{"id":6303412126,"date":"2022-03-03T02:47:13","date_gmt":"2022-03-03T02:47:13","guid":{"rendered":"https:\/\/www.jimmynewland.com\/wp\/?p=6303412126"},"modified":"2026-01-18T23:29:32","modified_gmt":"2026-01-18T23:29:32","slug":"equivalent-width-activity-for-exes","status":"publish","type":"post","link":"https:\/\/www.jimmynewland.com\/wp\/2022\/03\/03\/equivalent-width-activity-for-exes\/","title":{"rendered":"Equivalent Width Activity for EXES"},"content":{"rendered":"\n

Searching for Europium using Stellar Spectroscopy<\/h2>\n\n\n\n

The complete activity<\/a> is meant to take a full class and maybe even two. <\/h3>\n\n\n\n
\"\"\/
The visible spectrum of the sun. Credit: OpenStax Astronomy. Fraknoi, Morrison, and Wolf<\/a> <\/figcaption><\/figure>\n\n\n\n

We are going to compare the relative amount of the elements nickel and europium in a couple of stars.<\/p>\n\n\n\n

Plotting A Stellar Spectrum<\/h2>\n\n\n\n

Watch the \u201cHOW TO\u201d video: https:\/\/www.youtube.com\/watch?v=XkOUVOJrtrQ<\/a><\/p>\n\n\n\n

    \n
  1. If you haven\u2019t already, copy the data to your Google Drive<\/a> (use your initials in the file name).<\/li>\n\n\n\n
  2. Highlight the 2 columns of data. Most spreadsheets will assume the left column goes on the x-axis and the right column goes on the y-axis. This data is ready to go since column A is the wavelength in Angstroms and column B is the relative flux or amount of starlight. You can think of this as the brightness of a particular wavelength.<\/li>\n\n\n\n
  3. The easiest way to measure with the plot is if the chart type is set to \u2018smooth line\u2019.<\/li>\n\n\n\n
  4. Change the title of the graph to \u201cStar name Spectrum\u201d but use the real star name. \ud83d\ude42<\/li>\n\n\n\n
  5. Change the y-axis title to Relative Flux or something similar.<\/li>\n\n\n\n
  6. Change the limits on the x-axis and y-axis so just the region with the absorption feature is visible.<\/li>\n\n\n\n
  7. Change the tick marks on the x-axis and y-axis so you can easily read off the plot. I used 0.05 on the y-axis with 4 minor marks and 0.1 on the x-axis with 4 minor marks. I also turned on all the various tick marks.<\/li>\n<\/ol>\n\n\n\n

    Determining atomic abundance: Equivalent Width<\/h2>\n\n\n\n
    \"\"<\/a>
    Example plot for determining the equivalent width for absorption feature.<\/figcaption><\/figure>\n\n\n\n

    How to measure equivalent width<\/h2>\n\n\n\n
      \n
    1. First, count how far down from 1on the y-axis the \u201cbell curve\u201d bit goes and write that in a cell labeled Max Abs or something similar. This is the maximum absorption for this feature.
      <\/figure><\/li>\n\n\n\n
    2. Next, in an adjacent cell, hit = to enter a formula and click on the cell where you typed the value for the max absorption and divide that by 2. This is the half-max value.<\/li>\n\n\n\n
    3. We will use the half-max value to count down from 1 on the y-axis to where the curve meets that y-value on both the right and the left. Write down in an empty cell the left wavelength where the curve meets that half-max value and then write down in another empty cell the similar value on the right side of the curve.<\/li>\n\n\n\n
    4. Next, click an empty cell and click = to enter a formula. Be sure to put the difference between the right and left values in parentheses before you multiply by the max absorption.
      <\/figure><\/li>\n\n\n\n
    5. This value represents the equivalent width for this spectral feature. This is a numerical way to describe the relative abundance of a particular atom for a star. (Note: this is not the actual number of a particular atom.)<\/li>\n\n\n\n
    6. Repeat for the other stars!<\/li>\n<\/ol>\n\n\n\n

      Plotting Spectra with Python and Google Colab<\/h2>\n\n\n\n

      You can also try out some Python coding to plot the stellar spectra using Google Colab Notebook. Give it a try<\/a>!<\/p>\n\n\n\n

      \"\"<\/a>
      Google Colab Notebook Python Plot of Eu II Absorption near Ni I<\/figcaption><\/figure>\n\n\n\n

      There is also a helpful version with answers included<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

      Searching for Europium using Stellar Spectroscopy The complete activity is meant to take a full class and maybe even two. We are going to compare the relative amount of the elements nickel and europium in a couple of stars. Plotting A Stellar Spectrum Watch the \u201cHOW TO\u201d video: https:\/\/www.youtube.com\/watch?v=XkOUVOJrtrQ Determining atomic abundance: Equivalent Width How … Continue reading Equivalent Width Activity for EXES<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_crdt_document":"","jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[1],"tags":[],"class_list":["post-6303412126","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p3rYuP-6SAtrw","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.jimmynewland.com\/wp\/wp-json\/wp\/v2\/posts\/6303412126","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.jimmynewland.com\/wp\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.jimmynewland.com\/wp\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.jimmynewland.com\/wp\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.jimmynewland.com\/wp\/wp-json\/wp\/v2\/comments?post=6303412126"}],"version-history":[{"count":8,"href":"https:\/\/www.jimmynewland.com\/wp\/wp-json\/wp\/v2\/posts\/6303412126\/revisions"}],"predecessor-version":[{"id":6303424159,"href":"https:\/\/www.jimmynewland.com\/wp\/wp-json\/wp\/v2\/posts\/6303412126\/revisions\/6303424159"}],"wp:attachment":[{"href":"https:\/\/www.jimmynewland.com\/wp\/wp-json\/wp\/v2\/media?parent=6303412126"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.jimmynewland.com\/wp\/wp-json\/wp\/v2\/categories?post=6303412126"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.jimmynewland.com\/wp\/wp-json\/wp\/v2\/tags?post=6303412126"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}