It lies near the open cluster Stephenson 2, which is located about 5.8 kiloparsecs (19,000 light-years) away from Earth in the Scutum–Centaurus Arm of the Milky Way galaxy, and is assumed to be one of a group of stars at a similar distance, although some studies consider it to be an unrelated or foreground red supergiant.

However, it was not considered to be a member of Stephenson 2 due to its outlying position, abnormally high brightness, and slightly atypical proper motion, instead being categorized as an unrelated red supergiant.

However, Stephenson 2 DFK 1's radial velocity is calculated to be only 89 kilometers per second and therefore leading to the study's statement that the star is a field red supergiant unassociated with the cluster.

[9][2] However certain enigmatic properties, such as the star's significant infrared excess, have led the authors of Davies (2007) to state that it might be an extreme red hypergiant, much like VY Canis Majoris.

It assumes membership of the Stephenson 2 cluster at 5.5 kpc and it is based on 12 and 25 μm flux densities, giving a relatively modest luminosity of 90,000 L☉.

[12][6] An effective temperature of 3,200 K was calculated in a 2012 study by SED integration using the DUSTY model,[10] which would make it much cooler than the coolest red supergiants predicted by stellar evolutionary theory (typically around 3,500 K).

[14] In 2007, Davies et al. estimated Stephenson 2 DFK 1's spectral type at M5 or M6, unusual and very late for even a red supergiant star, based on its CO-bandhead absorption.

[3] A radius of 2,150 R☉ (1.50×109 km; 10.0 au; 930,000,000 mi) was derived from a bolometric luminosity of nearly 440,000 L☉ and an estimated effective temperature of 3,200 K, which is considerably larger than theoretical models of the largest red supergiants predicted by stellar evolutionary theory (around 1,500 R☉).

Stephenson 2 DFK 1 has been estimated to have a mass loss rate of roughly 1.35×10−5 M☉ per year,[10] which is among the highest known for any red supergiant star.

It is possible that Stephenson 2 DFK 1 underwent an extreme mass loss episode recently due to its significant infrared excess.

[5][6] The radius of 2,150 R☉ could possibly be an overestimation due to the method used and the fact that the limit for star size predicted by stellar evolutionary theory is estimated to only be roughly 1,500 R☉.