HD 155448

HD 155448 is a quintuple star system consisting of 5 young B-type stars . With an apparent magnitude of 8.72,^[3] it is too dim to be visible with the naked eye.

Parallax measurements from the Hipparcos spacecraft in 1997 give the system a distance of 1,976 light years with a margin of error larger than the parallax itself.^[2] 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.^[8] Gaia 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.^[9][7] For components A, B, and D, the Gaia EDR3 parallaxes are 0.9566±0.0440 mas,^[5] 0.8401±0.0384 mas,^[6] and 0.7837±0.0263 mas^[7] respectively, implying a distance around 4,000 light years.

Before 2011, this star was mistaken as either a Herbig Ae/Be star^[10] or a post-AGB object.^[11] 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 in Chile concluded that the "B" star is actually a binary star, thus reclassifying it as a quintuple star system.^[4] 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.^[12] However, analysis in 2011 states that the stars are not gravitationally bound to each other.^[4]

All of the stars are currently on the ZAMS. At present the primary star has a mass greater than 7 solar masses and an effective temperature of 25,000 K, while the companions have masses ranging from 3-6 times the mass of the Sun, and temperatures ranging from 10,000-16,000 K.

References