Image credit & copyright: I created these collages using NASA/ESA Hubble Space Telescope images. Non-annotated version below.
It was January 2, 2002: A new light appears in the constellation Monoceros that until this moment hadn’t even been known to exist. Today, what caused this event is still a mystery but none the less, you are witnessing something fascinating. What looks like a cloud of expanding material from a disturbed star isn’t actually expanding at all; it’s relatively stationary.
Immediately after the event was noticed astronomers eagerly worked to collect data on the new light and almost immediately things such as gamma ray bursts and supernovae were ruled out and it was then determined that what they were looking at was a nova from a previously unseen distant star about 2-3,000 light years away. Later investigation would reveal that this result was not the case and improved data moved the star to roughly 20,000 light years away thus, it was not a white dwarf but a star much larger and brighter than our Sun. That also placed this incredible object into the category of variable star, of which, it was the 838th discovered in the constellation Monoceros. The name V838 Monocerotis was then born.
It wasn’t long before V838 brightened from obscurity to naked eye visibility; only about 1 month. During this time it was 600,000 times brighter than our Sun and it grew to the size of roughly Jupiter’s orbit making it one of the brightest and largest stars in the Milky Way. Soon after this massive brightening it faded away just to have yet another brightening that March, this time in infrared wavelengths. It then dimmed again and wouldn’t you know it; it brightened yet again in infrared in April before finally disappearing as if it had never been there. Well, as far as amateur astronomers are concerned.
What caused this to happen? The answer to that is nobody truly knows. The leading theory is that 2 massive stars actually came into contact and merged to form a single massive star. Reddining and outbursts would almost certainly accompany this process as well.
A second theory is a process known as Common Envelope Events (CEEs). This is when a star robs material from its counterpart and can’t handle it all so the two stars actually then share the material together in a “shared envelope” of material.
A third though unlikely theory is that the star was caught swallowing up its planets.
This shell of material isn’t expanding at all: Here’s the mind blowing aspect to this object. Or should I say, one of the mind-blowing aspects. This material we’re looking at wasn’t expelled by the star and it actually isn’t expanding. The gas and dust seen here is likely leftovers from the formation of the star (s) and an expansion as large as this is nearly impossible to have happen in a decade or even a few thousand years. At these distances you cannot see material movement on timescales such as this. M1 the Crab Nebula has been observed in detail for over 100 years and there hasn’t been much change seen at all and its expanding outward from the star at 3 million miles per hour! This illusion of expansion is actually caused by light. You are watching waves of light move throughout the cloud, as it moves it travels outward from the star creating the illusion of an expanding shell when in fact the shell isn’t a shell but instead a fairly static material cloud. You’re actually watching the speed of light as it travels through the region. That’s something to wrap your head around.
Name: V838 Monocerotis, V838 Mon, Nova Monocerotis 2002, Nova Mon 2002, GSC 04822-00039.
What is it?: Red Variable Star.
How far away is it?: About 20,000 light years.
Discovery Date: January 6, 2002.
Apparent Magnitude: An extremely dim 15+.
Where is it? (General): Constellation Monoceros (The Unicorn).
Where is it? (Exact RA/Dec J2000): RA 07h 04m 04.85s / DEC −03° 50′ 50.1″.