Philosophy
I suppose that this news will make one feel better...three times the chance of alien encounter[s]. Regardless, it is humbling.
It really is full of stars.
Scientists said Wednesday that the number of stars in the universe had been seriously undercounted, and they estimated that there could be three times as many stars out there as had been thought.
This undercounting, of cool, dim dwarf stars in certain galaxies, could throw a monkey wrench into astronomers’ understanding of how galaxies formed and grew over the eons.
“It’s very problematic,” said Pieter van Dokkum, a professor of astronomy at Yale who reported the findings in the journal Nature with Charlie Conroy of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.
The conundrum is that astronomers cannot actually count the dwarf stars, which have masses less than a third of that of the Sun, in galaxies outside the Milky Way. So instead, they counted the brighter Sun-like stars and assumed that there were about 100 unseen dwarfs for each larger Sun-like star, as is the case in the Milky Way.
Yet not every galaxy looks like the Milky Way, with its spiraling pinwheel arms. Some are blobby and elliptical, and it was an untested assumption that the distribution of star sizes in elliptical galaxies is the same as in the Milky Way.
Dr. van Dokkum and Dr. Conroy took an innovative approach to counting what they could not see. Because the dwarfs are cooler, the fingerprint of certain colors they emit and absorb is different from that of larger stars. Thus, while they could not see individual stars, the astronomers could calculate the number of dwarfs required to produce the telltale color fingerprint they detected in the light coming from the whole galaxy.
And they found that in eight elliptical galaxies, the ratio of dwarf stars to Sun-like stars was 1,000 or 2,000 to 1, rather than the 100 to 1 in the Milky Way. A typical elliptical galaxy, thought to consist of about 100 billion stars, would have one trillion or more stars. Ellipticals account for about a third of all galaxies, leading to the new estimate of at least three times as many stars over all.
“We may have to abandon this notion of using the Milky Way as a template for the rest of the universe,” Dr. van Dokkum said. If the findings are correct, an undercount of dwarfs would mean astronomers have underestimated the masses of galaxies, and that would mean that galaxies developed earlier and faster than currently thought.
“Which would be very interesting, actually,” said Richard Ellis, a professor of astronomy at the California Institute of Technology who was not involved in the research. “It’s very important that papers like this are published so that we are reminded how fragile our knowledge of the universe is.”
Yet Dr. Ellis said he remained skeptical. “It’s good data and it’s a sound analysis,” he said, “but there are a few escape clauses.”
For one, the research assumes that the stars in an elliptical galaxy are made of exactly the same stuff as those in spiral galaxies, an assumption that cannot be tested yet.
Also inconclusive: whether we now have three times as many wishes.
- Allan Sandage...a New Paper By Lynden-bell And Schweizer
Allan Sandage was an observational astronomer who was happiest at a telescope. On Hubble’s sudden death Allan Sandage inherited the programmes using the world’s largest optical telescope at Palomar to determine the distances and number counts of...
- Deceased--leonard Searle
Leonard Searle October 23rd, 1930 to July 2nd, 2010 "Leonard Searle dies at 79; astronomer's work provided key information on the Big Bang" The former director of the Carnegie Observatories also played a crucial role in the construction of the twin...
- Cecilia Helena Payne-gaposchkin...the Sun
Cecilia Helena Payne-Gaposchkin May 10th, 1900 to December 7th, 1979 Cecilia Helena Payne-Gaposchkin was an English-born American astronomer who was the first to apply laws of atomic physics to the study of the temperature and density of stellar bodies,...
- Double Star Observations--galileo Galilei
Galileo Galilei Demonstrates His Astronomical Theories to a Monk This is somewhat unusual...that earlier observations of double stars negated the conclusions written in Galileo Galilei's Dialogue Concerning the Two Chief World Systems [1632]...such...
- Value Of Amateur Scientists--"hanny's Voorwerp"
Hanny van Arkel "Hanny's Voorwerp" Another example of the value of amateur scientists. "Dutch Teacher Stumbles Upon A Space 'Ghost'" August 9th, 2008 NPR A Dutch primary school teacher has accidentally discovered what some are calling a...
Philosophy
More Stars
I suppose that this news will make one feel better...three times the chance of alien encounter[s]. Regardless, it is humbling.
"How Many Stars? Three Times as Many as We Thought, Report Says"
by
Kenneth Chang
December 1st, 2010
The New York Times
by
Kenneth Chang
December 1st, 2010
The New York Times
It really is full of stars.
Scientists said Wednesday that the number of stars in the universe had been seriously undercounted, and they estimated that there could be three times as many stars out there as had been thought.
This undercounting, of cool, dim dwarf stars in certain galaxies, could throw a monkey wrench into astronomers’ understanding of how galaxies formed and grew over the eons.
“It’s very problematic,” said Pieter van Dokkum, a professor of astronomy at Yale who reported the findings in the journal Nature with Charlie Conroy of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.
The conundrum is that astronomers cannot actually count the dwarf stars, which have masses less than a third of that of the Sun, in galaxies outside the Milky Way. So instead, they counted the brighter Sun-like stars and assumed that there were about 100 unseen dwarfs for each larger Sun-like star, as is the case in the Milky Way.
Yet not every galaxy looks like the Milky Way, with its spiraling pinwheel arms. Some are blobby and elliptical, and it was an untested assumption that the distribution of star sizes in elliptical galaxies is the same as in the Milky Way.
Dr. van Dokkum and Dr. Conroy took an innovative approach to counting what they could not see. Because the dwarfs are cooler, the fingerprint of certain colors they emit and absorb is different from that of larger stars. Thus, while they could not see individual stars, the astronomers could calculate the number of dwarfs required to produce the telltale color fingerprint they detected in the light coming from the whole galaxy.
And they found that in eight elliptical galaxies, the ratio of dwarf stars to Sun-like stars was 1,000 or 2,000 to 1, rather than the 100 to 1 in the Milky Way. A typical elliptical galaxy, thought to consist of about 100 billion stars, would have one trillion or more stars. Ellipticals account for about a third of all galaxies, leading to the new estimate of at least three times as many stars over all.
“We may have to abandon this notion of using the Milky Way as a template for the rest of the universe,” Dr. van Dokkum said. If the findings are correct, an undercount of dwarfs would mean astronomers have underestimated the masses of galaxies, and that would mean that galaxies developed earlier and faster than currently thought.
“Which would be very interesting, actually,” said Richard Ellis, a professor of astronomy at the California Institute of Technology who was not involved in the research. “It’s very important that papers like this are published so that we are reminded how fragile our knowledge of the universe is.”
Yet Dr. Ellis said he remained skeptical. “It’s good data and it’s a sound analysis,” he said, “but there are a few escape clauses.”
For one, the research assumes that the stars in an elliptical galaxy are made of exactly the same stuff as those in spiral galaxies, an assumption that cannot be tested yet.
Also inconclusive: whether we now have three times as many wishes.
- Allan Sandage...a New Paper By Lynden-bell And Schweizer
Allan Sandage was an observational astronomer who was happiest at a telescope. On Hubble’s sudden death Allan Sandage inherited the programmes using the world’s largest optical telescope at Palomar to determine the distances and number counts of...
- Deceased--leonard Searle
Leonard Searle October 23rd, 1930 to July 2nd, 2010 "Leonard Searle dies at 79; astronomer's work provided key information on the Big Bang" The former director of the Carnegie Observatories also played a crucial role in the construction of the twin...
- Cecilia Helena Payne-gaposchkin...the Sun
Cecilia Helena Payne-Gaposchkin May 10th, 1900 to December 7th, 1979 Cecilia Helena Payne-Gaposchkin was an English-born American astronomer who was the first to apply laws of atomic physics to the study of the temperature and density of stellar bodies,...
- Double Star Observations--galileo Galilei
Galileo Galilei Demonstrates His Astronomical Theories to a Monk This is somewhat unusual...that earlier observations of double stars negated the conclusions written in Galileo Galilei's Dialogue Concerning the Two Chief World Systems [1632]...such...
- Value Of Amateur Scientists--"hanny's Voorwerp"
Hanny van Arkel "Hanny's Voorwerp" Another example of the value of amateur scientists. "Dutch Teacher Stumbles Upon A Space 'Ghost'" August 9th, 2008 NPR A Dutch primary school teacher has accidentally discovered what some are calling a...