Astronomers studied the famous 1901 nova with the Chandra X-ray Observatory (blue color) in February 2000 and again November 2013 with additional data from Hubble (yellow color), and the Very Large Array (pink). The 13-span provided some interesting data and new questions.
First a little backgound. In 1901 GK Persei suddenly became one of the brightest objects in the sky. It was a classic nova, one where material was collected by a white dwarf star from a companion star builds up to a point when nuclear fusion reactions can occur and the outer layers of the white dwarf are blown away by the explosion. The results of the explosion can be seen for weeks and sometimes years especially if we use world class observatories. Think of these explosions as mini-supernovae. Supernova are responsible for making the heavy elements that make planets, moons and even us. Studying these smaller explosions gives us clues to dynamics of larger one.
The debris from the nova has expanded of a speed around 1,126,510 kmh / 700,000 mph. That means in the 13 years between observations the blast wave moved over 144 billion km / 90 billion miles.
The luminosity of the Persei remnant has decreased by about 40 percent, that’s pretty reasonable but the temperature of the explosion has remained constant at about a million degrees Celsius. The temperature should have dropped, suggesting the blast wave is expanding into a region of lower density.
The optical data show clumps of material ejected in the explosion as expected, there is a point souce in the lower left of the image, the nature of which is unknown.
A more indepth explanation of the image can be found here.
The galaxy pictured here is NGC 4424, located in the constellation of Virgo. It is not visible with the naked eye but has been captured here with the NASA/ESA Hubble Space Telescope.
Although it may not be obvious from this image, NGC 4424 is in fact a spiral galaxy. In this image it is seen more or less edge on, but from above you would be able to see the arms of the galaxy wrapping around its centre to give the characteristic spiral form .
In 2012 astronomers observed a supernova in NGC 4424 — a violent explosion marking the end of a star’s life. During a supernova explosion, a single star can often outshine an entire galaxy. However, the supernova in NGC 4424, dubbed SN 2012cg, cannot be seen here as the image was taken ten years prior to the explosion. Along the central region of the galaxy, clouds of dust block the light from distant stars and create dark patches.
To the left of NGC 4424 there are two bright objects in the frame. The brightest is another, smaller galaxy known as LEDA 213994 and the object closer to NGC 4424 is an anonymous star in our Milky Way.
Hubble sees a happy face created by a beautiful gravitation lens. I saw this at NASA’s Image of the Day yesterday. Oddly enough I was just thinking about faces we precieve like the famous Face on Mars and now there is the face on Ceres. The face on Ceres will be short lived as Dawn will be there shortly, just as well the Ceres face looks scary.
The caption from the NASA Image of the Day site (credit: ESA):
In the center of this image, taken with the NASA/ESA Hubble Space Telescope, is the galaxy cluster SDSS J1038+4849 — and it seems to be smiling.
You can make out its two orange eyes and white button nose. In the case of this “happy face”, the two eyes are very bright galaxies and the misleading smile lines are actually arcs caused by an effect known as strong gravitational lensing. Continue reading →
Periastron observations from NASA’s Rossi X-ray Timing Explorer, the X-Ray Telescope aboard NASA’s Swift, the Hubble Space Telescope’s STIS instrument, were put together produce models and computer simulations to determine how the two stars in the nebula to interact.
NASA’s Hubble Space Telescope has revisited the famous Pillars of Creation, revealing a sharper and wider view of the structures in this visible-light image.
Astronomers combined several Hubble exposures to assemble the wider view. The towering pillars are about 5 light-years tall. The dark, finger-like feature at bottom right may be a smaller version of the giant pillars. The new image was taken with Hubble’s versatile and sharp-eyed Wide Field Camera 3.
The pillars are bathed in the blistering ultraviolet light from a grouping of young, massive stars located off the top of the image. Streamers of gas can be seen bleeding off the pillars as the intense radiation heats and evaporates it into space. Denser regions of the pillars are shadowing material beneath them from the powerful radiation. Stars are being born deep inside the pillars, which are made of cold hydrogen gas laced with dust. The pillars are part of a small region of the Eagle Nebula, a vast star-forming region 6,500 light-years from Earth.
