CCD photometry of the Galactic globular cluster M13

Paltrinieri, B.; Ferraro, F. R.; Pecci, F. Fusi; Carretta, E.

doi:10.1046/j.1365-8711.1998.01175.x

Cited by 33 publications

(26 citation statements)

References 11 publications

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“…There is a bump on the luminosity function called the RGB (Red Giant Branch) bump, which has been confirmed by both theory and observation. 12) In the case of M13, the RGB bump comes at 14.75 ± 0.05 magnitude, which is very close to the peak point of each line in Fig. 4.…”

Section: Globular Clustersupporting

confidence: 75%

Detection of Small GEO Debris by Use of the Stacking Method.

Yanagisawa

Nakajima

Kimura

et al. 2002

Trans. Japan Soc. Aero. S Sci.

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In this paper we propose a new method known as "the stacking method" to detect small pieces of unknown GEO debris, in which several images taken with a CCD camera are used to detect this debris. With this method, the streaks of stars are completely eliminated, and the sky background fluctuation decreases significantly. This allows the detection of very dark debris that is not visible on a single image. We tested this method by using the 45 cm telescope at the Yatsugatake Observatory and a small CCD camera manufactured by Nakanishi Image Laboratory (N.I.L). The globular cluster M13 was observed to evaluate the method and to calculate the limiting magnitude. The three regions of the geostationary orbit were also observed to search for unknown GEO debris. One possible piece of GEO debris about 1 m big was detected as a result of analysis that used the stacking method. The limiting magnitude shows that we can detect GEO debris of about 50 cm in size. With this method, by means of observation using the facilities at the Bisei Spaceguard Center (BSGC), a 1 m telescope, and an SITe CCD camera, we may be expected to detect GEO debris of about 10 cm in size.

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Section: Globular Clustersupporting

confidence: 75%

Detection of Small GEO Debris by Use of the Stacking Method.

Yanagisawa

Nakajima

Kimura

et al. 2002

Trans. Japan Soc. Aero. S Sci.

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“…Only the reddest HB members in M13 appear more luminous than stars in M3 at the same colour, and are interpreted by Catelan and de Freitas Pachego (1995) and Ferraro et al (1997a) as being more evolved than corresponding stars in M3. Estimates of the luminosity level of turn-off and HB for M3 and M13 are given by Buonanno et al (1994), Ferraro et al (1997b), Paltrinieri et al (1998). Also these data do not show any noticeable difference in the relative positions of the evolutionary loci in the two clusters.…”

Section: The Case Of M3 and M13mentioning

confidence: 78%

Mixing, enhanced helium and blue tails in globular clusters

Caloi¹

2001

A&A

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Abstract. We investigate the consequences of an increase in the envelope helium abundance of pre-helium flash red giants in globular clusters, an occurrence suggested by chemical peculiarities in many red giant atmospheres. Comparing predictions with the CM diagrams of a few crucial globular clusters, one finds no evidence for a substantial increase in the surface helium content of horizontal branch members of these clusters, at least for objects in the RR Lyrae region or close to it. The possibility that the most peculiar giants belong to the asymptotic giant branch is discussed. The consequences of a delay in the helium flash are briefly examined.

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“…ZNG 4 has a V magnitude of 13.964 (Paltrinieri et al 1998). Considering the distance modulus of M 13 to be 14.42 and E(B−V) towards M 13 to be 0.02 (Kraft & Ivans 2003), we estimated the absolute magnitude (M v ) of the star to be −0.522.…”

Section: Discussionmentioning

confidence: 99%

“…The position of ZNG 4 in the color-magnitude diagram of M 13 (Paltrinieri et al 1998) is shown in Fig. 1.…”

Section: Of the 82 M Subarumentioning

confidence: 99%

“…However the ZNG 4 area of the cluster was not included in their observations (Rey, private communication). We used the published CCD photometry of ZNG 4 by Paltrinieri et al (1998), who give, B = 14.096 and V = 13.964. (B − V) = 0.132 and E(B − V) = 0.02 (Kraft & Ivans 2003) will yield (B − V) 0 = 0.112 which corresponds to T eff = 8373 K (Flower 1996).…”

Section: Atmospheric Parametersmentioning

confidence: 99%

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Chemical composition of UV-bright star ZNG 4 in the globular cluster M 13

Ambika

Parthasarathy

Aoki

et al. 2004

A&A

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Abstract.We present a detailed model-atmosphere analysis of ZNG 4, a UV-bright star in the globular cluster M 13. From the analysis of a high resolution (R ≈ 45 000) spectrum of the object, we derive the atmospheric parameters to be T eff = 8500 ± 250 K, log g = 2.5 ± 0.5 and [Fe/H] = −1.5. Except for magnesium, chromium and strontium, all other even Z elements are enhanced with titanium and calcium being overabundant by a factor of 0.8 dex. Sodium is enhanced by a factor of 0.2 dex. The luminosity of ZNG 4 and its position in the color-magnitude diagram of the cluster indicate that it is a Supra Horizontal Branch (SHB) (post-HB) star. The underabundance of He and overabundances of Ca, Ti, Sc and Ba in the photosphere of ZNG 4 indicate that diffusion and radiative levitation of elements may be in operation in M 13 post-HB stars even at T eff of 8500 K. Detailed and more accurate abundance analysis of post-HB stars in several globular clusters is needed to further understand their abundance anomalies.

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CCD photometry of the Galactic globular cluster M13

Cited by 33 publications

References 11 publications

Detection of Small GEO Debris by Use of the Stacking Method.

Detection of Small GEO Debris by Use of the Stacking Method.

Mixing, enhanced helium and blue tails in globular clusters

Chemical composition of UV-bright star ZNG 4 in the globular cluster M 13

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