S Pegasi Star Facts
By : John Whitworth / Updated : Mar 30th, 2026 22:05
Contents
S Pegasi is a variable star located in the constellation of Pegasus, The Winged Horse. S Pegasi colour is red, which means that the star is one of the colder stars in the Universe, colder than our star.
S Pegasi temperature range is between 2,400 to 3,700 Kelvin. S Pegasi effective temperature is 3,298 Kelvin which is cooler than the Sun's effective temperature which is 5,777 Kelvin. A star's size doesn't determine a star's temperature, the majority of the largest and smallest stars in the Universe are red stars. Red stars are also amongst the coolest with only brown dwarf stars cooler. Based on a parallax of 2.52, S Pegasi distance from Earth can be calculated at being 1,294.30 light years away or 324.68 parsecs.
S Pegasi cannot be seen by the naked eye, you will need a telescope to observe it.
S Pegasi is A Omicron Cetivariable star. Variable stars are stars whose size and/or brightness changes over time. S Pegasi brightness ranges from 11.103 (dimmest) to 7.619 over a period of 328.6 days.
Physical Properties
S Pegasi Colour and Spectral Type
S Pegasi spectral type of M5E-M8.5E which means its colour and type is red variable star. There is no relationship between colour and size. For example, a red star can be large or small. Small stars are more energy efficient than larger stars and live longer.
S Pegasi Surface Gravity
The Surface Gravity of S Pegasi as measured in CGS (Centimeter-Gram-Second) is 0.106. The gravity has a relationship to its mass and radius. The larger the mass, the larger the gravity. S Pegasi surface gravity has an uncertainty range of between - and +.
S Pegasi Location
S Pegasi location in sky is determined by the right ascension (R.A.) and declination (Dec.). These are equivalent to the Longitude and Latitude on Earth. The Right Ascension (Longitude) is expressed in time (hh:mm:ss) and is how far the star is along Earth's celestial equator. If the R.A. is positive, then it's eastwards and vice versa.
The Declination (Latitude) is how far north or south the object is compared to the celestial equator and is expressed in degrees. If the value is positive, it is north of the celestial equator. For S Pegasi, the location is 23h 20m 32.63 and +08° 55` 08.3 .
Based on the location of Pegasus, S Pegasi can be located in the northern hemisphere of the celestial sky. The celestial hemisphere is equivalent to the hemispheres on Earth. S Pegasi is north of the Ecliptic. The Ecliptic is the path that the Earth takes as it orbits the Sun. As the Earth is titled, we therefore have Celestial and Ecliptic hemispheres and they can be different for a star.
S Pegasi Magnitude (Apparent / Absolute / Visible)
A number represents a star’s magnitude, whether apparent/visual or absolute. The smaller the number, the brighter the star is. The Sun is the brightest star and therefore has the lowest of all magnitudes, -26.74. A faint star will have a high number.
S Pegasi apparent magnitude is 8.83, which is a measure of the star's brightness as seen from Earth. Apparent Magnitude is also known as Visual Magnitude.
If you use the 1997 parallax value, S Pegasi' absolute magnitude is 1.27. If you use the 2007 parallax value, S Pegasi' absolute magnitude is 0.84. Absolute Magnitude is the star's apparent magnitude from 10 parsecs or 32.6 light years. The magnitude assumes nothing is between the object and the viewer, such as dust clouds. To compare different stars' actual brightness, you would best use Absolute rather than Apparent Magnitude.
S Pegasi cannot be seen from the Earth with the naked eye, it is just too far and too dim to be seen. Only objects with a magnitude of 6.5 or less can be seen on a clear night.
S Pegasi Distance from Earth
S Pegasi distance from Earth is 1058.97 light-years away from Earth or 324.68 parsecs. If you want that in miles, it is about 6,225,287,911,440,247.482, based on 1 Ly = 5,878,625,373,183.61 miles. The distance is calculated using the parallax from the original Hipparcos data released in 1997 which is 3.08000.
In 2007, Hipparcos data was revised with a new parallax of 2.52000, which puts the S Pegasi distance from Earth as 1294.30 light years or 396.83 parsecs. It should not be taken as though the star is moving closer or further away from Earth. It is purely that the distance was recalculated.
An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun. When you use the 2007 distance, S Pegasi is roughly 81,851,492.714 Astronomical Units from the Earth/Sun give or take a few.
