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
3 Hydrogen atom 2 1 p http://www.bbc.co.uk/education/guides/zq7thyc/revision/6 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? Evolution of our universe First 3 minutes: H, He, Li
13,7 billion years time
Big Bang 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 Relativeflux
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) Evolution of our universe Era of galaxies
13,7 billion years time
Big Bang Chemical evolution of the elements From H and He to “metals” Evolution of chemical elements in our Galaxy
H, He stars
medium Interstellar
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 -
It’s most likely to win Dust condensation temperature (K) the lottery Meléndez, Asplund, Gustafsson, Yong. 2009 Condensation in the solar nebula
Mercury
Venus Condensation The late accreted gas in the convection
Meléndez 2009Meléndez al.et zone was The missing deficient in refractories were refractories used to form dust, planetesimals & terrestrial planets Link between chemical composition & planets Finding planets around solar twins
Large Programme: 100 nights at La Silla 3.6m telescope + HARPS spectrograph
Solar System Jupiter
Mars
Mercury
Venus Earth
Jupiter twin in HIP 11915
HIP 11915b HIP 11915 • Star is very similar to the Sun in physical properties AND chemical composition
Composition adequate to form rocky planets !
Sol HIP 11915
Cr Mg HIP 11915 may have rocky planets because Meléndez et al. 2009 et Meléndez chemical composition like the Sun ! Sun is deficient in chemical elements that are abundant in rocky planets HIP 11915: candidate for solar system twin !
? Solar System
Neptune Earth
Planetary system in HIP 68468 Earth - Super
Neptune Super 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 Baliunas et al.269 ApJ 438, 1995
S index Activity cycle from chromospheric index S 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) 37 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