ALPHA CENTAURI / STELLAR DOSSIER

Proxima Centauri

4.25 light-years from Sol

Our nearest stellar neighbor is faint in the sky, but anything but quiet up close.

Stellar view ↗

01
Artist’s impression of Proxima Centauri
M5.5 V · red dwarf

Small star. Powerful outbursts.

Stellar conditions ↗

02
EFFECTIVE TEMPERATURE3,040 K

A cooler kind of star.

Proxima Centauri3,040 K
Sol5,770 K
Shared scale 0–10,000 K · effective, not core temperature

Evolution ↗

03
H–R MAPBRIGHTER ↑
SOLHEREHOTTERCOOLER →
CURRENT PHASE

A very long main sequence.

  1. NOWHydrogen fusion
  2. INTERIORDeep mixing
  3. OUTLOOKTrillions of years
A red dwarf’s long-term outlook, not a countdown. Deep convection supplies fresh hydrogen; this is not the Sun’s giant-stage sequence.

Stellar family

04

Alpha Centauri A ↗

The brighter member of the distant binary pair.

Alpha Centauri B ↗

A cooler sun sharing A’s roughly 80-year orbit.

Photosphere & activity ↗

05
An imagined close view of Proxima’s photosphere and dark active regions. Fine structure and placement are not resolved observations of this star. Red-orange tones are illustrative, with exposure compressed to reveal detail.The quiet between outbursts ↗ ARTIST’S IMPRESSION · 3 VIEWS

Diameter comparison ↗

06
0.145 × Sol

Luminosity ↗

07
≈ 0.00162 × Sol

Total energy emitted · all wavelengths

Estimated from size and temperature · target beam below 1% of Sol
Sources ↗
PROXIMA CENTAURI

Instrument detail

Artist’s impression of Proxima Centauri

Artist’s impression · structure and color are illustrative.

The nearest star hides in plain sight.

Beyond Sol, Proxima is the closest star to us, about 4.25 light-years away. Yet it is too faint to see with the unaided eye. It belongs to the Alpha Centauri system, well apart from the brighter A–B pair. Nearness alone does not make a star conspicuous: Proxima’s small size and cool photosphere produce only a faint glow compared with our Sun.

Cool does not mean calm.

Proxima repeatedly releases energy in stellar flares. Observations across several wavelengths have caught intense, rapid outbursts, revealing a much more restless environment than its dim appearance suggests. Such radiation matters for nearby planets and their atmospheres. A flare tells us about the star’s magnetic activity; by itself it cannot settle whether any particular planet could support life.

Years measured in days.

The worlds featured here orbit remarkably close to their star: Proxima b takes about eleven days, and d about five. Around a dim red dwarf, the region receiving temperate levels of starlight lies much nearer the star than it does around Sol. Being in that region is not evidence of oceans or life. Atmosphere, stellar activity and the planet’s own history still determine what conditions might be possible.

A slow burn on a vast clock.

Very low-mass red dwarfs mix material deeply through their interiors. This brings more of their hydrogen supply into the fusion process, allowing them to shine for extraordinarily long spans. Models predict lifetimes measured in trillions of years, far beyond the present age of the universe. Proxima’s phase graphic therefore shows its long-lived mode of operation rather than borrowing the Sun’s path through a giant stage.

STELLAR PROFILESIZE · TEMPERATURE · EVOLUTION

A star in perspective.

DIAMETER / SOL0.145 ×

About 14.5% of our Sun’s diameter.

Circles compare diameter, not mass or luminosity. Rounded values from ESO’s interferometry study.

EFFECTIVE TEMPERATURE

A cooler kind of star.

  • Proxima Centauri≈ 3,040 K
  • Sol≈ 5,770 K

Shared scale: 0–10,000 K. Effective temperature describes total emitted energy per unit surface area; it is not the core temperature.

LIFE PHASE

A very long main sequence.

  1. NOWHydrogen fusion
  2. INTERIORDeep mixing
  3. OUTLOOKTrillions of years

A red dwarf’s long-term outlook, not a countdown. Deep convection supplies fresh hydrogen; this is not the Sun’s giant-stage sequence.

Research · size and temperature ↗
LIFE & HUMAN SURVIVAL / THE STAR ITSELF
POSSIBILITY FOR LIFEIncompatible with known life

The star’s hot gaseous layers cannot provide the cool, stable environment required by life as we know it. Conditions on any orbiting worlds are a separate question.

