scholarly journals The Far-away Blues: Exploring the Furthest Extents of the Boötes I Ultra-faint Dwarf Galaxy

2021 ◽  
Vol 923 (2) ◽  
pp. 218
Author(s):  
Carrie Filion ◽  
Rosemary F. G. Wyse
Keyword(s):  
Stellar Population ◽  
Dwarf Galaxy ◽  
Apparent Magnitude ◽  
Horizontal Branch ◽  
Stellar Content ◽  
Dynamical Models ◽  
Tidal Interactions ◽  
Horizontal Branch Stars ◽  
Blue Straggler

Abstract Establishing the spatial extents and the nature of the outer stellar populations of dwarf galaxies is necessary for the determination of their total masses, current dynamical states, and past evolution. We here describe our investigation of the outer stellar content of the Boötes I ultra-faint dwarf galaxy, a satellite of the the Milky Way. We identify candidate member blue horizontal branch and blue straggler stars of Boötes I, both tracers of the underlying ancient stellar population, using a combination of multiband Pan-STARRS photometry and Gaia astrometry. We find a total of twenty-four candidate blue horizontal branch member stars with apparent magnitudes and proper motions consistent with membership of Boötes I, nine of which reside at projected distances beyond the nominal King profile tidal radius derived from earlier fits to photometry. We also identify four blue straggler stars of appropriate apparent magnitude to be at the distance of Boötes I, but all four are too faint to have high-quality astrometry from Gaia. The outer blue horizontal branch stars that we have identified confirm that the spatial distribution of the stellar population of Boötes I is quite extended. The morphology on the sky of these outer envelope candidate member stars is evocative of tidal interactions, a possibility that we explore further with simple dynamical models.

scholarly journals Determination of the OB Stellar Population of IZw18 on the Basis of its Hγ and Hδ Absorption lines

1999 ◽  
Vol 194 ◽  
pp. 444-447
Author(s):  
A. Sinanyan ◽  
D. Kunth ◽  
J. Lequeux ◽  
G. Comte ◽  
A. Petrosian
Keyword(s):  
Spectral Range ◽  
Stellar Population ◽  
Dwarf Galaxy ◽  
Absorption Lines ◽  
Spectroscopic Observations ◽  
Narrow Spectral Range ◽  
Blue Compact Dwarf Galaxy

On the basis of new spectroscopic observations of the blue compact dwarf galaxy IZw18 in the narrow spectral range between 4000Å and 4500Å absorption components of Hγ and Hδ lines were discovered. Equivalent widths of Hγ and Hδ lines have been measured. From available data the OB population of IZw18 was analyzed.

scholarly journals The star formation history of the Fornax dwarf spheroidal galaxy

2009 ◽  
Vol 5 (S262) ◽  
pp. 353-354
Author(s):  
Enrico V. Held ◽  
Eline Tolstoy ◽  
Luca Rizzi ◽  
Mary Cesetti ◽  
Andrew A. Cole ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Stellar Population ◽  
Main Sequence ◽  
Dwarf Galaxy ◽  
Star Formation History ◽  
Stellar Content ◽  
Formation History ◽  
First Results ◽  
History Of

AbstractWe present the first results of a comprehensive HST study of the star-formation history of Fornax dSph, based on WFPC2 imaging of 7 Fornax fields. Our observations reach the oldest main-sequence turnoffs, allowing us to address fundamental questions of dwarf galaxy evolution, such as the spatial variations in the stellar content, and whether the old stellar population is made up of stars formed in a very early burst or the result of a more continuous star formation.

scholarly journals CCD Photometry in the Core of the Fornax Dwarf Galaxy

1988 ◽  
Vol 126 ◽  
pp. 583-584
Author(s):  
Robert M. Light ◽  
P. Seitzer
Keyword(s):  
Globular Clusters ◽  
Stellar Population ◽  
Dwarf Galaxy ◽  
Field Population ◽  
Ccd Photometry ◽  
The Core ◽  
The Galaxy ◽  
Good Determination ◽  
Giant Branch Stars

The present study is concerned with the examination of properties of stars in the core of the Fornax dwarf spheroidal galaxy. Previous studies have shown that Fornax has a very diverse stellar population. Four of the globular clusters associated with Fornax were found to have metallicities significantly lower than the mean metallicity of the field population of the galaxy (Buonanno et al. 1985); these clusters point out an older, metal-poor population. Also, there are a number of luminous carbon stars, which are indicative of a much younger population (see Mould and Aaronson 1986). Studies of the field population of Fornax (Demers, Kunkel, and Hardy, 1979; Buonanno et al., 1985) have shown a dispersion in metallicity. We have measured a large sample of giant branch stars, enabling a good determination of mean properties of the Fornax stellar population, as well as allowing a comparison of stars as a function of distance from the center of Fornax.

