II Pegasi

II Pegasi
	estrella
Datos d'observación
Ascensión reuta (α)	358,76688186043 °
Declinación (δ)	28,633680054028 °
Distancia a la Tierra	39,363 pc
Magnitú aparente (V)	8,88 (Banda U (es) ); 8,2 (Banda B (es) ); 6,9 (Banda R (es) ); 7,0988 (Banda G (es) ); 5,485 (Banda J (es) ); 4,952 (Banda H (es) ); 4,724 (Banda K (es) )
Constelación	Pegaso (es)
Velocidá radial	−20,5 km/s
Parallax	25,4046 mas
Radiu	3,4 Radius solars
Diámetru	2 370 000 km
Tipu espectral	K2+IVeFe-1
Otros nomes
	Ver llista HD 224085 (Catálogu Henry Draper); HIP 117915 (Catálogu Hipparcos); IRAS 23525+2821 (IRAS (es) ); SAO 91578 (Catálogu SAO); 2MASS J23550404+2838010 (2MASS (es) ); GJ 4375 (Catálogu Gliese); 1ES 2352+28.3 (Einstein Slew survey, Version No. 1 (en) ); 1RXS J235503.5+283802 (1RXS (en) ); 2EUVE J2355+28.6 (The second Extreme Ultraviolet Explorer source catalog (en) ); AG+28 2842 (Astronomische Gesellschaft Katalog (es) ); ASCC 738952 (All-sky Compiled Catalogue (en) ); BD+27 4642 (Bonner Durchmusterung); EUVE J2355+28.6 (The first Extreme Ultraviolet Explorer source catalog (en) ); GC 33168 (Boss General Catalogue (es) ); GCRV 14960 (General Catalogue of Stellar Radial Velocities (es) ); HIC 117915 (Hipparcos Input Catalogue (en) ); LFT 1838 (Luyten Five-Tenths catalogue (en) ); LHS 4044 (Luyten Half-Second catalogue (en) ); LSPM J2355+2838 (LSPM-NORTH catalog (en) ); LTT 17045 (Luyten Two-Tenths catalogue (en) ); NLTT 58392 (New Luyten Two-Tenths catalogue (en) ); PLX 5777 (General Catalogue of Trigonometric Stellar Parallaxes (es) ); PLX 5777.00 (General Catalogue of Trigonometric Stellar Parallaxes (es) ); PPM 115949 (Catálogo de estrellas PPM (es) ); RBS 2059 (ROSAT All-Sky Survey Bright Source Catalogue (en) ); TYC 2258-1427-1 (Tycho Catalogue (en) ); UBV 20529 (UBV Photoelectric Photometry Catalogue (en) ); UBV M 27327 (Photoelectric catalogue, magnitudes and colors of stars in the UBV and UCBV systems (en) ); uvby98 100224085 V (uvbyβ Photoelectric Photometric Catalogue (en) ); II Peg (General Catalogue of Variable Stars); YZ 28 14346 (Yale Observatory Zone Catalog (en) ); uvby98 100224085 (uvbyβ Photoelectric Photometric Catalogue (en) ); [ZEH2003] RX J2355.0+2838 1 (The Hamburg/RASS Catalogue of optical identifications. Northern high-galactic latitude ROSAT Bright Source Catalogue X-ray sources (en) ); SBC9 1462 (Eighth catalogue of the orbital elements of spectroscopic binary systems (en) ); 1XRS 00000+278 (A catalog of X-ray sources (en) ); 3A 2355+284 (The Ariel V (3A) catalogue of X-ray sources - II. Sources at high galactic latitude ( b > 10 ) (en) ); AT 2355+284 (The Ariel V sky survey of fast-transient X-ray sources (en) ); Ci 20 1461 (Catalogue of proper motion stars (en) ); LAL 46867 (A catalogue of those stars in the "Histoire Celeste Francaise" of J. De Lalande for which tables of reduction to the epoch 1800 have been published by Professor Schumacher (en) ); PM 23525+2821 (Catalogs of proper-motion stars. I. Stars brighter than visual magnitude 15 and with annual proper motion of 1" or more (en) ); RX J2355.0+2838 (X-ray survey of the Large Magellanic Cloud by ROSAT (en) ); RX J2355.0+2837 (X-ray survey of the Large Magellanic Cloud by ROSAT (en) ); SBC7 971 (Seventh catalogue of the orbital elements of spectroscopic binary systems (en) ); XSS J23556+2848 (RXTE all-sky slew survey. Catalog of X-ray sources at \|b\|>10{deg} (en) ); YZC 24 14346 (Catalogue of the positions and proper motions of "nnn" stars. Zone between declination +20 and + 25 (en) ); Ci 19 3131 (Catalogue of proper motion stars (en) ); Gaia DR1 2855095246776191744 (Gaia DR1 (es) ); WEB 20737 (Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Radial velocities: The Wilson-Evans-Batten catalogue (en) ); Gaia DR2 2855095251072482432 (Gaia DR2 (es) );

