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Calibration of post-agb supergiants as standard extragalactic candles for hst
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Bond, Howard E. |
| Copyright Year | 1998 |
| Description | This report summarizes activities carried out with support from the NASA Ultraviolet, Visible, and Gravitational Astrophysics Research and Analysis Program. The aim of the program is to calibrate the absolute magnitudes of post-asymptotic-giant-branch (post-AGB or PAGB) stars, which we believe will be an excellent new "standard candle" for measuring extragalactic distances. The reason for this belief is that in old populations, the stars that are evolving through the PAGB region of the HR (Hertzsprung-Russell) diagram arise from only a single main-sequence turnoff mass. In addition, the theoretical PAGB evolutionary tracks show that they evolve through this region at constant luminosity; hence the PAGB stars should have an extremely narrow luminosity function. Moreover, as the PAGB stars evolve through spectral types F and A (en route from the AGB to hot stellar remnants and white dwarfs), they have the highest luminosities attained by old stars (both bolometrically and in the visual band). Finally, the PAGB stars of these spectral types are very easily identified, due to their large Balmer jumps, which are due to their very low surface gravities. |
| File Size | 393546 |
| Page Count | 9 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19990042137 |
| Archival Resource Key | ark:/13960/t9964gn99 |
| Language | English |
| Publisher Date | 1998-01-01 |
| Access Restriction | Open |
| Subject Keyword | Astronomy Astrophysics White Dwarf Stars Ultraviolet Spectra Luminosity Main Sequence Stars Stellar Evolution Globular Clusters Magnitude Asymptotic Giant Branch Stars Milky Way Galaxy A Stars Supergiant Stars Visible Spectrum F Stars Distance Photometry Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Technical Report |
