Maartje Sevenster

The Commonwealth Scientific and Industrial Research Organisation | CSIRO · Agriculture and Food

Direct land use change (dLUC) can contribute significantly to carbon footprint and life cycle assessment results. A tool that covers all crops grown in all countries is important to provide high-quality and consistent inventory data but comes with significant challenges managing data. This analysis shows that the use of such high-level data in a co...

Purpose Regional values for prospective soil organic carbon (SOC) change in Australian cropland were derived via state-of-the-art modelling. This paper evaluates the applicability of the results in the context of life cycle assessment (LCA). Methods Results of soil carbon modelling need to align with LCA requirements in order to be applicable. The...

Focus Press was one of the first companies worldwide to commission a quantitative social life-cycle assessment (LCA) of their full supply chain. The LCA was performed with limited scope and had the function of a pilot study to test methodology as well as process and to allow Focus Press to establish how social LCA could be used to achieve their obj...

Bio-based and biodegradable packaging materials are popular because they are generally perceived to be more environmentally friendly. A comparison of the life cycles of such packaging material that are fossil-based plastic or a metal equivalents does not always support this perception and the environmental outcomes are highly dependent on the end-o...

In recent years, there has been a growing concern from the scientific community regarding the significant environmental impacts of animal agriculture. In order to draw consumer attention to this issue, there have been a number of initiatives, such as ecolabeling, that seek to influence consumer purchasing behavior. The growth in popularity of smartph...

It is becoming more common to include the effects of delayed greenhouse gas emissions as an additional aspect in carbon footprinting. Although full dynamic assessment is the only accurate option to calculate those effects, the linear approach as outlined in, for example, the International Reference Life Cycle Data System (ILCD) Handbook, which is a...

A recurring issue in LCA is the impact assessment of inventory items that are associated with a probability lower than one. In many production life cycles, smaller or larger calamities may occur that are quite clearly not part of day-to-day operations. Taking the impacts of such calamities into account requires the use of risk measures that allow c...

In this project, the scope for product specific rules for carbon footprinting of (green) coffee is investigated and a proposal is drafted for further work toward actual definition and implementation of such a standard.

In den 1960er Jahren erlebte die Welt eine lange, nachhaltige Periode des Wirtschaftswachstums, die vielen Ländern Wohlstand und Reichtum brachte. Bereits Mitte/Ende der 1960er Jahre kam jedoch bei Boulding (1966) und Mishan (1967) die Frage auf, ob aufgrund der wachsenden Umweltbelastungen kontinuierliches Einkommenswachstum möglich bzw. wünschens...

We present the results of 22 GHz H_2O maser observations of a sample of 85 post-Asymptotic Giant Branch (post-AGB) candidate stars, selected on the basis of their OH 1612 MHz maser and far-infrared properties. All sources were observed with the Tidbinbilla 70-m radio telescope and 21 detections were made. 86 GHz SiO Mopra observations of a subset o...

We derive the distribution of maser stars in the inner Milky Way (MW) based on an analysis of lV-diagrams (lVd) for two samples of maser stars: 771 OH/IR stars and 363 SiO-maser stars. They are all close to the plane of the MW and have long. from -45 to +45deg. The two lVds are compared and found to be very similar. They also compare well with the...

We have searched color-selected AGB stars from the ISOGAL and MSX mid-IR surveys in the Galactic Bulge and Plane for 86 GHz (v=1, J=2-1) SiO maser emission with the 30-m IRAM telescope. The SiO masers instantaneously reveal the line-of-sight velocity of the stars, which in combination with the less numerous and slightly different population of OH/I...

Dust- and gas mass loss rates and distances are determined for a sample of about 330 infra-red carbon stars that probe a distance up to about 5.5 kpc. The dependence of the dust- and gas mass loss rates, and the expansion velocity upon galactic longitude (l) are studied. It is found that the expansion velocity significantly depends on l, but that t...

Millimetre observations of IRAS selected red carbon stars are presented. About 260 stars have been observed with SEST and IRAM in the CO (1-0) and CO (2-1) lines and partially in HCN (1-0) and SiO (3-2). An overall detection rate, in at least one line, of about 80% is achieved. The survey represents the second largest survey for AGB stars, and the...

The results of a large millimetre survey of infrared carbon stars is presented. The Table provides the detailed outcome of the observations. IRAS name, transition and molecule, velocity resolution, rms noise, peak temperature, integrated intensity, central velocity and expansion velocity are presented. (2 data files).

Using 766 compact objects found in a systematic survey of the Galactic plane in the 1612 MHz masing OH line, new light is cast on the IR properties of evolved stars on the thermally pulsing asymptotic giant branch (AGB) and beyond. The usual mid-IR selection criteria for post-AGB, based on IRAS colors, largely fail to distinguish early post-AGB sta...

