Tau Bootis: Extrasolar Planet, F-Type Binary Star, H-R Diagram, LOFAR YouTube Lecture Handouts

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Tau Bootis: Extrasolar Planet, F-Type Binary Star, H-R Diagram, LOFAR | Science & Technology

Title: Tau Bootes

Tau Bootes

  • Extrasolar planet
  • 51 Light years away
  • Binary Stellar System
  • Discovered in 1996 was B
  • By Paul Butler by Radial Velocity Method
  • Confirmed by Michel Mayor & Didier Queloz
  • It consists of a hot and young F-type star, tau Boötis A, and a smaller M3-type (red dwarf) star, tau Boötis B.
  • In 1996, a hot-Jupiter exoplanet was discovered orbiting the primary star tau Boötis A.
  • Named tau Boötis b, the alien world has a mass almost 6 times that of Jupiter and an orbital period of 3 days and 7.5 hours.
  • Minimum Mass 5.9 times of Jupiter
  • Orbits star in Torch Orbit
  • F-type star
  • 3.3 days to complete one orbit of its star
  • 0.049 AU from its star

Hertzsprung - Russell Diagram

Hertzsprung - Russell Diagram
  • The Hertzsprung -Russell (H-R) Diagram is a graph that plots stars color (spectral type or surface temperature) vs. its luminosity (intrinsic brightness or absolute magnitude) . On it, astronomers plot stars՚ color, temperature, luminosity, spectral type, and evolutionary stage. This diagram shows that there are 3 very different types of stars:
  • Most stars, including the sun, are “main sequence stars,” fueled by nuclear fusion converting hydrogen into helium. For these stars, the hotter they are, the brighter. These stars are in the most stable part of their existence; this stage generally lasts for about 5 billion years.
  • As stars begin to die, they become giants and supergiant՚s (above the main sequence) . These stars have depleted their hydrogen supply and are very old. The core contracts as the outer layers expand. These stars will eventually explode (becoming a planetary nebula or supernova, depending on their mass) and then become white dwarfs, neutron stars, or black holes (again depending on their mass) .
  • Smaller stars (like our Sun) eventually become faint white dwarfs (hot, white, dim stars) that are below the main sequence. These hot, shrinking stars have depleted their nuclear fuels and will eventually become cold, dark, black dwarfs.
Hertzsprung - Russell Diagram
Star TypeColorApproximate Surface TemperatureAverage Mass (The Sun = 1)Average Radius (The Sun = 1)Average Luminosity (The Sun = 1)Main CharacteristicsExamples
OBlueover 25,000 K60151,400, 000Singly ionized helium lines (H I) either in emission or absorption. Strong UV continuum.10 Lacertra
BBlue11,000 - 25,000 K18720,000Neutral helium lines (H II) in absorption.Rigel Spica
ABlue7,500 - 11,000 K3.22.580Hydrogen (H) lines strongest for A0 stars, decreasing for other A՚s.Sirius, Vega
FBlue to White6,000 - 7,500 K1.71.36Ca II absorption. Metallic lines become noticeable.Canopus, Procyon
GWhite to Yellow5,000 - 6,000 K1.11.11.2Absorption lines of neutral metallic atoms and ions (e. g. , once-ionized calcium) .Sun, Capella
KOrange to Red3,500 - 5,000 K0.80.90.4Metallic lines, some blue continuum.Arcturus, Aldebaran
MRedunder 3,500 K0.30.40.04 (very faint)Some molecular bands of titanium oxide.Betelgeuse, Antares

Tau Bootes Detection

  • LOFAR (Low Frequency Array)
  • Understand Planet՚s interior & Atmospheric properties
  • Possible habitability
  • Astronomers using the Low Frequency Array (LOFAR) , a large radio telescope network located mainly in the Netherlands, have detected circularly polarized bursty emission from the tau Boötis ( Boötis) system.
  • Using the LOFAR radio telescope, Dr. Turner, Professor Jayawardhana and their colleagues observed three planet-hosting systems: tau Boötis, 55 Cancri and Upsilon Andromedae.
  • Only the tau Boötes system exhibited a significant radio signature, a unique potential window on the planet՚s magnetic field.
  • The magnetic field of Earth-like exoplanets may contribute to their possible habitability by shielding their own atmospheres from solar wind and cosmic rays, and protecting the planet from atmospheric loss

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