Difference between revisions of "Triggers:CNe"
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| + | Close binary systems with orbital periods from 0.05 to 230 days. One of the components of these systems is a hot dwarf star that suddenly, during a time interval from one to several dozen or several hundred days, increases its brightness by 7-19 mag in V, then returns gradually to its former brightness over several months, years, or decades. Cool components may be giants, subgiants, or dwarfs of K-M type (from GCVS). | ||
| + | |||
* there is roughly 30 novae per year in the Milky Way and about 20 in other galaxies | * there is roughly 30 novae per year in the Milky Way and about 20 in other galaxies | ||
* absolute magnitude <math>M_V = -8 mag</math> | * absolute magnitude <math>M_V = -8 mag</math> | ||
| − | * amplitude between | + | * spectra of novae near maximum light resemble A-F absorption spectra of luminous stars at first |
| + | * amplitude between 7 and 19 mag in V | ||
* quick rise of few days | * quick rise of few days | ||
* slow decline, between few days and 100 days (fast: type A, slow: type B, very slow: type C) | * slow decline, between few days and 100 days (fast: type A, slow: type B, very slow: type C) | ||
* 15 days after maximum its Mv = -5.5mag, independent on speed or class | * 15 days after maximum its Mv = -5.5mag, independent on speed or class | ||
| + | * small changes at minimum light may be present | ||
'''Recurrent novae''': | '''Recurrent novae''': | ||
Revision as of 16:05, 14 December 2009
Close binary systems with orbital periods from 0.05 to 230 days. One of the components of these systems is a hot dwarf star that suddenly, during a time interval from one to several dozen or several hundred days, increases its brightness by 7-19 mag in V, then returns gradually to its former brightness over several months, years, or decades. Cool components may be giants, subgiants, or dwarfs of K-M type (from GCVS).
- there is roughly 30 novae per year in the Milky Way and about 20 in other galaxies
- absolute magnitude <math>M_V = -8 mag</math>
- spectra of novae near maximum light resemble A-F absorption spectra of luminous stars at first
- amplitude between 7 and 19 mag in V
- quick rise of few days
- slow decline, between few days and 100 days (fast: type A, slow: type B, very slow: type C)
- 15 days after maximum its Mv = -5.5mag, independent on speed or class
- small changes at minimum light may be present
Recurrent novae:
- are produced by a white dwarf star and a red giant circling about each other in a close orbit
- recurrent every 10-100 years
- smaller amplitude: 4-9 mag
- M_V at minimum is about 0-1 mag
- example: RS Oph - 3 outbursts between 1957 and 1991 (AAVSO), exhibits some small variation in the baseline in minimum
- decline within few days
