Hubble Image: Galaxy IC559 in constellation of Leo

Credit: ESA/Hubble, NASA, D. Calzetti (UMass) and the LEGUS Team

Far beyond the stars in the constellation of Leo (The Lion) is irregular galaxy IC 559.

IC 559 is not your everyday galaxy. With its irregular shape and bright blue spattering of stars, it is a fascinating galactic anomaly.

It may look like sparse cloud, but it is in fact full of gas and dust which is spawning new stars.

Discovered in 1893, IC 559 lacks the symmetrical spiral appearance of some of its galactic peers and not does not conform to a regular shape.

It is actually classified as a Megallanic spiral or "type Sm" galaxy, an irregular galaxy with some evidence of a spiral structure.

Irregular galaxies make up about a quarter of all known galaxies and do not fall into any of the regular classes of the Hubble sequence.

Most of these uniquely shaped galaxies were not always so, IC 559 may have once been a conventional spiral galaxy that was then distorted and twisted by the gravity of a nearby cosmic companion.

This image, captured by the NASA/ESA Hubble Space Telescope's Wide Field Camera 3 (WFC3), combines a wide range of wavelengths spanning the ultraviolet, optical, and infrared parts of the spectrum.

Hubble Image: Spiral galaxies engaged in a cosmic tug-of-war

Credit: ESA/Hubble & NASA, Acknowledgement: Luca Limatola

From objects as small as Newton's apple to those as large as a galaxy, no physical body is free from the stern bonds of gravity, as evidenced in this stunning picture captured by the Wide Field Camera 3 and Advanced Camera for Surveys onboard the NASA/ESA Hubble Space Telescope.

Here we see two spiral galaxies engaged in a cosmic tug-of-war but in this contest, there will be no winner.

The structures of both objects are slowly distorted to resemble new forms, and in some cases, merge together to form new, super galaxies.

This particular fate is similar to that of the Milky Way Galaxy, when it will ultimately merge with our closest galactic partner, the Andromeda Galaxy.

There is no need to panic however, as this process takes several hundreds of millions of years.

Not all interacting galaxies result in mergers though. The merger is dependent on the mass of each galaxy, as well as the relative velocities of each body.

It is quite possible that the event pictured here, romantically named 2MASX J06094582-2140234, will avoid a merger event altogether, and will merely distort the arms of each spiral without colliding—the cosmic equivalent of a hair ruffling!

These galactic interactions also trigger new regions of star formation in the galaxies involved, causing them to be extremely luminous in the infrared part of the spectrum.

For this reason, these types of galaxies are referred to as Luminous Infrared Galaxies (LIRGs).

This image was taken as part of as part of a Hubble survey of the central regions of LIRGs in the local Universe, which also used the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) instrument.

Hubble extends stellar tape measure 10 times farther into space

By applying a technique called spatial scanning to an age-old method for gauging distances called astronomical parallax, scientists now can use NASA’s Hubble Space Telescope to make precision distance measurements 10 times farther into our galaxy than previously possible. 

Credit: NASA /ESA, A.Feild /STScI

Using NASA’s Hubble Space Telescope, astronomers now can precisely measure the distance of stars up to 10,000 light-years away—10 times farther than previously possible.

Astronomers have developed yet another novel way to use the 24-year-old space telescope by employing a technique called spatial scanning, which dramatically improves Hubble's accuracy for making angular measurements.

The technique, when applied to the age-old method for gauging distances called astronomical parallax, extends Hubble's tape measure 10 times farther into space.

"This new capability is expected to yield new insight into the nature of dark energy, a mysterious component of space that is pushing the universe apart at an ever-faster rate," said Noble laureate Adam Riess of the Space Telescope Science Institute (STScI) in Baltimore, Md.

Parallax, a trigonometric technique, is the most reliable method for making astronomical distance measurements, and a practice long employed by land surveyors here on Earth.

The diameter of Earth's orbit is the base of a triangle and the star is the apex where the triangle's sides meet.

The lengths of the sides are calculated by accurately measuring the three angles of the resulting triangle.

Astronomical Parallax works reliably well for stars within a few hundred light-years of Earth.

For example, measurements of the distance to Alpha Centauri, the star system closest to our sun, vary only by one arc second.

This variance in distance is equal to the apparent width of a dime seen from two miles away.

This illustration shows how the precision stellar distance measurements from NASA’s Hubble Space Telescope have been extended 10 times farther into our Milky Way galaxy than possible previously. 

This greatly extends the volume of space accessible to refining the cosmic yardstick needed for measuring the size of the universe. 

This most solid type of measurement is based on trigonometric Parallax, which is commonly used by surveyors. 

