Smithsonian at the Poles: Contributions to International Polar

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WHAT IS THIS GAS DOING? Much has been learned about dense gas in the Galactic Center region through radio spectroscopy. Early observations of F(2 j 2) OH absorption (Robinson et al., 1964; Goldstein et al., 1964) suggested the existence of copious molecular material within 500 pc of the Galactic Center. This was confi rmed by detection of extensive J � 1 j 0 12 CO emission (Bania, 1977; Liszt and Burton, 1978). Subsequent CO surveys (Bitran, 1987; Stark et al., 1988; Bitran et al., 1997; Oka et al., 1998) have measured this emission with improving coverage and resolution. These surveys show a complex distribution of emission, which is chaotic, asymmetric, and nonplanar; there are hundreds of clouds, shells, arcs, rings, and fi laments. On scales of 100 pc to 4 kpc, however, the gas is loosely organized around closed orbits in the rotating potential of the underlying stellar bar (Binney et al., 1991). Some CO-emitting gas is bound into clouds and cloud complexes, and some is sheared by tidal forces into a molecular intercloud medium of a kind not seen elsewhere in the galaxy (Stark et al., 1989). The large cloud complexes, Sgr A, Sgr B, and Sgr C, are the among the largest molecular cloud complexes in the galaxy (M � 10 6.5 Msun). Such massive clouds must be sinking toward the center of the galactic gravitational well as a result of dynamical friction and hydrodynamic effects (Stark et al., 1991). The deposition of these massive lumps of gas upon the center could fuel a starburst or an eruption AST/RO BLACK HOLE OBSERVATIONS 371 FIGURE 2. Spatial– spatial (l, b) integrated intensity maps for the three transitions observed with AST/RO. Transitions are identifi ed at the left on each panel. The emission is integrated over all velocities where data are available. All three maps have been smoothed to the same 2� resolution. Electronic versions of results from this region as published in Martin et al. (2004) may be requested from the author via e-mail. of the central black hole (Genzel and Townes, 1987; Stark et al., 2004). To better understand the molecular gas of the Galactic Center, we need to determine its physical state— its temperature and density. This involves understanding radiative transfer in CO, the primary tracer of molecular gas. Also useful would be an understanding of the atomic carbon lines, [CI], since those lines trace the more diffuse molecular regions, where CO is destroyed by UV radiation but H2 is still present. Hence, a key project of the Antarctic Submillimeter Telescope and Remote Observatory reported by Martin et al. (2004) has been the mapping of CO 4– 3 and CO 7– 6 emission from the inner Milky Way, allowing determination of gas density and temperature. Galactic Center gas that Binney et al. (1991) identify as being on x2 orbits has a density near 10 3.5 cm 3 , which renders it only marginally stable against gravitational coagulation into a few giant molecular clouds. This suggests a relaxation oscillator mechanism for starbursts in the Milky Way, whereby infl owing gas accumulates in a ring at 150-pc radius until the critical density is reached and the resulting instability leads to the sudden formation of giant clouds and the deposition of 4 � 10 7 Msun, of gas onto the Galactic Center. Depending on the accretion rate near the inner Lindblad resonance, this cycle will repeat with a timescale on the order of 20 Myr, leading to starbursts on the same timescale. When we analyze our data (Stark et al., 2004), we
