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15 Junio 2005: It's Tough Being Small(At Least in the Trapezium Region...) The observed distribution of stars as a function of mass has a well-established behavior known as the initial mass function (IMF). For normal stars the IMF says that the quantity of more massive stars is lower than the number of less massive counterparts. In other words, smaller stars are more numerous than bigger ones. How does the IMF behave at lower masses, e.g. subsolar masses or for brown dwarfs, or even planetary size bodies? Stars in the Orion Trapezium region are bombarded by intense ultraviolet radiation. Does such a hostile environment influence the IMF? We do not yet know the answers to these questions. To help provide answers, Gemini South Flamingos-I observations of the outer Trapezium region by Lucas et al. have probed the region to very faint levels in the infrared. These observations provide partial but very instructive clues. Lucas …

3 Junio 2005: The cover of the June, 2005 NOAO/NSO Newsletter features this false color image of the dynamic solar chromosphere, taken on 18 January 2005. Daily images like this one, made with the new SOLIS vector spectromagnetograph, have been obtained with various instruments on Kitt Peak for 31 years. The June Newsletter contains articles on a new roadmap for optical-infrared astronomy, related partnership opportunities at NOAO, and recent Gemini science instrument productivity.

1 Junio 2005: Dust Growth and Planet Formation Silicates found in the general interstellar medium or molecular clouds are exclusively amorphous, non-crystalline dust grains. However, both amorphous and crystalline dust grains are observed in more evolved stellar and planetary systems including those that, while still young, are in their later stages of formation. Thus, crystalline dust is present near T Tauri and Herbig Ae/Be stars, which are only a million or so years old, debris disks such as Beta Pic, which is 15-20 million years old, and our solar system, which is billions of years old (e.g., Comet C/1996 Q1). During the early formation and evolution of the dust in these systems, crystalline silicates form by a process that is still a mystery. The earlier we can look into the process of stellar evolution the better we can understand how the dust surrounding a young star is processed. Spectroscopy in the mid-infrared provides …

18 Mayo 2005: Curtains of gas and dust open dramatically to reveal the inner area of this starforming region. The unceremoniously named bright star SAO 152320 shines with intense light in the center of this field. Clouds of gas glow strongly and dust shrinks quickly under its radiative prowess. This vista lies some 4,000 light years away toward the constellation Monoceros. This is a portion of a much larger nebula called Gum 1.

6 Mayo 2005: The draft report of the O/IR Long Range Planning Committee is available for community review and input until May 15. See the O/IR Long Range Planning Committee web page for more information and to download a draft report.

28 Abril 2005: A joint Chile-United Kingdom team led by Simon Casassus (University of Chile) has used the NOAO-built Phoenix near-infrared spectrometer on Gemini South to obtain high-resolution spectra (R~75,000) of the [Al VI] 3.66-micron line region in the planetary nebula NGC 6302 (the Bug Nebula). By modeling the multi-component structure of the line, the team has been able to derive values for the electric quadrupole constant in the [Al VI] transition and measure a reliable isotopic ratio for aluminum. This is the first time such a constant in an atomic transition has been measured in any astrophysical object. The isotopic ratio of Aluminum (Al-26/Al-27) is of astrophysical interest because it is a signpost of recent nucleosynthesis. Al-27 is the stable isotope, while Al-26 is radioactive – with a half-life of 720,000 years. Because the ratio is poorly established, the origin of Al-26 is currently assigned to a range of astrophysical processes ranging …

16 Abril 2005: These images show two views of the active galaxy Centaurus A—in visible light from Cerro Tololo and in infrared light from two instruments aboard the NASA-JPL Spitzer Space Telescope. For more details, see the Image Gallery page.

12 Abril 2005: Recent spectroscopic studies of infrared light reflected from the surface of Sedna reveal that it is probably unlike Pluto and Charon since Sedna's surface does not display evidence for a large amount of either water or methane ice. Due to Sedna’s extreme distance from the Sun, the frigid surface has probably been untouched for millions of years by anything except cosmic rays and solar ultraviolet radiation. Gemini Observatory astronomer Chad Trujillo led an effort by the same California Institute of Technology research team responsible for Sedna's original discovery to obtain spectra of this distant planetoid using the Near Infrared Imager (NIRI) on Gemini North. Their aim was to better understand the surface of this distant world and how it has evolved since its formation. “It is likely that Sedna has experienced an extremely isolated life in the outskirts of our solar system,” said Trujillo. “Out there beyond what we used …

5 Abril 2005: The winter rains were plentiful in 2004-2005, giving rise to a beautiful display of wildflowers along the road to Kitt Peak. A number of telescopes are visible in the background of this image from March 2005, including the Mayall 4-meter telescope at the peak of the mountain.

