Washington photometry of nearby F, G, and K dwarfs

González, Guillermo; Piche, Francois

doi:10.1086/116209

Cited by 7 publications

(10 citation statements)

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“…Fig. 20) and dwarfs from Gonzalez and Piché (1992). Models for dwarfs of solar metallicity (solid line) and [Fe/H] = -2.0 (dotted line) from Paltoglou and are also shown.…”

Section: Appendix: Conversions Between Washington and Other Systemsmentioning

confidence: 99%

“…• Accurate photometry of a sample of very nearby dwarfs was obtained by Gonzalez and Piché (1992). They also measured B −V colors for these stars.…”

Section: Appendix: Conversions Between Washington and Other Systemsmentioning

confidence: 99%

“…It can be seen that there is a simple relation between Washington M −T 2 color and V −I and that the relation does not depend on metallicity. .-Relation between Washington M − T 2 and B −V for Landolt/Washington standards (giants plotted as stars, dwarfs as filled squares, unknown spectral types as open circles)and dwarfs fromGonzalez and Piché (1992). The models of Paltoglou and for solar abundance dwarfs (solid line) and [Fe/H] = -2.0 dwarfs (dotted line) are also shown.…”

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confidence: 99%

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Mapping the Galactic Halo. I. The “Spaghetti” Survey

Morrison

Mateo

Olszewski

et al. 2000

The Astronomical Journal

130

142

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We describe a major survey of the Milky Way halo designed to test for kinematic substructure caused by destruction of accreted satellites. We use the Washington photometric system to identify halo stars efficiently for spectroscopic followup. Tracers include halo giants (detectable out to more than 100 kpc), blue horizontal branch stars, halo stars near the main sequence turnoff, and the "blue metal-poor stars" of Preston et al. (1994). We demonstrate the success of our survey by showing spectra of stars we have identified in all these categories, including giants as distant as 75 kpc. We discuss the problem of identifying the most distant halo giants. In particular, extremely metal-poor halo K dwarfs are present in approximately equal numbers to the distant giants for V > 18, and we show that our method will distinguish reliably between these two groups of metal-poor stars.We plan to survey 100 square degrees at high galactic latitude, and expect to increase the numbers of known halo giants, BHB stars and turnoff stars by more than an order of magnitude. In addition to the strong test that this large sample will provide for the question "was the Milky Way halo accreted from satellite galaxies?", we will improve the accuracy of mass measurements of the Milky Way beyond 50 kpc via the kinematics of the many distant giants and BHB stars we will find.We show that one of our first datasets constrains the halo density law over galactocentric radii of 5-20 kpc and z heights of 2-15 kpc. The data support a flattened power-law halo with b/a of 0.6 and exponent -3.0. More complex models with a varying axial ratio may be needed with a larger dataset.

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“…Fig. 20) and dwarfs from Gonzalez and Piché (1992). Models for dwarfs of solar metallicity (solid line) and [Fe/H] = -2.0 (dotted line) from Paltoglou and are also shown.…”

Section: Appendix: Conversions Between Washington and Other Systemsmentioning

confidence: 99%

“…• Accurate photometry of a sample of very nearby dwarfs was obtained by Gonzalez and Piché (1992). They also measured B −V colors for these stars.…”

Section: Appendix: Conversions Between Washington and Other Systemsmentioning

confidence: 99%

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confidence: 99%

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Mapping the Galactic Halo. I. The “Spaghetti” Survey

Morrison

Mateo

Olszewski

et al. 2000

The Astronomical Journal

130

142

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“…As yet another example,Gonzalez (1999) has recently pointed out that even the orbit of the solar system in the Galaxy appears to be finely tuned to reduce comet impacts: compared to other stars of the same age, the sun steers an unusually quiet path through the Galaxy-an orbit with unusally low eccentricity and small amplitude of vertical motion out of the disk. This could be explained anthropically, perhaps through the effect of Galactic tidal distortions on the Oort comet cloud which create catastrophic storms of comet impacts in the inner solar system(Heisler and Tremaine 1986, Matese andWhitmire 1996).…”

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confidence: 99%

Why the universe is just so

2000

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Some properties of the world are fixed by physics derived from mathematical symmetries, while others are selected from an ensemble of possibilities. Several successes and failures of "anthropic" reasoning in this context are reviewed in the light of recent developments in astrobiology, cosmology and unification physics. Specific issues raised include our spacetime location (including the reason for the present age of the universe), the timescale of biological evolution, the tuning of global cosmological parameters, and the origin of the Large Numbers of astrophysics and the parameters of the Standard Model. Out of the twenty parameters of the Standard Model, the basic behavior and structures of the world (nucleons, nuclei, atoms, molecules, planets, stars, galaxies) depend mainly on five of them: m e , m u , m d , α, and α G (where m proton and α QCD are taken as defined quantities). Three of these appear to be independent in the context of Grand Unified Theories (that is, not fixed by any known symmetry) and at the same time have values within a very narrow window which provides for stable nucleons and nuclei and abundant carbon. The conjecture is made that the two light quark masses and one coupling constant are ultimately determined even in the "Final Theory" by a choice from a large or continuous ensemble, and the prediction is offered that the correct unification scheme will not allow calculation of (m d − m u )/m proton from first principles alone.

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“…Balmer-line data are from groups 2, 4, and 7 listed by Taylor (1992, Table 1). In practice, this relation is assumed to hold for 0.81 ≤ θ BL ≤ 1.02. k This relation applies to the photometry of Gonzalez & Piché (1992). For values of (R − I) C derived from that source, σ = 20.7n −0.5 mmag, with n being the number of measurements.…”

Section: Appendix A: Color-index Transformationsmentioning

confidence: 99%

Statistical cataloging of archival data for luminosity class IV–V stars

Taylor

2003

A&A

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Abstract. This paper is one of a pair in which temperatures and metallicity catalogs for class IV-V stars are considered. The temperature catalog described here is derived from a calibration based on stellar angular diameters. If published calibrations of this kind are compared by using color-index transformations, temperature-dependent differences among the calibrations are commonly found. However, such differences are minimized if attention is restricted to calibrations based on Johnson V − K. A calibration of this sort from Di Benedetto (1998) is therefore tested and adopted. That calibration is then applied to spectroscopic and photometric data, with the latter predominating. Cousins R − I photometry receives special attention because of its high precision and low metallicity sensitivity. Testing of temperatures derived from the calibration suggests that their accuracy and precision are satisfactory, though further testing will be warranted as new results appear. These temperatures appear in the catalog as values of θ ≡ 5040/T (effective). Most of these entries are accompanied by measured or derived values of Cousins R − I. Entries are given for 951 stars.

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Washington photometry of nearby F, G, and K dwarfs

Cited by 7 publications

References 0 publications

Mapping the Galactic Halo. I. The “Spaghetti” Survey

Mapping the Galactic Halo. I. The “Spaghetti” Survey

Why the universe is just so

Statistical cataloging of archival data for luminosity class IV–V stars

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