A very belated post of images taken in the Fall 2022 semester with our telescope.
This assignment is intended to give students the opportunity to practice taking imaging data with the 16” telescope and CCD, and to learn how to do basic image calibration and alignment using AstroImageJ.
The variety of colour choices should help with understanding about how to observe extended objects through a telescope, and how the colourful astronomical imagery, which is so common in our textbooks, and all over the internet, is made.
The goal was simply to take an image of a Messier list object (e.g. star cluster, nebula or galaxy) which you will then process with standard procedures in the open source AstroImageJ software to make a well composed and attractive image.
Students were also asked to write a caption suitable for an “Astronomy Picture of the Day” like display.
This shows a selection of the 18 submissions (from 7 observing groups) from Fall 2022.
The Crab Nebula, M1
Almost a millennium ago, Chinese astronomers observed a new star: one so bright that it was outshone only by the moon. Today, we know that what they witnessed over the span of two years was not just a star; it was the explosive death of one. In the image above we see the Crab Nebula (M1), which was formed from the remnants of that supernova and the pulsar (a special type of neutron star) it left behind. While M1 with its apparent magnitude of 8.38 can no longer be observed with the naked eye, we can use telescopes and filters to gain insights into its composition and evolution. The broad, interior portion of M1 pictured in green is thought to be synchrotron emission produced by the interaction between charged particles and the strong magnetic field of the pulsar whereas as the red and blue “filamentary” structures map the locations of hydrogen and oxygen respectively. Data Collection by Anubhav Sharma ‘23, William Flanders, Darshan Patel ‘24 Processing and caption by Darshan Patel ‘23
The Eagle Nebula, M16
The Eagle Nebula is famously known for its ‘Pillars of Creation’ feature, and this picture indicates exactly why. Roughly 7,000 lightyears (just under 2,000 pc) away, M16 resides in the constellation Serpens. With such close proximity to the Milky Way, the nebula is quite large on the sky (this picture has a field of view of 30 arcmin, with the nebula spanning nearly the entire frame). It has ideal viewing in late summer and early fall, and rises to its peak just 1-2 hours after nightfall. Its recognizable star-forming cloud regions contain high amounts of atomic hydrogen, causing bright H-alpha emission. This image was taken using an H-alpha filter to capture this emission (magenta), along with O-III (cyan) and clear (yellow) filters. The abundance of H-alpha is clear from the purple color of the nebula in the image, though emission in the other filters is present. Image taken using Haverford College’s Strawbridge Observatory 16” telescope. Data Collection, Processing and Caption by Hedy Goodman ‘23 and August Muller ‘23
Globular Cluster, M22
The stars around us have structure. The Messier 22 globular cluster pictured here is a stark example of that. The stars here are far closely grouped together, old, and cold (so far as a nuclear furnace can be cold). In a globular cluster like this, little dust remains and few new stars are born. Those that remain cannot be young. On our sky, the M22 globular cluster is among the brightest of its kind, although more so due to its relative proximity to Earth than anything else. This picture was created by combining light observed at bluer, visual (centered on a greenish-yellow), and infrared wavelengths. Data by Ben Alexander ‘24, Lydia Guertin ‘24, Becca Lindenbam ’24 Processing and caption by Ben Alexander ‘24This globular cluster in the direction of the constellation Sagittarius is the brightest of the Messier globular clusters, hence why it was the first globular cluster ever discovered! The cluster is best seen in August, and can easily be observed with an amateur telescope because of its brightness. These clusters contain some of the oldest known stars, and M22 is no exception. The mostly-monotone image demonstrates the small distribution of stellar ages; the blue and green filters correspond to slightly different wavelengths of visible light, meaning these stars all have approximately the same radiative energies. You may notice purple hues in the center of the image: this is infrared emission from dust and gas expelled from the outer layers of stars as they age and stop fusion in their cores. M22 is only one of four known globular clusters to contain a planetary nebula, a classic example of these expelled layers, another reason M22 is so important to study! Typically, planetary nebulae, along with all gas and dust in globular clusters, are absorbed by the gravitational pull of stars, which makes the standalone planetary nebula of M22 unusual. This cluster is 3,250 parsecs from Earth, and has been magnified by a factor of approximately 300 to capture this image. Data by Ben Alexander ‘24, Lydia Guertin ‘24, Becca Lindenbam ’24 Processing by Becca Lindenbaum ‘24 caption by Lydia Guertin ‘24
The Ring Nebula, M57
One ring to rule them all The Ring Nebula (M57) is one of the most well known nebulae in the northern hemisphere. It dwells in the constellation of Lyra, and every summer it looks down from heaven. It is about 1 lightyear across and 2500 lightyears away from us. It is a planetary nebula – the colorful atmosphere is forged by the dying sun-like star in the center through ionization. We took this image on September 8th, 2022 with a 16-inch telescope and a 4096 pixels × 4096 pixels CCD. The red color of the outer part of the ring represents Hɑ emission; the green color of the inner part represents the doubly ionized Oxygen emission; and the brightness scale is provided by the image without filters. These ionized emissions differ the Ring Nebula from the other (white) stars in the background. Image credit: Xingyun Yang ‘24, JT Turner ‘24, Intouch Srijumnong ‘24 Caption by Xingyun Yang Processing by JT Turner ‘24Image credit: Xingyun Yang ‘24, JT Turner ‘24, Intouch Srijumnong ‘24 Processing by Indy Srijumnong‘24Image credit: Emma Martignoni ‘24, Petra Mengistu ‘24, Woodkensia Charles ‘24 Processing by Emma Martignoni, Caption by Petra Megistu The Ring Nebula, M57, is one of the four planetary nebulae in the Messier catalog, having an apparent magnitude of 8.8. As characteristic to planetary nebulae, M57 is most distinctly identified by its unique ring shape representing the ionized outflow of gas from the remnant core of a dying star. This ring shape, however, is our perceived presentation of the thin spherical shell of ejected material from the white dwarf as projected onto a side view. Although it is difficult to see the central white dwarf, the ejected material is visible as a colorful annular halo observed in the different narrowband emission filters. Since the outer regions of gas are at a cooler temperature, the red outer halo reflects H-alpha emission resulting from relatively low energy photons, whereas the green color of the inner ionized gaseous regions show O-III emission due to the higher energy photons from the evolving white dwarf. Hence, the surrounding ejected gas and dust material contain ionized H-alpha and O-III accumulated in an apparent ring structure enclosing the dying star, while the surrounding stars shown in blue display portions of the Lyra Constellation as imaged using an open filter.
M57, or the Ring Nebula, is a planetary nebula glowing with the remnants of a sun-like star. The faint, tiny blue dot in the center of the ring is the star’s hot core, a white dwarf. This image was taken in late September from over 2,000 lightyears away, located in the constellation Lyra near the star Vega. M57 is tilted towards earth so astronomers with a moderately sized telescope can see the ring face-on with an apparent magnitude 8.8. While the Ring Nebula was discovered in 1779 by French astronomer Antoine Darquier de Pellepoix, it has fascinated astronomers with its intricate structure of complex nebulosity as well as providing amaetrue astronomers with an easy-to-find target in the summertime. Image credit: Rachel Langgin BMC ‘23 and Sophia Lanava BMC ’24. Processing by Rachel Langgin BMC ‘23Processing by Sophia Lanava ‘24
