The Night Sky - Episode 24
MELOTTE 15
This is episode 24 in my series on our night sky
At the very centre of the Heart Nebula lies a small but mighty cluster of stars known as Melotte 15 — a region often called “the Heart of the Heart.” While the surrounding nebula steals the spotlight with its dramatic shape and glowing hydrogen clouds, it’s this tightly packed cluster that quietly powers the entire scene.
Melotte 15 and its surrounding nebulosity
A total of 148 exposures for a total of about 12 hours of data, were shot to complete this image.
Image by Achint Thomas
Melotte 15 is home to several massive, young stars whose intense ultraviolet radiation and stellar winds sculpt the nebula around them. These stars are cosmic architects, carving pillars, compressing gas, and triggering the birth of new stars in a process that has been unfolding for millions of years. What looks like gentle glow in an image is, in reality, a violent and energetic nursery where light, gravity, and gas are locked in a constant dance.
Melotte 15 is a star cluster at the center of the Heart nebula.
Image by Achint Thomas
In long-exposure astrophotography, Melotte 15 reveals a beautiful contrast — brilliant star cores piercing through delicate veils of ionised hydrogen and oxygen. Narrowband imaging, in particular, transforms the region into a tapestry of reds, golds, and blues, revealing invisible details that the human eye could never perceive on its own.
Every time I frame Melotte 15, I’m reminded that this isn’t just a cluster of distant stars — it’s a living system, still shaping its environment, still forging futures in nuclear fire. The Heart Nebula may span light-years, but at its centre, it pulses with energy, chaos, and creation.
The Heart has a heart — and it’s beating.
Check out the image of the Heart nebula I have captured.
Capture details
Camera: ZWO ASI 533MC Pro
Gain: 100
Sensor Temperature: -10°C
Lens: Sigma 100-400mm f/5-6.3 DG OS HSM
Focal length: 400mm (equivalent to 640mm full-frame)
f-Ratio: 6.3
Sub-exposure length: 300 secconds
Number of exposures: 148 (Optolong L-Enhance and Astronomik h-Alpha filters)
Total integration time: ~12 hours
Calibration frames: 30 darks, 30 flats, 30 dark flats
Mount: SkyWatcher Star Adventurer GTi
Guide camera: ZWO 120mm mini
Guide scope: ZWO Mini Guide scope
Capture control: ZWO ASIAir Pro
Dew control: SvBony dew heater
Field Power: AIMTOM 194Wh Portable Power Station
Sky quality: Bortle 5
Moon phase: Various
Processing: PixInsight