Hubble's Wide Field Camera 3 (WFC3) has captured a striking new image of the grand design spiral galaxy NGC 5248.
This Hubble image shows the Grand Design spiral galaxy NGC 5248, located approximately 42 million light-years away in the constellation Bootes. The color images were created from separate exposures taken in the visible, ultraviolet, and near-infrared regions of the spectrum using Hubble's WFC3 instrument. Six filters were used to sample different wavelengths. Color is obtained by assigning different hues to each monochromatic image associated with an individual filter. Image credits: NASA / ESA / Hubble / F. Belfiore / J. Lee / PHANGS-HST team.
NGC5248 It is located in the constellation Bootes, about 42 million light years away.
This spiral galaxy, also known as Caldwell 45, LEDA 48130, UGC 8616, IRAS 13353+0908, and TC 830, has a diameter of 95,000 light years.
beginning discovered It was discovered on April 15, 1784 by German-born British astronomer William Herschel and is a member of the NGC 5248 galaxy group.
NGC 5248 has an apparent magnitude of 10, so it doesn't appear very bright, but it can be spotted with a small telescope.
The galaxy is noteworthy Because of the nuclear ring, which has “hot spots” of starburst activity.
“NGC 5248 is one of the so-called 'grand design' spirals, with prominent spiral arms extending from near the center through the disk,” Hubble astronomers said in a statement.
“There is also a faint bar structure in the center between the inner edges of the spiral arms, which is less obvious in this visible-light portrait from Hubble.”
“Features like this that break a galaxy's rotational symmetry have profound effects on how matter moves through it and ultimately on its evolution over time.”
“They can supply gas from the outer reaches of the galaxy to the inner star-forming regions and even to the black hole at the center of the galaxy, where it can start an active galactic nucleus.”
“These gas flows have significantly shaped NGC 5248, with many bright regions of intense star formation spread throughout the disk and dominated by populations of young stars.”
“This galaxy has two very active ring-like starburst regions filled with young star clusters around its core.”
“While these 'nuclear rings' are noteworthy enough, nuclear rings usually tend to prevent gas from penetrating further into the center of the galaxy.”
“The fact that NGC 5248 has a second ring inside the first shows how powerful its flow of matter and energy is.”
“Due to its relatively close proximity and highly visible starburst region, this galaxy is a target for professional and amateur astronomers alike.”
Astronomers using the International Gemini Observatory’s Gemini North Telescope have imaged NGC 4449, a prime example of starburst activity caused by an ongoing merger with a nearby dwarf galaxy.
NGC 4449 is located in the constellation Canes Venatici and is about 12.5 million light-years away from Earth.
Also known as Caldwell 21, LEDA 40973, and UGC 7592, the galaxy has a diameter of about 20,000 light-years.
NGC 4449 was discovered on April 27, 1788, by German-born British astronomer William Herschel.
It is part of the M94 galaxy group, located near the Local Group, which contains our own Milky Way galaxy.
“The galaxy’s rolling red clouds and glowing blue veil light up the sky with the color of newly forming stars,” the astronomers said.
“The galaxy is classified as an Irregular Magellanic Galaxy, reflecting its loose spiral structure and similarity to the Large Magellanic Cloud, the prototype of the Magellanic Cloud.”
Stars have been forming actively within NGC 4449 for billions of years, but new stars are currently being produced at a much higher rate than in the past.
This unusually explosive and intense star formation activity qualifies this galaxy to be called a starburst galaxy.
“While starbursts typically occur in the centers of galaxies, star formation in NGC 4449 is more widespread, as evidenced by the fact that the youngest stars are found both in the galaxy’s central core and in the outflow that surrounds the galaxy,” the researchers said.
“This global starburst activity resembles the earliest star-forming galaxies in the universe, which grew by merging and agglomerating with smaller stellar systems.”
“And like its galactic progenitors, NGC 4449’s rapid star formation is likely driven by interactions with nearby galaxies.”
A member of the M94 galaxy group, NGC 4449 sits very close to several smaller galaxies around it.
Astronomers have found evidence of interactions between NGC 4449 and at least two other satellite galaxies.
One is a very faint dwarf galaxy that is actively absorbing, as evidenced by the diffuse streaming of stars on one side of NGC 4449.
“This stealthy merger is nearly undetectable by visual inspection due to its diffuse nature and low stellar mass,” the scientists said.
“But this galaxy harbors a huge amount of dark matter, and we can detect its presence through its large gravitational influence on NGC 4449.”
“Another object that offers a clue to past mergers is a massive globular cluster embedded within the outer halo of NGC 4449.”
Astronomers believe the cluster is the surviving core of a former gas-rich satellite galaxy that is now being absorbed into NGC 4449.
“As NGC 4449 interacts with and absorbs other, smaller galaxies, the gas is compressed and shocked by tidal interactions between the galaxies,” the astronomers said.
