At the Core


SagA*quietThere’s a supermassive black hole at the center of our Milky Way galaxy. It’s known as Sagittarius A* and shown in the center of this infrared (red and yellow) and X-ray (blue) composite image. Data from observations taken in orbit by Chandra‘s X-ray telescope was used to create an image the diffuse emission surrounding the black hole. See the close-up inset. The inset’s field of view covers an area about 1/2 light-year across the galactic center some 26,000 light-years away. These X-ray emissions originate in hot gas drawn from the winds of massive young stars near the galactic center. The Chandra data indicate that only 1% or so of the gas within the black hole’s gravitational influence ever reaches the event horizon after losing enough heat and angular momentum to fall into the black hole. The rest of the gas escapes in an outflow. This explains why the Milky Way’s black hole is so quiet, much fainter than might be expected in energetic X-rays.

Note: All data is subject to future verification. Beowulf Shaeffer was unavailable for comment.

Image Credit: NASA

And in Other News from Outer Space …


Astronomers report that the supermassive black hole at the center of the galaxy (known as Sgr A*) is becoming more active. The black hole’s output varies a little across the electromagnetic spectrum on a daily basis, but over the last few years, Sgr A*’s X-ray flares have become more energetic.

Beowulf Shaeffer was unavailable for comment.

Don’t Panic


This animation shows the different components that make up our home galaxy, the Milky Way.  It starts at the black hole at the core of the Milky Way and the stars that orbit around it, before zooming out through the central Galactic Bulge, which hosts about ten billion stars. The zoom continues through a younger population of stars in the stellar disc, the home to most of the Milky Way’s stars. The discs and bulge are embedded in the stellar halo, a spherical structure that consists of a large number of globular clusters. These are the oldest stars in the Galaxy. An even larger halo of invisible dark matter is believed to surround the Milky Way. Its gravitational effect is evident in the motions of stars in the Galaxy.

Finally, this ESA-porduced video shows the extent of the stellar survey conducted by ESA’s Hipparcos mission, which surveyed more than 100,000 stars as far as 300 light-years from the Sun. ESA’s Gaia survey is in the process of cataloging a billion stars up to 30,000 light-years away.

If you’re going hitchhiking, remember to take your towel.

Video Credit: ESA

Zooming in on the Galactic Center


This video sequence zooms from a broad view of the Milky Way into the dusty central region for a much closer look. A 4-million solar mass black hole lurks at the center surrounded by a swarm of rapidly orbiting stars. The animation of the stars’ motion is based on 26 years of data from ESO’s telescopes. One of the stars (S2) passed very close to the black hole in May. The video ends with a simulation of the motions of the stars.

Video Credit: ESO

The Heart of the Galaxy


This image resembles red ink filtering through water or a crackling stream of electricity, but it is actually a view of our cosmic home. It’s the central plane of the Milky Way as seen by ESA’s Planck satellite and the Atacama Pathfinder Experiment (APEX) operated at an altitude of around 5100m in the Chilean Andes by the European Southern Observatory. While APEX is best at viewing small patches of sky in great detail, Planck data is ideal for studying areas of sky at the largest scales. The two data sets complement each other and offer a unique perspective on the sky.

The bright pockets scattered along the galactic plane this view are compact sources of submillimetre radiation: very cold, clumpy, dusty regions that may are being studied for information on multiple questions ranging from how individual stars form to how the entire Universe is structured. From right to left, notable sources include NGC 6334 (the rightmost bright patch), NGC 6357 (just to the left of NGC 6334), the galactic core itself (the central, most extended, and brightest patch in this image), M8 (the bright lane branching from the plane to the bottom left), and M20 (visible to the upper left of M8).

Image Credit: ESA / ESO

Here Comes the Sun


ESA’s Gaia mission is mapping the nearby stars in the galaxy. This video is based on over 600,000 stars mapped so far, but Gaia is on track to measure the parallax distances to over one billion stars during five-year mission. The video zooms from outside the Milky Way into the region mapped by Gaia. A few notable stars are labelled with their common names, and others stars are labelled with numbers from Gaia‘s catalog. Eventually, the point of view approaches our home star Sol (the Sun), then resolves the reflective glow of the Earth.

Video Credit: ESA

The Milky Way


milkywayDust bands and gas clouds stand out against the glowing heart of the Milky Way Galaxy in this composite of views from both the southern sky and the northern sky. The southern data were obtained at ESO’s La Silla Observatory in Chile, and the northern were captured by the Roque de los Muchachos Observatory on La Palma off the northwest coast of Africa in 1984 and 1985. Click the image to embiggen it.

