FIDUCIAL STELLAR POPULATION SEQUENCES FOR THE u′g′r′i′z′ SYSTEM

Clem, James L.; VandenBerg, Don A.; Stetson, P. B.

doi:10.1088/0004-6256/135/2/682

Cited by 69 publications

(127 citation statements)

References 18 publications

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“…They also derive a photometric parallax relation using ugriz photometry of globular clusters. The agreement between the CFHT/MegaCam and the SDSS ugriz filter sets, after correcting the MegaCam u-band photometry (Clem et al 2008), enables us to use their photometric metallicity and parallax methods on our dataset. Photometric metal abundances of the F and G dwarfs with 0.2 < (g − r) ≤ 0.4, are determined via the following equation of Ivezic et al (2008).…”

Section: The Metallicity Distributionmentioning

confidence: 95%

The Metallicity Distribution of Distant F and G Type Stars in the CFHT Legacy Survey Deep Field

Karataş

Kilic

Güneş

et al. 2009

Publ. – Astron. Soc. Aust

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Abstract:We study the metal abundances of F and G type stars in the Galactic disk and halo using the CanadaFrance-Hawaii Telescope Legacy Survey D4 field. For a sample of stars within 7 kpc of the Galactic plane, we derive mean abundance values of [Fe/H] = −0.77 ± 0.36 dex for the thick disk, and [Fe/H] = −1.42 ± 0.98 dex for the stellar halo, respectively. These metallicites are consistent with the metallicity estimates from the Sloan Digital Sky Survey Data Release 6. We do not find a vertical abundance gradient for the thick disk between 1 kpc and 4 kpc. However, stars within 1 kpc of the Galactic plane are saturated in our dataset, and therefore we cannot rule out the observed vertical metallicity gradient for the thick disk stars in the SDSS. Moreover, we find a negative trend in the halo metallicity with increasing distance from the Galactic plane. This trend could be due to a contribution from an increasing number of very metal poor stars that belong to the outer halo. However, systematic effects in photometric metallicities are largest for the most metal poor stars, and therefore these effects cannot be ruled out.

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Section: The Metallicity Distributionmentioning

confidence: 95%

The Metallicity Distribution of Distant F and G Type Stars in the CFHT Legacy Survey Deep Field

Karataş

Kilic

Güneş

et al. 2009

Publ. – Astron. Soc. Aust

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“…Artificial stars experiments are not only useful for understanding the detection limits, but also for understanding the behavior of the photometric measurements at these faint magnitudes. Separation between point and extended sources is a prevailing problem in galactic and extragalactic studies, and several methods are commonly used (e.g., Harris et al 1991;Bertin & Arnouts 1996;Clem et al 2008;Durret et al 2009;Cho et al 2012). We preferred to use a combination of the SEXTRACTOR output parameter class_star, a stellarity likelihood, and the ALLSTAR parameter sharp, which measures deviations from the derived psf.…”

Section: Photometry Completenessmentioning

confidence: 99%

Isolated ellipticals and their globular cluster systems

Salinas

Alabi

Richtler

2015

A&A

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As tracers of star formation, galaxy assembly, and mass distribution, globular clusters have provided important clues to our understanding of early-type galaxies. But their study has been mostly constrained to galaxy groups and clusters where early-type galaxies dominate, leaving the properties of the globular cluster systems (GCSs) of isolated ellipticals as a mostly uncharted territory. We present Gemini-South/GMOS g i observations of five isolated elliptical galaxies: NGC 3962, NGC 2865, IC 4889, NGC 2271, and NGC 4240. Photometry of their GCSs reveals clear color bimodality in three of them, but remains inconclusive for the other two. All the studied GCSs are rather poor with a mean specific frequency S N ∼ 1.5, independently of the parent galaxy luminosity. Considering information from previous work as well, it is clear that bimodality and especially the presence of a significant, even dominant, population of blue clusters occurs at even the most isolated systems, which casts doubts on a possible accreted origin of metal-poor clusters, as suggested by some models. Additionally, we discuss the possible existence of ultra-compact dwarfs around the isolated elliptical NGC 3962.

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“…As discussed in SG07, we set the target priorities to preferentially observe stars with a high likelihood of being Segue 1 members. Using the theoretical isochrones of Clem et al (2008) and Girardi et al (2004), we chose targets whose color and apparent magnitudes minimize the distance from the best-fitting Segue 1 isochrone. The highest priority targets were those located within 0.1 mag of the red giant branch (RGB) tracks, or within 0.2 mag of the horizontal branch, with additional preference being given to brighter stars (Figure 1).…”

Section: Target Selectionmentioning

confidence: 99%

The Least-Luminous Galaxy: Spectroscopy of the Milky Way Satellite Segue 1

Geha

Willman

Simon

et al. 2009

ApJ

225

294

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We present Keck/DEIMOS spectroscopy of Segue 1, an ultra-low-luminosity M V = −1.5 +0.6 −0.8 Milky Way satellite companion. While the combined size and luminosity of Segue 1 are consistent with either a globular cluster or a dwarf galaxy, we present spectroscopic evidence that this object is a dark matter-dominated dwarf galaxy. We identify 24 stars as members of Segue 1 with a mean heliocentric recession velocity of 206 ± 1.3 km s −1 . Although Segue 1 spatially overlaps the leading arm of the Sagittarius stream, its velocity is 100 km s −1 different from that predicted for recent Sagittarius tidal debris at this position. We measure an internal velocity dispersion of 4.3 ± 1.2 km s −1 . Under the assumption that these stars are gravitationally bound and in dynamical equilibrium, we infer a total mass of 4.5 +4.7 −2.5 × 10 5 M in the mass-follow-light case; using a two-component maximum-likelihood model, we determine a mass within 50 pc of 8.7 +13 −5.2 × 10 5 M . These imply mass-) and M/L V = 2440 +1580 −1775 , respectively. The error distribution of the M/L is nearly lognormal, thus Segue 1 is dark matter-dominated at a high significance. Although we cannot rule out the possibility that Segue 1 has been tidally disrupted, we do not find kinematic evidence supporting tidal effects. Using spectral synthesis modeling, we derive a metallicity for the single red giant branch star in our sample of [Fe/H] = −3.3 ± 0.2 dex. Finally, we discuss the prospects for detecting gamma rays from annihilation of dark matter particles and show that Segue 1 is the most promising satellite for indirect dark matter detection. We conclude that Segue 1 is the least luminous of the ultra-faint galaxies recently discovered around the Milky Way, and is thus the least-luminous known galaxy.

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FIDUCIAL STELLAR POPULATION SEQUENCES FOR THE u′g′r′i′z′ SYSTEM

Cited by 69 publications

References 18 publications

The Metallicity Distribution of Distant F and G Type Stars in the CFHT Legacy Survey Deep Field

The Metallicity Distribution of Distant F and G Type Stars in the CFHT Legacy Survey Deep Field

Isolated ellipticals and their globular cluster systems

The Least-Luminous Galaxy: Spectroscopy of the Milky Way Satellite Segue 1

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