“Red glowing regions scattered throughout the image indicate this process, showing an abundance of ionized hydrogen, a clear sign of ongoing star formation.”
“Dark filaments of cosmic dust that thread their way throughout the Galaxy are causing countless hot, young, blue star clusters to emerge from the galactic oven.”
“At the current rate, NGC 4449’s supply of gas to support star formation will last only another billion years or so.”
Astronomers using the Atacama Large Millimeter/Submillimeter Array (ALMA) have detected more than 100 molecular species at the center of starburst galaxy NGC 253. This is far more than anything previously observed in galaxies outside the Milky Way.
Artist's impression of the center of starburst galaxy NGC 253. Image credit: NRAO/AUI/NSF.
In the Universe, some galaxies form stars much faster than our Milky Way. These galaxies are called starburst galaxies.
Exactly how such extremely prolific star formation occurs and how it ends is still a mystery.
The probability of star formation is determined by the properties of the raw material from which stars are formed, such as molecular gas, which is a gaseous substance made up of various molecules.
For example, stars form in dense regions within molecular clouds where gravity can work more effectively.
Some time after a star has been actively forming, explosions from existing or dead stars can energize the surrounding material and prevent future star formation.
These physical processes affect the galaxy's chemistry and imprint signatures on the strength of the signals from its molecules.
Because each molecule emits light at a specific frequency, observations over a wide frequency range can analyze its physical properties and provide insight into the mechanism of starbursts.
It was observed by Dr. Nanase Harada of the National Astronomical Observatory of Japan as part of the ALMA Comprehensive High-Resolution Extragalactic Molecular Inventory (ALCHEMI). NGC253 a starburst galaxy located 11.5 million light-years away in the constellation Corina.
They were able to detect more than 100 molecular species in the galaxy's central molecular belt.
This chemical raw material is most abundantly found outside the Milky Way, and includes molecules such as ethanol and the phosphorus-containing species PN, which were first detected beyond the Milky Way.
First, astronomers found that the dense molecular gas likely fuels active star formation in this galaxy.
Each molecule emits at multiple frequencies, and its relative and absolute signal strength varies with density and temperature.
Analysis of numerous signals from several molecular species revealed that the amount of dense gas at the center of NGC 253 is more than 10 times greater than the amount of gas at the center of the Milky Way. This could explain why NGC 253 forms about 30 stars. With the same amount of molecular gas, you can get many times more efficiency.
One mechanism by which molecular clouds compress and become denser is through collisions between them.
At the center of NGC 253, cloud collisions occur where gas streams and stars intersect, creating shock waves that travel at supersonic speeds.
These shock waves vaporize molecules such as methanol and HNCO and freeze them onto ice dust particles.
Once the molecules evaporate as a gas, they can be observed with radio telescopes such as ALMA.
Certain molecules also track ongoing star formation. It is known that complex organic molecules exist in abundance around young stars.
Schematic image of the center of NGC 253. Spectra from the ALCHEMI survey are shown where different tracer species are enriched.Image credits: ALMA / ESO / National Astronomical Observatory of Japan / NRAO / Harada other.
The study suggests that in NGC 253, active star formation creates a hot, dense environment similar to that found around individual protostars in the Milky Way.
The amount of complex organic molecules at the center of NGC 253 is similar to that found around galactic protostars.
In addition to the physical conditions that can promote star formation, the study also uncovered harsh environments left behind by previous generations of stars that could slow the formation of future stars.
When a massive star dies, a massive explosion known as a supernova occurs, releasing energetic particles called cosmic rays.
Molecular composition of NGC 253 revealed by enhancement of species such as H3○+ and HOC+ Molecules in this region are stripped of some of their electrons by cosmic rays at least 1,000 times faster than molecules near the solar system.
This suggests that there is a significant energy input from the supernova, making it difficult for the gas to condense and form a star.
Finally, the ALCHEMI survey provided an atlas of 44 molecular species, double the number obtained in previous studies outside the Milky Way.
By applying machine learning techniques to this atlas, the researchers were able to identify which molecules can most effectively track the star formation story described above from beginning to end.
As explained above with some examples, certain molecular species track phenomena such as shock waves and dense gas that can help star formation.
Young star-forming regions are rich in chemicals, including complex organic molecules.
On the other hand, the developed starbursts show an enhancement of cyanogen radicals, which indicate an energy output in the form of ultraviolet photons from massive stars, which could also hinder future star formation.
“Finding these tracers may help plan future observations to take advantage of the broadband sensitivity improvements expected over this decade as part of the ALMA 2030 development roadmap. “Simultaneous observation of molecular transitions will become more manageable,” the scientists said.
Their paper will appear in Astrophysical Journal Appendix Series.
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Nanase Harada other. 2024. ALCHEMI Atlas: Principal component analysis reveals starburst evolution of NGC 253. APJS 271, 38; doi: 10.3847/1538-4365/ad1937
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