Astro Bob: See meteors from Halley's Comet and a bright supernova in Virgo
The annual Eta Aquariid meteor shower happens this week. Have a scope? You might be able to spot an exploding star.
DULUTH — Are you game for a meteor shower just before dawn? If you've never seen the Eta Aquariids this is an ideal year to give it a whirl. The moon, famous for spoiling the show, will be a crescent and safely tucked out of view in the evening sky. That leaves the predawn sky ideal for watching our favorite, fiery streaks.
The recent Lyrid meteor display originates from a lesser known comet named C/1861 G1 (Thatcher), but the Eta Aquariid (EH-tuh uh-KWAR-ee-id) shower has the most famous parent of all — Halley's Comet. Each time it passes near the sun, solar heating boils dust and debris from Halley's nucleus. The material then settles and spreads along its orbit like a path of breadcrumbs dropped to mark a trail. Twice a year, the Earth plows through that material, and we experience a meteor shower.
This week we pass through Halley's outbound orbit, with meteors radiating from a point in the sky near Eta Aquarii, hence the shower's name. Come late October, Earth zips through the inbound leg, giving us the Orionid meteor shower. While most of us will only see Halley's Comet just once in our lifetime, its progeny flash across the early morning sky twice a year.
Because Aquarius climbs much higher in the sky viewed from the Southern Hemisphere, observers there will see a stronger display. In fact, from a dark sky, 50-60 meteors per hour will be visible, making this one of the best showers of the year in that hemisphere. The radiant hovers considerably lower in the southeastern sky for us in the north, so numbers will be lower — from 10 to 30 per hour.
Face south or east, relax in a lounge chair and look up from as dark a sky as you can find. Outside of getting up at the odd hour, meteor-watching takes little effort. Meteor experts predict the shower will reach maximum around 3 a.m. CDT on Friday, May 6, but numbers should also be good a day earlier on May 5 since the peak is broad. My forecast looks good, and I plan to be out watching. Good luck and clear skies!
I normally like to stick to things you can view with the naked eye or binoculars in my posts, but there's a particularly bright supernova currently visible in the galaxy NGC 4647 in Virgo you simply must know about. To see it you only need a 6-inch telescope and a dark sky or an 8-inch under more light-polluted conditions.
Japanese observer Koichi Itagaki discovered the exploding star on April 16 when it was still faint, but it's since risen to magnitude 12.5. That's bright for a supernova located 63 million light-years away! NGC 4647 is paired with the much brighter galaxy M60, both situated just 4.5° west-northwest of the 3rd magnitude, naked-eye star Vindemiatrix in northern Virgo.
I observed it on May 3 and couldn't believe how bright the star — dubbed SN 2022hrs — appeared in relation to its host galaxy. Truly an amazing thing to see and ponder. Can you imagine how impressive the sight would be from a planet orbiting a star within the galaxy? No doubt it would cast shadows.
We often hear that a supernova occurs when a star at least eight times as massive as the sun runs out of nuclear fuel and implodes. This creates a shock wave that rebounds throughout the star and blows it apart. Not this one. Before the explosion, the star was an Earth-sized, super-dense white dwarf closely orbiting a companion sun.
The dwarf funneled gas from its partner until the weight of the overlying material compressed and heated the dwarf's core to such a high temperature that it underwent runaway nuclear fusion . The reaction released so much energy it blasted the star to bits. That's what you're seeing in your telescope. Of course, given the distance, the cataclysm shrinks down to a simple point of light. But for a short time that single point shines nearly as bright as the entire galaxy.
"Astro" Bob King is a freelance writer for the Duluth News Tribune.