HD 155448 is a quintuple star system consisting of 5 young B-type stars . With an

apparent magnitude Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...

of 8.72, it is too dim to be visible with the naked eye.

Parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different sightline, lines of sight and is measured by the angle or half-angle of inclination between those two lines. Due to perspective (graphica ...

measurements from the

Hipparcos ''Hipparcos'' was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions and distances of ...

spacecraft in 1997 give the system a distance of 1,976

light years A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astro ...

with a margin of error larger than the parallax itself. The ''New Hipparcos Reduction'' gives a distance of 6,272 light years, but still with a statistical margin of error larger than the parallax value.

Gaia In Greek mythology, Gaia (; , a poetic form of ('), meaning 'land' or 'earth'),, , . also spelled Gaea (), is the personification of Earth. Gaia is the ancestral mother—sometimes parthenogenic—of all life. She is the mother of Uranus (S ...

parallaxes are available for the visible components. For component C, the Gaia Data Release 2 and Gaia Early Data Release 3 (EDR3) parallaxes are both negative and somewhat meaningless. For components A, B, and D, the Gaia EDR3 parallaxes are , , and respectively, implying a distance around 4,000 light years. Before 2011, this star was mistaken as either a

Herbig Ae/Be star A Herbig Ae/Be star (HAeBe) is a pre-main-sequence star – a young () star of spectral types A or B. These stars are still embedded in gas-dust envelopes and are sometimes accompanied by circumstellar disks. Hydrogen and calcium emission lines ...

or a

post-AGB A post-AGB star (pAGB, abbreviation of post-asymptotic giant branch) is a type of luminous supergiant star of intermediate mass in a very late phase of stellar evolution. The post-AGB stage occurs after the asymptotic giant branch (AGB or second-as ...

object. When the system was studied in 2011, it was originally believed to contain only 4 stars (or at least more than 2 stars). In 2011, a study conducted at the

European Southern Observatory The European Organisation for Astronomical Research in the Southern Hemisphere, commonly referred to as the European Southern Observatory (ESO), is an intergovernmental organization, intergovernmental research organisation made up of 16 m ...

in Chile concluded that the "B" star is actually a

binary star A binary star or binary star system is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved as separate stars us ...

, thus reclassifying it as a quintuple star system. HD 155448 A, B, C, and D. Periods have been estimated at 27,000 years for Bab, 59,000 years for AB, 111,000 years for Ac, and 327,000 years for AD. However, analysis in 2011 states that the stars are not gravitationally bound to each other. All of the stars are currently on the ZAMS. At present the primary star has a mass greater than 7

solar masses The solar mass () is a frequently used unit of mass in astronomy, equal to approximately . It is approximately equal to the mass of the Sun. It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies ...

and an

effective temperature The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature ...

of 25,000 K, while the companions have masses ranging from 3-6 times the

mass of the Sun The solar mass () is a frequently used unit of mass in astronomy, equal to approximately . It is approximately equal to the mass of the Sun. It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies a ...

, and temperatures ranging from 10,000-16,000 K.

References

{{Scorpius B-type main-sequence stars Scorpius 155448 Be stars 084228 Durchmusterung objects 5