A post-AGB star (pAGB, abbreviation of post-asymptotic giant branch) is a type of luminous supergiant star of intermediate mass in a very late phase of stellar evolution. The post-AGB stage occurs after the asymptotic giant branch (AGB or second-ascent red giant) has ended. The stage sees the dying star, initially very cool and large, shrink and heat up.[1] The duration of the post-AGB stage varies based on the star's initial mass, and can range from 100,000 years for a solar-mass star to just over 1,000 years for more massive stars. The timescale gets slightly shorter with lower metallicity.[2]
Towards the end of this stage, post-AGB stars also tend to produce protoplanetary nebulae as they shed their outer layers, and this creates a large infrared excess and obscures the stars in visible light. After reaching an effective temperature of about 30,000 K, the star is able to ionise its surrounding nebula, producing a true planetary nebula.
Propertiesedit
Post-AGB stars span a large range of temperatures, as they are in the process of heating up from very cool temperatures (3,000 K or less) up to about 30,000 K. Technically, the post-AGB stage only ends when the star reaches its maximum temperature of 100-200,000 K,[2] but beyond 30,000 K, the star ionises the surrounding gas and would be considered a central star of a planetary nebula more often than a post-AGB star.
On the other hand, the luminosity of post-AGB stars is usually constant throughout the post-AGB stage, and slightly dependent on the star’s core mass, and getting slightly brighter with lower metallicity.[3][2]
Examplesedit
Due to the dust usually obscuring them, many post-AGB stars are visually relatively dim. However there are still some post-AGB stars visible to the naked eye, the brightest of which is 89 Herculis.
^Habing, Harm (1997). Paresce, Francesco (ed.). AGB and POST-AGB STARS: an Overview. Science with the VLT Interferometer. Science with the VLT Interferometer. ESO Astrophysics Symposia. Berlin, Heidelberg: Springer. pp. 183–191. doi:10.1007/978-3-540-69398-7_23. ISBN978-3-540-69398-7.
^ abcBertolami, Marcelo Miguel Miller (2016-04-01). "New models for the evolution of post-asymptotic giant branch stars and central stars of planetary nebulae". Astronomy & Astrophysics. 588: A25. arXiv:1410.1679. Bibcode:2016A&A...588A..25M. doi:10.1051/0004-6361/201526577. ISSN 0004-6361.
^Vickers, Shane B.; Frew, David J.; Owers, Matt S.; Parker, Quentin A.; Bojičič, Ivan S. (2016). "Improving the distances of post-AGB objects in the Milky Way". Journal of Physics: Conference Series. 728 (7): 072013. Bibcode:2016JPhCS.728g2013V. doi:10.1088/1742-6596/728/7/072013. hdl:10722/237688. S2CID 126383516.
March 12, 2024
post, star, post, star, pagb, abbreviation, post, asymptotic, giant, branch, type, luminous, supergiant, star, intermediate, mass, very, late, phase, stellar, evolution, post, stage, occurs, after, asymptotic, giant, branch, second, ascent, giant, ended, stage. A post AGB star pAGB abbreviation of post asymptotic giant branch is a type of luminous supergiant star of intermediate mass in a very late phase of stellar evolution The post AGB stage occurs after the asymptotic giant branch AGB or second ascent red giant has ended The stage sees the dying star initially very cool and large shrink and heat up 1 The duration of the post AGB stage varies based on the star s initial mass and can range from 100 000 years for a solar mass star to just over 1 000 years for more massive stars The timescale gets slightly shorter with lower metallicity 2 Towards the end of this stage post AGB stars also tend to produce protoplanetary nebulae as they shed their outer layers and this creates a large infrared excess and obscures the stars in visible light After reaching an effective temperature of about 30 000 K the star is able to ionise its surrounding nebula producing a true planetary nebula Properties editPost AGB stars span a large range of temperatures as they are in the process of heating up from very cool temperatures 3 000 K or less up to about 30 000 K Technically the post AGB stage only ends when the star reaches its maximum temperature of 100 200 000 K 2 but beyond 30 000 K the star ionises the surrounding gas and would be considered a central star of a planetary nebula more often than a post AGB star On the other hand the luminosity of post AGB stars is usually constant throughout the post AGB stage and slightly dependent on the star s core mass and getting slightly brighter with lower metallicity 3 2 Examples editDue to the dust usually obscuring them many post AGB stars are visually relatively dim However there are still some post AGB stars visible to the naked eye the brightest of which is 89 Herculis Other examples include L2 Puppis RV Tauri R Scuti U MonocerotisReferences edit Habing Harm 1997 Paresce Francesco ed AGB and POST AGB STARS an Overview Science with the VLT Interferometer Science with the VLT Interferometer ESO Astrophysics Symposia Berlin Heidelberg Springer pp 183 191 doi 10 1007 978 3 540 69398 7 23 ISBN 978 3 540 69398 7 a b c Bertolami Marcelo Miguel Miller 2016 04 01 New models for the evolution of post asymptotic giant branch stars and central stars of planetary nebulae Astronomy amp Astrophysics 588 A25 arXiv 1410 1679 Bibcode 2016A amp A 588A 25M doi 10 1051 0004 6361 201526577 ISSN 0004 6361 Vickers Shane B Frew David J Owers Matt S Parker Quentin A Bojicic Ivan S 2016 Improving the distances of post AGB objects in the Milky Way Journal of Physics Conference Series 728 7 072013 Bibcode 2016JPhCS 728g2013V doi 10 1088 1742 6596 728 7 072013 hdl 10722 237688 S2CID 126383516 Retrieved from https en wikipedia org w index php title Post AGB star amp oldid 1193737151, wikipedia, wiki, book, books, library,
