INX300_ProjectChoice2_VirtualAstronomy (1)

INX300: Astronomy Seneca College 2023 Choice 2: Exploring the Night Sky with Stellarium Web 20% of the course mark. Due by Dec.1 . In this project you will use the free browser-run version Stellarium Web https://stellarium-web.org/ to virtually “observe” the night sky and the visible planets, to collect and analyze data of stars and stellar clusters. Stellarium Web has the advantage that it does not require download and setting up of multiple options, unlike the full version (also free and available from https://stellarium.org ). Stellarium Web has only a few basic settings, while still correctly representing the night sky for the chosen times and locations. In Part 1 of the project you will view planets visible in the evening sky and summarize their properties. In Part 2 you will explore and analyze properties of stars in one constellation of the season. In Part 3 you will analyze open clusters of stars. You can choose to work in a group of 3 students and do all 3 parts of the project. It is recommended to split the work in a way that you contribute to each part. If you work alone choose either Parts 1 and 2, or Parts 2 and 3. Familiarize yourself with the Stellarium Web options first: Fig.1. The Stellarium Web screen with the viewing options. Course Project - Choice 4 Prof. M. Nenkova 1

INX300: Astronomy Seneca College 2023 Open Stellarium Web ( https://stellarium-web.org ) , set the observing location to Toronto and the time to an evening in March 2023. Set the viewing options for constellations (on), landscape (on), atmosphere (off for better seeing), deep sky objects (on). In View Settings in the upper left corner set Ecliptic Line on. Fast forward the time controls by holding the cursor over the arrows for minutes or hours. Scroll the mouse wheel to zoom in and out and notice how the FOV (field of view) changes. Drag the mouse to look in different horizon directions. Click on various objects (planets, stars, star clusters, galaxies) and read the information panel appearing in the upper left. Center on the object by clicking on this button, then zoom on the centered object. Part 1: Virtual Observations of Planets in Fall 2023 In your report state all planets that are above the horizon for your choice of an evening time and date (in Fall 2023 semester). Write down their Stellarium magnitudes and distances from Earth (in A.U.). Take a screenshot of Stellarium Web (with FOV between about 90 o and 120 o ) that shows the planets, the ecliptic line, the date and time of your virtual observation, and insert it in your report. Jupiter and its Galilean moons.  Set the date and time to see Jupiter above the horizon, and turn off the atmosphere to darken the sky. Center on the planet. Zoom in the field of view to see details on Jupiter and its moons. To observe Jupiter’s rotation click and hold the pointer on the minutes to fast-forward time. Measure and record how much time the Great Red Spot needs to transit (to cross the visible disk of Jupiter) .  Adjust the zoom (the FOV) to observe the orbital motions of the Galilean moons (Io, Europa, Ganymede and Callisto) and take a screenshot to insert in this part of your report. Measure the approximate transit times of each moon (the time it takes to go across Jupiter) as you fast- forward the minutes. Record your results in Table 1.  Explore the 4 Galilean Moons. After recording the transit times record each moon’s radius, as shown in Stellarium Web . Compare to Earth’s Moon radius of 1,737 km by showing the ratio of each Jupiter’s Moon radius to Earth’s Moon’s radius. Ex., if a moon’s radius is 1560 km, you will show the ratio of 0.90 in the table. (Round-off to 2 digits after the decimal point.) Table 1 (adjust the column sizes as needed) Jupiter’s moon Io Europa Ganymede Callisto Time for Transit (hrs:min) Radius (km) Jupiter’s moon radius to Earth’s Moon radius Surface Features seen in Stellarium Web Course Project - Choice 4 Prof. M. Nenkova 2

