Announcement: Gemini Observatory

12 Diciembre 2006: A British team led by Matt Burleigh (University of Leicester) and P. F. L. Maxted (Keele University) have discovered and characterized an extremely rare stellar system composed of a white dwarf and brown dwarf pair. Named WD 0137-349, this pairing is the only known close, detached binary system with a white dwarf and a confirmed substellar companion. The system is exceptionally intriguing given the measured orbital period of P = 116 minutes. Such a short period implies that the stars orbit within one solar radius from one another. This is close enough that the brown dwarf must have survived the period of common envelope evolution where it was completely engulfed by the atmosphere of the red giant progenitor of the white dwarf. Earlier work by Maxted et al. had already established a mass of 0.39 +/- 0.035 Msun for the white dwarf and of 0.053 +/- 0.006 Msun for the …

13 Noviembre 2006:

31 Octubre 2006: Robert A. Simcoe of the MIT-Kavli Center for Astrophysics and Space Research has found new evidence of intensive heavy-element enrichment in intergalactic gas, occurring less than 1 billion years (Gyr) after the Big Bang. His discovery of a high concentration of carbon atoms in the spectra of two very distant quasars implies that vigorous star formation was already underway in some neighborhoods when the universe was only 7% of its present age. Charting the evolution of the carbon abundance is like taking a core sample of the early universe's stellar content. Since carbon nuclei are created through fusion in stellar cores, one would expect their abundance to decline at early times, approaching the formation epoch of the first stars. Simcoe's new observations show that the level of triply ionized carbon (i.e. carbon which has been stripped of three electrons, usually denoted as C IV) remains surprisingly constant as far as …

30 Octubre 2006: An international team of researchers used Gemini mid-infrared images to investigate a sample of nearby Luminous InfraRed Galaxies (LIRGs) which are analogous to those LIRGs which are major contributors to the obscured star formation rate (SFR) density at redshift z=1, when the universe was half of its present age. The data were obtained with the mid-infrared imager/spectrograph T-ReCS on Gemini South. In Figure 1 the diffraction-limited images reveal that at high-spatial resolution, approximately 0.3 arcsecond at the observed wavelengths of 8 and 10 microns, the morphology of the mid-infrared emission in the nuclear regions of these galaxies is strikingly similar to that of the ionized gas (Paschen-alpha) revealed by Hubble Space Telescope (HST) NICMOS observations at near-infrared wavelengths. The observed mid-infrared emission of these LIRGs generally consists of bright nuclear emission, multiple circumnuclear and/or extranuclear H II regions, and diffuse emission. The stellar emission, traced by the NICMOS near-infrared continuum …

16 Octubre 2006: Hawai'i Earthquake Update for Gemini North(as of 5:00 PM HST, Thursday, November 9, 2006) A fairly serious earthquake happened Sunday morning near Waikoloa, on the west side of the Big Island. At magnitude 6.6 this was a much stronger earthquake than we are accustomed to here in Hawai'i. Shortly after the event Gemini had staff on the summit to assess the damage to the telescope. We will provide updates as they warrant and information becomes available. The following item was updated at 5h00 pm HST on Thursday, November 9th Repairs to the Gemini North Secondary System have been successfully completed! The system was thoroughly tested in the lab and will be reattached to the top end of the telescope on Friday November 10th. The first half of Friday night is currently scheduled for engineering tests and, if these are successful, the telescope will be handed over for instrument tests. In …

13 Octubre 2006: Using the near infrared integral field spectrograph CIRPASS at Gemini South, Ruben Diaz and an international team of astronomers, have discovered a previously unknown hidden mass concentration that looks like a second nucleus in the starburst galaxy M83. The mass concentration is located at the youngest end of a giant star forming arc near the galaxy's center (geminiann06019a). This concentration probably represents the wreckage of the nucleus of the smaller galaxy which is being "swallowed" by M83. This double nucleus arrangement is also associated with complex kinematics near the galaxy center (geminiann06019b). The masses of the objects were derived from the kinematics of the ionized gas. The nucleus of the intruder body has an estimated mass of about 16 million times the mass of the Sun, compared to 2 million solar masses for the optical "main" nucleus. The two nuclei are about 100 parsecs apart and are probably harboring black …

29 Septiembre 2006: On 2005 December 21.0773 UT, the space-based Swift Gamma Ray Burst Explorer (Burst Alert Telescope) detected a classical short gamma ray burst. The total duration of this event (named GRB 051221a) was about 1.4 seconds. Alicia M. Soderberg (CALTECH) and her collaborators have studied the burst and its afterglow in great detail using several datasets provided by space observations, radio observations with the VLA and optical observations with Gemini. They derived a detailed set of physical parameters for this burst and their analysis helps to better understand the nature of the progenitor of short bursts and their host environments. The Gemini North Telescope staff was alerted and began observations about 2.8 hours after the burst using the Gemini Multi-Object Spectrograph (GMOS). It detected a bright optical source (Figure 1), and the evolution of this afterglow was followed over several days (Figure 2). The optical source detected by GMOS corresponds to …