Using objects found in a systematic survey of the Galactic plane in the 1612 MHz masing OH line, we discuss in detail two "sequences" of post-AGB evolution, a red and a blue. We argue that the red and the blue groups separate by initial mass at Mi = 4 M, based on evolutionary sequence turnoff colors, spectral energy distributions, outflow velocitie...

We show how the continuity equation can be used to determine pattern speeds in the Milky Way Galaxy (MWG). This method, first discussed by Tremaine & Weinberg in the context of external galaxies, requires projected positions, (l,b), and line-of-sight velocities for a spatially complete sample of relaxed tracers. If the local standard of rest (LSR)...

The Milky Way Galaxy (MWG) contains both a bar and spirals. The pattern speed/rotation frequency, \(\Omega_p\), of these components have been measured with a variety of models. For the bar, models have found values \(40 \lesssim \Omega_p \lesssim 60 {\rm km s}^{-1} {\rm kpc}^{-1}\) (Binney et al. 1991; Fux 1999; Englmaier & Gerhard 1999; Weiner & S...

The ATCA/VLA Galactic Plane survey detected OH 1612 MHz maser emission from a total of 766 sources. In most cases the detected sources have double-peaked spectral profiles which are characteristic of OH/IR stars. A small number of sources however have irregular spectra and uncertain classifications. We discuss the maser results for two sources with...

All current bulge-disk models for the inner Galaxy fall short of reproducing self-consistently the observed microlensing optical depth by a factor of 2 (>2 σ). We show that the least mass-consuming way to increase the microlensing optical depth is to add density roughly halfway between the observer and the highest microlensing source density. We pr...

We present observations of the region between 5° ≤ ℓ ≤ 45° and |b| ≤ 3°, in the OH 1612.231 MHz line, taken from 1993 to 1995 with NRAO's Very Large Array** (VLA). These observations are the last part of a larger survey, covering |ℓ| ≤ 45° and |b| ≤ 3°, with the Australia Telescope Compact Array (ATCA) and the VLA. The region was systematically obs...

We present observations of the region between 5 ' 45 andjbj3, in the OH 1612.231 MHz line, taken from 1993 to 1995 with NRAO's Very Large Array ?? (VLA). These observations are the last part of a larger survey, coveringj'j45 andjbj3, with the Australia Telescope Compact Array (ATCA) and the VLA. The region was systematically observed on a 30 0 30 0...

We have observed a sample of OH 1612 MHz masing objects in all four OH ground-state transitions with the Australia Telescope Compact Array. One likely post-asymptotic giant branch (AGB) object is found to emit in the 1612, 1665, and 1720 MHz transitions. We discuss the evidence that this object may be an early post-AGB object and the possibility fo...

File table2 contains information on the compact OH-maser sources detected in the northern galactic Disk region with the Very Large Array. (1 data file).

We present dynamical distribution functions for evolved stars in the inner galactic plane. We use an axisymmetric, two-component Stackel potential that satisfies recent constraints on the galactic potential, amongst others a slightly declining local rotation curve. We show that this potential is adequate to model stellar-kinematic samples with radi...

We analyse a sample of 507 evolved (OH/IR) stars in the region (10°>ℓ>−45°), (|b|<3°). We derive average ages for subsets of this sample, and use those sets as beacons for the evolution of the Galaxy. In the bulge, the oldest OH/IR stars in the plane are 7.5 Gyr (1.3 M⊙), and in the disc 2.7 Gyr (2.3 M⊙). The vertical distribution of almost all AGB...

We determine the most likely values of the free parameters of an N-body model for the Galaxy developed by Fux via a discrete–discrete comparison with the positions on the sky and line-of-sight velocities of an unbiased, homogeneous sample of OH/IR stars. Via Monte Carlo simulation, we find the plausibility of the best-fitting models, as well as the...

The Galaxy's has a weak Bar, of SAB-type, and the corotation radius is near 3.5 kpc with the inner-ultra-harmonic resonance near 2.5 kpc, as derived from an unbiased set of stellar positions and losa velocities. I speculate upon - and present some evidence for - a scenario in which the Bar formed about 5 Gyr ago and induced an inward flow of gas th...

We present observations of the region between -45 deg <= l <= 10 deg and |b| <= 3 deg in the OH 1612.231 MHz line, taken in 1994 January with the Australia Telescope Compact Array (ATCA) These observations are part of a larger survey, covering l <= 45 deg and |b| <= 3 deg, with the ATCA and the Very Large Array. In a previous article we have discus...

