{{Stars of Canes Venatici}}
{{Stars of Canes Venatici}}
[[Category:Star systems]]
[[Category:Extragalactic stars]]
[[Category:Extragalactic stars]]
[[Category:X-ray binaries]]
[[Category:X-ray binaries]]
X-ray binary in the Whirlpool Galaxy
M51-ULS-1, also known as RX J132943+47115, is a high-mass X-ray binary (HMXB) system in the constellation of Canes Venatici.[1][2][3] The binary system is located in the Whirlpool Galaxy, a nearby spiral galaxy some 28 million light years (or 8.6 million parsecs) away.[1][2] The binary system has an apparent visual magnitude of 24.01.[1] The binary system was discovered in 1995 in a ROSAT survey of X-ray sources in the Whirlpool Galaxy and NGC 5195.[4]
M51-ULS-1 is a high-mass X-ray binary system in the Whirlpool Galaxy consisting of two components, a blue supergiant, and a compact object.[2][3][5] The binary system has an predicted age between 4 and 16 million years old; it was also found that the system is probably no older than 100 million years old.[3] The compact object orbits the more massive blue supergiant star in a orbit with a semi-major axis of 50 R☉, and it was found that the semi-major axis of the binary is no larger than 3 astronomical units.[3]
The primary star, M51-ULS-1 A, is a massive, luminous early to late blue supergiant star.[2][3][6] The primary star has a spectral type of B2-8la discovered using Hubble Space Telescope photometry.[3] The primary star has a mass of about 20 M☉.[2] The primary star has an estimated size of <25 R☉,[3][6] based on a luminosity of ~260,000 L☉[c] and a derived effective temperature of approximately 26,000 K.[3][d]
It is predicted that the primary star might undergo a hydrogen-poor supernovae in the future.[3]
The secondary object, M51-ULS-1 B, is a stellar remnant and is either a black hole or neutron star.[2][3][5] If the secondary object is a black hole, it would have a mass of 10 M☉; classifying the secondary object as a stellar-mass black hole.[3] If it is a black hole, using its mass it would have a Schwarzschild radius of roughly 30 kilometers.[3] If the secondary object is a neutron star, it would have mass of 1.4 M☉.[3] It is known that the secondary object is accreting 10-6 M☉ worth of material every year.[3]
In September 2020, a candidate exoplanet named M51-ULS-1 b was discovered in the system using the Chandra X-ray Observatory.[2][3][5] The putative exoplanet is mainly notable for being the first extragalactic planet candidate with strong evidence.[2][3][5] The potential exoplanet was detected by the eclipses of the X-ray source (XRS);[3] i. e. M51-ULS-1 B, the compact object orbiting the primary star. The candidate exoplanet is likely slightly smaller than the planet Saturn.[3][7] The unconfirmed exoplanet orbits both of the objects in the system in about 70 years, and has a semi-major axis of 45 AU.[2][3][5] It was suggested that the planet could be a white dwarf, however this was ruled out because of the fact it would cause a lensing event and not a dip in flux.[3] It was also proposed that it may be a cloud of gas, however the discoverers found this as an unlikely explanation.[3] Because M51-ULS-1 b orbits a potential black hole it may be classified as a blanet.
- ^ Assumed radius if the secondary object is a neutron star
- ^ Schwarzschild radius if the secondary object is a black hole
- ^ 1039 erg/s = 260,010.4004 L☉
- ^ Applying the Stefan–Boltzmann law with a nominal solar effective temperature of 5,772 K:
- ( 5 , 772 26 , 068 ) 4 ⋅ 260 , 010.4004 = 25 R ⊙ {\displaystyle {\sqrt {{\biggl (}{\frac {5,772}{26,068}}{\biggr )}^{4}\cdot {260,010.4004}}}=25\ R_{\odot }} .
