Person: Leavitt, Henrietta Swan
Henrietta Leavitt was an American astronomer who discovered the relation between the luminosity and the period of Cepheid variables. This was a vital step in measuring the distance to remote galaxies.
Mathematical Profile (Excerpt):
- George Roswell Leavitt was a Congregationalist minister, born in Lowell, Massachusetts, who had studied at Williams College before being awarded a doctorate in divinity from the Andover Theological Seminary.
- Also living with them is Mary Kendrick, Henrietta's aunt, and a 25 year old servant Catherine McDonald.
- The course that Leavitt took at the Society for the Collegiate Instruction of Women was very arts based and contained little science.
- Delighted to have Leavitt's assistance without having to pay her, he set her the task of studying photographic plates from which she had to record the required data.
- However, it was known that many stars changed in brightness so one of Leavitt's tasks was to look out for such variable stars.
- In September 1896 Leavitt applied for a passport to travel abroad.
- The application was to allow her to go abroad and return "in about two years." The application gives a physical description of Leavitt: Age - 28, Stature - 5 ft 8 ins, Forehead - High, Eyes - Gray, Nose - Long, Mouth - Medium, Chin - Long, Hair - Black, Complexion - Light, Face - Long.
- On her return, Leavitt went to Harvard to discuss her work with Pickering.
- Aiming to take up her position by the end of July, Leavitt set out for Cambridge but, stopping to visit a relative in Ohio, she discovered the relative was ill and so she spent time helping out.
- It was these plates that Leavitt was working on, measuring magnitudes and position of stars.
- In 1908 Leavitt published a full account of her work in the 21-page paper 1777 Variables in the Magellanic Clouds.
- This allowed Leavitt to make the vitally important observation that the periods of the variables was related to their absolute magnitudes.
- Leavitt needed to continue to work on making further measurements.
- By December 1908 Leavitt was in hospital in Boston.
- Leavitt did not refer to these variable stars as Cepheid variables, but they are known today by that name after the first such star discovered in 1784 by John Goodricke.
- Leavitt's discovery allowed the scale of the universe to be determined, although more work was required since the relation that she discovered only allowed relative distances to be determined while other techniques were required to determine the distance to at least one such variable star to calibrate the scale.
- Leavitt was not given the chance to participate in this as Pickering used her skills on other projects.
- For the next four years Leavitt worked at the Harvard Observatory, except for a break of three months in the first half of 1913 when she had surgery to her stomach.
- Harlow Shapley was working on the size of the Milky Way galaxy and he contacted Pickering in August 1917 with questions for Leavitt concerning variables in globular clusters.
- Only after writing again in July 1918 did Shapley receive a response from Pickering saying that Leavitt had plates to investigate his question.
- In March 1921 Shapley became Director of the Harvard Observatory and by this time Leavitt was Head of Stellar Photometry.
- Leavitt died at 10.30 p.m. on 12 December, and her funeral was held at the Chapel of the 1st Congregational Church on 14 December.
- In 1925 Gösta Mittag-Leffler wrote to Leavitt at the Harvard Observatory, not being aware that she had died.
- The letter was given to Shapely who informed Mittag-Leffler of Leavitt's death.
- However, his reply does him no credit for it is clear that he was trying to take much of the credit for Leavitt's discovery, probably in the hope that Mittag-Leffler would nominate him for a Nobel prize!
Born 4 July 1868, Lancaster, Worcester County, Massachusetts, USA. Died 12 December 1921, Cambridge, Middlesex, Massachusetts, USA.
View full biography at MacTutor
Tags relevant for this person:
Astronomy, Origin Usa, Women
Thank you to the contributors under CC BY-SA 4.0! 
- Github:
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- non-Github:
- @J-J-O'Connor
- @E-F-Robertson
References
Adapted from other CC BY-SA 4.0 Sources:
- O’Connor, John J; Robertson, Edmund F: MacTutor History of Mathematics Archive
