[Intro] Delta Scuti variable Is a subclass of young pulsating star Sometimes termed dwarf cepheid When the V-band amplitude is larger [Instrumental] [Verse] These variables are important standard candles And have been used to establish the distance To the LMC, globular clusters Open clusters, and the Galactic Center [Verse 2] The variables follow a period-luminosity relation In certain passbands Like other standard candles Such as Cepheids [Pre-chorus] SX Phoenicis variables are generally Considered to be a subclass of Delta Scuti variables That contain old stars And can be found in globular clusters [Chorus] Delta Scuti variable Is a subclass of young pulsating star Sometimes termed dwarf cepheid When the V-band amplitude is larger Delta Scuti variable Is a subclass of young pulsating star Sometimes termed dwarf cepheid When the V-band amplitude is larger [Verse 3] Delta Scuti stars exhibit Both radial and non-radial luminosity pulsations Non-radial pulsations are move inwards and some outward Radial pulsations are a special case [Verse 4] The stars have a helium rich atmosphere As helium is compressed it Becomes more ionised Which is more opaque [Pre-chorus] So at the dimmest part in the cycle the star Has highly ionised opaque helium in its atmosphere Blocking part of the light From escaping (from escaping) [Chorus] Delta Scuti variable Is a subclass of young pulsating star Sometimes termed dwarf cepheid When the V-band amplitude is larger Delta Scuti variable Is a subclass of young pulsating star Sometimes termed dwarf cepheid When the V-band amplitude is larger [Instrumental] [Outro] Delta Scuti
[Intro] RV Tauri variables Are luminous variable stars That have distinctive light variations With alternating deep and shallow minima [Instrumental] [Verse] RV Tauri variables Exhibit changes in luminosity Which are tied to radial pulsations Of their surfaces Their changes in brightness Are also correlated With changes In their spectral type [Verse 2] While at their brightest The stars have spectral types F or G At their dimmest Their spectral types change to K or M [Chorus] RV Tauri variables Are luminous variable stars That have distinctive light variations With alternating deep and shallow minima RV Tauri variables Are luminous variable stars That have distinctive light variations With alternating deep and shallow minima [Verse 3] The pulsations cause the star To be hottest and smallest Approximately halfway From the primary minimum Towards a maximum The coolest temperatures Are reached near To a deep minimum [Verse 4] When the brightness Is increasing Hydrogen emission lines appear In the spectrum And many spectral lines Become doubled Due to a shock wave In the atmosphere [Pre-chorus] The emission lines fade a few days After maximum brightness [Chorus] RV Tauri variables Are luminous variable stars That have distinctive light variations With alternating deep and shallow minima RV Tauri variables Are luminous variable stars That have distinctive light variations With alternating deep and shallow minima [Instrumental] [Outro] RV Tauri
[Instrumental] [Chorus] W Virginis variables Are a subclass of Type II Cepheids Exhibit pulsation periods Between 10-20 days [Verse] They were first recognized As being distinct from Classical Cepheids By Walter Baade In 1942 [Chorus] W Virginis variables Are a subclass of Type II Cepheids Exhibit pulsation periods Between 10-20 days [Verse 2] In a study of Cepheids In the Andromeda Galaxy that proposed That stars in that galaxy Were of two populations [Chorus] W Virginis variables Are a subclass of Type II Cepheids Exhibit pulsation periods Between 10-20 days [Instrumental] [Verse 3] They were first recognized As being distinct from Classical Cepheids By Walter Baade In 1942 [Chorus] W Virginis variables Are a subclass of Type II Cepheids Exhibit pulsation periods Between 10-20 days W Virginis variables Are a subclass of Type II Cepheids Exhibit pulsation periods Between 10-20 days [Outro] W Virginis