372 SMITHSONIAN AT THE POLES / MARTIN observe gas approaching this density and thus beginning the next stage of its long descent in the black hole at the heart of our galaxy. In the Thanksgiving feast analogy, the gas that we can see coagulating on these outer orbits and beginning its slow trip inward is the future dinner for the black hole at the center of our galaxy. When it arrives at the center of the galaxy, it will provide the fuel for a burst of star formation activity (a starburst) at the very heart of the Milky Way and, hence, for the fi reworks that will light up our night skies in the millennia to come. ACKNOWLEDGMENTS This research was supported in part by the National Science Foundation under NSF grant number ANT- 0126090 and was conducted with the assistance of the many collaborators of the Antarctic Submillimeter Telescope Remote Observatory (AST/RO). LITERATURE CITED Bania, T. M. 1977. Carbon Monoxide in the Inner Galaxy. Astrophysical Journal, 216: 381– 403. Binney, J., O. E. Gerhard, A. A. Stark, J. Bally, and K. I. Uchida. 1991. Understanding the Kinematics of Galactic Centre Gas. Monthly Notices of the Royal Astronomical Society, 252: 210– 218. Bitran, M., H. Alvarez, L. Bronfman, J. May, and P. Thaddeus. 1997. A Large Scale CO Survey of the Galactic Center Region. Astronomy and Astrophysics, Supplement Series, 125: 99– 138. Bitran, M. E. 1987. CO in the Galactic Center: A Complete Survey of CO Emission in the Inner 4 kpc of the Galaxy. Ph.D. diss., University of Florida, Gainesville. Chamberlin, R. A., A. P. Lane, and A. A. Stark. 1997. The 492 GHz Atmospheric Opacity at the Geographic South Pole. Astrophysical Journal, 476: 428– 433. Genzel, R., and C. H. Townes. 1987. Physical Conditions, Dynamics, and Mass Distribution in the Center of the Galaxy. Annual Review of Astronomy and Astrophysics, 25: 377– 423. Goldstein, S. J., E. J. Gundermann, A. A. Penzias, and A. E. Lilley. 1964. OH Absorption Spectra in Sagittarius. Nature, 203: 65– 66. Kim, S., C. L. Martin, A. A. Stark, and A. P. Lane. 2002. AST/RO Observations of CO J � 7j6 and J � 4j3 Emission toward the Galactic Center Region. Astrophysical Journal, 580: 896– 903. Lane, A. P. 1998. “Submillimeter Transmission at South Pole.” In Astrophysics From Antarctica, ed. G. Novack and R. H. Landsberg, p. 289. Astronomical Society of the Pacifi c Conference Series, No. 141. San Francisco: Astronomical Society of the Pacifi c. Liszt, H. S., and W. B. Burton. 1978. The Gas Distribution in the Central Region of the Galaxy. II— Carbon Monoxide. Astrophysical Journal, 226: 790– 816. Martin, C. L., W. M. Walsh, K. Xiao, A. P. Lane, C. K. Walker, and A. A. Stark. 2004. The AST/RO Survey of the Galactic Center Region I. The Inner 3 Degrees. Astrophysical Journal, Supplement Series, 150: 239– 262. Ojha, R., A. A. Stark, H. H. Hsieh, A. P. Lane, R. A. Chamberlin, T. M. Bania, A. D. Bolatto, J. M. Jackson, and G. A. Wright. 2001. AST/ RO Observations of Atomic Carbon near the Galactic Center. Astrophysical Journal, 548: 253– 257. Oka, T., T. Hasegawa, F. Sato, M. Tsuboi, and A. Miyazaki. 1998. A Large-Scale CO Survey of the Galactic Center. Astrophysical Journal, Supplement Series, 118: 455– 515. Robinson, B. J., F. F. Gardner, K. J. van Damme, and J. G. Bolton. 1964. An Intense Concentration of OH Near the Galactic Centre. Nature, 202: 989– 991. Stark, A. A., J. Bally, G. R. Knapp, and R. W. Wilson. 1988. “The Bell Laboratories CO Survey.” In Molecular Clouds in the Milky Way and External Galaxies, ed. R. L. Dickman, R. L. Snell, and J. S. Young, p. 303. New York: Springer-Verlag. Stark, A. A., J. Bally, R. W. Wilson, and M. W. Pound. 1989. “Molecular Line Observations of the Galactic Center Region.” In The Center of the Galaxy: Proceedings of the 136th Symposium of the International Astronomical Union, ed. M. Morris, p. 129. Dordrecht: Kluwer Academic Publishers. Stark, A. A., J. Bally, O. E. Gerhard, and J. Binney. 1991. On the Fate of Galactic Centre Molecular Clouds. Monthly Notices of the Royal Astronomical Society, 248: 14P– 17PP. Stark, A. A., J. Bally, S. P. Balm, T. M. Bania, A. D. Bolatto, R. A. Chamberlin, G. Engargiola, M. Huang, J. G. Ingalls, K. Jacobs, J. M. Jackson, J. W. Kooi, A. P. Lane, K.-Y. Lo, R. D. Marks, C. L. Martin, D. Mumma, R. Ojha, R. Schieder, J. Staguhn, J. Stutzki, C. K. Walker, R. W. Wilson, G. A. Wright, X. Zhang, P. Zimmermann, and R. Zimmermann. 2001. The Antarctic Submillimeter Telescope and Remote Observatory (AST/RO). Publications of the Astronomical Society of the Pacifi c, 113: 567– 585. Stark, A. A., C. L. Martin, W. M. Walsh, K. Xiao, A. P. Lane, and C. K. Walker. 2004. Gas Density, Stability, and Starbursts near the Inner Lindblad Resonance of the Milky Way. Astrophysical Journal Letters, 614: L41– L44.
