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HD 189733
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Star HD 189733

Binary star HD 189733 is located 64 light years away from the Sun. It consists of a orange star and a red dwarf. There is at least one exoplanet in this system.
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Sun distance
64 light years
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HD 189733 A

Orange star, BY Draconis variable
Spectral class: K2V C

Location +

Ascension iconRight ascension: 20h 0m 43.716s
Declination iconDeclination: 22° 42' 35.068'' (northern hemisphere)
Parallax iconParallax: 50.567
Distance iconSun distance: 64.500 ly | 19.8 pc
Star position
The position of a star tells us where it appears in the sky, similar to how we use coordinates like latitude and longitude on Earth. In astronomy, the three main coordinates are right ascension, declination and distance. .. icon More about Star position in StellarGuide

Basic characteristic

icon weight
Mass: 80.6 % M Sun
| 844 M Jupiter
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Star mass
Mass of the star HD 189733 A is 0.806 solar masses.

The mass of a star is the total amount of matter it contains. It is one of the most important properties of a star, as it determines almost everything about how the star lives, changes, and dies. In astronomy, star mass is usually measured in solar masses (M☉) — where 1 solar mass is equal to the mass of our Sun... icon More about Star mass in StellarGuide
radius icon
Size: 81 % R Sun
| 8 R Jupiter
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Star size
Radius of the star HD 189733 A is 0.805 solar radii.

The size of a star refers to its radius — the distance from its center to its surface. Star size is usually measured in solar radii (R☉), where 1 solar radius equals approximately 696,000 kilometers. Depending on their type and life stage, stars can be much smaller or larger than the Sun... icon More about Star size in StellarGuide
temperature icon
Temperature: 4875 K | 0.84 T Sun
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Star temperature
Surface temperature of HD 189733 A is 4875 K, which is 84 % of the temperature on the surface of the Sun.

The temperature of a star refers to the temperature at its surface, also called the photosphere. It is measured in kelvins (K), the standard unit for temperature in astronomy. A star’s temperature tells us a lot about its physical properties and where it stands in its evolutionary stage... icon More about Star temperature in StellarGuide
time icon
Age: 0.6 billions years | 0.13 Sun
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Star age
Star HD 189733 A is 0.6 billion years old, which is about 0.13 of the Sun's age.

The age of a star tells us how long it has been shining since it formed. Knowing a star’s age helps astronomers understand its life stage, how it has changed over time, and what will happen to it in the future... icon More about Star age in StellarGuide
luminosity icon
Luminosity: 0.328 L Sun
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Star luminosity
Luminosity is the total amount of energy a star gives off every second. Think of it as the star’s true brightness — not just how bright it looks from Earth. This is important because some stars may appear dim simply because they are far away, not because they’re actually faint... icon More about Star luminosity in StellarGuide

Photometry

Magnitude iconApparent magnitude (V): 7.7
Magnitude iconAbsolute magnitude (V): 6.2
Absolute stellar magnitude in different parts of the electromagnetic spectrum from infrared (K band) to ultraviolet (U band).
5
10
15
20
25
30
35
K
2.1
H
1.6
J
1.2
Grp
0.8
I
0.8
G
0.6
V
0.5
Gbp
0.5
B
0.4
U
0.3

HD 189733 B

Red dwarf, High proper motion star
Spectral class: M4V

Location +

Distance iconDistance from the primary: 216 AU

Basic characteristic

icon weight
Mass: 30 % M Sun
| 272.4 M Jupiter
 (estimate)
+
Star mass
The mass of the star HD 189733 B is unknown. Based on its other characteristics, it is estimated to be about 30 % of the Sun's mass.

The mass of a star is the total amount of matter it contains. It is one of the most important properties of a star, as it determines almost everything about how the star lives, changes, and dies. In astronomy, star mass is usually measured in solar masses (M☉) — where 1 solar mass is equal to the mass of our Sun... icon More about Star mass in StellarGuide
radius icon
Size: 30 % R Sun
| 2.9 R Jupiter
(estimate)
+
Star size
Radius of the star HD 189733 B is not known. Its estimated value based on other similar stars is about 30 % solar radii.

