(Press-News.org) Astronomers using NASA's Hubble Space Telescope and Chandra X-ray Observatory and telescopes on the ground may have found the most crowded galaxy in our part of the universe.
The ultra-compact dwarf galaxy, known as M60-UCD1, may be the densest galaxy near to Earth, packed with an extraordinary number of stars. This galaxy is providing astronomers with clues to its intriguing past and its role in the galactic evolutionary chain.
M60-UCD1, estimated to be about 10 billion years old, is near the massive elliptical galaxy NGC 4649, also called M60, about 54 million light years from Earth. It is the most luminous known galaxy of its type and one of the most massive, weighing 200 million times more than our sun, based on observations with the Keck 10-meter telescope in Hawaii.
What makes M60-UCD1 so remarkable is that about half of this mass is found within a radius of only about 80 light years. The density of stars is about 15,000 times greater -- meaning the stars are about 25 times closer to each other -- than in Earth's neighborhood in the Milky Way galaxy.
"Traveling from one star to another would be a lot easier in M60-UCD1 than it is in our galaxy, but it would still take hundreds of years using present technology," said Jay Strader of Michigan State University in Lansing. Strader is the lead author of a paper about the research, which was published Sept. 20 in The Astrophysical Journal Letters.
The 6.5-meter Multiple Mirror Telescope in Arizona was used to study the amount of elements heavier than hydrogen and helium in stars in M60-UCD1. The values were found to be similar to our sun.
"The abundance of heavy elements in this galaxy makes it a fertile environment for planets and, potentially, for life to form," said co-author Anil Seth of the University of Utah.
Another intriguing aspect of M60-UCD1 is the presence of a bright X-ray source in its center, revealed in Chandra data. One explanation for this source is a giant black hole weighing in at about 10 million times the mass of our sun.
Astronomers want to find out whether M60-UCD1 was born as a jam-packed star clusters or become more compact as stars were ripped away from it. Large black holes are not found in star clusters, so if the X-ray source is in fact due to a massive black hole, it was likely produced by collisions between M60-UCD1 and one or more nearby galaxies. M60-UCD1's great mass and the abundances of elements heavier than hydrogen and helium are also arguments for the theory it is the remnant of a much larger galaxy.
"We think nearly all of the stars have been pulled away from the exterior of what once was a much bigger galaxy," said co-author Duncan Forbes of Swinburne University in Australia. "This leaves behind just the very dense nucleus of the former galaxy, and an overly massive black hole."
If this stripping did occur, then the galaxy originally was 50 to 200 times more massive than it is now, and the mass of its black hole relative to the original mass of the galaxy would be more like that of the Milky Way and many other galaxies. The stripping could have taken place long ago and M60-UCD1 may have been stalled at its current size for several billion years.
INFORMATION:
NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra Program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.
NASA's Hubble and Chandra find evidence for densest nearby galaxy
2013-09-25
ELSE PRESS RELEASES FROM THIS DATE:
Astronomers discover densest galaxy ever
2013-09-25
Imagine the distance between the sun and the star nearest to it – a star called Alpha Centauri. That's a distance of about 4 light years. Now, imagine as many as 10,000 of our suns crammed into that relatively small space.
That is about the density of a galaxy that was recently discovered by an international team of astronomers led by a Michigan State University faculty member.
"This galaxy is more massive than any ultra-compact drawfs of comparable size," said Jay Strader, MSU assistant professor of physics and astronomy, "and is arguably the densest galaxy known in ...
New study shows how ICU ventilation may trigger mental decline
2013-09-25
PHILADELPHIA— At least 30 percent of patients in intensive care units (ICUs) suffer some form of mental dysfunction as reflected in anxiety, depression, and especially delirium. In mechanically-ventilated ICU patients, the incidence of delirium is particularly high, about 80 percent, and may be due in part to damage in the hippocampus, though how ventilation is increasing the risk of damage and mental impairment has remained elusive.
Now, a new study published in the American Journal of Respiratory and Critical Care Medicine from researchers at the University of Oviedo ...
