Using NASA’s Hubble Space Telescope, astronomers have captured for the first time snapshots of fledging white dwarf stars beginning their slow-paced, 40-million-year migration from the crowded center of an ancient star cluster to the less populated suburbs.
White dwarfs are the burned-out relics of stars that rapidly lose mass, cool down and shut off their nuclear furnaces. As these glowing carcasses age and shed weight, their orbits begin to expand outward from the star cluster’s packed downtown. This migration is caused by a gravitational tussle among stars inside the cluster. Globular star clusters sort out stars according to their mass, governed by a gravitational billiard ball game where lower mass stars rob momentum from more massive stars. The result is that heavier stars slow down and sink to the cluster’s core, while lighter stars pick up speed and move across the cluster to the edge. This process is known as “mass segregation.” Until these Hubble observations, astronomers had never definitively seen the dynamical conveyor belt in action.
Astronomers used Hubble to watch the white-dwarf exodus in the globular star cluster 47 Tucanae, a dense swarm of hundreds of thousands of stars in our Milky Way galaxy. The cluster resides 16,700 light-years away in the southern constellation Tucana.
NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission.
As we’ve seen with Ceres, every new image of Pluto taken from now on will be the best image we’ve ever seen of Pluto… and this is true for the above.
NASA’s New Horizons spacecraft was only 75,000,000 km away (46.6 million miles) when this image was taken. Clear in the picture is that the Plutonian surface is complex and variable. It’s going to be exciting to find out what’s going on here…
In early July it’s going to make a much closer flyby of the dwarf planet where all these surface features will be brought out in sharp detail. Almost everything we know about Pluto will come from this flyby.
The brightly glowing plumes seen in this image are reminiscent of an underwater scene, with turquoise-tinted currents and nebulous strands reaching out into the surroundings.
However, this is no ocean. This image actually shows part of the Large Magellanic Cloud (LMC), a small nearby galaxy that orbits our galaxy, the Milky Way, and appears as a blurred blob in our skies. The NASA/ESA Hubble Space Telescope has peeked many times into this galaxy, releasing stunning images of the whirling clouds of gas and sparkling stars (opo9944a, heic1301, potw1408a).
This image shows part of the Tarantula Nebula’s outskirts. This famously beautiful nebula, located within the LMC, is a frequent target for Hubble (heic1206, heic1402).
In most images of the LMC the colour is completely different to that seen here. This is because, in this new image, a different set of filters was used. The customary R filter, which selects the red light, was replaced by a filter letting through the near-infrared light. In traditional images, the hydrogen gas appears pink because it shines most brightly in the red. Here however, other less prominent emission lines dominate in the blue and green filters.
This data is part of the Archival Pure Parallel Project (APPP), a project that gathered together and processed over 1000 images taken using Hubble’s Wide Field Planetary Camera 2, obtained in parallel with other Hubble instruments. Much of the data in the project could be used to study a wide range of astronomical topics, including gravitational lensing and cosmic shear, exploring distant star-forming galaxies, supplementing observations in other wavelength ranges with optical data, and examining star populations from stellar heavyweights all the way down to solar-mass stars.
A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Josh Barrington.
is when a planet or body appears to be moving backwards in the sky for a short
amount of time, as pictured above.
This occurs when the planets “pass” each other, since all orbits are of varying sizes and speeds. Below is a picture to illustrate as much; wherein the Sun is labeled S and rests in the middle of the orbits, T(1-5) represetns the observer’s planet (presumably Earth) and P(1-5) represents the observed planet (ex; Mars). To the right is a blue bar, labeled A(1-5). This represents the celestial sphere, or the backdrop of stars (this is pictured above, where we see Mars moving around and the stars staying still).
you were younger, you probably spent some time in the car on the highway
watching the other cars. When the car we are in gains on one ahead of it, we
know both are moving forward. But as we pass the car, it appears, briefly, as
if it were moving backwards. Like in the image below, we know the tractor trailer isn’t moving backwards; but it appears that, relative to our motion and perspective, it looks like it is.
A similar phenomenon happens with the planets,
since they all orbit at different speeds. We know none of them are literally moving backwards; they are apparently moving backwards. In other words, they just look like they’re reversing direction.
turns retrograde more frequently than any other planet, but the outer planets
are in retrograde motion more often than Mercury. Mercury’s short orbit keeps
it 28 degrees from the Sun, and when it reaches its edge, it appears to change
directions again. Venus and Mars are in retrograde for about 7-10% of the year,
and Jupiter and Pluto are in retrograde for large periods of the year.
Naturally, many of us are born while a planet is in Retrograde.
Large spiral galaxy NGC 4945 is seen edge-on near the center of this cosmic galaxy portrait. In fact, NGC 4945 is almost the size of our own Milky Way Galaxy. Its own dusty disk, young blue star clusters, and pink star forming regions standout in the sharp, colorful telescopic image. About 13 million light-years distant toward the expansive southern constellation Centaurus, NGC 4945 is only about six times farther away than Andromeda, the nearest large spiral galaxy to the Milky Way. Though the galaxy’s central region is largely hidden from view for optical telescopes, X-ray and infrared observations indicate significant high energy emission and star formation in the core of NGC 4945. Its obscured but active nucleus qualifies the gorgeous island universe as a Seyfert galaxy and home to a central supermassive black hole.
Yay for a fellow Finn, amazing Petri Kehusmaa who I know from a Finnish astronomy forum!
Astronomy (exh. 1850). James Sant (British, 1820-1916). Oil on canvas.
A tour de force in James Sant’s oeuvre, Astronomy is a masterful study of colour and contrast. With an almost Italianate chiaroscuro, the sitter is captured deep in thought, her classical beauty reminiscent of a celestial goddess from antiquity.