The Unusual Luminosity Function of the Globular Cluster M10

Pollard, D. L.; Sandquist, Eric L.; Hargis, Jonathan R.; Bolte, Michael

doi:10.1086/430872

Cited by 16 publications

(24 citation statements)

References 33 publications

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“…Observations were obtained with GNIRS on Gemini North as apart of GN-2017A-Q-70. We used the short camera, the 0.3" slit, and the 110.5 lines mm −1 a ID From Pollard et al (2005) b Ks magnitudes from 2MASS (Skrutskie et al 2006) c AGB Star grating to achieve a resolution of R ≈ 3500 in the K band. We observed the wavelength range between 22800Å-24000Å to measure 13 C 16 O features at 2.34 µm and 2.37 µm.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

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Carbon Isotope Ratios in M10 Giants

Maas

Gerber

Deibel

et al. 2019

ApJ

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We measured carbon abundances and the 12 C/ 13 C ratio in 31 giant branch stars with previous CN and CH band measurements that span -2.33 < M V < 0.18 in the globular cluster M10 (NGC 6254). Abundances were determined by comparing CO features at ∼ 2.3 µm and specifically the 13 CO bandhead at 2.37 µm, to synthetic spectra generated with MOOG. The observed spectra were obtained with GNIRS on Gemini North with a resolution of R ≈ 3500. The carbon abundances derived from the IR spectra agree with previous [C/Fe] measurements found using CN and CH features at the near-UV/blue wavelength range. We found an average carbon isotope ratio of 12 C/ 13 C = 5.10 +0.18 −0.17 for first generation stars (CN-normal; 13 stars total) and 12 C/ 13 C = 4.84 +0.27 −0.22 for second generation stars (CN-enhanced; 15 stars). We therefore find no statistically significant difference in 12 C/ 13 C ratio between stars in either population for the observed magnitude range. Finally, we created models of the expected carbon, nitrogen, and 12 C/ 13 C surface abundance evolution on the red giant branch due to thermohaline mixing using the MESA stellar evolution code. The efficiency of the thermohaline mixing must be increased to a factor of ≈ 60 to match [C/Fe] abundances, and by a factor of ≈ 666 to match 12 C/ 13 C ratios. We could not simultaneously fit the evolution of both carbon and the 12 C/ 13 C ratio with models using the same thermohaline efficiency parameter.

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Section: Observations and Data Reductionmentioning

confidence: 99%

“…Finally, our conclusions are summarized in Section 7. Pollard et al (2005). Our sample includes RGB stars plotted as red stars and AGB stars as red circles.…”

Section: Introductionmentioning

confidence: 99%

Carbon Isotope Ratios in M10 Giants

Maas

Gerber

Deibel

et al. 2019

ApJ

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“…NGC 6254 has previously been studied using ground-based facilities by Rosenberg et al (2000b) andvon Braun et al (2002) in VI and by Pollard et al (2005) in BVI. bands.…”

Section: Ngc 6254-m 10 (Figure 11)mentioning

confidence: 99%

Uncloaking Globular Clusters in the Inner Galaxy

Alonso-García

Mateo

Sen

et al. 2012

The Astronomical Journal

118

100

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Extensive photometric studies of the globular clusters located toward the center of the Milky Way have been historically neglected. The presence of patchy differential reddening in front of these clusters has proven to be a significant obstacle to their detailed study. We present here a well defined and reasonably homogeneous photometric database for 25 of the brightest Galactic globular clusters located in the direction of the inner Galaxy. These data were obtained in the B, V, and I bands using the Magellan 6.5 m Telescope and the Hubble Space Telescope. A new technique is extensively used in this paper to map the differential reddening in the individual cluster fields, and to produce cleaner, dereddened color-magnitude diagrams for all the clusters in the database. Subsequent papers will detail the astrophysical analysis of the cluster populations, and the properties of the obscuring material along the clusters' lines of sight.

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“…Currently developed and available theoretical models of red giant evolution seem not to predict any obvious peculiarity of the evolution of stars in the lower RGB, appropriate to the red giants with the characteristics typical for GC stars. This general conclusion can be checked, for example, by examining various sets of theoretical LFs developed by different groups and applied, in particular, by Hargis et al (2004), Pollard et al (2005), Fekadu et al (2007) for the comparison of the theoretical LFs with observed RGB LFs of a number of GCs.…”

Section: The Empirical Results Versus Theorymentioning

confidence: 99%

“…NGC 6254 (M10). In the I-band RGB LF by Pollard et al (2005), there is an obvious dip at I ≈ 15.0, and the RGB base is at I ≈ 16.3. Therefore, the magnitude difference ΔI dip base is around 1.3 mag.…”

Section: Additional Evidence Of the Knee-related Dip/gap In The Lowermentioning

confidence: 95%

Revealing Probable Universal Features in the Lower Red Giant Branch Luminosity Functions of Galactic Globular Clusters

Kravtsov

2009

The Astronomical Journal

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This paper aims at demonstrating, for the first time, very probable universal peculiarities of the evolution of stars in the lower red giant branch (RGB) of Galactic globular clusters (GCs), reflected in two corresponding dips in the luminosity functions (LFs). By relying on the database of Hubble Space Telescope photometry of GCs, we analyze the lower RGB LFs of a sample of 18 GCs in a wide metallicity range, Δ[Fe/H] ≈ 1.9 dex. We first show that in the F555W−(F439W−F555W) color-magnitude diagrams (CMDs), the lower RGB of GCs, except for the most metal-poor of them, frequently shows an apparent "knee." It reveals itself as a fairly abrupt change of the RGB slope. At the same luminosity level, the RGB LFs show a feature in the form of a more or less pronounced dip. We find that the magnitude difference between the RGB base and the given feature is, on average, around Δ F555W dip base ≈ 1.4 mag. It shows a marginal variation with metallicity, if any, comparable to the error. At the same time, the magnitude difference between the dip and the RGB bump, Δ F555W bump dip , decreases with increasing metallicity and falls within the range 0.8 Δ F555W bump dip 1.7 mag. Generalized LFs (GLFs) have been obtained for three subsamples of GCs within limited metallicity ranges and with different horizontal branch (HB) morphology. They reproduce the "knee-related" dip that is statistically significant in two of the GLFs. This feature turns out to be more pronounced in the GLFs of GCs with either the blue or red HB morphology than with the intermediate one. The same GLFs also reveal an additional probable universal dip. It shows up below the RGB bump at Δ F555W slightly increasing from ∼0.3 to ∼0.5 mag with increasing metallicity. Also, the statistical significance of this "prebump" dip increases, on average, toward higher metallicity. Except for the well known RGB bump, no other universal features corresponding to those found here were so far empirically revealed or theoretically predicted in the lower RGB of GCs.

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The Unusual Luminosity Function of the Globular Cluster M10

Cited by 16 publications

References 33 publications

Carbon Isotope Ratios in M10 Giants

Carbon Isotope Ratios in M10 Giants

Uncloaking Globular Clusters in the Inner Galaxy

Revealing Probable Universal Features in the Lower Red Giant Branch Luminosity Functions of Galactic Globular Clusters

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