte hul kredser to stjerner, der er en del af stjernebilledet Kikkerten, der kan ses med det blotte øje på den sydlige halvkugle..."
- ^ May 6, 2020, scitechdaily.com: Astronomers Discover Hidden Black Hole “Near” Earth – Closest Ever Found to Our Solar System
- ^ a b Free Access: “A naked-eye triple system with a nonaccreting black hole in the inner binary” by Th. Rivinius, D. Baade, P. Hadrava, M. Heida and R. Klement, 6 May 2020, Astronomy & Astrophysics, DOI
- ^ 6 May 2020, eso.org: Eso Instrument Finds Closest Black Hole to Earth. Invisible object has two companion stars visible to the naked eye Citat: "...The team found evidence for the invisible object by tracking its two companion stars using the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile. They say this system could just be the tip of the iceberg, as many more similar black holes could be found in the future...", backup
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Forfatter/Opretter: ESO/L. Calçada, Licens: CC BY 4.0
This artist’s impression shows the orbits of the objects in the HR 6819 triple system. This system is made up of an inner binary with one star (orbit in blue) and a newly discovered black hole (orbit in red), as well as a third object, another star, in a wider orbit (also in blue). The team originally believed there were only two objects, the two stars, in the system. However, as they analysed their observations, they were stunned when they revealed a third, previously undiscovered body in HR 6819: a black hole, the closest ever found to Earth. The black hole is invisible, but it makes its presence known by its gravitational pull, which forces the luminous inner star into an orbit. The objects in this inner pair have roughly the same mass and circular orbits. The observations, with the FEROS spectrograph on the 2.2-metre telescope at ESO’s La Silla, showed that the inner visible star orbits the black hole every 40 days, while the second star is at a large distance from this inner pair.
(c) ESO/Digitized Sky Survey 2. Acknowledgement: Davide De Martin, CC BY 4.0
This wide-field view shows the region of the sky, in the constellation of Telescopium, where HR 6819 can be found, a triple system consisting of two stars and the closest black hole to Earth ever found. This view was created from images forming part of the Digitized Sky Survey 2. While the black hole is invisible, the two stars in HR 6819 can be viewed from the southern hemisphere on a dark, clear night without binoculars or a telescope.