Semi-Empirical Determination of the Mass Distribution of Horizontal Branch Stars in M3

2007 ◽  
Author(s):  
Aldo A. R. Valcarce ◽  
Márcio Catelan ◽  
Richard J. Stancliffe ◽  
Guenter Houdek ◽  
Rebecca G. Martin ◽  
...  
Keyword(s):  
Mass Distribution ◽  
Horizontal Branch ◽  
Horizontal Branch Stars ◽  
Empirical Determination ◽  
Semi Empirical

scholarly journals The Stellar Populations of M32: Resolving the nearest elliptical with HST ACS/HRC

2009 ◽  
Vol 5 (S262) ◽  
pp. 135-138 ◽  
Author(s):  
Antonela Monachesi ◽  
S. C. Trager ◽  
Tod R. Lauer ◽  
Wendy Freedman ◽  
Alan Dressler ◽  
...  
Keyword(s):  
Stellar Population ◽  
Asymptotic Giant Branch ◽  
Asymptotic Giant Branch Stars ◽  
Horizontal Branch ◽  
Horizontal Branch Stars ◽  
Magnitude Diagram ◽  
Colour Distribution ◽  
Red Clump ◽  
Red Giant ◽  
Giant Branch Stars

AbstractWe present the deepest colour-magnitude diagram (CMD) of M32 to date, obtained from deep (F435W, F555W) photometry of HST ACS/HRC images. Due to the high resolution of our images, the small photometric errors, and the completeness level of our data we obtain the most detailed resolved photometric study of M32 to date. The CMD of M32 displays a wide colour distribution of red giant branch stars, mainly due to a metallicity spread, a strong red clump and bright asymptotic giant branch stars. The detection of a “blue plume” in M32 indicates the presence of a very young stellar population. There is not a noticeable presence of blue horizontal branch stars, suggesting that an old population with [Fe/H] < −1.5 does not significantly contribute to the light or mass of M32 in our observed fields.

scholarly journals CHEMICAL AND KINEMATICAL PROPERTIES OF BLUE STRAGGLER STARS AND HORIZONTAL BRANCH STARS IN NGC 6397

2012 ◽  
Vol 754 (2) ◽  
pp. 91 ◽  
Author(s):  
L. Lovisi ◽  
A. Mucciarelli ◽  
B. Lanzoni ◽  
F. R. Ferraro ◽  
R. Gratton ◽  
...  
Keyword(s):  
Horizontal Branch ◽  
Horizontal Branch Stars ◽  
Blue Straggler

scholarly journals Mid-UV Spectral Diagnostics

2009 ◽  
Vol 5 (S262) ◽  
pp. 351-352
Author(s):  
Sara R. Heap ◽  
Don Lindler
Keyword(s):  
Stellar Evolution ◽  
Stellar Population ◽  
Main Sequence ◽  
Horizontal Branch ◽  
Spectral Indices ◽  
Blue Stragglers ◽  
Horizontal Branch Stars ◽  
Spectral Diagnostics ◽  
Diagnostic Region

AbstractThe mid-ultraviolet is an important diagnostic region due to its sensitivity to the hottest stars of a stellar population. Sources of mid-UV flux include main sequence turn-off stars, the basic clocks of stellar evolution, and also blue horizontal branch stars and blue stragglers. We describe some observed trends in mid-UV colors and spectral indices.

scholarly journals Lte-Blanketed and Unblanketed Models for SDO Stars

1985 ◽  
Vol 111 ◽  
pp. 581-581
Author(s):  
L. Rossi
Keyword(s):  
White Dwarfs ◽  
Horizontal Branch ◽  
Horizontal Branch Stars ◽  
Hr Diagram

Sd0 stars have particular importance in astrophysics due to their position in the HR diagram between the hot horizontal-branch stars and the precursors of the white dwarfs. A careful determination of their parameters is therefore highly desirable.

scholarly journals UVIT observations of UV-Bright stars in four Galactic Globular Clusters

2019 ◽  
Vol 14 (S351) ◽  
pp. 464-467
Author(s):  
Ranjan Kumar ◽  
Ananta C. Pradhan ◽  
M. Parthasarathy ◽  
Devendra K. Ojha ◽  
Abhisek Mohapatra ◽  
...  
Keyword(s):  
Radial Distribution ◽  
Globular Clusters ◽  
Horizontal Branch ◽  
Uv Filters ◽  
Photometric Analysis ◽  
Horizontal Branch Stars ◽  
Blue Straggler ◽  
Imaging Telescope ◽  
Galactic Globular Clusters

AbstractWe have performed photometric analysis of four Galactic globular clusters (GGCs): NGC 4147, NGC 4590, NGC 5053 and NGC 7492 using far-UV and near-UV filters of the Ultraviolet Imaging Telescope (UVIT) on-board AstroSat. With the help of color-magnitude diagrams (CMDs), we have identified ~150 blue horizontal branch stars (BHBs), and ~40 blue straggler stars (BSS) in the four GGCs. We study the temperature and radial distribution of BHBs and BSS for the four GGCs.

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