Bodu (帛度)
Bó Dù (帛度, “Textile Ruler”) is a Chinese asterism consisting of two stars, established by the Wuxian (巫咸) tradition during the Han dynasty. Together with Tusi (屠肆), the Butcher Shop, it formed a double-asterism within the Chinese super-constellation of Tianshi (天市), the Celestial Market Place. Since 2025, "Bodu" is also the IAU-star name of 95 Her, a white subgiant in the constellation of Hercules.
Etymology and History
The term bo (帛) refers broadly to silk fabrics, while du (度) denotes either units or instruments of length measurement. Thus, Bodu could be interpreted as a tool used for measuring textiles, or by extension, as a shop engaged in the sale of such goods. The Han dynasty (202 BCE - 220 CE) classic Liji (礼记, Book of Rites) contains strict specifications for commodities, including textiles. It states: “Cloth and silk that are either too fine or too coarse to meet the standard, or whose widths are not properly measured, shall not be permitted in the market.” According to Han regulations, government-issued cloth was required to be “2 chi and 2 cun in width” (1 chi is about 23.1-24.3 cm in Han, 1 cun is 0.1 chi). The establishment of this asterism may have been informed by such institutional frameworks regulating textile production and trade.
Astrologers later generalized the meaning of Bodu to represent all measurement, commercial standardization, and market regulation. Since textile trade was primarily associated with women, some traditions even employed this asterism to divine matters related to women’s purchases in the marketplace.
Identification of stars
Some star charts depict Bodu as oriented east–west, while others depict it in a north–south arrangement. It is located near the Tusi (屠肆) (Butcher’s Shop) asterism, and several charts depict the two together as forming a connected rectangular shape. Given their small size and the low precision of ancient mapping techniques, slight variations in their relative positions are frequent. Interestingly, while the position of Tusi often varies across ancient catalogues, Bodu remains remarkably stable—aside from a few erroneous identifications of the coordinate in Huangyou Star Catalogue (皇祐星表) by modern scholars, the coordinates in various catalogues points to 95 Her and 102 Her. For visual representations of Bodu, see the entry Tusi (屠肆).
| Star Names or Orders(Traditional/Qing) | Yi Shitong[1]
Based on catalogue in 18th century |
Pan Nai[2]
based on Huangyou Star Catalogue |
Pan Nai[3]
based on catalogues in Yuan dynasty |
SUN X. & J. Kistemaker[4]
Han Dynasty |
Boshun Yang[5]
before Tang dynasty |
Boshun Yang[5]
Song Jingyou(1034) |
Boshun Yang[5]
Song Huangyou(1052) |
|---|---|---|---|---|---|---|---|
| 1st/Determinative | 95 Her | 96 Her | 96 Her | 96 Her | 102 Her | 95 Her | 95 Her |
| 2nd | 102 Her | 101 Her | 101 Her | 101 Her | 95 Her | 102 Her | 102 Her |
Maps (Gallery) source
| historical map | modern identification
(Yang 2023) |
same in Stellarium 25.1 |
|---|---|---|
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Star Name Discussion (IAU)
In 2025, the name of the historical constellation "Bodu" was suggested to be used for one of the stars in this constellation. In June 2025, WGSN chose to adopt the name Bodu for the star 95 Herculis, following the Yi Shitong catalog because earlier identifications are highly uncertain.
The Star
In the Bright Star Catalog (Hoffleit & Jaschek 1991), 95 Her refers to a binary of two bright stars: 95 Her A (HR 6730, HD 164669; Vmag=4.96) and 95 Her B (HR 6729, HD 164668; Vmag=5.18). The pair appear together in the Hipparcos catalog with designation HIP 88267, and in the Washington Double Star catalog as STF 2264 (WDS J18015+2136), with the separation recently measured to be 6.3 arcseconds. Gray & Garrison (1987) reported spectral types for the 95 Her A and B components of A2IV and G5III, respectively. The vivid color contrast of the pair was noted in the 19th century, with William Henry Smyth reporting A to be "greenish" and B to be "cherry red" (1833) and then later in his life as "pale green" and "reddish", meanwhile his contemporary Benedict Sestini reported both to be "gold yellow".
95 Her A is is somewhat brighter in the V-band, but 95 Her B is brighter in the infrared and actually has a higher bolometric luminosity and mass (it is the slightly more massive, and evolved of the two stars). Using Gaia astrometry Kervella et al. (2022) estimated the pair to be separated by 6.37", corresponding to 840 astronomical units, and their tangential velocities agree within 1.23+-0.05 km/s. No orbit for the pair has been published yet, which is unsurprising, as since the first report of the binary by William Herschel in 1780 (the year before he discovered Uranus), the separation has barely changed, and the position angle has only changed by about 9 degrees. Jim Kaler estimates the orbital period to be at least 11,000 years.
Following IAU WGSN policy, names are adopted for individual stars, and when the star turns out to be multiple, the name defaults to that of the primary star (usually the brighter of the two in the V band, where measured). The WGSN may later adopt other cultural/historical names for companions.
In this case, the name Bodu has been adopted by IAU WGSN specifically for the brighter (in the visible) of the pair: 95 Her A (HR 6730, HD 164669, HIP 88267 A), a hot white subgiant of 2.8 solar masses at a distance of 432 light years.
References
- ↑ Yi Shitong伊世同. Zhongxi Duizhao Hengxing Tubiao中西对照恒星图表1950. Beijing: Science Press.1981: 32.
- ↑ Pan Nai潘鼐. Zhongguo Hengxing Guance shi中国恒星观测史[M]. Shanghai: Xuelin Pree. 2009. p305.
- ↑ Pan Nai潘鼐. Zhongguo Hengxing Guance shi中国恒星观测史[M]. Shanghai: Xuelin Pree. 2009. p438.
- ↑ Sun Xiaochun. & Kistemaker J. The Chinese sky during the Han. Leiden: Brill. 1997, Pp241-6.
- ↑ 5.0 5.1 5.2 B.-S. Yang杨伯顺, Zhongguo Chuantong Hengxing Guance Jingdu ji Xingguan Yanbian Yanjiu 中国传统恒星观测精度及星官演变研究 (A Research on the Accuracy of Chinese Traditional Star Observation and the Evolution of Constellations), PhD thesis, (Hefei: University of Science and Technology of China, 2023). 248.