INX300: Astronomy Seneca College 2023 textbook). Traditionally, the brightest star seen in a constellation is labelled with the Greek letter alpha (  ), the second brightest is beta (  ), and so on. Stars are classified by their temperature and luminosity in the Hertzsprung-Russel diagram (H-R diagram) – an essential diagram in stellar astronomy. You can use this interactive H-R diagram to visualize and compare stars: https://astronomy.nmsu.edu/geas/labs/hrde/hrd_explorer.html The Spectral Type information in Stellarium Web shows the spectral class related to temperature (ex. F5, G3), and the luminosity class (a Roman numeral, sometimes accompanied by a small letter, denoting further details in the stellar spectrum). For example, if you click on the brightest star Sirius (a CMa) you will see its spectral type A1V. The spectral type of Regulus (  Leo) is B8IVn. Luminosity class V is for Main Sequence stars (the main stage of stellar evolution), class IV is intermediate between Main Sequence and Giants, while luminosity classes I to III are for giant and supergiant stars, many of which are in later stages of evolution. What you have to do in Part 2 :  Begin with brief introduction to explain the goal of the exercise and how to achieve it.  Set an evening time in March 2023 and turn off the atmosphere option to darken the sky. Take a screenshot of one constellation that you will use to collect star data and insert it in your report. Recall that constellations are defined areas in the sky (not just a pattern of bright stars).  Collect data from Stellarium Web for about 20 – 30 stars in that constellation and record them in an Excel table, as shown in the example of Table 2. Record the given data for apparent magnitude ( m ), distance ( d in Light Years) and Spectral Type for your selection of stars. Table 2. Sample data for “observed” stars in one constellation (Canis Major in this example) Observed Stars Apparent Magnitude, m Distance d (LY) Spectral Type Sirius (  CMa) -1.09 8.6 A1V Wezen (  CMa) 1.96 1606.72 F8Ia 19 CMa 4.72 96.5 F1.5V … … … … Continue until you fill in the table with data for about 30 stars. Do not include stars without a given distance d (LY). Usually the brightest stars are from classes A and B, but you need to search for stars of Spectral types F, G, K, or M for better representation of star types.  Calculate additional properties in columns appended to the table above – Spectral class code (used for plotting), distance D in units of parsecs (1 pc = 3.26 LY), and absolute magnitude M . The Spectral Class code is a number corresponding to the spectral class, using the following rule: The seven spectral classes O, B, A, F, G, K, M are labelled by numbers from 0 to 70, while each class is divided by subtypes from 0 to 9. This means that spectral class O has codes from 0 to 9; class B Course Project - Choice 4 Prof. M. Nenkova 4

INX300: Astronomy Seneca College 2023 has 10 – 19, class A has 20 – 29; class F has 30 – 39; class G has 40 – 49; class K has 50 – 59; class M has 60 – 69. For example, Sirius’s spectral type A1V will be coded with the number 21. Absolute magnitude M is defined as the apparent magnitude of stars if they were placed at the same distance of 10 pc from Earth. This is a way to compare stars by their intrinsic brightness, or luminosity, which is an important stellar parameter. It is convenient to write the formula for absolute magnitude in Excel and fill in the table column by copying the formulas. From the given apparent magnitude m and distance in parsecs D , calculate the absolute magnitude M using the equation: M = m – 5*log D + 5. See the example in Table 3 with calculated properties for each of the observed stars in the sample. Table 3 Calculated properties of the sample stars in Table 2. Observed Stars Apparent Magnitude, m Distance d (LY) Spectral Type Distance D (pc) Spectral Class Code Absolute Magnitude, M Sirius (  CMa) -1.09 8.6 A1V 2.64 21 1.80 Wezen (  CMa) 1.96 1606.72 F8Ia 492.86 38 -6.50 19 CMa 4.72 96.5 F1.5V 29.6 31.5 2.36 …. … … … … … …  Plot the diagram of Spectral Class Code (on the x-axis) vs. Absolute Magnitude M (on the y-axis) for the stars in your sample. This is a form of the Hertzsprung-Russell (H-R) diagram – the most essential diagram in stellar astronomy. Use a scatter plot format and plot the y-axis values in reverse order (because the magnitude numbers increase in inverse relation to brightness). Set the range of values on the x and y axes to avoid large empty areas in the plot. In your report include the data table and the plotted diagram with labelled axes.  Discuss your findings in a concluding paragraph and compare to the expected H-R diagram: consider the types of stars represented in the diagram, whether they are Main Sequence or Red Giants, whether they are bright and massive (upper Main Sequence) or not, what their properties are. Part 3: Analysis of an Open Star Cluster Select one open star cluster from the following list and find it with the search function in Stellarium Web . Each cluster has different labels in different catalogues (M is for the Messier catalogue, NGC for the New General Catalogue): M35 (or NGC 2168), M38 (or NGC 1912), M41 (The Little Beehive, NGC 2287), M44 (The Beehive Cluster, NGC 2632), M45 (The Pleiades), M67 (The Pac-Man cluster, NGC 2682), NGC 457 (The Owl). Course Project - Choice 4 Prof. M. Nenkova 5