20 Septiembre 2006: A GNIRS (Gemini South) study identifies a surprising class of distant massive galaxies with strongly suppressed star formation. An international team led by Mariska Kriek of Leiden Observatory (Holland) and Yale University has found that 45% of a small sample (20) of massive high-redshift galaxies exhibit very low or no star formation activity. The existence of "red and dead" massive galaxies at a time when the universe was between 1/4 to a 1/3 of its current age is surprising. During the past few years our knowledge of galaxy formation evolution has grown significantly. Several recent papers indicate that most of the stars in high-mass galaxies were formed at a higher redshift (earlier in the history of the universe) than those of low mass galaxies. This newly published work puts a new twist on the growing evidence that most massive galaxies formed at an extremely early epoch in the universe. Kriek's …

31 Agosto 2006: Quasars and EELR's Quasars are the most powerful and luminous single objects known in the universe. It is theorized that their huge energy output is driven by the accretion of material on a supermassive black hole at the center (or nucleus) of a host galaxy. While it has long been understood that the growth of such black holes is influenced by the nature of the surrounding galaxy, new evidence suggests that the black holes may, in turn, control the development of the galaxy. Exactly how this is done is unclear. One clue, seen in a large number of relatively nearby quasars, is the presence of extended emission-line regions (EELRs), which are luminous structures that often extend to several tens of thousands of parsecs (1 parsec = 3.26 light-years) from the galaxy's nucleus. EELRs are observed as knots or extended regions of light-emitting gas. It is not understood whether this extended …

31 Julio 2006: A team of Gemini Observatory astronomers led by Tom Geballe, and Spanish colleague Francisco Najarro (Instituto de Estructura de la Materia, Madrid), have proven that the star at the core of a spectacular cosmic bow shock near the Galactic Center is indeed an evolved massive star. It may also be the youngest, hottest and most massive star in the region of the Galactic Center. The nature of the Galactic Center source IRS-8, one of the brightest compact mid-infrared sources in the central infrared cluster, was unknown until the advent of adaptive optics (AO) imaging in the infrared. Its dimensions on the sky are roughly 1 arcsecond across, and it appeared as a fuzzy blob to observers until its surprising structure was revealed at Gemini during early AO observations in 2000. In an previous article, Geballe et al. (2004) showed that the IRS-8 bow shock would be a straightforward consequence of …

20 Julio 2006:

20 Julio 2006: Sperello di Serego Alighieri (Observatorio Astrofisico di Arcetri), Barbara Lanzoni (Observatorio Astronomico di Bologna) and Inger Jørgensen (Gemini Observatory) have just released new Gemini/HST results confirming that big galaxies form first and smaller ones later. This spread happens both in rich galaxy clusters and in the general low density field. Furthermore, they show that the first early-type galaxies that formed were the most massive ones in galaxy clusters. As the 100th refereed paper based on GMOS-North data, this work represents a significant milestone for the productivity of the Gemini telescopes and its instrument set. GMOS-North was commissioned on the Gemini North Telescope in late 2001. There are now many studies of the distant universe that have explored the formation and evolution of galaxies when the universe was less than half its current age (see related Gemini stories from: January 5, 2004, May 18, 2004 and July 7, 2004). The emerging …

18 Mayo 2006: In recent weeks the Gemini Science Archive (GSA) has passed three significant milestones and attained new levels of use unforeseen in the early days of its development. In this article, we have decided to reflect on the origins of the GSA, its current status in service to the Gemini community, and our plans for its future expansion into the world of the Virtual Observatory (VO). The first release of the GSA for public use, version 1.0, was in September 2004. At that time we expected its main function to be as a complex data repository, albeit one in which considerable “metadata” was stored along with the observation data. (Metadata is typically information that is itself not of direct scientific importance, but aids in the characterization of the science data. A good example would be data describing weather conditions during an observation run.) We have come a long way in the …

17 Mayo 2006: A new educational outreach program at Gemini Observatory is pairing local students with astronomers to do cutting-edge astronomy with an 8-meter telescope. The first observations from this program were executed early on the morning of May 13 when three Hilo High School students observed the disintegrating comet 73P/Schwassmann-Wachmann 3, and observed the comet in both visible and infrared light. The observations show the classic “head and tail” of the comet as well as multiple pieces of the comet’s body breaking off. “As a pilot project we are beyond thrilled that this worked as well as it did,” said Gemini’s Head of Science, Dr. Jean-René Roy. “These students are extremely engaged in the process. I expect we’ll see them back at Gemini someday as professional astronomers!” Hilo High School student Nicholas Higa and classmates Keane Nakatsu and Ken Oyadomari began working with Gemini astronomer Scott Fisher in March, 2006 when it …

