160 research outputs found
Host Range Extension for \u3ci\u3eChlorochlamys Chloroleucaria\u3c/i\u3e (Geometrinae, Geometridae) to Include \u3ci\u3eEriogonum Alatum\u3c/i\u3e (Polygonaceae)
(excerpt)
Chlorochlamys chloroleucaria (Guenée) is a common moth of eastern North America, recorded from Nova Scotia south to Cuba and Mexico and as far west as Manitoba, the Black Hills of South Dakota, Wyoming and central Colorado (Boulder and El Paso counties) (Ferguson 1985)
Host Range Extension for \u3ci\u3eChlorochlamys chloroleucaria\u3c/i\u3e (Geometrinae, Geometridae) to Include \u3ci\u3eEriogonum alatum\u3c/i\u3e (Polygonaceae)
In 2001 and 2002 we collected specimens of Chlorochlamys chloroleucaria from Eriogonum alatum Torr., winged false buckwheat. Eriogonum alatum occurs at elevations of 5000-10,000 feet on both sides of the Rocky Mountains, from Utah (Welsh et al. 1987) to western Nebraska, southeastern Wyoming (Dorn 1977) to western Oklahoma and the Texas panhandle to Arizona (Great Plains Flora Association 1986)
Host Range Extension for \u3ci\u3eChlorochlamys chloroleucaria\u3c/i\u3e (Geometrinae, Geometridae) to Include \u3ci\u3eEriogonum alatum\u3c/i\u3e (Polygonaceae)
In 2001 and 2002 we collected specimens of Chlorochlamys chloroleucaria from Eriogonum alatum Torr., winged false buckwheat. Eriogonum alatum occurs at elevations of 5000-10,000 feet on both sides of the Rocky Mountains, from Utah (Welsh et al. 1987) to western Nebraska, southeastern Wyoming (Dorn 1977) to western Oklahoma and the Texas panhandle to Arizona (Great Plains Flora Association 1986)
The IR Luminosity Functions of Rich Clusters
We present MIPS observations of the cluster A3266. About 100 spectroscopic
cluster members have been detected at 24 micron. The IR luminosity function in
A3266 is very similar to that in the Coma cluster down to the detection limit
L_IR~10^43 ergs/s, suggesting a universal form of the bright end IR LF for
local rich clusters with M~10^15 M_sun. The shape of the bright end of the
A3266-Coma composite IR LF is not significantly different from that of nearby
field galaxies, but the fraction of IR-bright galaxies (SFR > 0.2M_sun/yr) in
both clusters increases with cluster-centric radius. The decrease of the blue
galaxy fraction toward the high density cores only accounts for part of the
trend; the fraction of red galaxies with moderate SFRs (0.2 < SFR < 1 M_sun/yr)
also decreases with increasing galaxy density. These results suggest that for
the IR bright galaxies, nearby rich clusters are distinguished from the field
by a lower star-forming galaxy fraction, but not by a change in L*_IR. The
composite IR LF of Coma and A3266 shows strong evolution when compared with the
composite IR LF of two z~0.8 clusters, MS 1054 and RX J0152, with L*_IR \propto
(1+z)^{3.2+/-0.7},Phi*_IR \propto (1+z)^{1.7+/-1.0}. This L*_IR evolution is
indistinguishable from that in the field, and the Phi*_IR evolution is
stronger, but still consistent with that in the field. The similarity of the
evolution of bright-end IR LF in very different cluster and field environments
suggests either this evolution is driven by the mechanism that works in both
environments, or clusters continually replenish their star-forming galaxies
from the field, yielding an evolution in the IR LF that is similar to the
field. The mass-normalized integrated star formation rates (SFRs) of clusters
within 0.5R_200 also evolve strongly with redshift, as (1+z)^5.3.Comment: 15 pages, 8 figures, 1 table, accepted by Ap
Is NGC 3108 transforming itself from an early to late type galaxy -- an astronomical hermaphrodite?
A common feature of hierarchical galaxy formation models is the process of
"inverse" morphological transformation: a bulge dominated galaxy accretes a gas
disk, dramatically reducing the system's bulge-to-disk mass ratio. During their
formation, present day galaxies may execute many such cycles across the Hubble
diagram. A good candidate for such a "hermaphrodite" galaxy is NGC 3108: a
dust-lane early-type galaxy which has a large amount of HI gas distributed in a
large scale disk. We present narrow band H_alpha and R-band imaging, and
compare the results with the HI distribution. The emission is in two
components: a nuclear bar and an extended disk component which coincides with
the HI distribution. This suggests that a stellar disk is currently being
formed out of the HI gas. The spatial distributions of the H_alpha and HI
emission and the HII regions are consistent with a barred spiral structure,
extending some 20 kpc in radius. We measure an extinction- corrected SFR of
0.42 Msun/yr. The luminosity function of the HII regions is similar to other
spiral galaxies, with a power law index of -2.1, suggesting that the star
formation mechanism is similar to other spiral galaxies. We measured the
current disk mass and find that it is too massive to have been formed by the
current SFR over the last few Gyr. It is likely that the SFR in NGC 3108 was
higher in the past. With the current SFR, the disk in NGC 3108 will grow to be
~6.2x10^9 Msun in stellar mass within the next 5.5 Gyr. While this is
substantial, the disk will be insignificant compared with the large bulge mass:
the final stellar mass disk-to-bulge ratio will be ~0.02. NGC 3108 will fail to
transform into anything resembling a spiral without a boost in the SFR and
additional supply of gas.Comment: 9 pages, 3 figures, accepted for publication in MNRA
The 2dF Galaxy Redshift Survey: the blue galaxy fraction and implications for the Butcher—Oemler effect
We derive the fraction of blue galaxies in a sample of clusters at z < 0.11 and the general field at the same redshift. The value of the blue fraction is observed to depend on the luminosity limit adopted, cluster-centric radius and, more generally, local galaxy density, but it does not depend on cluster properties. Changes in the blue fraction are due to variations in the relative proportions of red and blue galaxies but the star formation rate for these two galaxy groups remains unchanged. Our results are most consistent with a model where the star formation rate declines rapidly and the blue galaxies tend to be dwarfs and do not favour mechanisms where the Butcher-Oemler effect is caused by processes specific to the cluster environmen
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