How long it will take to get to S Pegasi
The time it takes to travel to S Pegasi depends on how fast you are going. U.G. has done some calculations as to how long it will take to go at differing speeds. A note about the calculations, when I'm talking about years, I'm talking about non-leap years only (365 days).
The New Horizons space probe is the fastest one that we've sent into space at the time of writing. Its primary mission was to visit Pluto, which at the time of launch (2006), Pluto was still a planet.
Mach 1 is the speed of sound; Mach 2 is twice the speed. |Before retiring, Concorde was the fastest commercial aeroplane and the only passenger jet that could do Mach 2.
For some small screens, you may need to swipe the table to see the information. If you need an explanation, hover over the bold text. At methods are assuming you have unlimited fuel and travel at a constant speed.
- Walking - 216,994,775,728.675
- Car - 12,399,701,470.21
- Airbus A380 - 1,179,319,433.308
- Mach 1 - 1,131,257,880.762
- Mach 2 - 641,048,081.916
- New Horizons - 23,845,579.75
- Speed of Light - 1,294.3
Variable Type
S Pegasi is a Omicron Ceti variable type which means that its size changes over time. The Variable Type is usually named after the first star of that type to be discovered. S Pegasi brightness ranges from a magnitude of 11.103 to a magnitude of 7.619 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 328.6000 days.
S Pegasi Radial Velocity and Proper Motion
In simplistic terms, all non-rogue stars, like planets, orbit around a central object, although that is actually not true. Where is the centre of the Solar System. For simplicity it's the central star, such as the Sun. In the case of a star, it's the galactic centre. The constellations we see today will be different than they were 50,000 years ago or 50,000 years from now.
Proper motion details the movements of these stars and is measured in milliarcseconds. S Pegasi is moving -19.83 ± 1.24 milliarcseconds/year towards the north and -19.49 ± 2.26 milliarcseconds/year east if we saw them in the horizon.
The radial velocity, the speed at which the S Pegasi is moving away from the Sun, is 5.00000 km/s with an error of about 4.60 km/s . When the value is negative, the star and the Sun are getting closer to one another; likewise, a positive number means that two stars are moving away. It's nothing to fear as the stars are so far apart they won't collide in our lifetime, if ever.
S Pegasi Facts
Any red fact description is not peer reviewed; it is estimated using other pieces of facts, e.g. temperature if in red is based on the colour of the star.
| Primary Name | S Pegasi |
| Alternative Names | HD 220033, TYC 1162-250-1, HIP 115242, BD+08 5047a, S Peg |
| Spectral Type | M5E-M8.5E |
| Star Type based on Spectral Type | Variable Star |
| Colour | red |
| Galaxy | Milky Way |
| Constellation | Pegasus |
| Main Star | No |
| Absolute Magnitude | if(AbsMag1997.HasValue) { 1.27 } / / 0.84 |
| Visual / Apparent Magnitude | 8.83 |
| Visible From Earth | Requires a 7x50 Binoculars |
| Right Ascension (R.A.) | 23h 20m 32.63 |
| Declination (Dec.) | +08° 55` 08.3 |
| Galactic Latitude | -47.75579913 ° |
| Galactic Longitude | 88.34666665 ° |
| 1997 Distance from Earth | 3.08 Parallax (milliarcseconds) |
| 1058.97 Light Years | |
| 324.68 Parsecs | |
| 2007 Distance from Earth | 2.52 Parallax (milliarcseconds) |
| 1294.3 Light Years | |
| 396.83 Parsecs | |
| 81851492.7139048468 Astronomical Units | |
| Proper Motion Dec. | -19.83 ± 1.24 milliarcseconds/year |
| Proper Motion RA. | -19.49 ± 2.26 milliarcseconds/year |
| B-V Index | 1.29 |
| Radial Velocity | 5 ± 4.6 km/s |
| Effective Temp. (Kelvin) | 3298 |
| Surface Gravity (cgs) | 0.106 |
| Variable Star Class | Pulsating |
| Variable Star Type | Mira Variable |
| Mean Variability Period in Days | 328.6 |
| Variable Magnitude Range | 7.619 - 11.103 |
| Source Date | January 2015 |
| SIMBAD Source | Link |
| Source | Simbad, Vizier, Vizier, Vizier, Vizier, |