Coordenaes: 23^h 55^m 4.052^s, 28^° 38^′ 1.248^″

II Pegasi (II Peg / HD 224085 / HIP 117915) ye una estrella variable na constelación de Pegasu.^[7] La so magnitú aparente media ye +7,37 y alcuéntrase a 138 años lluz del Sistema Solar.

II Pegasi ye una estrella binaria cercana —la distancia ente les componentes ye de 0,032 UA— con un periodu orbital de 6,724 díes. La estrella principal, II Pegasi A, ye una subxigante naranxa con una masa de 0,90 mases solares, ente que II Pegasi B tien una masa de 0,38 mases solares.^[8] Por cuenta de la fuerte atraición gravitatoria, dambes estrelles roten rápido, unos cuatro vegaes más apriesa que'l Sol.^[9] La so velocidá al traviés del espaciu suxure que ye una vieya estrella de discu.^[10]

Sábese qu'II Pegasi ye una estrella acandilante en rayos X dende mediaos de la década de 1970. Ello ye que ente les estrelles que tán a menos de 50 pársecs del Sistema Solar, ye la más brillosa en rayos X; la so lluminosidá —en dicha rexón del espectru— llega a los 175,75 × 10²² W.^[11] Amás, ye brillosu y activa como radiofuente y na rexón ultravioleta. Catalogada como variable RS Canum Venaticorum, el so rellumu fluctúa ente magnitú +7,18 y +7,78 nun periodu de 6,703 díes.^[12]

En 2005 l'observatoriu espacial Swift reparó una enorme erupción, 100 millones de vegaes más intensa qu'un fogaral normal del Sol, n'II Pegasi A.^[10] Esti rellumu ye quiciabes la esplosión estelar magnética de mayor enerxía que se detectó nunca, con una intensidá comparable al d'una nova. Piénsase que la rápida rotación de les estrelles conduz a la formación d'estes enormes erupciones. Una erupción asina nel nuesu Sol provocaría una estinción masiva na Tierra. ^[13]

