Announcements

25 February 2009: Certainly one of the strangest objects in our Milky Way galaxy has been hiding as a variable X-ray source called SAX J1808.4-3658. This X-ray binary has been known to contain an accretion-powered millisecond pulsar located at a distance of 3,500 parsec (~11,500 light-years). It was also the first identified millisecond pulsar system among X-ray binaries. Recent observations with GMOS-S (Gemini Multi-Object Spectrograph – at Gemini South) have revealed a large periodic modulation of its quiescent optical emission. The observations show a light curve with a remarkably regular sinusoidal shape of ~0.4 magnitude in amplitude in r’ band (Figure 1). Conducted by the Canadian-Dutch team led by Zhongxiang Wang (McGill University), the new observations indicate that the light curve modulation is caused by irradiation of the companion star to the pulsar, and not by activity in the accretion disk. The pair is strange because it is comprised of an unusual couple: …

24 February 2009: This image of R136, the massive star cluster at the center of the 30 Doradus nebula in the Large Magellanic Cloud was taken on Spartan’s second commissioning run on the SOAR telescope.

20 February 2009: NOAO astronomer and U.S. IYA Project Director Stephen Pompea shows off the “Galileoscope” student telescope kit in Paris.

11 February 2009: In the context of the currently favored cosmological Λ-Cold Dark Matter model of the universe, the formation and evolution of galaxies remains a major unsolved problem. In particular, the detailed evolution of the bulge and disk components of spiral galaxies is not well represented in current simulations. The data–model discrepancies do not necessarily reflect a failure in the ΛCDM model, but may indicate physical regimes and processes that are either poorly understood or difficult to implement in large simulations. Given the significant challenges faced by current galaxy formation models, guidance towards a true understanding of disk galaxies must come from an observational perspective such as the one described here using the Gemini Multi-Object Spectrograph. A very useful probe in discerning between formation scenarios is a detailed breakdown of the age, metallicity (Z), and kinematic properties of the stellar population (SP) content comprising bulges of all types. Information about both light- …

29 January 2009: NOAO astronomer and U.S. IYA Project Director Stephen Pompea shows off the “Galileoscope” student telescope kit at IYA opening ceremonies at UNESCO Headquarters in Paris.

22 January 2009: Stuart Ryder, Australian Gemini Scientist at the Anglo-Australian Observatory, and colleagues from Europe and South Africa have used the 8-meter Gemini North telescope in Hawai‘i and its laser guide star adaptive optics system to reveal a supernova (SN 2008cs) in a galaxy (IRAS 17138-1017) 250 million light-years away (Figure 1). This is the first supernova to be discovered using laser guide star adaptive optics. Along the way, the researchers also turned up a second, “historical” supernova, SN 2004iq, in the same galaxy. Stellar evolution theory, along with the recent identifications of actual supernova progenitors, indicates that only stars more massive than ~8Msun will end their lives as core-collapse supernovae. Assuming that the ratio of such stars to less massive ones—the initial mass function—is the same everywhere in the universe, then the observed rate of supernovae can be used to gauge the rate of star formation, across a wide range of …

16 January 2009: Dr. Timothy Beers of Michigan State University has been appointed to Chair the Gemini Science Committee starting on February 1, 2009. In this capacity Timothy will lead the effort to assure that Gemini's current and future scientific mission fulfills the needs or our user communities. The appointment is for a period of 2 years. Timothy Beers is presently University Distinguished Professor of Astronomy at Michigan State University, and Associate Director of the Physics Frontier Center JINA (Joint Institute for Nuclear Astrophysics). Although his Ph.D. thesis at Harvard University (1983) was on the nature of substructure in clusters of galaxies, for the past 25 years he has worked on surveys and analysis of metal-poor stars in the Milky Way, and on the formation and evolution of galaxies as revealed by their elemental and kinematical signatures. He is a participant in current studies of the Milky Way Galaxy as survey scientist for …