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Smithsonian at the Poles Contributi
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Contents FOREWORD by Ira Rubinoff i
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Elaina Jorgensen, Alaska Fisheries
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CONTENTS vii Watching Star Birth fr
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x SMITHSONIAN AT THE POLES blooms i
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xii SMITHSONIAN AT THE POLES Change
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xiv SMITHSONIAN AT THE POLES Museum
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Advancing Polar Research and Commun
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James P. Espy (1785- 1860), the fi
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ology fueled hopes that the scienti
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Meteorologists also provided critic
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visualize weather patterns remotely
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in ice sheets. The latest collapse
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Cooperation at the Poles? Placing t
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British Association for the Advance
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cations, in which the Smithsonian s
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ence” (Robinson, 2006: 76), he ha
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Taylor, C. J. 1981. First Internati
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24 SMITHSONIAN AT THE POLES / KORSM
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36 SMITHSONIAN AT THE POLES / De VO
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From Ballooning in the Arctic to 10
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ern Svalbard in 1896 (Capelotti, 19
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FIGURE 2. The Andrée campsite in 1
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National Zoo in Washington, D.C.—
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FROM BALLOONING TO 10,000-FOOT RUNW
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e rapidly deployed to South America
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“Of No Ordinary Importance”: Re
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1942). Ethnological collecting had
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group. More importantly, Murdoch’
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gan to study the question of Indian
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small museums and culture centers i
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fer of Alaskan objects and informat
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fi rst time in polar research— di
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Boas, Franz. 1888a. “The Central
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Lindsay, Debra. 1993. Science in th
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80 SMITHSONIAN AT THE POLES / FIENU
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90 SMITHSONIAN AT THE POLES / BURCH
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100 SMITHSONIAN AT THE POLES / CROW
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From Tent to Trading Post and Back
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in befriending an extraordinary Inu
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The Smithsonian Institution’s pre
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of departure for research during th
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FIGURE 8. A drawing of the so-calle
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situated experiential education and
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the Past: Archaeologists, Native Am
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Brooding and Species Diversity in t
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iefl y consider below some of the i
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ment. Consequently, the selective e
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ated from the Antarctic. Strong cur
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the four main genera of brooding sc
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ing such cryptic speciation suggest
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LITERATURE CITED Absher, T. M., G.
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Madon-Senez, C. 1998. Disparité Mo
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Persistent Elevated Abundance of Oc
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ABUNDANCE OF ANTARCTIC OCTOPODS 199
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Considerations of Anatomy, Morpholo
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Many theories have been hypothesize
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FIGURE 4. A three dimensional recon
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are wider and more bulbous in the a
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mimicked the shape and profi le of
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faces for SEM observation. The spec
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DISCUSSION Imaging and dissection o
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out its length. The pulp chamber al
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pulpal neurons and dentin tubules.
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Scientifi c Diving Under Ice: A 40-
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TABLE 2. Principal Investigators an
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attaching ice anchors to the chunks
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dumping of weight under water. The
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MARINE LIFE HAZARDS Few polar anima
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Urine should be copious and clear a
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Environmental and Molecular Mechani
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face (�1.8°C) are likely to pose
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FIGURE 2. Illustrated selection shi
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FIGURE 4. Distribution of respirati
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invertebrates were placed in the ba
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Meehan, R. R., D. S. Dunican, A. Ru
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272 SMITHSONIAN AT THE POLES / DUNT
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Page 352 and 353: Capital Expenditure and Income (For
Page 354 and 355: tal breeding systems (Boyd, 1998; T
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Page 366 and 367: and perhaps others, may have invade
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Page 370 and 371: due in part to the great distances
Page 372 and 373: and (2) human-mediated responses to
Page 374 and 375: Lewis, P. N., M. Riddle, and C. L.
Page 376 and 377: Cosmology from Antarctica Robert W.
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Page 380 and 381: TELESCOPES AND INSTRUMENTS AT THE S
Page 382 and 383: Gaier, T., J. Schuster, and P. Lubi
Page 384: J. M. Kovac, C. L. Kuo, A. E. Lange
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Page 398 and 399: Watching Star Birth from the Antarc
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Page 404 and 405: Antarctic Meteorites: Exploring the
Page 406 and 407: at the Field Museum, and pieces wer
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Page 410 and 411: led these committees throughout the
Page 412 and 413: Index AAUS. See American Academy of
Page 414 and 415: temperature, 350-355 tourism, 354 B
Page 416 and 417: Fishing. See also Biological invasi
Page 418 and 419: McMurdo Station, xiv, 265-267, 393
Page 420 and 421: Rogick, Mary, 206 Ronne, Finn, 55 R
Page 422: U.S. Naval Support Force Antarctica
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