Image: Composite optical image of Sh2-132 taken with a small amateur telescope. It was created using narrow-band filters that are focused on the emission of ionised oxygen ([O III], blue) and ionised hydrogen (Hα, red). The green channel is a 60/40 combination of the Hα and the [O III], respectively. Image Credit: Marcel Drechsler
Have you ever looked up and wondered what lights a nebula from within? Welcome to FreeAstroScience.com, where we turn complex space science into simple, human stories just for you. Today, we’re visiting Sharpless 2‑132—Sh2‑132 for short—the Lion Nebula. It’s a glowing cloud of gas about 10,400 light‑years away, near the border of Cepheus and Lacerta. Read to the end for a deeper, clearer picture of what makes this nebula so special, and why it matters to all of us. We’re in this together—curious minds, wide skies.
Key Takeaway: Sh2‑132 is an emission nebula in Cepheus, ionized by fierce, massive stars—including two Wolf‑Rayet stars—that sculpt striking gaseous shells.
What makes Sh2‑132—the Lion Nebula—worth your attention?
Sh2‑132 sits on the southern edge of the constellation Cepheus, right on the border with Lacerta. It lies in the Milky Way’s Perseus Arm, within the young, energetic Cepheus OB1 association. That’s a stellar neighborhood full of hot, massive stars—exactly the kind of stars that make nebulae glow and evolve.
To understand its light, start with this: Sh2‑132 is an emission nebula. Gas there glows on its own. Ultraviolet light from hot stars strips electrons from atoms. When electrons recombine, the gas emits visible light—often a deep red from hydrogen. That’s the signature of H‑alpha.
Here’s the headline: two Wolf‑Rayet stars—HD 211564 and HD 211853 (also known as WR 153)—do much of the heavy lifting. Their intense radiation and hurricane‑force winds ionize the gas and push it into arcs and shells. An O8.5V star, plus many B‑type stars, add more ultraviolet power to the mix. Together, they turn a dim gas cloud into a luminous, sculpted Lion.
| Sh2‑132 at a glance | Details |
|---|---|
| Type | Emission nebula (H II region) |
| Other names | LBN 473; “The Lion Nebula” |
| Distance | ≈ 10,400 light‑years |
| Constellation | Cepheus (southern edge, near Lacerta) |
| Galactic context | Perseus Arm; Cepheus OB1 association |
| Ionizing sources | Wolf‑Rayet stars HD 211564 and HD 211853/WR 153; O8.5V and B‑type stars |
| Shell structures | Two radio‑revealed shells, “A” and “B” |
Which stars power its glow, and what do their winds build?
Wolf‑Rayet stars are massive stars in an advanced, short‑lived phase. They blast out ultraviolet light and fast stellar winds. In Sh2‑132, HD 211564 and HD 211853 (WR 153) act like cosmic leaf blowers, sweeping gas into arcs and bubbles. An O8.5V star adds more energy. Many B‑type stars lend support, extending the ionized zone.
- How the gas shines: Hydrogen dominates, so H‑alpha gives that classic red glow. Oxygen and sulfur add teal or gold hues in narrowband images. This light comes from atoms recombining after ionization.
- Where we find it: The nebula lives inside the Perseus Arm, a major star‑forming lane of the Milky Way. Cepheus, the “house‑shaped” northern constellation, frames the scene for backyard imagers.
Now, about those shells. Radio observations reveal two gaseous shells called Shell A and Shell B. Shell A holds a K‑type star near its center. Shell B wraps around an O‑type star and one of the Wolf‑Rayet stars. That geometry makes sense: the strongest winds carve the largest cavities and arcs in the gas.
Key Finding: Sh2‑132’s shells trace the history of stellar winds and radiation, giving us a map of past energy bursts.
Bold facts, gentle guidance
- What you’ll see: To the eye, Sh2‑132 is faint. With a large telescope and dark skies, you may glimpse structure. Cameras do far better.
- Imaging tips: Narrowband filters (Hα, OIII, SII) tease out the nebula’s different gases. Long integrations help you pull out filaments and the shell edges.
- When to try: From the Northern Hemisphere, late summer through autumn works well as Cepheus rides high.
- Expect nuance: Distances and star memberships can carry uncertainties. Astronomers refine them as new data arrives.
Why scientists care
- Feedback lab: Sh2‑132 lets us study “feedback”—how massive stars ionize, heat, and sweep up gas. That feedback can compress nearby clouds and spark new stars. Or it can blow gas away and shut star formation down.
- Cluster evolution: Researchers have explored the star clusters embedded in Sh2‑132, connecting young clusters with more evolved, open clusters. That helps piece together the region’s timeline.
FreeAstroScience Promise: We wrote this for you—clear, kind, and curious. Our goal is to keep your mind awake, because the sleep of reason breeds monsters. Here, we learn to question gently and think boldly, together.
Conclusion
Sh2‑132 is more than a pretty nebula. It’s a living record of power—Wolf‑Rayet winds, ultraviolet light, and expanding shells. We find it in Cepheus, inside the Milky Way’s Perseus Arm, where young, hot stars shape their surroundings. We can stand under the same night and feel a little less alone, knowing the Lion roars for all of us. Come back to FreeAstroScience.com for more science you can trust—and enjoy.
Sources and further reading
- Wikipedia: Emission Nebula — What makes gas clouds shine? https://en.wikipedia.org/wiki/Emission_nebula
- Vasquez et al. (2010). Ionized gas, molecules and dust in Sh2‑132. MNRAS. http://galaxymap.org/cat/view/sharpless/132
- Saurin, Bica, Bonatto (2010). Star clusters in the Sh2‑132 complex. MNRAS. https://ui.adsabs.harvard.edu/abs/2010MNRAS.407..133S/abstract
- Cappa et al. (2010). Radio/IR counterparts of the ring nebula around HD 211564. MNRAS. https://ui.adsabs.harvard.edu/abs/2010MNRAS.407.1105C/abstract
- NASA APOD (June 10, 2024): The Lion Nebula (Sh2‑132). https://apod.nasa.gov/apod/ap240610.html
- Wikipedia: Cepheus (constellation) — context for observers. https://en.wikipedia.org/wiki/Cepheus_(constellation)
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