1,745 research outputs found
Five new lichen species (Ascomycota) and a new record from southern New South Wales, Australia
Five lichen species (Ascomycota) are described as new from rocks in coastal and tableland localities of southern New South Wales: Catillaria gerroana P.M.McCarthy & Elix (Catillariaceae), Fellhanera robusta P.M.McCarthy & Elix (Pilocarpaceae), Menegazzia fortuita Elix & P.M.McCarthy (Parmeliaceae), Ramboldia curvispora P.M.McCarthy & Elix (Lecanoraceae) and Sarcogyne maritima P.M.McCarthy & Elix (Acarosporaceae). Arthonia lapidicola (Taylor) Branth & Rostrup (Arthoniaceae) is reported for the first time from Australia
Starburst-driven superwinds from infrared galaxies
New data is presented that indicate that strong far infrared galaxies commonly have largescale emission line nebulae whose properties are suggestive of mass outflows (superwinds), presumably driven by the high supernova rate associated with the central starburst. These data include longslit spectra of M82 which show that the radial variation of the gas pressure in the emission line nebula is in excellent agreement with a previous wind model. The M82 nebula also has a LINER spectrum, consistent with shock heating. Morphologically and spectroscopically similar emission line nebulae were found in NGC253, and Arp 220 and NGC6240. A longslit spectroscopic investigation was conducted of 20 additional very powerful far-infrared galaxies and found that they generally have spatially extended emission line nebulae whose spectra closely resemble that of the M82 nebula. If the superwind interpretation is correct, it could have many important consequences in extragalactic astronomy
Very Red and Extremely Red Galaxies in the Fields of z ~ 1.5 Radio-Loud Quasars
We previously identified an excess of mostly red galaxies around 31 RLQs at
z=1-2. These fields have an ERO (extremely red object, R-K>6) density 2.7 times
higher than the field. Assuming the EROs are passively evolved galaxies at the
quasar redshifts, they have characteristic luminosities of only ~L^*. We also
present new observations of four z~1.54 RLQ fields: (1) Wide-field J & Ks data
confirm an Abell richness ~2 excess within 140" of Q0835+580 but an excess only
within 50" of Q1126+101. (2) In 3 fields we present deep narrow-band redshifted
H-alpha observations. We detect five candidate galaxies at the quasar
redshifts, a surface density 2.5x higher than the field. (3) SCUBA sub-mm
observations of 3 fields detect 2 quasars and 2 galaxies with SEDs best fit as
highly reddened galaxies at the quasar z. (4) H-band adaptive optics (AO)
imaging is used to estimate redshifts for 2 red, bulge-dominated galaxies using
the Kormendy relation. Both have structural redshifts foreground to the quasar,
but these are not confirmed by photometric redshifts, possibly because their
optical photometry is corrupted by scattered light from the AO guidestar. (5)
We use quantitative SED fits to constrain the photometric redshifts z_ph for
some galaxies. Most galaxies near Q0835+580 are consistent with being at its
redshift, including a candidate very old passively evolving galaxy. Many very &
extremely red objects have z_ph z_q, and dust reddening is required to fit most
of them, including many objects whose fits also require relatively old stellar
populations. Large reddenings of E(B-V)~0.6 are required to fit four J-K
selected EROs, though all but one of them have best-fit z_ph>z_q. These objects
may represent a population of dusty high-z galaxies underrepresented in
optically selected samples. (Abridged)Comment: Missing object 1126.424 added to Table 4; title changed to save
people the apparent trouble of reading the abstract. 38 pages, 16 figures, 2
in color; all-PostScript figure version available from
http://astro.princeton.edu/~pathall/tp3.ps.g
Star Formation in Emission-Line Galaxies Between Redshifts of 0.8 and 1.6
Optical spectra of 14 emission-line galaxies representative of the 1999
NICMOS parallel grism Ha survey of McCarthy et al. are presented. Of the 14, 9
have emission lines confirming the redshifts found in the grism survey. The
higher resolution of our optical spectra improves the redshift accuracy by a
factor of 5. The [O II]/Ha values of our sample are found to be more than two
times lower than expected from Jansen et al. This [O II]/Ha ratio discrepancy
is most likely explained by additional reddening in our Ha-selected sample [on
average, as much as an extra E(B-V) = 0.6], as well as to a possible stronger
dependence of the [O II]/Ha ratio on galaxy luminosity than is found in local
galaxies. The result is that star formation rates (SFRs) calculated from [O
II]3727 emission, uncorrected for extinction, are found to be on average 4 +/-
2 times lower than the SFRs calculated from Ha emission. Classification of
emission-line galaxies as starburst or Seyfert galaxies based on comparison of
the ratios [O II]/Hb and [Ne III]3869/Hb is discussed. New Seyfert 1
diagnostics using the Ha line luminosity, H-band absolute magnitude, and Ha
equivalent widths are also presented. One galaxy is classified as a Seyfert 1
based on its broad emission lines, implying a comoving number density for
Seyfert 1s of 2.5{+5.9, -2.1} times 10^{-5} Mpc^{-3}. This commoving number
density is a factor of 2.4{+5.5,-2.0} times higher than estimated by other
surveys.Comment: 51 pages, 18 figures; Accepted for publication in the Astrophysical
Journal; Revised version with minor changes and an additional reference which
gives further support to our conclusion
Six new lichen species (Ascomycota) from Australia
Six lichens (Ascomycota) are described as new from Australia: Bapalmuia rotatilis P.M.McCarthy & Elix (Pilocarpaceae; southern New South Wales), Fellhanera incolorata P.M.McCarthy & Elix (Pilocarpaceae; southern New South Wales), Opegrapha gilmorei P.M.McCarthy & Elix (Opegraphaceae; Bass Strait, Tasmania), Protoparmelia ewersii Elix & P.M.McCarthy (Parmeliaceae; Northern Territory, South Australia), Ramboldia buleensis Elix & P.M.McCarthy (Lecanoraceae; southern New South Wales) and R. subplicatula Elix & P.M.McCarthy (central-western New South Wales)
Extragalactic Fields Optimized for Adaptive Optics
In this paper we present the coordinates of 67 55' x 55' patches of sky which
have the rare combination of both high stellar surface density (>0.5
arcmin^{-2} with 13<R<16.5 mag) and low extinction (E(B-V)<0.1). These fields
are ideal for adaptive-optics based follow-up of extragalactic targets. One
region of sky, situated near Baade's Window, contains most of the patches we
have identified. Our optimal field, centered at RA: 7h24m3s, Dec: -1deg27'15",
has an additional advantage of being accessible from both hemispheres. We
propose a figure of merit for quantifying real-world adaptive optics
performance, and use this to analyze the performance of multi-conjugate
adaptive optics in these fields. We also compare our results to those that
would be obtained in existing deep fields. In some cases adaptive optics
observations undertaken in the fields given in this paper would be orders of
magnitude more efficient than equivalent observations undertaken in existing
deep fields.Comment: 28 pages, 15 figures, 1 table; accepted for publication in PAS
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