Stars of the Draco Dwarf Spheroidal Galaxy Beyond Its Measured Tidal Boundary

Piatek, Slawomir; Pryor, C.; Armandroff, T. E.; Olszewski, Edward W.

doi:10.1086/318755

Cited by 23 publications

(38 citation statements)

References 46 publications

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“…The HB in Fig. 1 of Piatek et al (2001) is somewhat distorted due to RR Lyrae stars which are marked with open circles in Fig. 3.…”

Section: Comparison With the Cmd Of The Draco Dsphmentioning

confidence: 98%

“…Thus, we mainly discuss the dSph Draco in this section and briefly mention the dSphs Sextans and Ursa Minor. Figure 3 shows the observed CMD of the C0 field in the Draco dSph (Piatek et al 2001), which is characterised by the narrow RGB and the well-populated red HB. The HB in Fig.…”

Section: Comparison With the Cmd Of The Draco Dsphmentioning

confidence: 99%

“…The photometric errors and detection completeness in the simulations are taken from Piatek et al (2001). Both models can reproduce characteristics of the CMD of the dSph Draco, such as narrow RGB and heavily populated RHB.…”

Section: Comparison With the Cmd Of The Draco Dsphmentioning

confidence: 99%

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Extended star formation in dwarf spheroidal galaxies: The cases of Draco, Sextans, and Ursa Minor

Ikuta

Arimoto

2002

A&A

104

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Abstract. Star formation and chemical enrichment histories of the dwarf spheroidal galaxies (dSphs) Draco, Sextans, and Ursa Minor are investigated by means of chemical evolution models and a simulation code for colour-magnitude diagrams (CMDs). The CMD simulation code is designed to fully consider effects of the chemical evolution on stellar evolution and photometric properties. For this aim, star formation and chemical enrichment histories are calculated consistently in the code. Comparisons between the chemical evolution models and the observed abundance patterns reveal that the star formation rates were very low (1-5% of that of the solar neighbourhood disc) and that the initial star formation continued for a long duration ( >3.9-6.5 Gyr) in these dSphs. This star formation history can reproduce morphologies of the observed CMDs, such as narrow red giant branches and red horizontal branches and succeeds in solving the second parameter problem of the dSph Draco. Hence, both of the abundance patterns and the morphologies of the CMDs can be explained by the star formation histories characterised by the low star formation rate and the long duration of the star formation period. Because of the low star formation rates, plenty of gas remains at the final epoch of star formation. We suggest that gas stripping by the Galaxy results in termination of star formation in the dSphs.

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“…The HB in Fig. 1 of Piatek et al (2001) is somewhat distorted due to RR Lyrae stars which are marked with open circles in Fig. 3.…”

Section: Comparison With the Cmd Of The Draco Dsphmentioning

confidence: 98%

Section: Comparison With the Cmd Of The Draco Dsphmentioning

confidence: 99%

See 1 more Smart Citation

Extended star formation in dwarf spheroidal galaxies: The cases of Draco, Sextans, and Ursa Minor

Ikuta

Arimoto

2002

A&A

104

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“…On the basis of the infrared and optical observations, Cioni & Habing (2005) classified late-type stars of the Draco dSph. Piatek et al (2001) selected the members of the Draco dSph in R and V band photometry.…”

Section: Cross-correlation With Other Cataloguesmentioning

confidence: 99%

“…14, 24, and 64 showed hard spectra in both the spectral analysis and hardness ratios. Their optical counterparts were classified as stars in the Draco dSph by photometric methods (e.g, Piatek et al 2001;Rave et al 2003). Their X-ray-tooptical flux ratio is high, with log 10 ( (Table A.2).…”

