This star was first identified as entry 1618 in the work A Catalog of Circumpolar StarsbyStephen Groombridge published posthumously in 1838.[13] It has such a proper motion across the sky that it guaranteed the star was quite nearby and made it an early candidate for parallax measurements. In 1884 the parallax angle was measured as 0″.322 ± 0″.023, which is larger than the modern value of 0″.205.[14]
A search for excess infrared emission from this star by the Infrared Space Observatory came up negative, implying that Groombridge 1618 does not possess
a nearby debris disk (such as Vega does).[16] However, observations using the Herschel Space Observatory showed a small excess suggesting a low-temperature debris disk. The data can be modeled by a ring of coarse, highly-reflective dust at a temperature below 22 K orbiting at least 51 AU from the host star.[8] If this star does have a companion, astrometric measurements appear to place an upper bound of 3–12 times the mass of Jupiter on such a hypothetical object (for orbital periods in the range of 5–50 years).[17]
Observations collated by Marcy & Benitz (1989),[18] tend towards a single notable object with periodicity of 122 days as a planetary object with minimum mass 4 times that of Jupiter. This candidate planet was never confirmed and the signal the authors had found could have been due to intrinsic stellar activity from the star's young age.
If confirmed, the planet would be within the star's habitable zone.[note 1]
An examination of this system in 2010 using the MMT telescope fitted with adaptive optics failed to detect a planetary companion.[19]
The habitable zone for this star, defined where liquid water could be present on an Earth-like planet, is at a radius of 0.26–0.56 AU, where 1 AU is the average distance from the Earth to the Sun.[20]
The star is among five nearby K-type stars of a type in a 'sweet spot’ between Sun-analog stars and M stars for the likelihood of evolved life, per analysis of Giada Arney from NASA’s Goddard Space Flight Center.[21]
^ ab[9] when used to calculate the stellar flux reaching the outer atmosphere of an Earth-like planet orbiting Groombridge 1618 at the Inner Habitable Zone edge - the Runaway Greenhouse limit gives a of 0.9397 or 93.97% the stellar flux reaching the top of Earth's atmosphere. By applying the previously calculated stellar flux and the known 15% luminosity of Groombridge 1618 into the equation, ,[9] the distance of the Inner HZ - Runaway Greenhouse limit from Groombridge 1618 can be calculated as .
^ abGudel, M. (October 1992), "Radio and X-ray emission from main-sequence K stars", Astronomy and Astrophysics, 264 (2): L31–L34, Bibcode:1992A&A...264L..31G.
^ abAndrillat, Y.; Morguleff, N. (1967), Hack, Margherita (ed.), "Three potassium-flare stars", Proceedings of the Colloquium, held in Trieste, June 13–17, 1966, Trieste, p. 160, Bibcode:1967lts..conf..160A.
^Dyson, F. W.; Thackeray, W. G.; Christie, W. H. M. (1905). "New reduction of Groombridge's catalogue of circumpolar stars". Proceedings of the Royal Society of Edinburgh. Bibcode:1905Gmb...C......0D.
^Ball, Robert S. (1884). "On the Annual Parallax of Groombridge 1618". Dunsink Observatory Publications. 5 (2): 187–217. Bibcode:1884DunOP...5..187B.
^Byrne, P. B.; Doyle, J. G. (November 1990), "Activity in late-type stars. VII - Chromospheric and transition region line fluxes in 2 dM and 1 dM(e) stars", Astronomy and Astrophysics, 238 (1–2): 221–226, Bibcode:1990A&A...238..221B.
^Hershey, J. L.; Borgman, E. R. (1978). "Upper Limits on the Mass of a Dark Companion of Groombridge 1618 from the 40-year Sproul Plate Series". Bulletin of the American Astronomical Society. 10: 630. Bibcode:1978BAAS...10..630H.
^Marcy, Geoffrey W.; Benitz, Karsten J. (1989). "A search for substellar companions to low-mass stars". Astrophysical Journal, Part 1. 344 (1): 441–453. Bibcode:1989ApJ...344..441M. doi:10.1086/167812.
^
Bill Steigerwald (2019-03-07). ""Goldilocks" Stars May Be "Just Right" for Finding Habitable Worlds". NASA. Retrieved 2020-05-12. 'I find that certain nearby K stars like 61 Cyg A/B, Epsilon Indi, Groombridge 1618, and HD 156026 may be particularly good targets for future biosignature searches,' said Arney.
10h11m22.1400s, +49° 27′ 15.2492″
[9] when used to calculate the stellar flux reaching the outer atmosphere of an Earth-like planet orbiting Groombridge 1618 at the Inner Habitable Zone edge - the Runaway Greenhouse limit gives a 
of 0.9397 or 93.97% the stellar flux reaching the top of Earth's atmosphere. By applying the previously calculated stellar flux and the known 15% luminosity of Groombridge 1618 into the equation, 
,[9] the distance of the Inner HZ - Runaway Greenhouse limit from Groombridge 1618 can be calculated as 
.