20 Abril 2006: Astronomers traditionally attribute mid-infrared emission from young newly-forming stars to circumstellar disks. However, new observations using the Thermal-Region Camera and Spectrograph (T-ReCS) on Gemini South reveal that in at least one case the mid-infrared emission from a young stellar source is associated with a spectacular outflow. In a paper appeared in the May 1, 2006 Astrophysical Journal Letters, Gemini astronomer James De Buizer, offers a caution that mid-infrared emission from young stellar objects can be explained by processes other than circumstellar disks. The Gemini observations were focused on a young massive star in the G35.20-0.74 region in the outskirts of the Serpens constellation 7500 light years away. This young star has a known collimated outflow, which was first detected from its radio emission (white contours in Figure 2b). The new observations reveal a monopolar jet-like feature in the mid-infrared (Figure 2a). It is argued that this is thermal continuum emission …

12 Abril 2006: Eta Carinae The giant variable star Eta Carinae is one of the most remarkable stars in the southern sky. It lies just under 8,000 light-years away and, at about 100 times the mass of our Sun, is one of the most massive stars known. Eta Carinae is about five million times brighter than the Sun and is the brightest object outside of the solar system in the mid-infrared at 10-20 microns. It radiates most of its luminosity in the infrared part of the spectrum. First catalogued by the English astronomer Edmond Halley in 1677, Eta Carinae's brightness has evolved dramatically throughout recent history. The most spectacular events took place during the nineteenth century, when it outshone all bright stars except Sirius. It underwent a great eruption in the mid-19th century and ejected many solar masses of gas and dust. We now observe this mass loss as a spectacular bipolar nebula …

21 Marzo 2006: Astronomers from the University of Hawaii's Institute for Astronomy (IfA) used Gemini North to make "crucial" observations of an object designated as Asteroid 118401. The Gemini imaging conclusively showed that the body is ejecting dust like a comet, according to an IfA press release based on a paper in the March 23rd issue of Science Express. University of Hawaii graduate student Henry Hsieh and Professor David Jewitt, who led the research, suggest that asteroids and comets are much more closely related than previously thought. The fact that there may be a class of icy bodies like comets that live primarily in the main asteroid belt strongly supports the idea that these objects could be a major source of Earth's present-day water. The Gemini observations were made using the GMOS imager on the night of November 26, 2005. The Gemini observations complement other observations made by the ESO 1.0-meter, UH 2.2-meter …

15 Marzo 2006: A U.S.-led team of astronomers, led by Keivan Stassun of Vanderbilt University, has used Gemini South's high-resolution infrared spectrograph PHOENIX to uncover the dynamics of the eclipsing brown dwarf pair 2MASS J0532184-0546085. The observations of the pair, in the Orion Nebula, complemented data from the 0.9-meter telescope at Kitt Peak and the 0.9-meter, 1.0-meter and 1.3-meter telescopes at the Cerro Tololo Inter-American Observatory. The findings show that the radii of the failed stars are quite large (as models predict), but that the least massive of the pair is hotter than the larger partner. The temperature observations are contrary to expectations. The Gemini data consists of a suite of high-resolution spectra made from eight observations between December 2002 and January 2003. This allowed the team to sample the velocities of the two objects throughout their entire orbital phase. This is the first direct, accurate measurements of the physical properties of young …

10 Marzo 2006: Gemini Observatory has worked since its inception to become a unique facility offering northern and southern sky coverage with telescopes fully optimized for mid-infrared (7-25 micron) observing. MICHELLE, the Gemini North mid-infrared imager and spectrometer, was first on the scene, initially operating only in a purely imaging mode for the scientific community in semester 2003B. During that same time, commissioning also began for T-ReCS (the Thermal-Region Camera and Spectrograph) at Gemini South. Since 2003B, Gemini staff members have made tremendous progress in enhancing and improving the mid-infrared performance of our telescopes and instruments. Now, more than ever, Gemini is poised to make great strides in understanding our mid-infrared universe. Gemini Mid-Infrared Capabilities are Better than Ever Among the improvements and enhancements, the 2006A semester marks the commissioning of the imaging polarimetry mode of MICHELLE. Our mid-infrared instruments are now fully operational for the upcoming 2006B semester and performing better than …

2 Marzo 2006: A new era in astronomy education and outreach was ushered in with the opening of the ‘Imiloa Astronomy Center of Hawai‘i in Hilo, Hawai‘i. The unique 40,000-square-foot facility blends Hawaiian culture with the science of astronomy, using interactive exhibits, multi-media theaters and a state-of-the-art planetarium. The $28 million (U.S.) center was funded primarily through NASA and is located directly across from Gemini’s Hilo Base Facility on the University of Hawaii Hilo - Science and Technology Park. Gemini has been participating in the development of the center on many levels, from supplying content advisors to making the loan of our unused summit console for use in a Gemini-developed Virtual Observatory exhibit. Discussions are well underway to establish multiple partnerships with the center to leverage with Gemini’s local outreach and education programming. As part of the nine-day public preview events in mid-February, a fundraising dinner paid tribute to Senator Daniel K. Inouye …