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Astronomers detect dark matter halo around ancient dwarf galaxy（图）
Astronomers detect dark matter halo ancient dwarf galaxy
2021/3/5
The Milky Way is surrounded by dozens of dwarf galaxies thought to be relics of the first galaxies in the universe. Among the most primitive of these galactic fossils is Tucana II -- an ultrafaint dwa...
New way to weigh a white dwarf:Use the Hubble Space Telescope
white dwarf Hubble Space Telescope
2017/7/21
Astronomers have used, for the first time, a novel method to determine the mass of a nearby dead star. The star is a "white dwarf," the shrunken corpse of a star like our sun after it has burned up it...
Dwarf galaxies are enigmas wrapped in riddles. Although they are the smallest galaxies, they represent some of the biggest mysteries about our universe. While many dwarf galaxies surround our own Milk...
Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA)have discovered that a dim, cool dwarf star is generating a surprisingly powerful magnetic field, one that rivals the most...
Dark matter is called "dark" for a good reason. Although they outweigh particles of regular matter by more than a factor of 5, particles of dark matter are elusive. Their existence is inferred by thei...
A Two Micron All Sky Survey view of the Sagittarius dwarf galaxy. I. Morphology of the Sagittarius core and tidal arms
the Sagittarius core tidal arms
2014/12/24
We present the first all-sky view of the Sagittarius (Sgr) dwarf galaxy mapped by M-giant star tracers detected in the complete Two Micron All Sky Survey (2MASS). Near-infrared photometry of Sgr's pro...
Dark Matter Constraints from the Sagittarius Dwarf and Tail System
the Sagittarius Dwarf Tail System
2014/12/24
2MASS has provided a three-dimensional map of the >360 degree, wrapped tidal tails of the Sagittarius (Sgr) dwarf spheroidal galaxy, as traced by M giant stars. With the inclusion of radial velocity d...
A Two Micron All Sky Survey view of the Sagittarius dwarf galaxy. II. Swope telescope spectroscopy of M giant stars in the dynamically cold Sagittarius tidal stream
kinematics halo
2014/12/24
We have obtained moderate resolution (~6 km s-1) spectroscopy of several hundred M giant candidates selected from Two Micron All Sky Survey photometry. Radial velocities are presented for stars mainly...
The 2Mass Color-magnitude Diagram of the Center of the Sagittarius Dwarf Galaxy: Photometric Measurements of a Surprisingly High Mean Metallicity
abundances stellar
2014/12/23
We present the Two Micron All Sky Survey (2MASS) (J−K, K) color-magnitude diagram for the region within 1◦ of the center of the Sagittarius dwarf spheroidal galaxy. Using the slope of the ...
Using dark matter halos traced by galaxy groups selected from the Sloan Digital Sky Survey Data Release 4, we find that about 1/4 of the faint galaxies (0.1 Mr – 5log h> – 17.05, hereafter dwarfs) tha...
COMPARISON OF H alpha AND UV STAR FORMATION RATES IN THE LOCAL VOLUME: SYSTEMATIC DISCREPANCIES FOR DWARF GALAXIES
evolution dwarf
2014/12/23
Using a complete sample of ~300 star-forming galaxies within 11 Mpc of the Milky Way, we evaluate the consistency between star formation rates (SFRs) inferred from the far ultraviolet (FUV) non-ionizi...
We present a study of the variation of spatial structure of stellar populations within dwarf galaxies as a function of the population age. We use deep Hubble Space Telescope/Advanced Camera for Survey...
Failed dwarf galaxy survives galactic collision thanks to full dark-matter jacket
Failed dwarf galaxy survives galactic collision thanks full dark-matter jacket
2014/6/19
Like a bullet wrapped in a full metal jacket, a high-velocity hydrogen cloud hurtling toward the Milky Way appears to be encased in a shell of dark matter, according to a new analysis of data from the...
The Search for High-Mass X-ray Binaries in the Phoenix Dwarf Galaxy
High-Mass X-ray Binaries Phoenix Dwarf Galaxy
2012/2/23
We report on the first X-ray images of the Phoenix dwarf galaxy, taken with \emph{XMM-Newton} in July 2009. This local group dwarf galaxy shares similarities with the Small Magellanic Cloud (SMC) incl...
The Resolved Structure and Dynamics of an Isolated Dwarf Galaxy: A VLT and Keck Spectroscopic Survey of WLM
Resolved Structure Dynamics Isolated Dwarf Galaxy VLT Keck Spectroscopic Survey WLM
2012/2/23
We present spectroscopic data for 180 red giant branch stars in the isolated dwarf irregular galaxy WLM. Observations of the Calcium II triplet lines in spectra of RGB stars covering the entire galaxy...