Image Credit: ESO

The Milk Way’s Magnetic Field


The_magnetic_field_along_the_Galactic_plane_node_full_image_2This image looks like it was lifted from something by Van Gogh. The pastel tones and fine texture remind me of the brush strokes on one of the artist’s canvases. In fact, the picture is a visualization of data from ESA’s Planck satellite detailing the interaction between interstellar dust in the Milky Way and the structure of our Galaxy’s magnetic field.

Between 2009 and 2013, Planck scanned the sky to detect the Cosmic Microwave Background, the oldest light in the history of the Universe. It also detected significant foreground emission from diffuse material in our Galaxy which, although a nuisance for cosmological studies, is extremely important for studying the birth of stars and other phenomena in the Milky Way. One of the foreground sources at the wavelengths scanned is cosmic dust, a minor but crucial component of the interstellar medium that pervades the Galaxy. It’s mostly gas, and it is the raw material for stars to form.

These interstellar clouds of gas and dust are shepherded by the Galaxy’s magnetic field. The dust grains tend to align their longest axis at right angles to the direction of the field. As a result, the light emitted by dust grains is partly polarized. It vibrates in a preferred direction. From these and other similar observations, scientists found that filamentary interstellar clouds are preferentially aligned with the direction of the ambient magnetic field, suggesting a strong role played by magnetism in galaxy evolution.

The color scale of the image represents the total intensity of dust emission, revealing the structure of interstellar clouds in the Milky Way. The texture is based on measurements of the direction of the polarised light emitted by the dust, which in turn indicates the orientation of the magnetic field. The arrangement of the magnetic field is more orderly along the Galactic plane, where it follows the Galaxy’s spiral structure. Small clouds are seen just above and below the plane, where the magnetic field structure becomes less regular.

Image Credit: ESA / Planck Collaboration.
Acknowledgment: M.-A. Miville-Deschênes, CNRS – Institut d’Astrophysique Spatiale, Université Paris-XI, Orsay, France

Mergers and Acquistions


This animation depicts the predicted collision between our galaxy (The Milky Way) and our larger neighbor, the Andromeda galaxy. The two are being pulled together by their mutual gravity, and will crash together about 4 billion years from now. Later, around 6 billion years from now, the two galaxies will merge. The video also shows a third galaxy (the Triangulum) which will join in the pill up and may wind up merging with the Andromeda/Milky Way pair.

[youtube http://www.youtube.com/watch?v=fMNlt2FnHDg]

Video Credit: NASA

Don’t Panic


This animation shows the different components that make up our home galaxy, the Milky Way.  It starts at the black hole at the core of the Milky Way and the stars that orbit around it, before zooming out through the central Galactic Bulge, which hosts about ten billion stars. The zoom continues through a younger population of stars in the stellar disc, the home to most of the Milky Way’s stars. The discs and bulge are embedded in the stellar halo, a spherical structure that consists of a large number of globular clusters. These are the oldest stars in the Galaxy. An even larger halo of invisible dark matter is believed to surround the Milky Way. Its gravitational effect is evident in the motions of stars in the Galaxy.

Finally, this ESA-porduced video shows the extent of the stellar survey conducted by ESA’s Hipparcos mission, which surveyed more than 100,000 stars as far as 300 light-years from the Sun. ESA’s Gaia survey aims to study a billion stars up to 30,000 light-years away.

If you’re going hitchhiking, remember to take your towel.

Video Credit: ESA

Internet Astronomy: The Milky Way


milkwayThis 360-degree panorama covers all of the southern and northern celestial hemispheres. The plane of our Milky Way Galaxy, which we see edge-on from Earth, is the luminous band across the image. The projection used in the picture puts the viewer in front of our Galaxy with the Galactic Plane running horizontally through the image. It’s almost as if we were looking at the Milky Way from the outside because the solar system is near the galactic rim. From our vantage point the general components of our spiral galaxy come clearly into view, including its disc as well as the central bulge and nearby satellite galaxies.

Image Credit: ESO / S. Brunier

Our Black Hole


SagA*quietThere’s a supermassive black hole at the center of our Milky Way galaxy. It’s known as Sagittarius A* and shown in the center of this infrared (red and yellow) and X-ray (blue) composite image. Data from observations taken in orbit by Chandra‘s X-ray telescope was used to create an image the diffuse emission surrounding the black hole. See the close-up inset. The inset’s field of view covers an area about 1/2 light-year across the galactic center some 26,000 light-years away. These X-ray emissions originate in hot gas drawn from the winds of massive young stars near the galactic center. The Chandra data indicate that only 1% or so of the gas within the black hole’s gravitational influence ever reaches the event horizon after losing enough heat and angular momentum to fall into the black hole. The rest of the gas escapes in an outflow. This explains why the Milky Way’s black hole is so quiet, much fainter than might be expected in energetic X-rays.

Image Credit: NASA