High precision stellar spectroscopy: From the first stars to planets Jorge Meléndez Departamento de Astronomia, IAG, Universidade de São Paulo
My group: SAMPA Stellar Atmospheres, Planets & Abundances
SAMPA @ IAG/USP Stellar Atmospheres, Planets & Abundances
16 refereed SAMPA international publications in 2016 using high resolution spectroscopy
Spectroscopy Espectro solar Dark lines in the spectrum of the Sun and stars Hydrogen atom http://www.bbc.co.uk/education/guides/zq7thyc/revision/6 p 1 2 3
Stellar spectrum: chemical composition, temperature, luminosity, rotation, stellar activity, planets
What is the origin of the chemical elements? How our galaxy evolved? How planets form and evolve?
time Evolution of our universe First 3 minutes: H, He, Li 13,7 billion years Big Bang
Relative flux From the first stars to the Sun: chemical evolution Sun: [Fe/H] = 0 solar metallicity CD-38 245: [Fe/H] = - 4 (10-4 solar) HE 0107-5240: [Fe/H] = - 5.3 Population III: [Fe/H] = - Wavelength credits: N. Christlieb 9
Star with [Fe/H] = -3 (a thousand times more metal-poor than Sun) Asplund & Melendez (2008)
time Evolution of our universe Era of galaxies 13,7 billion years Big Bang
Chemical evolution of the elements From H and He to metals
Interstellar medium Evolution of chemical elements in our Galaxy H, He stars Ejecta is rich in metais
Discovery of the brightest ultra metal-poor star using the ESO La Silla Observatory in Chile Melendez et al. (2016)
Stellar Populations - Thin disk, Thick disk - Bulge - Halo - Globular Clusters, Open Clusters
How common is our Sun? How common is our solar system? How can we find Earth 2.0?
Solar twins: stars with properties very similar to our Sun (temperature, luminosity, chemical composition)
Δ abundance: Sun - <twins> vs. atomic number Z Sun typical : Δ = 0 Sun weird : Δ 0 Our solar system is not host by a typical Sun Meléndez, Asplund, Gustafsson, Yong. 2009
Sun s anomalies are strongly correlated to the dust condensation temperature of the elements! Correlation is highly significant probability ~10-9 to happen by chance It s most likely to win the lottery ~ 0.08 dex ~ 20% Dust condensation temperature (K) Meléndez, Asplund, Gustafsson, Yong. 2009
Condensation Condensation in the solar nebula Mercury Venus
Meléndez et al. 2009 The missing refractories were used to form dust, planetesimals & terrestrial planets The late accreted gas in the convection zone was deficient in refractories
Link between chemical composition & planets Finding planets around solar twins Large Programme: 100 nights at La Silla 3.6m telescope + HARPS spectrograph
Mercury Venus Earth Mars Solar System Jupiter Jupiter twin in HIP 11915 HIP 11915b
HIP 11915 Star is very similar to the Sun in physical properties AND chemical composition Sol HIP 11915 Composition adequate to form rocky planets! Mg Cr
Meléndez et al. 2009 Sun is deficient in chemical elements that are abundant in rocky planets HIP 11915 may have rocky planets because chemical composition like the Sun!
HIP 11915: candidate for solar system twin!?
Super-Earth Earth Solar System Neptune Super Neptune Planetary system in HIP 68468
Planet engulfment Star HIP 68468 shows chemical signatures of planet engulfment
Slower rotator Faster rotator dos Santos et al. A&A 592, A156
Evolution of rotation in Sun-like stars v = 1.2 ± 0.4 + 1.9 ± 0.4 t -0.6±0.3 dos Santos et al. A&A 592, A156
11-year activity cycle in the Sun. X-rays by Yohkoh 8/1991 9/2001
Ca II H and K lines have emission from the chromosphere, sensitive to magnetic activity Sun in Ha
S index Activity cycle from chromospheric index S Baliunas et al. 1995 ApJ 438, 269
Long-term (billion of years) evolution of magnetic stellar activity in Sun-like stars Freitas et al. 2017
How to detect Earth 2.0? Current instrumentation: precision of 1m/s Earth s effect on the Sun: 9 cm/s Challenges: stellar noise (mainly magnetic activity)
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SAMPA research areas - Discovery of primitive metal-poor stars - Chemical evolution of our galaxy - Fundamental properties of stars (chemical composition, age, mass) - Rotation and stellar magnetic activity - Discovery of planetary systems in solar twins - The search for Earth 2.0
Thanks! Questions? @DrJorgeMelendez