Because the stars are vastly farther away than a surveyor's sightline, Hubble must measure extremely small angles on the sky. 

Credit: NASA, ESA, and A. Feild (STScI)

Stars farther out have much smaller angles of apparent back-and-forth motion that are extremely difficult to measure.

Astronomers have pushed to extend the parallax yardstick ever deeper into our galaxy by measuring smaller angles more accurately.

This new long-range precision was proven when scientists successfully used Hubble to measure the distance of a special class of bright stars called Cepheid variables, approximately 7,500 light-years away in the northern constellation Auriga.

The technique worked so well, they are now using Hubble to measure the distances of other far-flung Cepheids.

Such measurements will be used to provide firmer footing for the so-called cosmic "distance ladder."

This ladder's "bottom rung" is built on measurements to Cepheid variables stars that, because of their known brightness, have been used for more than a century to gauge the size of the observable universe.

They are the first step in calibrating far more distant extra-galactic milepost markers such as Type Ia supernovae.

Riess and the Johns Hopkins University in Baltimore, Md., in collaboration with Stefano Casertano of STScI, developed a technique to use Hubble to make measurements as small as five-billionths of a degree.

To make a distance measurement, two exposures of the target Cepheid star were taken six months apart, when Earth was on opposite sides of the sun.

A very subtle shift in the star's position was measured to an accuracy of 1/1,000 the width of a single image pixel in Hubble's Wide Field Camera 3, which has 16.8 megapixels total.

A third exposure was taken after another six months to allow for the team to subtract the effects of the subtle space motion of stars, with additional exposures used to remove other sources of error.

ESO Image: Spiral galaxy ESO 137-001 spills blood and guts - Video

Credit: NASA, ESA

This new Hubble image shows spiral galaxy ESO 137-001, framed against a bright background as it moves through the heart of galaxy cluster Abell 3627.

This cluster is violently ripping the spiral's entrails out into space, leaving bright blue streaks as telltale clues to this cosmic crime.

This new Hubble image shows ESO 137-001, a galaxy located in the southern constellation of Triangulum Australe (The Southern Triangle)—a delicate and beautiful spiral galaxy, but with a secret.

This image not only captures the galaxy and its backdrop in stunning detail, but also something more dramatic—intense blue streaks streaming outwards from the galaxy, seen shining brightly in ultraviolet light.

These streaks are actually hot young stars, encased in wispy streams of gas that are being torn away from the galaxy by its surroundings as it moves through space.

This violent galactic disrobing is due to a process known as ram pressure stripping—a drag force felt by an object moving through a fluid.

The fluid in question here is superheated gas, which lurks at the centres of galaxy clusters.

This image also shows other telltale signs of this process, such as the curved appearance of the disc of gas and dust—a result of the forces exerted by the heated gas.

The cluster's drag may be strong enough to bend ESO 137-001, but in this cosmic tug-of-war the galaxy's gravitational pull is strong enough to hold on to the majority of its dust—although some brown streaks of dust displaced by the stripping are visible.

This video pans across the sky near to spiral galaxy ESO 137-001 in the constellation of Triangulum Australe (The Southern Triangle), ending on a view of the galaxy itself. 

This delicate and beautiful spiral galaxy is undergoing ram pressure stripping, where streaks of bright gas are being dragged out into space by the cluster it is moving through. 

Credit: NASA, ESA

Studying ram pressure stripping helps astronomers to better understand the mechanisms that drive the evolution of galaxies.

For example, it will leave this galaxy with very little of the cold gas that is essential for star formation, rendering the galaxy effectively incapable of forming new stars.

ESO 137-001 is part of the Norma Cluster, a cluster of galaxies near the centre of the Great Attractor, a region of space that earned its name by being so massive, and having a gravitational pull so strong, that it is pulling entire galaxy clusters towards it.

This region is located around 200 million light-years from our galaxy, the Milky Way. Both our galaxy and its home group, the Local Group, are slowly being hauled towards this mysterious region.

Hubble also imaged ESO 137-001's neighbour, ESO 137-002, which is also known to have a hot tail of gas extending outwards into space.

Despite being relatively close by cosmic standards, catching even a glimpse of the Norma Cluster is no mean feat.

Hubble's Wide Field Camera 3 (WFC3)

Observed from Earth, the cluster lies close to the plane of the Milky Way and is obscured by a thick smog of cosmic dust but Hubble is up to the challenge, using new data from Hubble's Wide Field Camera 3 (WFC3).

As with most images from Hubble, this is not just a pretty picture; it tells us a great deal about the harsh environment at the heart of a galaxy cluster, and the fate of galaxies like ESO 137-001 that find passage through it.