HD 21749 is an orange main-sequence star in the constellation Reticulum. It has an apparent visual magnitude of 8.143, which means it is too dim to be seen with the naked eye. From parallax measurements by the Gaia spacecraft, it is located 53 ly (16 pc) from Earth.

HD 21749（HIP 16069，2MASS J03265922-6329569）是一颗橙矮星，质量约为太阳的0.68倍，位于距地球53光年（16秒差距）处的网罟座中，在2019年1月7日，该恒星被发现有两个外行星：一个可能是岩质、热、亚海王星体积的外行星，被命名为HD 21749b；以及一个亚地球体积的外行星暂时命名为HD 21749c，这些系外行星是由凌日系外行星巡天卫星（TESS）发现的。

2019年4月15日 · NASA’s Transiting Exoplanet Survey Satellite (TESS) has discovered its first Earth-size world. The planet, HD 21749c, is about 89% Earth’s diameter. It orbits HD 21749, a K-type star with about 70% of the Sun’s mass located 53 light-years away in the southern constellation Reticulum, and is the second planet TESS has identified in the ...

2018年12月31日 · We hereby present HD 21749b (TOI 186.01), a sub-Neptune in a 36-day orbit around a bright (V = 8.1) nearby (16 pc) K4.5 dwarf. TESS measures HD21749b to be 2.61 +0.17−0.16 R⊕, and combined archival and follow-up precision radial velocity data put the mass of the planet at 22.7+2.2−1.9 M⊕.

2020年12月24日 · HD 21749 is a bright (V = 8.1 mag) K dwarf at 16 pc known to host an inner terrestrial planet HD 21749c as well as an outer sub-Neptune HD 21749b, both delivered by Transiting Exoplanet Survey Satellite (TESS).

We hereby present HD 21749b (TOI 186.01), a sub-Neptune in a 36 day orbit around a bright (V = 8.1) nearby (16 pc) K4.5 dwarf. TESS measures HD 21749b to be {2.61}-0.16 +0.17 R ⊕, and combined archival and follow-up precision radial velocity data …

2019年1月7日 · The third — and possibly fourth — planets orbit HD 21749, a K-type star about 80 percent the Sun’s mass and located 53 light-years away in the southern constellation Reticulum. The confirmed planet, HD 21749b, is about three times Earth’s size and 23 times its mass, orbits every 36 days, and has a surface temperature around 300 degrees ...

2019年3月9日 · 新闻中提到的行星被称为HD 21749b，它是由美国宇航局的新TESS (凌日系外行星勘测卫星)任务发现的。 值得注意的是一系列因素。 其中任何一个单独都不是什么大问题，但它们的结合使这个星球变得相当重要。 分解: a. HD 21749b的直径是地球的三倍，质量是地球的23倍，所以它是一个中型行星而不是小型行星。 这种大小的行星并不罕见，但是HD 21749b的大小和推断出的密度正好位于岩石类地球行星和稍大一些的类似海王星的气态行星之间的分界线上。 …

2019年4月19日 · 据悉，这颗行星和另一颗于今年1月份确认的“亚海王星”天体HD 21749b，都环绕着距地球约53光年的恒星HD 21749（质量约为太阳质量的80%）旋转。 科学家目前已经测出，HD 21749b的“体重”和宽度分别为地球的23倍和2.7倍。这表明，它是气态而非岩石行星。

2019年1月7日 · Using the first three months of publicly available data from NASA's TESS mission, scientists have confirmed a new planet known as HD 21749b, a "sub-Neptune" three times bigger and 23 times more...