Referencies

↑ Afirmao en: SIMBAD.
1 2 3 Afirmao en: Gaia DR2. Llingua de la obra o nome: inglés. Data d'espublización: 25 abril 2018.
↑ Afirmao en: VizieR. Llingua de la obra o nome: inglés.
↑ «Kinematics of chromospherically active binaries and evidence of an orbital period decrease in binary evolution» (n'inglés). Monthly Notices of the Royal Astronomical Society (3): páxs. 1069–1092. abril 2004. doi:10.1111/J.1365-2966.2004.07588.X.
↑ «Starspots» (n'inglés). The Astronomy and Astrophysics Review (3): páxs. 251-308. 2 mayu 2009. doi:10.1007/S00159-009-0020-6.
↑ «The Perkins catalog of revised MK types for the cooler stars» (n'inglés). The Astrophysical Journal Supplement Series: páxs. 245–266. ochobre 1989. doi:10.1086/191373.
↑ II Pegasi (SIMBAD)
↑ Tokovinin, A.; Thomas, S.; Sterzik, M.; Udry, S. (2006). «Tertiary companions to close spectroscopic binaries». Astronomy and Astrophysics 450 (2). páxs. 681-693. http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2006A%26A...450..681T&db_key=AST&nosetcookie=1.
↑ II Pegasi. Jumk.de/astronomie
1 2 Osten, Rachel A.; Drake, Stephen; Tueller, Jack; Cummings, Jay; Perri, Matteo; Moretti, Alberto; Covino, Stefano (2007). «Nonthermal Hard X-Ray Emission and Iron Kα Emission from a Superflare on II Pegasi». The Astrophysical Journal 654 (2). páxs. 1052-1067. http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2007ApJ...654.1052O&db_key=AST&nosetcookie=1.
↑ Makarov, Valeri V. (2003). «The 100 Brightest X-Ray Stars within 50 Parsecs of the Sun». The Astronomical Journal 126 (4). páxs. 1996-2008. http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2003AJ....126.1996M&db_key=AST&nosetcookie=1.
↑ II Pegasi (General Catalogue of Variable Stars)
↑ Monster stellar flare seen by NASA scientists dwarfs all others. NASA

Coordenaes: 23^h 55^m 4.052^s, 28^° 38^′ 1.248^″

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[8ba559d5760a03bedaaacc3c347bbfe4981560bf-1] Afirmao en: SIMBAD.

[b64af6c056b6c5f6a7ea17156dcd718d4744bbf8-2] 1 2 3 Afirmao en: Gaia DR2. Llingua de la obra o nome: inglés. Data d'espublización: 25 abril 2018.

[eedd662cbc889e46d17821464d4af8748a120b6c-3] Afirmao en: VizieR. Llingua de la obra o nome: inglés.

[cbfbdc1744bcf91d06a06a0fefd7f7a1dcc219b1-4] «Kinematics of chromospherically active binaries and evidence of an orbital period decrease in binary evolution» (n'inglés). Monthly Notices of the Royal Astronomical Society (3): páxs. 1069–1092. abril 2004. doi:10.1111/J.1365-2966.2004.07588.X.

[fb628117ae3ef5a67caf9a6ad303218b08407fa8-5] «Starspots» (n'inglés). The Astronomy and Astrophysics Review (3): páxs. 251-308. 2 mayu 2009. doi:10.1007/S00159-009-0020-6.

[94e37f50009615333c7acbe5725f757ef6342132-6] «The Perkins catalog of revised MK types for the cooler stars» (n'inglés). The Astrophysical Journal Supplement Series: páxs. 245–266. ochobre 1989. doi:10.1086/191373.

[7] II Pegasi (SIMBAD)

[Tokovinin-8] Tokovinin, A.; Thomas, S.; Sterzik, M.; Udry, S. (2006). «Tertiary companions to close spectroscopic binaries». Astronomy and Astrophysics 450 (2). páxs. 681-693. http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2006A%26A...450..681T&db_key=AST&nosetcookie=1.

[9] II Pegasi. Jumk.de/astronomie

[Osten-10] 1 2 Osten, Rachel A.; Drake, Stephen; Tueller, Jack; Cummings, Jay; Perri, Matteo; Moretti, Alberto; Covino, Stefano (2007). «Nonthermal Hard X-Ray Emission and Iron Kα Emission from a Superflare on II Pegasi». The Astrophysical Journal 654 (2). páxs. 1052-1067. http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2007ApJ...654.1052O&db_key=AST&nosetcookie=1.

[The_100_Brightest_X-Ray_Stars-11] Makarov, Valeri V. (2003). «The 100 Brightest X-Ray Stars within 50 Parsecs of the Sun». The Astronomical Journal 126 (4). páxs. 1996-2008. http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2003AJ....126.1996M&db_key=AST&nosetcookie=1.

[12] II Pegasi (General Catalogue of Variable Stars)

[13] Monster stellar flare seen by NASA scientists dwarfs all others. NASA

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