28 Marzo 2005: Can galaxies observed at very high redshifts (at a time when the universe was a fraction of its current age) evolve to look like today's nearby galaxies simply by growing older? The answer is no according to an international team of scientists led by Inger Jørgenson (Gemini Observatory) who used GMOS on Gemini North, combined with HST imaging data to survey distant galaxies and chart their evolution. The team's results demonstrate that cluster galaxies closer to us are not aged versions of the kinds of early galaxies seen in distant clusters that existed when the universe was half its current age, about seven billion years ago. To evolve into galaxies like those we see in nearby clusters, these galaxies require more than just a single episode of star formation as current theories suggest — the distant early "progenitors" have to undergo a set of profound transformations that most likely include …

25 Marzo 2005: This open star cluster in the constellation Scorpius is set against the dramatic backdrop of the Milky Way. At 800-1000 light years away, M7's 80-odd stars are spread over some 20-25 light-years and are in excess of 200 million years old. This image of M7 was taken during the Advanced Observing Program.

11 Marzo 2005: How do massive stars form? The time scale for massive star formation is much shorter than for low-mass stars. During the birth process, a massive core will form first and begin evolving (converting hydrogen to helium) while the larger protostar is still accreting material. Like their lower-mass cousins, massive stellar objects are obscured by overlying envelopes of gas and dust during their formation which makes this stage of massive star formation a challenge to observe. Despite the difficulty of discerning the massive cores as they form, progress is being made on both theoretical and observational fronts. New, large-aperture ground-based telescopes (like Gemini) are providing capabilities which allow astronomers to look much farther away to study more of these rare massive stars in their formative stages and evolve in their birth environments. An international team including Robert Blum (CTIO), Peter Conti (JILA), Augusto Damineli, Elysandra Figuerêdo, and Cássio Barbosa (University of …

10 Marzo 2005: The March 2005 NOAO-NSO Newsletter contains articles on the pending NSF Senior Review, observing opportunities in Semester 2005B, the Gemini WFMOS instrument concept, and the WIYN One-Degree Imager.

1 Marzo 2005: How do you hide something as big and bright as a galaxy? You smother it in cosmic dust. Researchers used data from NASA's Spitzer Space Telescope and the NOAO Deep Wide-Field Survey to uncover a hidden population of monstrously bright galaxies approximately 11 billion light-years away.

23 Febrero 2005: About 500 million years ago a spheroidal galaxy captured a small gas-rich galaxy in a merger that led to a burst of star formation. Using the integral field unit (IFU) on GMOS-South, Mark Swinbank (University of Durham, UK), led an international research team to explore this merging system that is still in the process of digesting the gas and stellar components of the two original galaxies. The galaxy SDSS J101345.39+011613.06, known simply as “E+A” (geminiann05002a), has a redshift of 0.1055, corresponding to a distance of roughly 490 Mpc (or 1.6 billion light-years). This hybrid galaxy has a disturbed morphology and shows signatures of both old low-mass stars (spectral type K) and massive but short-lived stars (spectral type A) distributed throughout. However, the youngest and most massive ones—the OB-type stars—are missing, which indicates that the last star-forming event in E+A took place a few hundred million years ago. Recent spectroscopy conducted …

10 Febrero 2005: Visible light images from NOAO telescopes (left) have been used by scientists from the Spitzer Science Center to help them better understand dozens of massive embryonic stars in the Trifid Nebula (M20), which were discovered in images from two instruments aboard the Spitzer Space Telescope (right).

31 Enero 2005: NOAO Astronomer Steve Ridgway is part of a team that used the CHARA array on Mount Wilson to make detailed measurements of the physical properties of Regulus, the brightest star in Leo. They found that Regulus’ frenetic spin gives the star a grossly bulging mid-section; its equatorial diameter is one-third larger than its north-south diameter. The star’s axis of rotation happens to point in the same direction as its motion through the galaxy—meaning Regulus zips along like an enormous, spinning bullet.

27 Enero 2005: A long-standing problem in understanding the evolution of stars has been determining the nature of the stellar progenitors for white dwarf stars. In particular, astronomers want to know how a rather massive star (up to seven times the mass of the Sun) can lose enough mass to become a white dwarf. Key questions include: Which main-sequence stars eventually end their life as white dwarfs? How much mass do they lose in late evolutionary stages? What process allows this to occur? Some answers can be found in the 100th published paper based upon Gemini data. A Canadian, U.S., and Australian team led by Ph. D. student Jason Singh Kalirai of the University of British Columbia selected 24 individual white dwarfs[1] in the field of the rich open star cluster NGC 2099 (M37). This initial identification was made from analysis of deep wide-field imaging using the Canada-France-Hawaii Telescope. By following up on …

11 Enero 2005: A current rendering of the 8.4-meter Large Synoptic Survey Telescope (LSST) which will use a special three-mirror design, creating an exceptionally wide field of view. The LSST Corporation has awarded a $2.3 million contract to the University of Arizona Steward Observatory Mirror Lab to purchase the glass and begin engineering work for the 8.4-meter diameter main mirror that will enable the LSST to survey the visible sky in only three nights. LSST press release

2 Enero 2005: Like the annual New Year’s fireworks display, astronomers at Gemini Observatory are ushering in 2005 with a striking image that dazzles the eye with stellar pyrotechnics. In this new image, the face-on spiral galaxy NGC 6946 is ablaze with colorful outbursts fueled by the births and deaths of multitudes of brilliant, massive stars.