WITHOUT PROTECTIONNot survivable

No breathable air or solid ground. Extreme heat and radiation make a close encounter lethal; a meaningful survival timer depends on where you are.

NASA · stellar structure and evolution ↗
10⁵1,000100.10.00110⁻⁵30,00010,0005,0002,500LUMINOSITY / SOL · BRIGHTER →HOTTER ← EFFECTIVE TEMPERATURE (K) → COOLERSUPERGIANTSGIANTSWHITE DWARFSMAIN SEQUENCESOLProxima Centauri
Proxima Centauri3,040 K · ≈ 0.00162 × Sol
Sol / reference5,770 K · 1 × Sol

Estimated from size & temperature. Both axes are logarithmic; equal steps represent equal ratios.

Small points are other worlds in this atlas. The soft band marks the main sequence; region labels are broad guides, not a path through time.

A very long main sequence.

  1. NOWHydrogen fusion
  2. INTERIORDeep mixing
  3. OUTLOOKTrillions of years

A red dwarf’s long-term outlook, not a countdown. Deep convection supplies fresh hydrogen; this is not the Sun’s giant-stage sequence.

Research ↗

Very low-mass red dwarfs mix material deeply through their interiors. This brings more of their hydrogen supply into the fusion process, allowing them to shine for extraordinarily long spans. Models predict lifetimes measured in trillions of years, far beyond the present age of the universe. Proxima’s phase graphic therefore shows its long-lived mode of operation rather than borrowing the Sun’s path through a giant stage.

How much energy leaves the star?

≈ 0.00162 × Sol

This compares total radiant power across all wavelengths, not just visible light or apparent brightness in our sky. The beams on the dashboard share a linear length scale.

The estimate combines this log’s diameter ratio (0.145 × Sol) and effective temperature (3,040 K): luminosity scales with radius squared and temperature to the fourth power. It is derived from rounded values, not an independent luminosity measurement.

Swinburne University · Stefan–Boltzmann law ↗

The nearest star hides in plain sight.

Beyond Sol, Proxima is the closest star to us, about 4.25 light-years away. Yet it is too faint to see with the unaided eye. It belongs to the Alpha Centauri system, well apart from the brighter A–B pair. Nearness alone does not make a star conspicuous: Proxima’s small size and cool photosphere produce only a faint glow compared with our Sun.

Cool does not mean calm.

Proxima repeatedly releases energy in stellar flares. Observations across several wavelengths have caught intense, rapid outbursts, revealing a much more restless environment than its dim appearance suggests. Such radiation matters for nearby planets and their atmospheres. A flare tells us about the star’s magnetic activity; by itself it cannot settle whether any particular planet could support life.

Years measured in days.

The worlds featured here orbit remarkably close to their star: Proxima b takes about eleven days, and d about five. Around a dim red dwarf, the region receiving temperate levels of starlight lies much nearer the star than it does around Sol. Being in that region is not evidence of oceans or life. Atmosphere, stellar activity and the planet’s own history still determine what conditions might be possible.

A slow burn on a vast clock.

Very low-mass red dwarfs mix material deeply through their interiors. This brings more of their hydrogen supply into the fusion process, allowing them to shine for extraordinarily long spans. Models predict lifetimes measured in trillions of years, far beyond the present age of the universe. Proxima’s phase graphic therefore shows its long-lived mode of operation rather than borrowing the Sun’s path through a giant stage.

An imagined close view of Proxima’s photosphere and dark active regions. Fine structure and placement are not resolved observations of this star. Red-orange tones are illustrative, with exposure compressed to reveal detail.

The quiet between outbursts

An imagined close view of Proxima’s photosphere and dark active regions. Fine structure and placement are not resolved observations of this star. Red-orange tones are illustrative, with exposure compressed to reveal detail.

An imagined flare near the stellar limb. Bright footpoints and arcing plasma evoke magnetic activity; this geometry does not reconstruct a specific observed event. Colors and brightness are adjusted for visibility.

A sudden release

An imagined flare near the stellar limb. Bright footpoints and arcing plasma evoke magnetic activity; this geometry does not reconstruct a specific observed event. Colors and brightness are adjusted for visibility.

An artistic view of Proxima Centauri against space. The luminous disk and fine gaseous texture are illustrative; color and exposure are adjusted for visibility, not a resolved stellar photograph.

The star against space

An artistic view of Proxima Centauri against space. The luminous disk and fine gaseous texture are illustrative; color and exposure are adjusted for visibility, not a resolved stellar photograph.

Stellar images are artistic interpretations, not resolved photographs of this star.