58 research outputs found
The Extragalactic Distance Database: Color-Magnitude Diagrams
The CMDs/TRGB (Color-Magnitude Diagrams/Tip of the Red Giant Branch) section
of the Extragalactic Distance Database contains a compilation of observations
of nearby galaxies from the Hubble Space Telescope. Approximately 250 (and
increasing) galaxies in the Local Volume have CMDs and the stellar photometry
tables used to produce them available through the web. Various stellar
populations that make up a galaxy are visible in the CMDs, but our primary
purpose for collecting and analyzing these galaxy images is to measure the TRGB
in each. We can estimate the distance to a galaxy by using stars at the TRGB as
standard candles. In this paper we describe the process of constructing the
CMDs and make the results available to the public.Comment: 8 pages, 5 figures, 1 long table, submitted to Astronomical Journa
Probe of dark galaxies via disturbed/ lopsided isolated galaxies
Searching for lopsided/interacting objects among ~1500 isolated galaxies
yields only eight strongly disturbed galaxies which may be explained as a
result of their interaction with massive dark objects. We present results of
spectral and photometric observations of these galaxies performed with the 6-m
telescope that lead to significant restriction on cosmic abundance of dark
galaxies.Comment: To appear in proceedings IAU Symp 244, 'Dark Galaxies and Lost
Baryons', June 200
Tip of the Red Giant Branch Distances. I. Optimization of a Maximum Likelihood Algorithm
Accurate distances to galaxies can be determined from the luminosities of
stars at the Tip of the Red Giant Branch (TRGB). We use a Maximum Likelihood
algorithm to locate the TRGB in galaxy color-magnitude diagrams. The algorithm
is optimized by introducing reliable photometric errors and a completeness
characterization determined with artificial star experiments. The program is
extensively tested using Monte-Carlo simulations, artificial galaxies, and a
sample of nearby dwarf galaxies observed with HST/WFPC2 and ACS. Our procedure
is shown to be reliable, to have good accuracy, and to not introduce any
systematic errors. The methodology is especially useful in cases where the TRGB
approaches the photometric limit and/or the RGB is poorly populated.Comment: submitted to A
Lena Delta hydrology and geochemistry: long-term hydrological data and recent field observations
The Lena River forms one of the largest deltas in the Arctic. We compare two sets of data to reveal new insights into the hydrological, hydrochemical, and geochemical processes within the delta: (i) long-term hydrometric observations at the Khabarova station at the head of the delta from 1951 to 2005; (ii) field hydrological and geochemical observations carried out within the delta since 2002. Periods with differing relative discharge and intensity of fluvial processes were identified from the long-term record of water and sediment discharge. Ice events during spring melt (high water) reconfigured branch channels and probably influenced sediment transport