5 January 2009: The newest addition to the Gemini Legacy imaging program is a laser-guide-star enabled near-infrared image of the well-known planetary nebula NGC 7027 (Figure 1). NGC 7027 lies at a distance of about 3,000 light-years from Earth and is located in the direction of the constellation Cygnus. The nebula itself is approximately 14,000 astronomical units from end-to-end, about 140 times larger than our Solar System. NGC 7027 is a planetary nebula, so-named because early observers with small telescopes thought that these targets resembled fuzzy ‘planets’ in the sky. We now know that objects like NGC 7027 are not planets, but the name has stuck throughout the years. We also know that objects like NGC 7027 give us a tantalizing peek into the future of our own Sun. Toward the end of their lives, when they get close to exhausting all of the nuclear fuel they are born with, stars like the …

23 December 2008: The Subaru and Gemini Observatories are pleased to announce a jointly sponsored science meeting that will be held at Kyoto University, Kyoto Japan, between May 18-21, 2009. An estimated two-hundred and fifty participants, approximately half coming from each community, will meet to present research conducted at the two observatories and to explore possible collaborations. The two main goals of the conference are to promote a mutual understanding of both communities and to highlight the international nature of modern astronomy. Other goals are to: Better understand the Subaru and Gemini instruments and science programs Foster scientific collaborations Define key areas of 'niche science' for both observatories Initiate scientific collaboration for, and with respect to, the International Year of Astronomy in 2009 The Scientific and Local Organizing Committees have recently been appointed. The SOC is led by two co-chairs Masashi Chiba (Tohoku University) and Timothy C. Beers (Michigan State University). The LOC …

23 December 2008: Professor Edmondson was one of the major players in the creation of the Association of Universities for Research in Astronomy (AURA) and the National Observatory.

15 December 2008: A recent optical spectroscopic study led by Guillermo Bosch (Universidad de La Plata), Elena and Roberto Terlevich (INAOE, Tonantzintla) used the spectro-imager GMOS-South to reveal that a surprisingly high fraction (>50%) of the stars in the cluster NGC 2070 are binary. This massive cluster is responsible for ionizing the gas in the spectacular 30 Doradus nebula located in the Large Magellanic Cloud. The fraction of binaries is an important factor influencing the initial mass function (IMF), the cluster’s age, and dynamical mass determination. Although a large amount of work has been done on 30 Doradus and its ionizing cluster, little is known of it binary fraction. Bosch and his colleagues obtained optical spectroscopy with the Gemini Multi-Object Spectrograph (GMOS) on Gemini South of 52 early-type stars on six epochs. Radial velocities derived for each night were very stable, with variation less than 1.0 km/sec. Twenty-five out of the 52 stars …

10 December 2008: Nathan Smith (University of California – Berkeley), Ken Hinkle (NOAO) and Nils Ride (Lund Observatory) have used the near infrared spectrograph PHOENIX on Gemini South to study the geometry and kinematics of the active circumstellar envelopes in the supergiant stars Betelgeuse and VY Canis Majoris. These two stars are shedding huge amounts of mass in their “last gasps” and could explode as supernovae any time now. Stars with initial mass of 20-40 solar mass are important, because their complex post-main sequence evolution is determined by their poorly understood mass loss. Massive stars shed copious amount of mass before exploding as supernovae; as instability of the interior and outer layers increases, such episodes of mass loss may be extremely intense in the late phases. Sampling the observable circumstellar envelopes around nearby massive stars can help to predict what type of supernovae we might expect in the event that they explode. Many …

3 December 2008: An international team led by Brazilian astronomer Denise Gonçalves used the Gemini Multi-Object Spectrograph (GMOS) on Gemini North to discover the most distant known symbiotic star. The star is part of a dwarf starburst galaxy in the Local Group called IC10 and is located about 750 kiloparsecs (about 2.5 million light-years) away. A symbiotic star is a variable binary star in which one star has expanded its outer envelope, in the late stages of its evolution, and is shedding mass quickly on another hot star (often a white dwarf). Some time in the future, the pair will end catastrophically with the white dwarf detonating as a Type Ia supernova as more material is dumped on it by the red giant. Symbiotic stars are critical in understanding Type Ia supernovae and the evolution of binary star systems. However, relatively few systems of this sort are known so finding them outside of …

2 December 2008: This issue includes articles on a NEWFIRM large-scale survey, science highlights from several NOAO Survey Programs, and a report from NOAO Director David Silva on “Strategy, Tactics, and Budgetary Results.”