The size of a star refers to its radius — the distance from its center to its surface. Star size is usually measured in solar radii (R☉), where 1 solar radius equals approximately 696,000 kilometers. Depending on their type and life stage, stars can be much smaller or larger than the Sun... icon More about Star size in StellarGuide
temperature iconTemperature: 3300 K
 (estimate)
+
Star temperature
Surface temperature of HD 189733 B is estimated to be 3300 K, which is 57 % of the temperature on the surface of the Sun.

The temperature of a star refers to the temperature at its surface, also called the photosphere. It is measured in kelvins (K), the standard unit for temperature in astronomy. A star’s temperature tells us a lot about its physical properties and where it stands in its evolutionary stage... icon More about Star temperature in StellarGuide

Photometry

Magnitude iconAbsolute magnitude (V): -1.5
Absolute stellar magnitude in different parts of the electromagnetic spectrum from infrared (K band) to ultraviolet (U band).
5
10
15
20
25
30
35
K
2.1
H
1.6
J
1.2
Grp
0.8
I
0.8
G
0.6
V
0.5
Gbp
0.5
B
0.4
U
0.3
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HD 189733 system structure

 HD 189733 A
HD 189733 A b 0.03 AU 361.8 M⊕ 12.8 R⊕ 2.2 days
HD 189733 B 216 AU

More about HD 189733

      a BY Draconis variable. Stars from this category exhibit periodic variations in their luminosity. The variability is caused by a rotation which shows and hides starspots on the surface. HD 189733 can be found in northern celestial hemisphere, you cannot see it with naked eye, but you can observe this star with basic telescope. The star is easily observable from Northern America, Europe and Asia. 

      HD 189733 is a BY Draconis variable. Stars from this category exhibit periodic variations in their luminosity. The variability is caused by a rotation which shows and hides starspots on the surface.
Other designations of this star
V452 Vulpeculae, BD+22 3887, Gaia DR2 1827242816201846144, Gliese 4130, GJ 4130, HIP 98505, SAO 88060, LTT 15851, NLTT 48568, Wolf 864, TYC 2141-972-1, 2MASS J20004370+2242391, Gaia DR3 1827242816201846144
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External sources
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simbad icon
Simbad database (UCAC3 226-217434)
Astronomical database SIMBAD (the Set of Identifications, Measurements and Bibliography for Astronomical Data)
gaia icon
Gaia database (Gaia DR3 1827242816176111360)
Archive from the Gaia mission

News from this star system

Radio signal from HD 189733 system observed using NenuFAR telescope
icon1. 8. 2026
Image: Radio signal from HD 189733 system observed using NenuFAR telescope
New analysis of radio data from the HD 189733 system reveals a tentative detection of a circularly polarized radio burst. While potentially planetary in origin, more observations are required to confirm if the signal is truly astrophysical....
Read article tag icon
Three dimensional simulation of photochemical haze formation in the atmosphere of HD 189733b
icon20. 6. 2026
Image: Three dimensional simulation of photochemical haze formation in the atmosphere of HD 189733b
New 3D simulations of HD 189733b reveal how photochemical haze particles behave in exoplanet atmospheres. The study shows these particles peak at 30 nanometers and accumulate along the planet's limbs, significantly impacting thermal structure and light emission....
Read article tag icon
Molecular signatures in a diverse set of transiting exoplanets
icon22. 3. 2026
Image: Molecular signatures in a diverse set of transiting exoplanets
A SPIRou survey of 14 exoplanets confirms water and carbon monoxide in several atmospheres and hints at hydrogen sulfide, showcasing the power of large-scale ground-based analysis....
Read article tag icon

Frequently Asked Questions

How far is the HD 189733 system from the Sun?

The HD 189733 system is 64 light years or 19.8 parsecs from the Sun.

What galaxy is the HD 189733 star in?

The HD 189733 is in the Milky Way galaxy just like the Sun.

How many stars are in the HD 189733 system?

The HD 189733 system contains 2 stars.

What type of star is the HD 189733?

The primary in the HD 189733 system is a Orange star star.

What temperature is star HD 189733?

The primary in the HD 189733 system has a temperature of 4875 K. Find out more about the temperature of stars in Stellar guide
Closest stars

 Gaia DR3 2026640967853712000
 - 3.4 ly

2MASS J2005+1911
 - 4.2 ly

Gaia DR3 2020972985439046016
 - 4.9 ly

Gaia DR3 2020935705110296448
 - 5 ly

Gaia EDR3 1828661426704706048
 - 5.5 ly
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