Holmberg IX V1

Last updated
Holmberg IX V1
HolmbergIXV1Model.png
3D Model of Holmberg IX V1
Observation data
Epoch J2000.0       Equinox J2000.0
Constellation Ursa Major
Right ascension 09h 57m 37.14s
Declination +69° 02′ 11.0″
Apparent magnitude  (V)20.7
Characteristics
A
Evolutionary stage Yellow supergiant
Spectral type G
B
Evolutionary stage Yellow supergiant
Spectral type G
Astrometry
Distance 13 million  ly
Absolute magnitude  (MV)-7.1
Orbit
PrimaryHolmberg IX V1 A
CompanionHolmberg IX V1 B
Period (P)270.7 days
Semi-major axis (a)547 R☉
Eccentricity (e)0
Inclination (i)55.7°
Details
A
Mass 15-20  M☉
Radius 337  R☉
Luminosity 54,450  L☉
Temperature 4,800  K
Metallicity [Fe/H]-0.328  dex
Age 10-15  Myr
B
Mass 15-20  M☉
Radius 306  R☉
Luminosity54,450  L☉
Temperature 5,040  K
Metallicity [Fe/H]-0.328  dex
Age 10-15  Myr
Other designations
EQ J095737+690211
Database references
SIMBAD data

Holmberg IX V1, also known as EQ J095737+690211 is a W Ursae Majoris type eclipsing contact binary star system in the constellation of Ursa Major. [1] [2] The binary system is located in the dwarf galaxy Holmberg IX, roughly 13 million light years (or 4 million parsecs) away. [3] [4] The binary system has a maximum visual magnitude of 20.7, [2] and is one of most extreme and rarest systems discovered. [4]

Contents

Characteristics

Holmberg IX V1 was first discovered by the Large Binocular Telescope (or the LBT) on Mt. Graham, Arizona, between January and October 2007. [2] [4] In the same variability survey, Prieto and his team also found a similar contact binary system designated SMC R47 in the Small Magellanic Cloud. [2]

Physical Properties

The binary system is made up of two yellow supergiant stars referred to as Holmberg IX V1 A and Holmberg IX V1 B. [1] [2] These stars are almost identical in their physical properties such as their luminosity, mass, and age. [2] The binary system is important because it helps us figure out the progenitors of unusual supernovae such as SN 2004et and SN 2006ov. [2]

The two yellow supergiant stars in this system are both estimated to be approximately 15 to 20 times the mass of the Sun, and are predicted to be 10 to 15 million years old. [2] The two stars in this binary system are classified as G-type yellow supergiants, and they both were originally O-type main-sequence stars with initial masses of 30 times more massive than the Sun. [2]

The metallicity of both stars in the binary system is Z = 0.004 (or -0.328 dex), equivalent to roughly 3 times less metal-rich than the Sun. [2]

Due to the two stars in this binary system equal in properties, the two stars likely appear a peanut shape, which is a common way of describing contact binaries like Holmberg IX V1. [4] The binary system is similar to other supergiant contact binary systems such as SMC R47 and BM Cassiopeiae. [2]

The primary star, called Holmberg IX V1 A has a diameter of 337 times larger than the Sun. [2] This was estimated using the Stefan-Boltzmann law, based on a temperature of 4,800 K, and an absolute luminosity of 54,450 times more luminous than the Sun (or -7.1). [2]

The secondary star, termed as Holmberg IX V1 B has a diameter of 306 time larger than the Sun. [2] This was found using the Stefan-Boltzmann law, based on a temperature of 5,040 K, and an absolute luminosity of 54,450 times more luminous than the Sun (or -7.1). [2]

Orbit

The two stars orbit each other every 270.7 days, on an orbit with zero eccentricity. [2] The binary stars also eclipse each other, typical for contact binaries, and classifying it as a W Ursae Majoris variable. [2]

Cepheid Variable Hypothesis

The data from the Large Binocular Telescope for Holmberg IX V1 could also fit a massive long-period Cepheid variable with a variable period of 135 days with a absolute luminosity of 49,659 times more luminous than the Sun (or -7.0). [2] However, the contact binary theory is more likely. [2]

See also

References

  1. 1 2 "SIMBAD Results for Holmberg IX V1". SIMBAD. Retrieved 2026-01-18.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Prieto (2008). "LBT Discovery of a Yellow Supergiant Eclipsing Binary in the Dwarf Galaxy Holmberg IX". NASA ADS. Archived from the original on 2023-11-26. Retrieved 2026-01-18.
  3. ↑ "NED Results for Holmberg IX". NASA/IPAC Extragalactic Database. Retrieved 2026-01-18.
  4. 1 2 3 4 "Holmberg IX Reveals A One Of A Kind Star System - And Then Astronomers Find Another". Science 2.0. Archived from the original on 2022-08-10. Retrieved 2026-01-18.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.