31:Tf2c,chart = { // Declare the chart dimensions and margins. const width = 928; const height = Math.round(width * 1.2) const marginTop = 40; const marginRight = 40; const marginBottom = 40; const marginLeft = 40; // Ceate the scales. const x = d3.scaleLinear([-0.39, 2.19], [marginLeft, width - marginRight]); const y = d3.scaleLinear([-7, 19], [marginTop, height - marginBottom]); const z = bv2rgb; // Create the SVG container. const svg = d3.create("svg") .attr("width", width + 28) .attr("height", height) .attr("viewBox", [-14, 0, width + 28, height]) .attr("style", "max-width: calc(100% + 28px); height: auto;") .style("margin", "0 -14px") .style("background", "#000") .style("color", "#fff") .style("display", "block") .attr("fill", "currentColor") .attr("font-family", "sans-serif") .attr("font-size", 10); // Create a small (sub pixel) rectangle for each star. svg.append("g") .selectAll("rect") .data(data) .join("rect") .attr("x", d => x(d.color)) .attr("y", d => y(d.absolute_magnitude)) .attr("fill", d => z(d.color)) .attr("width", 0.75) .attr("height", 0.75); // Create the axes. svg.append("g") .attr("transform", `translate(${marginLeft},0)`) .call(d3.axisLeft(d3.scaleLog(y.domain().map(m => Math.pow(10, 4.83 - m)), y.range()))); svg.append("g") .attr("transform", `translate(${width - marginRight},0)`) .call(d3.axisRight(y).ticks(null, "+")); svg.append("g") .attr("transform", `translate(0,${height - marginBottom})`) .call(d3.axisBottom(x).ticks(null, "+f")); svg.append("g") .attr("transform", `translate(0,${marginTop})`) .call(((temperatures) => d3.axisTop(x) .tickValues(temperatures.map(color)) .tickFormat((_, i) => temperatures[i].toLocaleString("en"))) (d3.range(3000, 10001, 1000).concat(20000))); svg.selectAll(".domain").remove(); svg.append("text") .attr("dy", 12) .attr("text-anchor", "middle") .attr("transform", `translate(${marginLeft},${(marginTop + height - marginBottom) / 2}) rotate(-90)`) .call(text => text.append("tspan").attr("fill-opacity", 0.8).text("← darker\xa0")) .call(text => text.append("tspan").attr("font-weight", "bold").text("\xa0Luminosity L☉\xa0")) .call(text => text.append("tspan").attr("fill-opacity", 0.8).text("\xa0brighter →")); svg.append("text") .attr("dy", -6) .attr("text-anchor", "middle") .attr("transform", `translate(${width - marginRight},${(marginTop + height - marginBottom) / 2}) rotate(-90)`) .call(text => text.append("tspan").attr("fill-opacity", 0.8).text("← darker\xa0")) .call(text => text.append("tspan").attr("font-weight", "bold").text("\xa0Absolute magnitude M\xa0")) .call(text => text.append("tspan").attr("fill-opacity", 0.8).text("\xa0brighter →")); svg.append("text") .attr("x", (marginLeft + width - marginRight) / 2) .attr("y", marginTop) .attr("dy", 12) .attr("text-anchor", "middle") .call(text => text.append("tspan").attr("fill-opacity", 0.8).text("← hotter\xa0")) .call(text => text.append("tspan").attr("font-weight", "bold").text("\xa0Temperature K\xa0")) .call(text => text.append("tspan").attr("fill-opacity", 0.8).text("\xa0colder →")); svg.append("text") .attr("x", (marginLeft + width - marginRight) / 2) .attr("y", height - marginBottom) .attr("dy", -6) .attr("text-anchor", "middle") .call(text => text.append("tspan").attr("fill-opacity", 0.8).text("← blue\xa0")) .call(text => text.append("tspan").attr("font-weight", "bold").text("\xa0Color B-V\xa0")) .call(text => text.append("tspan").attr("fill-opacity", 0.8).text("\xa0red →")); return svg.node(); }32:[{"id":"a01b08636a1314e9dc329d141684564156cb49190d762542f3b8d09a20f7c3275fe0be93d2ed6f9056af7b27708ed91037b729cf12263e63c0eb98abd43702fc","href":"https://static.observableusercontent.com/files/a01b08636a1314e9dc329d141684564156cb49190d762542f3b8d09a20f7c3275fe0be93d2ed6f9056af7b27708ed91037b729cf12263e63c0eb98abd43702fc","name":"catalog.csv","type":"text/csv","lastModified":1574897154074.379,"size":665977}] 2f:{"title":"Hertzsprung–Russell diagram","cells":[{"id":0,"value":"

Hertzsprung–Russell diagram

D3 › Gallery

\n\n# Hertzsprung–Russell diagram\n\nAn [HR diagram](https://en.wikipedia.org/wiki/Hertzsprung–Russell_diagram) plots the relationship between stars’ absolute magnitudes (brighter going up) and temperatures (warmer going left). For the large set of stars below, it effectively shows how [stars age over time](https://en.wikipedia.org/wiki/Stellar_evolution). Data: [Hipparcos](http://cdsarc.u-strasbg.fr/viz-bin/cat/I/311), [Gliese](http://cdsarc.u-strasbg.fr/viz-bin/cat/V/70A)","pinned":false,"hidden":false,"mode":"md"},{"id":73,"value":"$31","pinned":true,"hidden":false,"mode":"ojs"},{"id":443,"value":"data = FileAttachment(\"catalog.csv\").csv({typed: true})","pinned":true,"hidden":false,"mode":"ojs"},{"id":521,"value":"md`See [this helper notebook](/d/e697f4807166cbd9) for the source data.`","pinned":false,"hidden":false,"mode":"ojs"},{"id":365,"value":"function bv2rgb(bv) {\n bv = Math.max(-0.4, Math.min(2, bv));\n let t;\n return `#${[\n bv < 0 ? (t = (bv + 0.4) / 0.4, 0.61 + (0.11 * t) + (0.1 * t * t))\n : bv < 0.4 ? (t = bv / 0.4, 0.83 + (0.17 * t))\n : 1,\n bv < 0 ? (t = (bv + 0.4) / 0.4, 0.70 + (0.07 * t) + (0.1 * t * t))\n : bv < 0.4 ? (t = bv / 0.4, 0.87 + (0.11 * t))\n : bv < 1.6 ? (t = (bv - 0.4) / 1.20, 0.98 - (0.16 * t))\n : (t = (bv - 1.6) / 0.4, 0.82 - (0.5 * t * t)), \n bv < 0.4 ? 1\n : bv < 1.5 ? (t = (bv - 0.4) / 1.1, 1 - (0.47 * t) + (0.1 * t * t))\n : bv < 1.94 ? (t = (bv - 1.5) / 0.44, 0.63 - (0.6 * t * t))\n : 0\n ].map(t => Math.round(t * 255).toString(16).padStart(2, \"0\")).join(\"\")}`;\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":84,"value":"function temperature(color) {\n return 4600 * (1 / (0.92 * color + 1.7) + 1 / (0.92 * color + 0.62));\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":583,"value":"function color(temperature) {\n const u = 8464 / temperature;\n return (u - 2.1344 + Math.hypot(0.9936, u)) / 1.6928;\n}","pinned":true,"hidden":false,"mode":"ojs"}],"files":"$W32","stdlib":"1","titling":"auto"}