The colors in the image highlight emission from several chemical elements. Oxygen emission is blue, sulfur is orange, and hydrogen and nitrogen are green.
X-rays stream off the sun in this image showing observations from by NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR, overlaid on a picture taken by NASA’s Solar Dynamics Observatory (SDO). This is the first picture of the sun taken by NuSTAR. The field of view covers the west limb of the sun. Continue reading →
Starting the week off is this very nice Hubble image of NGC 4102, one of many objects in Ursa Major. This galaxy is viewable in the Northern Hemisphere with decently dark skies. Considering it is something in the order of 21 mega-parsecs away even a magnitude 11 is pretty good and this Hubble image – wow.
Ursa Major is a large constellation so here is a chart to show the approximate location.
The NASA/ESA Hubble Space Telescope observes some of the most beautiful galaxies in our skies — spirals sparkling with bright stellar nurseries, violent duos ripping gas and stars away from one another as they tangle together, and ethereal irregular galaxies that hang like flocks of birds suspended in the blackness of space.
However, galaxies, like humans, are not all supermodels. This little spiral, known as NGC 4102, has a different kind of appeal, with its tightly-wound spiral arms and understated, but charming, appearance.
NGC 4102 lies in the northern constellation of Ursa Major (The Great Bear). It contains what is known as a LINER, or low-ionization nuclear emission-line region, meaning that its nucleus emits particular types of radiation — specifically, emission from weakly-ionized or neutral atoms of certain elements. Even in this sense, NGC 4102 is not special; around one third of all nearby galaxies are thought to be LINER galaxies.
Many LINER galaxies also contain intense regions of star formation. This is thought to be intrinsically linked to their centers but just why, is still a mystery for astronomers — either the starbursts pour fuel inwards to fuel the LINERs, or this active central region triggers the starbursts. NGC 4102 does indeed contain a starburst region towards its center, where stars are being created at a rate much more furious than in a normal galaxy. This star formation is taking place within a small rotating disk, around 1000 light-years in diameter and with a mass some three billion times the mass of the sun.
This image uses infrared and visible observations taken using Hubble’s Wide Field Planetary Camera 2.
Have a look at this Hubble image of Mars AND comet Siding Spring in the same field of view during the close pass on 19 October. The comet came as close as 140,000 km / 87,000 miles – only a third of our Earth to Moon distance. I am trying to imagine what that would be like.
This composite of NASA Hubble Space Telescope images captures the positions of comet Siding Spring and Mars in a never-before-seen close passage of a comet by the Red Planet, which happened at 2:28 p.m. EDT October 19, 2014. The comet passed by Mars at approximately 87,000 miles (about one-third of the distance between Earth and the Moon). At that time, the comet and Mars were approximately 149 million miles from Earth.
The comet image shown here is a composite of Hubble exposures taken between Oct. 18, 8:06 a.m. EDT to Oct. 19, 11:17 p.m. EDT. Hubble took a separate photograph of Mars at 10:37 p.m. EDT on Oct. 18.
The Mars and comet images have been added together to create a single picture to illustrate the angular separation, or distance, between the comet and Mars at closest approach. The separation is approximately 1.5 arc minutes, or one-twentieth of the angular diameter of the full Moon. The background starfield in this composite image is synthesized from ground-based telescope data provided by the Palomar Digital Sky Survey, which has been reprocessed to approximate Hubble’s resolution. The solid icy comet nucleus is too small to be resolved in the Hubble picture. The comet’s bright coma, a diffuse cloud of dust enshrouding the nucleus, and a dusty tail, are clearly visible.
This is a composite image because a single exposure of the stellar background, comet Siding Spring, and Mars would be problematic. Mars is actually 10,000 times brighter than the comet, and so could not be properly exposed to show detail in the Red Planet. The comet and Mars were also moving with respect to each other and so could not be imaged simultaneously in one exposure without one of the objects being motion blurred. Hubble had to be programmed to track on the comet and Mars separately in two different observations.
The images were taken with Hubble’s Wide Field Camera 3.