European Association for Astronomy Education

Source: ESO Photo Release eso1504

Image cVISTA views the Trifid Nebula and reveals hidden variable stars.
Image credit: ESO/VVV consortium/D. Minniti

A new image taken with ESO’s VISTA survey telescope reveals the famous Trifid Nebula in a new and ghostly light. By observing in infrared light, astronomers can see right through the dust-filled central parts of the Milky Way and spot many previously hidden objects. In just this tiny part of one of the VISTA surveys, astronomers have discovered two unknown and very distant Cepheid variable stars that lie almost directly behind the Trifid. They are the first such stars found that lie in the central plane of the Milky Way beyond its central bulge. (learn more)

Credits: ESA/Hubble heic1323

The NASA/ESA Hubble Space Telescope has observed the variable star RS Puppis over a period of five weeks, showing the star growing brighter and dimmer as it pulsates. These pulsations have created a stunning example of a phenomenon known as a light echo, where light appears to reverberate through the murky environment around the star.(read more)

Source: SpaceTelescope

V1 in M31.
Image credit: NASA, ESA and the Hubble Heritage Team (STScI/AURA)

Though the Universe is filled with billions upon billions of stars, the NASA/ESA Hubble Space Telescope has been trained on a single variable star that in 1923 altered the course of modern astronomy. And, at least one famous astronomer of the time lamented that the discovery had shattered his world view.

The star goes by the inauspicious name of Hubble variable number one, or V1, and resides two million light-years away in the outer regions of the neighbouring Andromeda galaxy, or M31. V1 is a special class of pulsating star called a Cepheid variable that can be used to make reliable measurements of large cosmic distances.

The star helped Edwin Hubble show that Andromeda lies beyond our galaxy. Prior to the discovery of V1 many astronomers, including Harlow Shapley, thought spiral nebulae, such as Andromeda, were part of our Milky Way galaxy. Others weren't so sure. In fact, Shapley and Heber Curtis held a public debate in 1920 over the nature of these nebulae. But it took Edwin Hubble's discovery just a few years later to settle the debate.

Hubble sent a letter, along with a light curve of V1, to Shapley telling him of his discovery. After reading the note, Shapley reportedly told a colleague, "Here is the letter that destroyed my Universe." The Universe became a much bigger place after Edwin Hubble's discovery.

In commemoration of this landmark observation, astronomers with the Space Telescope Science Institute's Hubble Heritage Project partnered with the American Association of Variable Star Observers (AAVSO) to study the star. AAVSO observers followed V1 for six months, producing a plot, or light curve, of the rhythmic rise and fall of the star's light. Based on this data, the Hubble Heritage team scheduled Hubble telescope time to capture Wide Field Camera 3 images of the star at its dimmest and brightest light levels.

These observations were presented on 23 May at the meeting of the American Astronomical Society in Boston.

Source: Kepler Mission

Artist's rendering comparing the size and color of the stars in the triple-eclipsing system HD 181068.
Image credit: NASA/KASC

We are entering a golden era for "stellar physics" – a term coined to describe research about the formation, evolution, interior and the atmospheres of stars. Thanks to a partnership forged among stellar astrophysics, scientists and NASA’s Kepler Mission, a goldmine of data is now available to support the world's efforts to detect planets in the habitable zone around other stars.(read more)

Source: AAVSO Alert Notice 427

The American Association of Variable Stars Observers (AAVSO) requests ground-based observations of the Trapezium region of the Orion Nebula (M42), along with surrounding regions in Orion, in conjunction with upcoming observations with the MOST Satellite.  All AAVSO observers are encouraged to participate in this project, and we are requesting observations for a number of different targets from both instrumental and visual observers.

The Orion Nebula(M42). The white region slightly left and up of the centre of the image is the Trapezium region.

This observing program headed by Dr. Matthew Templeton is exploring low-amplitude variability in bright stars of the Trapezium using the Canadian satellite MOST (Microvariability and Oscillations of Stars). This is an exploratory proposal to search for low-amplitude variability in these young stars due to any number of potential causes: pulsations, magnetic activity and rotation, or accretion processes are all possible. MOST will be capable of measuring the light curves of many stars in the Trapezium with precision better than 1 mmag.

The observations will be conducted at some point during the December 2010 - January 2011 time-frame, and will span approximately one month.  We are requesting observations before, during, and after the observing window, and several of the targets are worthwhile long-term monitoring objects as well. Observers from multiple longitudes are especially encouraged.  Since this is an equatorial source, both northern and southern hemisphere observers are encouraged to participate. (read more)