18 November 2008: Astronomers using the Gemini North telescope and W.M. Keck Observatory on Hawaii’s Mauna Kea have obtained the first-ever direct images identifying a multi-planet system around a normal star. The Gemini images allowed the international team to make the initial discovery of two of the planets in the confirmed planetary system.

30 October 2008: The 8.4-meter mirror blank for the Large Synoptic Survey Telescope (LSST) has been successfully lifted from the furnace hearth at the Steward Observatory Mirror Lab, installed into a turning ring, and tilted to a vertical position. It is now ready for core cleanout, which will reduce its mass from 46,500 kg to 16,600 kg. The mirror is scheduled to be completed in January 2012, and will be the largest two-surface optical mirror ever made from a single substrate.

28 October 2008: A group of astronomers using a battery of 8-meter telescopes, including both Gemini North and South, have discovered a small pair of gravitationally bound Kuiper Belt objects with an enormous separation (Figure 1). The extreme binary, 2001 QW322, orbits at 43 astronomical units or about 6.5billion kilometers from the Sun. The two bodies are separated by about 125,000 kilometers (one third the distance from the Earth to the Moon) which is very large for these two tiny bodies. As a comparison, this is approximately equivalent to a pair of baseballs gravitationally "connected" and orbiting each other at a distance of 200 kilometers! 2001 QW322 was discovered in August 2001 with the Canada-France-Hawai‘i Telescope. Since then, (from 2002-2007), the pair has been monitored closely using 8-meter-class telescopes (Gemini North,Gemini South and the European Southern Observatory’s Very Large Telescope) to obtain high precision photometric observations of the faint double system (mg = …

7 October 2008: Supernova 2006jc occurred when its massive progenitor star ended its life in spectacular fashion. The star exploded following a Luminous Blue Variable (LBV)-like outburst two years before (Pastorello et al.2007, Nature, 447, 829). An international team led by Seppo Mattila (Queen’s University, Belfast and University of Turku) observed the supernova and followed its evolution between days 86-493 after the explosion with an array of telescopes including the Gemini North telescope (using the Near Infrared Imager NIRI), the United Kingdom Infrared Telescope (UKIRT) and the Spitzer Space Telescope. This exceptional event has contributed significantly to our understanding of how core-collapse supernovae (SNe) and their progenitors can add to the dust content of the universe. Mattila et al. imaged SN 2006jc in the near infrared between days 86 and 493 with the UKIRT and Gemini North telescopes (Figure 1). Mid-IR observations were obtained with the Spitzer Space Telescope before the explosion and …

7 October 2008: A deep new image of the Virgo cluster has revealed monumental tendrils of ionized hydrogen gas 400,000 light-years long connecting the elliptical galaxy M86 and the disturbed spiral galaxy NGC 4438. Taken with the wide-field Mosaic imager on the National Science Foundation’s Mayall 4-meter telescope at Kitt Peak National Observatory, this Hydrogen-alpha image and related spectroscopic measurements of the filament provide striking evidence of a previously unsuspected high-speed collision between the two galaxies, creating enough heat to slow down and even stop star formation in the galaxy.

15 September 2008: A U.S. astronomer using the Gemini South and Blanco telescopes in Chile has added a startling new clue to the ongoing mystery over the "engine" of the historical 1843 outburst of Eta Carinae, a bright star in the southern skies. The new observations by Nathan Smith of the University of California, Berkeley, reveal faint but extremely fast material indicative of a powerful shock wave produced by the 1843 event, suggesting that its driving mechanism was an explosion rather than a steady wind. The result is featured in the September 11, 2008 issue of the journal Nature.