Astronomy 3040 Astrobiology Spring_2016 Day-7

Homework -1 Due Monday, Feb. 8 Chapter 2: 1, 3, 16 23, 24, 26 29, 30, , 54, 56 The appendices will be useful

Project aIVPayloadPlannersGuide2007.pdf aIVPayloadPlannersGuide2007.pdf This is the Delta-IV payload guide overview. 20MB. Planetary quarantine program.

March 5, :48:43 CST

5 THE HABITABLE ZONE BY STELLAR TYPES The Habitable Zone (HZ) in green is defined here (and often) as the distance from a star where liquid water is expected to exist on the planets surface (Kasting, Whitmire, and Reynolds 1993). B0 Stellar Radii and Planetary Orbital Semi-Major Axis (A.U.) A0 F0 G0 K0 M0 Stellar Mass (Sun=1) Solar System Habitable Zone

Kepler Mission

How do you Find Exo-Planets? 4 Methods Radial velocity shifts of the parent star Direct Imaging Gravitational Lensing Transits

Radial Velocity

9 PROBING THE RIGHT SEARCH SPACE The first 50 known extrasolar planets are also shown along with the planets in our solar system. The limit for planet detection using Doppler spectroscopy is shown. The range of habitable planets (0.5 to 10 M  ) in the HZ is shown in green.

1 st Direct IR Images

1 st direct Optical Image

A Transit

13 U SING P HOTOMETRY TO D ETECT P LANETS Transits Planet crosses line of sight between observer and star and blocks a small amount of light from the star Transit of Mercury in 2003 Transit of HD observed with HST

14 G EOMETRY FOR T RANSIT P ROBABILITY Not all planetary orbits are aligned along our line of sight to a star Diameter of Sun d* is about 0.01 AU. Diameter of Earth orbit D is 2 AU Random probability of detecting a Sun-Earth analog is about 0.5% So one needs to look at thousands of stars IF all have an Earth

15 P HOTOMETRY CAN D ETECT E ARTH- S IZED P LANETS The relative change in brightness (  L/L) is equal to the relative areas (A planet /A star ) To measure 0.01% must get above the Earth’s atmosphere This is also needed for getting a high duty cycle Method is robust but you must be patient: Require at least 3 transits, preferably 4 with same brightness change, duration and temporal separation (the first two establish a possible period, the third confirms it) Jupiter: 1% area of the Sun (1/100) Earth or Venus 0.01% area of the Sun (1/10,000)

16 Kepler P HOTOMETER – Concept (it’s changed) Bandpass: nm ; Exposures: 15 min (1 min asteroseismology mode) Focal plane and pointing stability are essential. Only 35-pixel “postage-stamps” are read out. Raw pixel data is sent down.

C ONTINUOUSLY V IEWABLE H IGH D ENSITY S TAR F IELD One region of high star field density far (>55°) from the ecliptic plane where the galactic plane is continuously viewable is centered at RA=19 h 45 m Dec=35°. The 55° ecliptic plane avoidance limit is defined by the sunshade size for a large aperture wide field of view telescope in space. 17

FOV

On the Sky

Kepler Fields and Images Image is de-focussed to FWHM ~6” Each of the 42 CCDs (2048x2048) samples 6 square degrees

21 E XTENDED S OLAR N EIGHBORHOOD The stars sampled are similar to the immediate solar neighborhood. Young stellar clusters, ionized HII regions and the neutral hydrogen, HI, distribution define the arms of the Galaxy. The view is from the north galactic pole looking down onto the galactic plane

Neighborhood

Search Space

Kepler Filter vs. BVRIvs. ugriz

Star Formation - Chemistry Todd Boroson/NOAO/AURA/NSF Richard Rand, University of New Mexico

Elemental Abundance

Ages and Chemical Composition Ages come from main-sequence turnoff. Stars are mostly hydrogen and helium. Abundance of heavy elements is 0 – 3%. Heavy elements are made in massive stars. New heavy elements are ejected into space. New stars form with some heavy elements. Abundance of heavy elements records the history of star formation.

Chemical Enrichment

Effect of Metallicity