Sheet1Common nameHIP numberparallax in arcsecondsVisual (apparent) magnitude4390.22938.5612420.191911.4914750.28038.0915990.11644.2320210.13382.8237650.13405.7438210.16803.4648560.12289.9853360.13245.1754960.12299.856430.269112.177510.12285.7679810.13395.24Tau Ceti81020.27423.49121140.13875.79127810.132410.55155100.16504.26165370.31083.72173780.11063.52198490.19824.43209680.120711.42210880.181410.82224490.12463.19233110.11356.22234520.11748.31Kapteyn's_star241860.25538.86255780.115012.48258780.17577.97268570.172811.56270720.11153.59279130.11544.39292950.17328.15309200.242911.12Sirius323490.3792-1.44329840.11496.58332260.18139.89334990.124610.81346030.157211.65Luyten's star362080.26339.84Procyon 372790.28590.4377660.168611.19389560.122512.02453430.16167.64471030.111410.91499080.20526.6499860.12809.26513170.13839.65530200.177511.64537670.151010.03540350.39247.49542110.20698.82565280.11079.81575440.185510.8575480.299611.12578020.11699.76605590.112511.28613170.11954.24618740.130512.24624520.121811.39649240.11734.74658590.13119.05671550.18418.46Proxima Centauri708900.772311.01712530.163511.32alpha2 Centauri716810.74211.35alpha Centauri 716830.7421-0.01725090.221812.07725110.235211.72726590.14934.54731820.13368.01731840.16935.72749950.159510.57760740.16859.31769010.121911.83800180.118010.56803460.124310.27804590.151910.13808240.234510.1828090.154011.73828170.17429.02839450.137811.77841400.15829.31844050.16714.33844780.16766.33847090.14355.91847200.11385.47852950.12957.54855230.22049.38856050.202711.39861620.22099.15862140.198310.94862870.12309.62869610.161810.49869630.161811.39869740.11913.42869900.172110.75Barnard's_star879370.54909.54885740.12839.37886010.19664.03899370.12413.55912620.12890.03917680.28038.94917720.28459.7934490.121811.57938990.112810.76947610.17039.12961000.17344.67Altair976490.19440.76992400.16373.55994610.16525.32997010.16127.97998250.11335.731011800.125610.541030390.182211.411030960.14208.551042140.28715.21042170.28546.051050900.25346.691061060.148310.331062550.124811.961087060.111611.991088700.27584.691093880.114010.41Kruger 601108930.24959.591118020.11579.061124600.198110.291130200.212710.161132290.116010.421132830.13096.481132960.14538.68Fomalhaut1133680.13011.171135760.12287.881140460.30397.351146220.15325.571161320.160110.051174730.16758.981200050.15957.7

Experiment E.1The Hertzsprung-Russell DiagramThe HR diagram was originally constructed using data from the nearest stars. This is because it is necessary to know the distances of the stars in order to calculate their absolute magnitudes. The distances of nearby stars can be found using trigonometric parallax.The spreadsheet contains data on 137 of the 150 stars closest to us (apart from the sun.) It gives the Hipparcos catalogue number (from the Hipparcos space mission), the parallax angle and the apparent magnitude for each star. (A few have been omitted because the Hipparcos catalogue does not list data needed for this work or they lie far outside the main sequence and will distort the scales.)Step 1. Use the parallax angles given to calculate the distance to each star in parsecs. (Distance in parsecs is the inverse of the parallax angle in arcseconds.)Step 2. Use the distance and apparent magnitude to calculate the absolute magnitude for each star. (Use the formula M = m 5 log (d/10), where d is in parsecs.The HR diagram also uses the temperature or colour of the stars. In practical astronomy, this is done by observing the star through different filters. In particular, two filters are used in the visible region. The V filter lets a range of visible light through, centred around green in the visible spectrum. The B filter passes light in the blue region of the spectrum. Star catalogues such as the Hipparcos catalogue list B-V values. Bluer, hotter stars have a lower B-V value and redder, cooler stars have a higher value.Step 3. Access the catalogue of the Hipparcos mission to find the B-V value for each star. This chore can be shared among the members of the class.You can access this catalogue in two ways:a) Via Cambridge University.Go to http://archive.ast.cam.ac.uk/hipp/hipparcos.html Enter the Hipparcos catalogue number from the spreadsheet under Target nameSelect Hipparcos identifier in the Use of name window.Make sure the B-V box is ticked.Call up the selected star and find the B-V value near the bottom of the list.b) Via the European Space AgencyGo to http://www.rssd.esa.int/index.php?project=HIPPARCOS&page=hipsearch Enter the Hipparcos catalogue number in the Hipparcos Identifier window.Call up the selected star and find the B-V value near the bottom of the list.Now use the data to produce an HR diagram for nearby stars. Remember that the vertical scale (absolute magnitude) has lower numbers at the top. i.e. opposite to the usual arrangement (You can reverse the direction once you have constructed a graph. You will need values from 5 to 20.) The B-V, horizontal scale should have values from 0 to 2.

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