Praesepe: Magnitudes and Colors.

Johnson, Harold L.

doi:10.1086/145654

Cited by 71 publications

(47 citation statements)

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“…We performed a second determination with the same approach using B − V = 0.87 ± 0.01, which is an average of the values obtained by Johnson (1952) and Upgren et al (1979) with a conservative choice for the associated errors, and the value for E(B − V) quoted in Sect. 1.…”

Section: Stellar Parametersmentioning

confidence: 99%

The GAPS programme with HARPS-N at TNG

Malavolta

Nascimbeni

Piotto

et al. 2016

A&A

100

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Context. Open cluster (OC) stars share the same age and metallicity, and, in general, their age and mass can be estimated with higher precision than for field stars. For this reason, OCs are considered an important laboratory to study the relation between the physical properties of the planets and those of their host stars, and the evolution of planetary systems. However, only a handful of planets have been discovered around OC mainsequence stars so far, all of them in single-planet systems. For this reason we started an observational campaign within the GAPS collaboration to search for and characterize planets in OCs Aims. We monitored the Praesepe member Pr 0211 to improve our knowledge of the eccentricity of the hot Jupiter (HJ) that is already known to orbit this star and search for additional intermediate-mass planets. An eccentric orbit for the HJ would support a planet-planet scattering process rather than a disk-driven migration after its formation. Methods. From 2012 to 2015, we collected 70 radial velocity (RV) measurements with HARPS-N and 36 with TRES of Pr 0211. Simultaneous photometric observations were carried out with the robotic STELLA telescope to characterize the stellar activity. We discovered a long-term trend in the RV residuals that we show as being due to the presence of a second, massive, outer planet. Orbital parameters for the two planets are derived by simultaneously fitting RVs and photometric light curves, with the activity signal modelled as a series of sinusoids at the rotational period of the star and its harmonics. Results. We confirm that Pr 0211b has a nearly circular orbit (e = 0.02 ± 0.01), with an improvement of a factor two with respect to the previous determination of its eccentricity, and estimate that Pr 0211c has a mass M p sin i = 7.9 ± 0.2 M J , a period P > 3500 days and a very eccentric orbit (e > 0.60). This kind of peculiar system may be typical of open clusters if the planet-planet scattering phase, which lead to the formation of HJs, is caused by stellar encounters rather than by unstable primordial orbits. Pr 0211 is the first multi-planet system discovered around an OC star.

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Section: Stellar Parametersmentioning

confidence: 99%

The GAPS programme with HARPS-N at TNG

Malavolta

Nascimbeni

Piotto

et al. 2016

A&A

100

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“…Table 1 summarizes the identifications, coordinates, and magnitudes of each target star. Their position in the color−magnitude diagram taken from D 'Orazi et al (2006), Johnson (1953), Johnson & Knuckles (1955), and Johnson (1952) for Berkeley 32, NGC 752, Hyades, and Preasepe, respectively, are shown in Fig. 1.…”

Section: Observational Materialsmentioning

confidence: 99%

Chemical abundance analysis of the open clusters Berkeley 32, NGC 752, Hyades, and Praesepe

Carrera

Pancino

2011

A&A

130

139

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Context. Open clusters are ideal test particles for studying the chemical evolution of the Galactic disc. However, the number and accuracy of existing high-resolution abundance determinations, not only of [Fe/H], but also of other key elements, remains largely insufficient. Aims. We attempt to increase the number of Galactic open clusters that have high quality abundance determinations, and to gather all the literature determinations published so far. Methods. Using high-resolution (R ∼ 30 000), high-quality (S /N ≥ 60 per pixel), we obtained spectra for twelve stars in four open clusters with the fibre spectrograph FOCES, at the 2.2 Calar Alto Telescope in Spain. We employ a classical equivalent-width analysis to obtain accurate abundances of sixteen elements: Al, Ba, Ca, Co, Cr, Fe, La, Mg, Na, Nd, Ni, Sc, Si, Ti, V, and Y. We derived oxygen abundances by means of spectral synthesis of the 6300 Å forbidden line. Results. We provide the first determination of abundance ratios other than Fe for NGC 752 giants, and ratios in agreement with the literature for the Hyades, Praesepe, and Be 32. We use a compilation of literature data to study Galactic trends of [Fe/H] and [α/Fe] with Galactocentric radius, age, and height above the Galactic plane. We find no significant trends, but some indication for a flattening of [Fe/H] at large R gc , and for younger ages in the inner disc. We also detect a possible decrease in [Fe/H] with |z| in the outer disc, and a weak increase in [α/Fe] with R gc .

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“…Colour-magnitude diagram of NGC 2632. The photoelectric data of Johnson (1952) are plotted. The ZAMS from Bertelli et al (1994) and the isochrone of solar metallicity and log(age) = 8.9 by Girardi et al (2000) are set at E(B − V) = 0.00 and (m − M) 0 = 6.25.…”

Section: Identification Of the Stragglersmentioning

confidence: 99%

New catalogue of blue stragglers in open clusters

Ahumada

Lapasset

2006

A&A

158

242

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We present a catalogue of blue-straggler candidates in galactic open clusters. It is based on the inspection of the colour-magnitude diagrams of the clusters, and it updates and supersedes the first version (Ahumada & Lapasset 1995). A new bibliographical search was made for each cluster, and the resulting information is organised into two tables. Some methodological aspects have been revised, in particular those concerning the delimitation of the area in the diagrams where the stragglers are selected. A total of 1887 blue-straggler candidates have been found in 427 open clusters of all ages, doubling the original number. The catalogued stars are classified into two categories mainly according to membership information.

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Praesepe: Magnitudes and Colors.

Cited by 71 publications

References 0 publications

The GAPS programme with HARPS-N at TNG

The GAPS programme with HARPS-N at TNG

Chemical abundance analysis of the open clusters Berkeley 32, NGC 752, Hyades, and Praesepe

New catalogue of blue stragglers in open clusters

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