within the delta. Based on summer field measurements during 2005β2012 of discharge and sediment fluxes along main delta channels, both are increased between the apex and the front of the delta. This increase is to a great extent connected with an additional influx of water from tributaries, as well as an increase of suspended and dissolved material released from the ice complex. Summer concentrations of major ion and biogenic substances along the delta branches are partly explained by water sources within the delta, such as thawing ice complex waters, small Lena River branches and estuarine areas
Lignite from Central Watershed of the Yenisei River and Prospects for their use for Manufacture of Germanium
ΠΠΈΠ³Π½ΠΈΡΡ ΡΡΠ΅Π΄Π½Π΅Π³ΠΎ ΡΠ΅ΡΠ΅Π½ΠΈΡ Ρ. ΠΠ½ΠΈΡΠ΅ΠΉ, Π»ΠΎΠΊΠ°Π»ΠΈΠ·ΠΎΠ²Π°Π½Π½ΡΠ΅ Π² ΠΏΡΠ΅Π΄Π΅Π»Π°Ρ
ΠΌΠ΅Π·ΠΎΠΊΠ°ΠΉΠ½ΠΎΠ·ΠΎΠΉΡΠΊΠΈΡ
ΠΎΡΠ»ΠΎΠΆΠ΅Π½ΠΈΠΉ
ΠΠ°ΡΡΠΊΠΎΠΉ Π²ΠΏΠ°Π΄ΠΈΠ½Ρ, ΡΠ°ΡΡΠΌΠ°ΡΡΠΈΠ²Π°ΡΡΡΡ ΠΊΠ°ΠΊ Π½ΠΎΠ²ΡΠΉ ΠΏΠ΅ΡΡΠΏΠ΅ΠΊΡΠΈΠ²Π½ΡΠΉ ΠΈΡΡΠΎΡΠ½ΠΈΠΊ Π³Π΅ΡΠΌΠ°Π½ΠΈΠ΅Π²ΠΎΠ³ΠΎ ΡΡΡΡΡ
Π² Π ΠΎΡΡΠΈΠΈ. ΠΡΠΈΠ²Π΅Π΄Π΅Π½Ρ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΡ ΠΈΠ·ΡΡΠ΅Π½ΠΈΡ ΡΠΈΠ·ΠΈΠΊΠΎ-Ρ
ΠΈΠΌΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΠ²ΠΎΠΉΡΡΠ² ΠΈ ΡΠ΅Ρ
Π½ΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΉ, ΠΏΠΎΠ·Π²ΠΎΠ»ΡΡΡΠΈΠ΅ ΠΎΡΠ΅Π½ΠΈΡΡ Π²ΠΎΠ·ΠΌΠΎΠΆΠ½ΠΎΡΡΡ Π²ΡΠ΄Π΅Π»Π΅Π½ΠΈΡ Π³Π΅ΡΠΌΠ°Π½ΠΈΡ ΠΈΠ· Π»ΠΈΠ³Π½ΠΈΡΠΎΠ² Π² ΠΏΡΠΎΡΠ΅ΡΡΠ΅ ΠΈΡ
ΡΠΆΠΈΠ³Π°Π½ΠΈΡ Π΄Π»Ρ ΠΎΡΡΠ°Π±ΠΎΡΠΊΠΈ, Π° Π² ΠΏΠΎΡΠ»Π΅Π΄ΡΡΡΠ΅ΠΌ Π΄Π»Ρ ΠΏΡΠΎΠΌΡΡΠ»Π΅Π½Π½ΠΎΠΉ ΡΠ΅Ρ
Π½ΠΎΠ»ΠΎΠ³ΠΈΠΈ Π΅Π³ΠΎ ΠΈΠ·Π²Π»Π΅ΡΠ΅Π½ΠΈΡLignite from central watershed of the Yenisei river localized within the Meso-Cenozoic cavity deposit
considered as a promising new source of germanium raw materials in Russia. Germanium separating
possibility from lignite during the combustion process has been studied on the base of physical and
chemical properties research in order to develop the industrial technolog
ACS imaging of 25 galaxies in nearby groups and in the field
We present HST/ACS images and color-magnitude diagrams for 25 nearby galaxies
with radial velocities V_LG < 500 km/s. Distances are determined based on the
luminosities of stars at the tip of the red giant branch that range from 2 Mpc
to 12 Mpc. Two of the galaxies, NGC 4163 and IC 4662, are found to be the
nearest known representatives of blue compact dwarf (BCD) objects. Using
high-quality data on distances and radial velocities of 110 nearby field
galaxies, we derive their mean Hubble ratio to be 68 km/(s Mpc) with standard
deviation of 15 km/(s Mpc). Peculiar velocities of most of the galaxies, V_pec
= V_LG - 68 D, follow a Gaussian distribution with sigma_v = 63 km/s, but with
a tail towards high negative values. Our data displays the known correlation
between peculiar velocity and galaxy elevation above the Local Supercluster
plane. The small observed fraction of galaxies with high peculiar velocities,
V_pec < -500 km/s, may be understood as objects associated with nearby groups
(Coma I, Eridanus) outside the Local volume.Comment: 17 pages, 8 figures, accepted to A
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