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Importance of Planet Radius

Importance of planet radius

In order to calculate the volume of the planet, you must know the planet radius. Finding the planet radius is the first step to finding whether or not your exoplanet could support life. Your findings will allow your team to create a strong and compelling request for your exoplanet to be studied by the James Webb Space Telescope.

Planet Mass Planet Radius Planet Period Host Star Data Planet Volume Star Radius & Mass Planet Density Distance From Star Planet Composition In The Habitable Zone? Could This Planet Support Life?

Task 1: Finding Exoplanet Radius Using Light Curve

four different light curves over Quarter 3, Quarter 7, Quarter 11, Quarter 15, versus normalized flux for Kelper 62.
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Lower points on the light curve mean that less of the star’s light is being detected at that time. This could be caused by a planet partially blocking the star’s light. Look at the annotated light curve below to learn about the different parts of a light curve.
Normalized Flux graph. Maximum - The planet is not blocking any of the star's light 0.995 Normalized Flux Ingress - the planet begins to block the star's light Egress - only part of the planet is blocking the star's light 0.99 Minimum - the entire planet is blocking the star's light Normalized Flux: the percentage of the star's light detected by sensors Midtransit - halfway through the period of time when the entire planet is blocking the star's light
Using the minimum and maximum light values from this light curve, we will determine the change in light, or delta-f, which we will use to find the planet radius.
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Now that you have a better understanding of light curves, watch the following video to learn about the equation we will use to find the planet radius.

Remember, this equation is the first step in determining if your exoplanet is rocky or gaseous, and whether it could support liquid water on its surface!

Receive Radius of Host Star
 
red arrow pointing to the radius of the star in the equation for the radius of the planet equals the square root of the change in brightness of the star multiplied by the radius of the star squared.
 
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Look confusing? Don’t worry, you don’t have to do this math by hand! Input your numbers into the google sheet as directed below and the equations will be automatically calculated for you.

Send the following message to request the radius of the star from the Host Star team.
“Radius team to Host Star team. We require the stellar radius from the Host Star team in order to proceed.”
image for instructions for sending messages in the chat feature in Zoom. 1. Copy and paste the message from your task card to the chat. 2. Hit enter to send the message. 3. Unmute yoursself and read the message out loud to ensure that it is received. Make sure the message is being send to 'everyone'

While you wait, did you know...

While you wait, did you know...There are many strange types of exoplanets out there. Some are covered in lava, others in ice. On HD 189733b the clouds are full of glass! What features do you think your exoplanet has?
If you are still waiting for the radius of the star, continue working through the task card and return to this section once you have received the information you need. Once you receive the star radius, send the following message in the chat:
“Radius team to Host Star team. Data received. Thank you.”
Watch the following video for instructions on how to use Google Sheets. Then, input the value for the radius of the star in cell B2 of the Google Sheet below.

The google sheet support

Calculate delta-f from the Light Curve
 
equation to calculate the delta-f from the light curve. Radius of the planet equals the square root of the changle in brightness of the star multiplied by the radius of the star. pointing to the delta-f component.
four different light curves over Quarter 3, Quarter 7, Quarter 11, Quarter 15, versus normalized flux for Kelper 452 b.
image of a scientist
This light curve shows a few different transits of the exoplanet Kepler 62f. To find the radius, we only need to look at one transit.
K62f Light Curve graph. Brightness on the y axis and time in days on the x axies. There is a U shaped dip to the graph. The brightness starts at 1 then dips to .99981 then goes back up to 1 over time.
Based on the light curve above, input the maximum brightness value of Kepler 62 in cell B2 of the Google Sheet below.
Then, input the mid-transit brightness value of Kepler 62 in cell B3 of the Google Sheet below.
The value of delta-f, or the change in brightness, will be calculated automatically in cell B4 in the Google Sheet above.

The radius of the planet, Kepler 62f, will be calculated automatically in units of Earth radii in cell B4 of the Google Sheet below.

what are Earth radii?

Earth Radii is a unit of equal length to the radius of our planet Earth

Image of a flow chart reads Planet Mass Planet Radius Planet Period Star Type Planet Volume Star Mass Planet Density Distance From Star Planet Composition Habitable Zone Could the exoplanet candidate support life?
image of a scientist
Congratulations, you have completed the first step! Think about what the planet radius tells you about your exoplanet. Is it large or small? How does it compare to Earth? Using the planet radius, you can now find the planet volume. The more research you complete the stronger your final request will be!