We present observations of the region between $ |\ell| \le 10^{\circ}$ and $ |b| \le 3^{\circ}$ in the OH 1612.231 MHz line, taken in 1993 October and November with the Australia Telescope Compact Array. The region was systematically searched for OH/IR stars and was covered completely with 539 pointing centres separated by 30. The size of the datas...

The large microlensing optical depth inferred from the OGLE and MACHO surveys towards the Galactic bulge appears to be inconsistent with the standard model of the Galaxy. The two present solutions, a massive disc or a bar aligned long the line of sight, are not particularly attractive since they are inconsistent with many observations. Here we repo...

We present observations of the region between -45°

We present observations of the region between |l|

An OH/IR star is an intermediate mass AGB star which loses mass and is optically obscured by its envelope. Such stars can be detected in the infrared and by radio maser lines. In particular the OH line (1612 MHz) is bright and has a distinctive profile, that allows us to determine the radial velocity of the central star. OH/IR stars are excellent t...

Part of a large survey of the inner galactic Plane ( $ | \ell | < 45^{\circ} $ and $ | b | < 3^{\circ} $ total) in the OH 1612MHz line in search for OH/IR stars is analysed. We find strong evidence for a central m=2 distortion based on geometrical considerations. The observed deviation from axisymmetry cannot be explained by lopsidedness and agrees...

An OH/IR star is an intermediate mass AGB star which loses mass and is optically obscured by its envelope. Such stars can be detected in the infrared and by radio maser lines. In particular the OH line (1612 MHz) is bright and has a distinctive profile, that allows us to determine the radial velocity of the central star. OH/IR stars are excellent t...

This is the third catalogue of photometric data in the Stroemgren system obtained during the period October 1990-January 1992 in the framework of the Long-Term Photometry of Variables (LTPV) program at the European Southern Observatory. All data have been obtained with the Danish 50-cm telescope. The mean values of the r.m.s. deviations of the diff...

Part of a large survey of the inner galactic Plane ( $ | \ell | < 45^{\circ} $ and $ | b | < 3^{\circ} $ total) in the OH 1612MHz line in search for OH/IR stars is analysed. We find strong evidence for a central m=2 distortion based on geometrical considerations. The observed deviation from axisymmetry cannot be explained by lopsidedness and agrees...

Two samples of OH/IR stars in our Galaxy are compared; one very close to the Galactic Centre (GC), the other in the Bulge and the Disk. The two are very distinct in density distribution, kinematics and astrophysical properties. Part of the observed kinematics is explained by assuming an extended mass concentration in the centre. We describe the sam...

In this paper we present the third catalogue of photometric data in the Stroemgren system obtained during the period October 1990-January 1992 in the framework of the Long-Term Photometry of Variables (LTPV) program at the European Southern Observatory. The catalogue is available in computer readable form at the Centre de Donnees de Strasbourg.

The ground-state radio transitions of OH have been observed toward the nucleus of the nearby active galaxy Centaurus A, using the Australia Telescope Compact Array. The main lines at rest frequencies 1667 and 1665 MHz show molecular absorption at velocities similar to those observed for other molecular species at millimeter wavelengths, which indic...

We have surveyed the inner part of the Galaxy for OH 1612 MHz maser emission from OH/IR stars. The full survey is expected to give around 2000 detections. Here we report initial results for the Bulge region between | l | < 10° and | b | < 3°. The observations discussed here were taken with the Australia Telescope Compact Array in Oct-Nov 1993. For...

The evolution of interstellar molecular hydrogen was studied, with a special interest for the formation and evolution of molecular clouds and star formation within them, by a two-dimensional hydrodynamical simulation performed on a rectangular grid of physical sizes on the order of 100 pc. It is filled with an initial density of approx. 1 cm(exp -3...

The Milky Way Galaxy (MWG) contains both a bar and spirals. The pattern speed/rotation frequency, Wp\Omega_p , of these components have been measured with a variety of models. For the bar, models have found values 40 Wp km s-1 kpc-140 \lesssim \Omega_p \lesssim 60 {\rm km s}^{-1} {\rm kpc}^{-1} (Binney et al. 1991; Fux 1999; Englmaier & Gerhard 1...

Thesis (Doctoral)--Rijksuniversiteit te Leiden, 1997. Includes bibliographical references.

Dust- and gas mass loss rates and distances are determined for a sample of about 330 infra-red carbon stars that probe a distance up to about 5.5 kpc. The dependence of the dust- and gas mass loss rates, and the expansion velocity upon galactic longitude ($l$) are studied. It is found that the expansion velocity significantly depends on $l$, but th...