Observational Proof of the ZZ Ceti Red Edge
نویسندگان
چکیده
منابع مشابه
Pulsating or not ? A search for hidden pulsations below the red edge of the ZZ Ceti instability strip ⋆
The location of the red edge of the ZZ Ceti instability strip is defined observationally as being the lowest temperature for which a white dwarf with a H-rich atmosphere (DA) is known to exhibit periodic brightness variations. Whether this cut-off in flux variations is actually due to a cessation of pulsation or merely due to the attenuation of any variations by the convection zone, rendering t...
متن کاملGravity Modes in Zz Ceti Stars. Ii. Eigenvalues and Eigenfunctions
We report on numerical calculations of nonadiabatic eigenvalues and eigenfunctions for g-modes in ZZ Ceti variables. The spectrum of overstable l \ 1 modes delineates the instability strip. Its blue edge occurs where for the n \ 1 mode. Here u is radian frequency and is about 4 times the uq c B 1 q c thermal time at the bottom of the surface convection zone. As a ZZ Ceti cools, its convection z...
متن کاملGravity-modes in Zz Ceti Stars Iii. Eigenvalues and Eigenfuctions
We report on numerical calculations of nonadiabatic eigenvalues and eigenfunctions for g-modes in ZZ Ceti variables. The spectrum of overstable l = 1 modes delineates the instability strip. Its blue edge occurs where ωτc ≈ 1 for the n = 1 mode. Here ω is radian frequency and τc is about four times the thermal timescale at the bottom of the surface convection zone. As a ZZ Ceti cools, its convec...
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We report the discovery of a new long–period ZZ Ceti star through the analysis of photometric time series gathered on 7 nights between 1995 and 1996. The light curve displays a periodic variation with a period of ∼ 18 min in white light and the frequency analysis reveals a low frequency peak at ∼ 0.92 mHz with an amplitude varying from 0.007 to 0.025 mag present every night. BPM 24754 is the 28...
متن کاملPG 1541 + 650 : A new ZZ Ceti white dwarf ?
We report the discovery of a new pulsating DA white dwarf, or ZZ Ceti, from the list of the Palomar-Green survey, rediscovered in the ongoing Hamburg Quasar survey (HQS). PG1541+650 is one of the ZZ Ceti candidates listed in the analysis of 80 DA white dwarfs from the HQS. With an effective temperature of 12000 K, for a surface gravity logg=7.79, it lies in the ZZ Ceti instability strip. It is ...
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ژورنال
عنوان ژورنال: International Astronomical Union Colloquium
سال: 2000
ISSN: 0252-9211
DOI: 10.1017/s0252921100058693