Iowa State, Ames Lab chemists help find binding site of protein that allows plant growth
2013-09-25
AMES, Iowa – Using a new and super-sensitive instrument, researchers have discovered where a protein binds to plant cell walls, a process that loosens the cell walls and makes it possible for plants to grow.
Researchers say the discovery could one day lead to bigger harvests of biomass for renewable energy.
Finding that binding target has been a major challenge for structural biologists. That's because there are only tiny amounts of the protein involved in cell growth and because cell walls are very complex, said Mei Hong, one of the project's lead researchers who's ...
Lighting up can bring you down in colorectal surgery
2013-09-25
Infection, pneumonia, blood clots and kidney failure are all possible complications after any major surgery. A new study shows that smoking boosts the risk of such complications following some of the most common colorectal procedures, including surgery for colon cancer, diverticulitis or inflammatory bowel disease. Lighting up also increases a patient's risk of death after surgery compared with patients who have never smoked.
The study, published in the Annals of Surgery, is unique because it focuses on elective, or non-emergency, surgeries.
"Elective surgeries are ...
Stepfamilies add to caregiver burden
2013-09-25
ANN ARBOR—Caregiving is always tough, but it's that much tougher when caregivers have to rely on family ties that are ambiguous, strained or virtually nonexistent, suggests a University of Michigan study.
Published online this month in the Journal of Marriage and Family, the U-M study is one of the first to explore how divorce and remarriage affect wives who are caregivers.
The issue affects large numbers of Americans. More than 35 million Americans are remarried, and nearly half a million adults over age 65 remarry every year. At the same time, Americans are living ...
Living better with heart failure by changing what you eat
2013-09-25
ANN ARBOR, Mich. -- Diet can dramatically lower hypertension and improve heart function in patients with a common type of heart failure, according to research presented at today's Heart Failure Society of America meeting in Orlando, Fla.
After 21 days of following a low-sodium Dietary Approaches to Stop Hypertension (DASH) eating plan, patients saw a drop in blood pressure similar to taking anti-hypertension medicine.
"Our work suggests diet could play an important role in the progression of heart failure, although patients should always talk to their doctor before ...
New CU-Boulder-led study finds 'microbial clock' may help determine time of death
2013-09-25
An intriguing study led by the University of Colorado Boulder may provide a powerful new tool in the quiver of forensic scientists attempting to determine the time of death in cases involving human corpses: a microbial clock.
The clock is essentially the lock-step succession of bacterial changes that occur postmortem as bodies move through the decay process. And while the researchers used mice for the new study, previous studies on the human microbiome – the estimated 100 trillion or so microbes that live on and in each of us – indicate there is good reason to believe ...
Late Cretaceous Period was likely ice-free
2013-09-25
COLUMBIA, Mo. – For years, scientists have thought that a continental ice sheet formed during the Late Cretaceous Period more than 90 million years ago when the climate was much warmer than it is today. Now, a University of Missouri researcher has found evidence suggesting that no ice sheet formed at this time. This finding could help environmentalists and scientists predict what the earth's climate will be as carbon dioxide levels continue to rise.
"Currently, carbon dioxide levels are just above 400 parts per million (ppm), up approximately 120 ppm in the last ...
MicroRNA-31 might predict lung-cancer spread
2013-09-25
COLUMBUS, Ohio – Determining whether a patient's lung cancer has spread to nearby lymph nodes is critical for identifying the most effective therapy, but it usually requires surgery. A new study suggests, however, that measuring levels of a particular molecule in a sample of tumor tissue might accurately answer the question.
Researchers at The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute (OSUCCC – James) have discovered that levels of microRNA-31 (miR-31) predict the spread of the most common ...
Fat and obesity gene also affects hip fracture
2013-09-25
Australian researchers have demonstrated a strong association between the FTO (fat and obesity) gene and hip fracture in women. While the gene is already well known to affect diabetes and obesity, this is the first study to show that its high-risk variant can increase the risk of hip fracture by as much as 82%.
The study, undertaken by Dr Bich Tran and Professor Tuan Nguyen from Sydney's Garvan Institute of Medical Research, examined six gene variants (single nucleotide polymorphisms, or SNPs) of the FTO gene, taken from the DNA of 943 women in the Dubbo Osteoporosis ...