Chemical Evolution in Our Galaxy during the Last 5 Gyr

Geiss, J.; Gloeckler, G.; Charbonnel, C.

doi:10.1086/342869

Cited by 39 publications

(24 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A fraction of the gas will most likely be accreted by the Milky Way providing new fuel for star-formation. The infall of low-metallicity gas on to the Milky Way might solve the so-called G-dwarf problem (see Geiss et al 2002, and references therein). 3.…”

Section: Discussionmentioning

confidence: 99%

The Parkes H I Survey of the Magellanic System

Brüns¹,

Kerp²,

Staveley‐Smith

et al. 2005

A&A

282

477

View full text Add to dashboard Cite

Abstract. We present the first fully and uniformly sampled, spatially complete H  survey of the entire Magellanic System with high velocity resolution (∆v = 1.0 km s −1 ), performed with the Parkes Telescope . Approximately 24 percent of the southern sky was covered by this survey on a ≈5 grid with an angular resolution of HPBW = 14. 1. A fully automated data-reduction scheme was developed for this survey to handle the large number of H  spectra (1.5 × 10 6 ). The individual Hanning smoothed and polarization averaged spectra have an rms brightness temperature noise of σ = 0.12 K. The final data-cubes have an rms noise of σ rms ≈ 0.05 K and an effective angular resolution of ≈16 . In this paper we describe the survey parameters, the datareduction and the general distribution of the H  gas. , if all H  gas is at the same distance of 55 kpc. Approximately two thirds of this H  gas is located close to the Magellanic Clouds (Magellanic Bridge and Interface Region), and 25% of the H  gas is associated with the Magellanic Stream. The Leading Arm has a four times lower H  mass than the Magellanic Stream, corresponding to 6% of the total H  mass of the gaseous features.We have analyzed the velocity field of the Magellanic Clouds and their neighborhood introducing a LMC-standard-of-rest frame. The H  in the Magellanic Bridge shows low velocities relative to the Magellanic Clouds suggesting an almost parallel motion, while the gas in the Interface Region has significantly higher relative velocities indicating that this gas is leaving the Magellanic Bridge building up a new section of the Magellanic Stream. The Leading Arm is connected to the Magellanic Bridge close to an extended arm of the LMC. The clouds in the Magellanic Stream and the Leading Arm show significant differences, both in the column density distribution and in the shapes of the line profiles. The H  gas in the Magellanic Stream is more smoothly distributed than the gas in the Leading Arm. These morphological differences can be explained if the Leading Arm is at considerably lower z-heights and embedded in a higher pressure ambient medium.

show abstract

Section: Discussionmentioning

confidence: 99%

The Parkes H I Survey of the Magellanic System

Brüns¹,

Kerp²,

Staveley‐Smith

et al. 2005

A&A

282

477

View full text Add to dashboard Cite

show abstract

“…By comparing the elemental abundances in the Protosolar Cloud (PSC) with those in the LIC and nearby interstellar medium (ISM), Geiss concluded that the composition of matter in the solar ring of the Milky Way could not have evolved from matter with a PSC composition in a closed system environment. To account for the LIC composition Geiss et al (2002) proposed that a significant fraction of the gas in the Galactic disk comes from quasi-continuous infall of low-metallicity material from dwarf galaxies and, using a simple mixing model, showed that the difference found in the LIC and PSC compositions can be explained my this process (see Fig. 19a).…”

Section: Mixing Models and Late Galactic Evolutionmentioning

confidence: 99%

Johannes Geiss’ Investigations of Solar, Heliospheric and Interstellar Matter

Gloeckler

Fisk

2007

Space Sci Rev

Self Cite

View full text Add to dashboard Cite

Johannes Geiss is a world leader and foremost expert on measurements and interpretation of the composition of matter that reveals the history, present state, and future of astronomical objects. With his Swiss team he was first to measure the composition of the noble gases in the solar wind when in the late 1960s he flew the brilliant solar wind collecting foil experiments on the five Apollo missions to the moon. Always at the forefront of the art of composition measurements, he with his colleagues determined the isotopic and elemental composition of the solar wind using instruments characterized by innovative design that have provided the most comprehensive record of the solar wind composition under all solar wind conditions at all helio-latitudes. He discovered heavy interstellar pickup ions, from which the composition of the neutral gas of the Local Interstellar Cloud is determined, and the "Inner Source" of pickup ions. Johannes Geiss played a key role both in the in-situ measurements and modeling of molecular ions in comets, and the interpretation of these data. He and co-workers measured the composition of plasmas in the magnetospheres of Earth and Jupiter. Here we highlight Johannes Geiss' many discoveries and seminal contributions to our knowledge of the composition of matter of the Sun, solar wind, interstellar gas, early universe, comets and magnetospheres.

show abstract

“…14 N is-at least in part-a secondary nucleus, and it is produced in significant amounts in low mass stars. Therefore, in a closed system, the 14 N/ 16 O ratio should increase with time, contrary to measurements that indicate a lower N/O ratio in the LIC than in the PSC (Gloeckler and Geiss 2001;Geiss et al 2002;Gloeckler 2005).…”

Section: Galactic Evolution During the Last 5 Gyrmentioning

confidence: 59%

Linking Primordial to Solar and Galactic Composition

Geiss

Gloeckler

2007

Space Sci Rev

Self Cite

View full text Add to dashboard Cite

Evolution and composition of baryonic matter is influenced by the evolution of other forms of matter and energy in the universe. At the time of primordial nucleosynthesis the universal expansion and thus the decrease of the density and temperature of baryonic matter were controlled by leptons and photons. Non-baryonic dark matter initiated the formation of clusters and galaxies, and to this day, dark matter largely determines the dynamics and geometries of these baryonic structures and indirectly influences their chemical evolution. Chemical analyses and isotopic abundance measurements in the solar system established the composition in the protosolar cloud (PSC). The abundances of nuclear species in the PSC led to the discovery of the magic numbers and the nuclear shell model, and they allowed the identification of nucleosynthetic sites and processes. To this day, we know the abundances of the ∼300 stable and long-lived nuclides infinitely better in the PSC than in any other sample of matter in the universe. Thus, we know the exact composition of a Galactic sample of intermediate age, allowing us to check on theories of Galactic evolution before and after the formation of the solar system. This paper specifically discusses the nucleosynthesis in the early universe and the Galactic evolution during the last 5 Gyr.

show abstract

Chemical Evolution in Our Galaxy during the Last 5 Gyr

Cited by 39 publications

References 38 publications

The Parkes H I Survey of the Magellanic System

The Parkes H I Survey of the Magellanic System

Johannes Geiss’ Investigations of Solar, Heliospheric and Interstellar Matter

Linking Primordial to Solar and Galactic Composition

Contact Info

Product

Resources

About