Lessons from Early Earth: UV Surface Environment of Earth-Like Planets orbiting close-by M-stars
Lisa Kaltenegger, Carl Sagan Institute at Cornell Lessons from Early Earth: UV Surface Environment of Earth-Like Planets orbiting close-by M-stars
Sarah Rugheimer & Jack O’Malley-James
Lisa Kaltenegger, Carl Sagan Institute at Cornell Astronomers & exoplaneteers use this – it is free: https://arxiv.org/archive/astro-ph Exoplanets : 4000+ Candidates : 5000+
4 Howard et al. 2013 Howard et al ‘12 Incident flux
4000 FEarth
10 FEarth
1 FEarth
Likely rocky < 2 Earth radii
Fig courtesy Zeng 2016, Kaltenegger 2017 CONCEPT “Habitable” Zone = surface water
Teff
Luminosity & distance = Remotely Detectable Life Atm. fingerprint of life COMBINATION: Ozone/Oxygen & Methane
(Water, CO2 climate indicators) Surfaces interesting
7 Kaltenegger et al 2007 Earth(s): Past & present Kaltenegger et al 2007, Rugheimer & Kaltenegger 2018
COMBINATION: Ozone/Oxygen & Methane (VIS&NIR, or IR)
(Water, CO2 climate indicators) – careful “everything” absorbs in the UV Paper Earth transit UV: Betremieux & Kaltenegger 2013
8 Question you ask => wavelength you pick Kaltenegger et al 2007, 2017 Kaltenegger et al 2007 3 % of all stars 80 % of all stars Diameter: 100x 10 x UV: low after initial evolution some show high UV activity for bio of years STELLAR IRRADIATION PROFILE – RED STARS GENERALLY HEAT SURFACE MORE EFFECTIVELY Kasting et al. 1993
Rugheimer, Kaltenegger et al. 2013, 2015, 2017
UV IRRADIATION
O‘Malley-James & Kaltenegger 2019 UV surface radiation environment for Earth through time
Rugheimer, Segura, Kaltenegger & Sasselov 2015 UV SURFACE FLUX
Atmosphere Models: - Modern Earth - Young Earth
Compared to - 1bar Earth - 0.1 bar - Anoxic … Top of atm
Examples shown: Proxima b Ross 128 b
O‘Malley-James & Kaltenegger 2019 Atmosphere Models:
Compared to - 1bar Earth - 0.5 bar - 0.1 bar - Anoxic
Examples shown: Proxima b …Flaring _ Non-flaring
O‘Malley-James & Kaltenegger 2019 Life: additional biosignatures Biofluorescence as UV defense
18 OMalley-James & Kaltenegger MNRAS 2018, 2019
How to detect a large range of life remotely Database for surface reflectivity of life
hosted at Carl Sagan Institute Cornell carlsaganinstitute.org
21 Hegde et al, 2015, Hegde & Kaltenegger 2019 Change of the reflectivity of vegetation through time (to 750 -500 Mio years) O’Malley-James & Kaltenegger 2018
Expand timeline for Surface photosynthesis (to 1 billion years) O’Malley-James & Kaltenegger 2019 Kaltenegger et al 2007 Kaltenegger et al 2009 CATALOG REFERENCE SPECTRA & albedo (disk integrated) for the diversity of Solar System Objects (planets & moons)
Madden & Kaltenegger 2018 4 Mio stars, 200,000 Target stars, 1800 stars: sensitive to 2 Earth radius planets receiving Earth’s irradiation, 600 stars: sensitive to 1 Earth radius planets receiving Earth’s irradiation Kaltenegger et al. 2019 Extremely Large Telescopes (ELTs)27 REFERENCE SPECTRA CATALOG
Madden & Kaltenegger 2018 Stars => what is detectable
Visible
Rugheimer, Kaltenegger et al. 2013, 2015 Stars => what is detectable Depends on the wavelength UV surface radiation for different host stars through time
Rugheimer, Segura, Kaltenegger & Sasselov 2015 Kaltenegger et al. 2007
Contrast 1000 Contrast
] ]
1.01
apparent Radius [R Radius apparent 1.0 1.005 1.0 33 e.g. Kaltenegger et al. 2009, 2010, Rauer et al. 2011, Belu et al 2011, Munoz- Garcia et al. 2012 M0
M9
HST SPECTRA
Rugheimer, Segura, Kaltenegger et al 2015 M9
M0
Rugheimer et al 2015