Beta Piscis Austrini, also named Tiangang, is a star in the southern constellation of Piscis Austrinus that makes part of a binary star system. It is visible to the naked eye with an apparent visual magnitude of +4.29. Based upon an annual parallax shift of 22.84 mas as seen from the Earth, the star is located 143 light years from the Sun. These coordinates are a source of X-ray emission with a luminosity of , which is most likely coming from an external source.
Nomenclature Beta Piscis Austrini is a Bayer designation that is Latinized from β Piscis Austrini, and abbreviated Beta PsA or β PsA.
In Chinese astronomy, Tiān Gāng (, Celestial Rope) is a single-star asterism which represents ropes used to pitch tents. It has been identified with different stars over time, including Beta and Delta Piscis Austrini. AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 6 日 . R. H. Allen's Star Names (1899) described Tien Kang as including Beta, Delta, and Zeta. The IAU Working Group on Star Names approved the name Tiangang for Beta Piscis Austrini on 17 September 2026.
Characteristics Beta Piscis Austrini is a white-hued A-type main sequence star with a stellar classification of A1 V. It has an estimated 2.20 times the mass of the Sun and spins with a rather slow projected rotational velocity of 26 km/s. However, the stellar equator is seen nearly pole-on, yielding an equatorial rotational velocity of . As a result of its fast rotation, it has an oval shape, with the equatorial circumference being longer than the polar circumference, as well as an equatorial temperature cooler than the polar temperature, due to gravity darkening. The star is radiating 26 times the solar luminosity from its photosphere.
The star is moving through the Galaxy at a speed of 14.4 km/s relative to the Sun. Its projected Galactic orbit carries it between and from the center of the Galaxy.
There is evidence for an infrared excess, indicating the presence of an orbiting debris disk. This has an estimated temperature of 188 K, indicating an orbital distance of 12 AU from the host star.
Beta Piscis Austrini has a proper motion companion named CD-32°17127, of apparent magnitude 7.04. It is a G-type main-sequence star of spectral class G1V, with 1.04 times the mass of the Sun, 1.03 times the Sun's radius, a luminosity 1.22 times solar and an effective temperature of . This star is separated from by 1,376 astronomical units.
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