| Named after | Henry Draper |
|---|---|
 Related media on Commons | |
TheHenry Draper Catalogue (HD) is anastronomicalstar catalogue published between 1918 and 1924, givingspectroscopicclassifications for 225,300 stars; it was later expanded by theHenry Draper Extension (HDE), published between 1925 and 1936, which gave classifications for 46,850 more stars, and by theHenry Draper Extension Charts (HDEC), published from 1937 to 1949 in the form of charts, which gave classifications for 86,933 more stars. In all, 359,083 stars were classified as of August 2017.[1][2]
The HD catalogue is named afterHenry Draper, an amateur astronomer, and covers the entire sky almost completely down to an apparentphotographic magnitude of about 9; the extensions added fainter stars in certain areas of the sky.[3] The construction of theHenry Draper Catalogue was part of a pioneering effort to classify stellar spectra, and its catalogue numbers are commonly used as a way of identifying stars.[4][5]
The origin of theHenry Draper Catalogue dates back to the earliest photographic studies of stellar spectra.Henry Draper made the first photograph of a star'sspectrum showing distinctspectral lines when he photographedVega in 1872. He took over a hundred more photographs of stellar spectra before his death in 1882. In 1885,Edward Pickering began to supervise photographic spectroscopy atHarvard College Observatory, using theobjective prism method. In 1886, Draper's widow,Mary Anna Palmer Draper, became interested in Pickering's research and agreed to fund it under the name Henry Draper Memorial.[6][7] Pickering and his coworkers then began to take an objective-prism survey of the sky and to classify the resulting spectra.[8]
| Secchi | Draper | Comment |
|---|---|---|
| I | A, B, C, D | Hydrogen lines dominant. |
| II | E, F, G, H, I, J, K, L | |
| III | M | |
| IV | N | Did not appear in the catalogue. |
| — | O | Wolf–Rayet spectra with bright lines. |
| — | P | Planetary nebulae. |
| — | Q | Other spectra. |
A first result of this work was theDraper Catalogue of Stellar Spectra, published in 1890. This catalogue contained spectroscopic classifications for 10,351 stars, mostly north ofdeclination −25°. Most of the classification was done byWilliamina Fleming.[10] The classification scheme used was to subdivide the previously usedSecchi classes (I to IV) into more specific classes, given letters from A to N. Also, the letter O was used for stars whose spectra consisted mainly of bright lines, the letter P forplanetary nebulae, and the letter Q for spectra not fitting into any of the classes A through P. No star of type N appeared in the catalogue, and the only star of type O was theWolf–Rayet starHR 2583.[9]
Antonia Maury and Pickering published a more detailed study of the spectra of bright stars in the northern hemisphere in 1897.[11] Maury used classifications numbered from I to XXII; groups I to XX corresponded to subdivisions of the Draper Catalogue types B, A, F, G, K, and M, while XXI and XXII corresponded to the Draper Catalogue types N and O.[12] She was the first to place B stars in their current position, prior to A stars, in the spectral classification.[13]
In 1890, the Harvard College Observatory constructed theBoyden Observatory inArequipa,Peru in order to study the sky in theSouthern Hemisphere, and a study of bright stars in the southern hemisphere was published byAnnie Jump Cannon and Pickering in 1901.[14][15] Cannon used the lettered types of theDraper Catalogue of Stellar Spectra, but dropped all letters except O, B, A, F, G, K, and M, used in that order, as well as P for planetary nebulae and Q for some peculiar spectra. She also used types such as B5A for stars halfway between types B and A, F2G for stars one-fifth of the way from F to G, and so forth.[16]
Between 1910 and 1915, new discoveries increased interest in stellar classification, and work on theHenry Draper Catalogue itself started in 1911. From 1912 to 1915, Cannon and her coworkers classified spectra at the rate of approximately 5,000 per month.[17] The catalogue was published in 9 volumes of theAnnals of Harvard College Observatory between 1918 and 1924. It contains rough positions, magnitudes, spectral classifications, and, where possible, cross-references to theDurchmusterung catalogs for 225,300 stars.[18] The classification scheme used was similar to that used in Cannon's 1901 work, except that types such as B, A, B5A, F2G, and so on, had been changed to B0, A0, B5, F2, and so on. As well as the classes O through M, P was used for nebulae and R and N forcarbon stars.[19]
Pickering died on February 3, 1919, leaving 6 volumes to be overseen by Cannon.[20] Cannon found spectral classifications for 46,850 fainter stars in selected regions of the sky in theHenry Draper Extension, published in six parts between 1925 and 1936.[2][21] She continued classifying stars until her death in 1941. Most of these classifications were published in 1949 in theHenry Draper Extension Charts (the first portion of these charts was published in 1937.) These charts also contained some classifications by Margaret Walton Mayall, who supervised the work after Cannon's death.[22][23]
The catalogue and its extensions were the first large-scale attempt to cataloguespectral types of stars,[5] and its construction led to theHarvard classification scheme of stellar spectra which is still used today.[24]
Stars contained in the main portion of the catalogue are of mediummagnitude, down to about 9m (about1/15 as bright as the faintest stars visible with thenaked eye). The extensions contain stars as faint as the 11th magnitude selected from certain regions of the sky.[3][25] Stars in the original catalogue are numbered from 1 to 225300 (prefixHD) and are numbered in order of increasingright ascension for theepoch 1900.0. Stars in the first extension are numbered from 225301 to 272150 (prefixHDE), and stars from the extension charts are numbered from 272151 to 359083 (prefixHDEC). However, as the numbering is continuous throughout the catalog and its extensions, the prefixHD may be used regardless as its use produces no ambiguity.[26] Many stars are customarily identified by their HD numbers.[4]
TheHenry Draper Catalogue and theExtension were available from theNASAAstronomical Data Center as part of their thirdCD-ROM ofastronomical catalogues.[27] Currently, theCatalogue andExtension are available from theVizieR service of theCentre de Données astronomiques (French for "Astronomical Data Center") atStrasbourg as catalogue number III/135A.[28] Because of their format, putting theHenry Draper Extension Charts into a machine-readable format was more difficult, but this task was eventually completed by 1995 by Nesterov, Röser and their coworkers, and the charts are now available atVizieR as catalogue number III/182.[1]
TheHenry Draper Catalogue and its extensions are available on line free of charge at theVizieR service of theCentre de Données astronomiques de Strasbourg:
