We put it together in very short notice. Fortunately a webcast is pretty easy to put together.
Keck is hosting a sizable team of folks who are here to observe comet ISON. Astronomers from several institutions are participating in the NASA Comet ISON Observing Campaign. They have a total of 6½ nights, but only the last few hours of each night as the comet rises in the dawn. Comet C/2012 S1 ISON is starting to encounter significant publicity, we may as well take advantage of this.
It was a lot of fun. I particularly like the spot (41:00) where I made the mistake of saying spectra were not very pretty to look at in a room full of spectroscopists. These folks love spectra and quickly corrected me, leading to a nice discussion on why spectra are so valuable to astronomy, often more valuable than photos.
The video is embedded below. A lot of good information about comet ISON, indeed about comets in general. Nothing like having a room full of comet experts…
I will probably make my first attempt to photograph C/2012 S1 ISON this coming weekend. A couple reasons for waiting… The bright Moon will have moved out of the morning sky by then. The comet, currently around magnitude ten, is brightening rapidly.
On the other hand the comet is plunging towards the Sun, rising later each day. Wait much longer and the photographic opportunity will slip away, at least until after Thanksgiving, when the comet will again appear after perihelion.
In the meantime, one of my favorite comet photos from years past…
Comet C/2007 N3 Lulin on the morning of 22 Feb 2009
Supposedly twins, each of our two telescopes has its own peculiar personality. Anyone who works on the crew can tell the telescopes apart at a glance. I do not need the caption to know this is Keck 1. Each telescope has a unique configuration, a unique set of instruments, plus many little differences that take time to appreciate and come to love…
The Keck 1 Telescope awaiting lights out and release for the night
Powerful new survey telescopes led by the California Institute of Technology (Caltech) are being combined with the W. M. Keck Observatory to provide insight into rare, exotic cosmic explosions. Caltech’s intermediate Palomar Transient Factory (iPTF) recently described the first direct detection of the progenitor of a rare type of supernova in a nearby galaxy. The findings were published n the September 20 issue of Astrophysical Journal Letters [http://dx.doi.org/10.1088/2041-8205/775/1/L7].
The paper describes the detection of a Type Ib supernova, a rare explosion in which the progenitor star lacks an outer layer of hydrogen, the most abundant element in the universe. It has proven difficult to pin down which kinds of stars give rise to Type Ib supernovae. One of the most promising ideas, according to graduate student and lead author Yi Cao, is they originate from Wolf-Rayet stars. These objects are 10 times more massive and thousands of times brighter than the Sun and have lost their hydrogen envelope by means of very strong stellar winds. Until recently, no solid evidence existed to support this theory. Cao and colleagues believe that the young supernova they discovered, iPTF13bvn, occurred at a location formerly occupied by a likely Wolf-Rayet star.
Supernova iPTF13bvn was spotted on June 16, less than a day after the onset of its explosion. With the aid of the world-leading adaptive optics system installed on the Keck II telescope, one of Keck Observatory’s two 10-meter telescopes in Hawaii, the team obtained a high-resolution image of this supernova to determine its precise position. Then they compared the Keck Observatory image to a series of pictures of the same galaxy (NGC 5806) taken by the Hubble Space Telescope in 2005, and found one starlike source spatially coincident to the supernova. Its intrinsic brightness, color, and size — as well as its mass-loss history, inferred from supernova radio emissions — were characteristic of a Wolf-Rayet star.
“All evidence is consistent with the theoretical expectation that the progenitor of this Type Ib supernova is a Wolf-Rayet star,” said Cao. “Our next step is to check for the disappearance of this progenitor star after the supernova fades away. We expect that it will have been destroyed in the supernova explosion.”
Though Wolf-Rayet progenitors have long been predicted for Type Ib supernova, the new work represents the first time researchers have been able to fill the gap between theory and observation, according to study coauthor and Mansi Kasliwal from the Carnegie Institution for Science. “This is a big step in our understanding of the evolution of massive stars and their relation to supernovae,” she said.
The iPTF builds on the legacy of the Caltech-led Palomar Transient Factory (PTF), designed in 2008 to systematically chart the transient sky by using a robotic observing system mounted on the 48-inch Samuel Oschin Telescope on Palomar Mountain near San Diego, California. This state-of-the-art, robotic telescope scans the sky rapidly over a thousand square degrees each night to search for transients.
Apparent the species can range in color from a pale gold, to a dark, almost black, red. I have seen this species a couple times now. The previous specimens I had found were the characteristic red, seeing this gold nudi I thought I had found something new to me.
But it is a red dendrodoris. This is a well known, but undescribed species that is found on island reefs. This fellow was in a cave at Horseshoe, depth about 35ft.
An undescribed species of Dendrodoris, depth 35ft on the Kohala Coast
University of Texas at Austin astronomer Steven Finkelstein has led a team that has discovered and measured the distance to the most distant galaxy ever found, using the W. M. Keck Observatory on the summit of Mauna Kea, Hawaii. The galaxy is seen as it was at a time just 700 million years after the Big Bang. The result will be published in the Oct. 24 issue of the journal Nature.
Initial observations from NASA’s Hubble Space Telescope identified many candidates for galaxies in the early universe, but this galaxy is the earliest and most distant definitively confirmed, using the 10-meter, Keck I telescope fitted with Keck Observatory’s newest instrument, MOSFIRE.
This image from the Hubble Space Telescope CANDELS survey highlights the most distant galaxy in the universe with a measured distance, dubbed z8_GND_5296. Credit: V. Tilvi, S.L. Finkelstein, C. Papovich, A. Koekemoer, CANDELS, and STScI/NASAWhat makes this distance so exciting, is “we get a glimpse of conditions when the universe was only about 5 percent of its current age of 13.8 billion years,” said Casey Papovich of Texas A&M University, second author of the study.
Astronomers can study how galaxies evolve because light travels at a finite speed, about 186,000 miles per second. Thus when we look at distant objects, we see them as they appeared in the past. The farther astronomers can push their observations, the farther into the past they can see.
“We want to study very distant galaxies to learn how they change with time,” Finkelstein said. “This helps us understand how the Milky Way came to be.”
The devil is in the details, however, when it comes to making conclusions about galaxy evolution, which means astronomers must employ the most rigorous methods and utilize the most powerful instruments to measure the distances to these galaxies in order to understand at what epoch of the universe they are seen.
The Hubble CANDELS survey uses colors from HST images to identify potentially distant galaxies. Finkelstein’s team selected z8_GND_5296, and dozens of others, for follow-up spectroscopy from the approximately 100,000 CANDELS galaxies. This method is good, but not foolproof, Finkelstein says. Using colors to sort galaxies is tricky because more nearby objects can masquerade as distant galaxies.
In order to accurately determine the distance to these galaxies, astronomers use spectroscopy to measure how much a galaxy’s light wavelengths have shifted toward the red end of the spectrum over their travels from the galaxy to Earth. This phenomenon is called “redshift”, and is due the expansion of the universe.
The team used Keck Observatory’s Keck I telescope in Hawaii, one of the two largest optical/infrared telescopes in the world, to measure the redshift of z8_GND_5296 at 7.51, the highest galaxy redshift ever confirmed. The redshift means this galaxy hails from a time only 700 million years after the Big Bang.
Mark Kassis stands beside the MOSFIRE spectrographKeck I was fitted with the new MOSFIRE instrument, which made the measurement possible, Finkelstein said. “The instrument is great. Not only is it sensitive, it can look at multiple objects at a time,” he said, which allowed his team to observe 43 galaxies in only two nights at Keck Observatory, and obtain the highest quality observations possible.
In addition to its great distance, the team’s observations showed that the galaxy z8_GND_5296 is forming stars extremely rapidly — producing stars at a rate 150 times faster than our own Milky Way galaxy. This new distance record-holder lies in the same part of sky as the previous record-holder (redshift 7.2), which also happens to have a very high rate of star-formation.
“So we’re learning something about the distant universe,” Finkelstein said. “There are way more regions of very high star formation than we previously thought. … There must be a decent number of them if we happen to find two in the same area of the sky.”
In addition to their studies with Keck, the team also observed z8_GND_5296 in the infrared with NASA’s Spitzer Space Telescope. Spitzer measured how much ionized oxygen the galaxy contains, which helps pin down the rate of star formation. The Spitzer observations also helped rule out other types of objects that could masquerade as an extremely distant galaxy, such as a more nearby galaxy that is particularly dusty.
Other team members include Bahram Mobasher of the University of California, Riverside; Mark Dickinson of the National Optical Astronomy Observatory; Vithal Tilvi of Texas A&M; and Keely Finkelstein and Mimi Song of UT-Austin.
Astronomy Talk: The Wonder of Comet ISON, A Relic From the Beginning of the Solar System
Thursday October 24, 2013
07:00 pm – 08:00 pm
An image of comet C/2012 S1 ISON acquired by the Hubble Space Telescope on October 9th, 2013, credit: NASA, ESA, and the Hubble Heritage TeamKahilu Theatre
Dr. Carey Lisse, head of NASA’s Comet ISON Observation Campaign, will present a timely talk on how and when comets were formed, and where they come from. Also a Senior Research Scientist with Johns Hopkins University Applied Physics Laboratory, Lisse will relate how comets may have helped start life on the Earth, and also how they may have ended it for millions of creatures at least 4 times in the past. He’ll also give a bit of the history of comet observing by mankind, and explain how Comet 2012 S1 (ISON) fits into this picture of comets as relics from the beginning of our solar system.
Mercury will exit the evening sky this week. Currently about 10° above the setting Sun, it will quickly orbit back into the Sun’s glare. It will pass through inferior conjunction on November 1st to reappear in the dawn around November 6th.