Section: Lmxb Candidatesmentioning

confidence: 99%

XMM-Newtonstudy of the Draco dwarf spheroidal galaxy

Saeedi

Sasaki

Ducci

2016

A&A

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Aims. We present the results of the analysis of five XMM-Newton observations of the Draco dwarf spheroidal galaxy (dSph). The aim of the work is the study of the X-ray population in the field of the Draco dSph. Methods. We classified the sources on the basis of spectral analysis, hardness ratios, X-ray-to-optical flux ratio, X-ray variability, and cross-correlation with available catalogues in X-ray, optical, infrared, and radio wavelengths. Results. We detected 70 X-ray sources in the field of the Draco dSph in the energy range of 0.2−12 keV and classified 18 AGNs, 9 galaxies and galaxy candidates, 6 sources as foreground stars, 4 low-mass X-ray binary candidates, 1 symbiotic star, and 2 binary system candidates. We also identified 9 sources as hard X-ray sources in the field of the galaxy. We derived the X-ray luminosity function of X-ray sources in the Draco dSph in the 2−10 keV and 0.5−2 keV energy bands. Using the X-ray luminosity function in the energy range of 0.5−2 keV, we estimate that ∼10 X-ray sources are objects in the Draco dSph. We have also estimated the dark matter halo mass that would be needed to keep the low-mass X-ray binaries gravitationally bound to the galaxy.

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Scaling Laws for Dark Matter Halos in Late-Type and Dwarf Spheroidal Galaxies

Kormendy

Freeman

2004

Symp. - Int. Astron. Union

112

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Published mass models fitted to kinematic data are used to study the systematic properties of dark matter (DM) halos in Sc -Im and dwarf spheroidal (dSph) galaxies. Halo parameters are derived for rotationally supported galaxies by decomposing rotation curves V (r) into visible-and dark-matter contributions. The visible matter potential is calculated from the surface brightness assuming that the mass-to-light ratio M/L is constant with radius. "Maximum disk" values of M/L are adjusted to fit as much of the inner rotation curve as possible without making the halo have a hollow core. Rotation curve decomposition is impossible fainter than absolute magnitude M B ≃ −14, where V becomes comparable to the velocity dispersion of the gas. To increase the luminosity range further, we include central densities of dSph and dIm galaxies estimated via the Jeans equation for their stars (dSph) or H I (dIm). Combining these data, we find that DM halos satisfy well defined scaling laws analogous to the "fundamental plane" relations for elliptical galaxies. Halos in less luminous galaxies have smaller core radii r c , higher central densities ρ • , and smaller central velocity dispersions σ. Scaling laws provide new constraints on the nature of DM and on galaxy formation and evolution:1. A continuous sequence of decreasing mass extends from the highest-luminosity Sc I galaxies with M B ≃ −22.4 (H 0 = 70 km s −1 Mpc −1 ) to the lowest-luminosity galaxy with sufficient data (an ultrafaint dSph with M B ≃ −1).2. The high DM densities in dSph galaxies are normal for such tiny galaxies. Because virialized DM density depends on collapse redshift z coll , ρ • ∝ (1 + z coll ) 3 , and because the DM densities in the faintest dwarfs are about 500 times higher than those in the brightest spirals, therefore the collapse redshifts of the faintest dwarfs and the brightest spirals are related by (1 + z dwarf )/(1 + z spiral ) ≃ 8.3. The high DM densities in the dSph companions of our Galaxy imply that they are real galaxies formed from primordial density fluctuations. They are not tidal fragments. Tidal dwarfs cannot retain even the low DM densities of their giant-galaxy progenitors. In contrast, dSph galaxies generally have higher DM densities than those of possible giant-galaxy progenitors.4. We show explicitly that spiral, irregular, and spheroidal galaxies with M V > ∼ −18 form a sequence of decreasing baryon-to-DM surface density with decreasing luminosity. We suggest that these dS, dIm, and dSph galaxies form a sequence of decreasing baryon retention (caused by supernova-driven winds) or decreasing baryon capture (after cosmological reionization) in smaller galaxies.5. In all structural parameter correlations, dS+Im and dSph galaxies behave similarly; any differences between them are small. We conclude that the difference between z ∼ 0 galaxies that still contain gas (and that still can form stars) and those that do not (and that cannot form stars) is a second-order effect.The primary effect appears to be the physics that control...

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Stars of the Draco Dwarf Spheroidal Galaxy Beyond Its Measured Tidal Boundary

Cited by 23 publications

References 46 publications

Extended star formation in dwarf spheroidal galaxies: The cases of Draco, Sextans, and Ursa Minor

Extended star formation in dwarf spheroidal galaxies: The cases of Draco, Sextans, and Ursa Minor

XMM-Newtonstudy of the Draco dwarf spheroidal galaxy

Scaling Laws for Dark Matter Halos in Late-Type and Dwarf Spheroidal Galaxies

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