Magnus Vilhelm Persson

First author publications

Constraining the physical structure of the inner few 100 AU scales of deeply embedded low-mass protostars.

M. V. Persson, D. Harsono, J. J. Tobin, E. F. van Dishoeck, J. K. Jørgensen, N. Murillo and S.-P. Lai

Open access : http://arxiv.org/abs/1603.01061
Publisher access : Astronomy & Astrophysics

DOI : 10.1051/0004-6361/201527666
Data : https://zenodo.org/record/47642

The physical structure of deeply-embedded low-mass protostars (Class 0) on scales of less than 300 AU is still poorly constrained. Determining this is crucial for understanding the physical and chemical evolution from cores to disks. In this study two models of the emission, a Gaussian disk intensity distribution and a parametrized power-law disk model, are fitted to sub-arcsecond resolution interferometric continuum observations of five Class 0 sources, including one source with a confirmed Keplerian disk. For reference, a spherically symmetric single power-law envelope is fitted to the larger scale (∼1000 AU) emission and investigated further for one of the sources on smaller scales. A thin disk model can approximate the emission and physical structure in the inner few 100 AU scales of the studied deeply-embedded low-mass protostars and paves the way for analysis of a larger sample with ALMA. While the disk radii agree with previous estimates the masses are different for some of the sources studied. Assuming a typical temperature distribution, the fractional amount of mass in the disk above 100 K varies in between 7% to 30%. Kinematic data are needed to determine the presence of any Keplerian disk. Using previous observations of p-H218O, we estimate the relative gas phase water abundances roughly an order of magnitude higher than previously inferred when both warm and cold H2 was used as reference. A spherically symmetric single power-law envelope model fails to simultaneously reproduce both the small and large scale emission.

Published in the electronic version of Astronomy & Astrophysics, Volume 590, June 2016.

Detection of water toward IRAS 16293-2422 with ALMA and SMA

The deuterium fractionation of water on solar-system scales in deeply-embedded low-mass protostars

M. V. Persson, J. K. Jørgensen, E. F. van Dishoeck and D. Harsono

Open access : http://arxiv.org/abs/1402.1398
Publisher access : Astronomy & Astrophysics

DOI : 10.1051/0004-6361/201322845
Data : https://zenodo.org/record/47123

The paper presents high-resolution ground-based observations of HDO toward three deeply-embedded low-mass protostars with the Plateau de Bure Interferometer. The spectra to the right shows the water emission toward the three protostars IRAS2A, IRAS4A-NW, and IRAS4B in NGC 1333 of the Perseus star forming region. The combination of the H218O and HDO observations leads to a HDO/H2O ratio of 7.4±2.1×10-4 for IRAS 2A, 19.1±5.4×10-4 for IRAS 4A-NW, and 5.9±1.7×10-4 for IRAS 4B. The HDO/H2O ratios show a weak dependence on the adopted excitation temperature in the calculations. Radiative transfer models were run for IRAS 2A and IRAS 16293-2422 (see previous article). These HDO/H2O ratios, from the radiative transfer models, agree with the direct LTE calculations for IRAS 16293-2422 within a factor of 2-3, and for IRAS 2A within a factor of 4. The differences seen between the models and calculations are mainly due to optical depth effects in the HDO line.

Published in Astronomy & Astrophysics, Volume 563, March 2014.

Detection of water toward IRAS 16293-2422 with ALMA and SMA

Warm water deuterium fractionation in IRAS 16293-2422 - The high-resolution ALMA and SMA view

M. V. Persson, J. K. Jørgensen and E. F. van Dishoeck

ArXiv open access : http://arxiv.org/abs/1211.6605
Publisher access : Astronomy & Astrophysics

DOI : 10.1051/0004-6361/201220638
Data : Science Verfication Data page

In this letter we present high-resolution ground-based (ALMA and SMA interferometric telescopes) observations of two isotopologues of water toward the deeply-embedded low-mass proto-binary IRAS 16293-2422. The moment map to the right shows the extent of the emisison. The combination of the H218O and HDO observations leads to a HDO/H2O ratio (deuterium fractionation of water) of 9.2 ±2.6 × 10-4. This ratio is significantly lower than previous estimates in the warm gas close to the source. It is also lower by a factor of ˜5 than the ratio deduced in the outer envelope. The observations reveal the physical and chemical structure of water vapor close to the protostars on solar-system scales (i.e. ≤100 AU). Toward one of the sources (source B), the line is redshifted and in absorption, a typical indication of infall.

Published in Astronomy & Astrophysics, Volume 549 January 2013.

Detection of water toward IRAS 16293-2422 with ALMA and SMA

Subarcsecond resolution observations of warm water toward three deeply embedded low-mass protostars

M. V. Persson, J. K. Jørgensen and E. F. van Dishoeck

ArXiv open access : http://arxiv.org/abs/1203.4969
Publisher access : Astronomy & Astrophysics

DOI : 10.1051/0004-6361/201117917
Data : https://zenodo.org/record/47123

The paper presents high-resolution ground-based observations of water toward two deeply-embedded low-mass protostars with the Plateau de Bure Interferometer.
The spectra to the right is from the paper and shows the detections of H218O and several other molecules toward the three protostars IRAS2A, IRAS4A-NW and IRAS4B in NGC 1333 of the Perseus star forming region. The results show that water is common in the inner regions of low-mass protostars and readily observed. The deduced abundances are high, although most of the water is still locked up as ice on the surface of dust grains. In the paper, abundances and the different molecules detected are discussed.

Published in Astronomy & Astrophysics Volume 541, May 2012.

Detection of water toward IRAS 2A, IRAS 4A-NW and IRAS 4B

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