A reassessment of the double isotope ratio (C-13)O/C(O-18) in molecular clouds

Taylor, David K.; Dickman, R. L.

doi:10.1086/167493

Cited by 11 publications

(12 citation statements)

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“…Typical solar active region parameters resulted in typically observed magnetic fluxes (Parnell et al 2009;Zhang et al 2010) and flare energies (Kretzschmar 2011;Schrijver et al 2012). We then scaled the model using the largest measured sunspot magnetic field (Solanki et al 2006), and the area of the largest sunspot group ever reported, which developed in March−April 1947 (Nicholson 1948;Taylor 1989).…”

Section: Summary and Discussionmentioning

confidence: 99%

“…These considerations lead us to conjecture that 30% at most of the area of the largest observed sunspot group, as reported by Nicholson (1948) and Taylor (1989), i.e. a maximum of 1800 MSH, can be involved in a flare.…”

Section: Taking Into Account the Fragmentation Of Fluxmentioning

confidence: 91%

“…These sizes follow a log-normal distribution up 3000 MSH, but there are a few larger groups. The largest one was observed in April 1947, and its area was about 5400−6000 MSH (Nicholson 1948;Taylor 1989). For illustration, we provide in Fig.…”

Section: Excluding Unobserved Regions In the Parameter Spacementioning

confidence: 99%

“…However, several other large sunspot groups, whose areas were at least 3500 MSH, did generate major geomagnetic storms. Among those are the March 1989 event, which led to the Quebec blackout (Taylor 1989), and the December 1128 event, which produced aurorae in Asia and which corresponds to the first reported sunspot drawing (Willis & Stephenson 2001). Therefore, we conservatively keep 6000 MSH as the maximum value.…”

Section: Excluding Unobserved Regions In the Parameter Spacementioning

confidence: 99%

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The standard flare model in three dimensions

Aulanier

Démoulin

Schrijver

et al. 2012

A&A

202

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Context. Solar flares strongly affect the Sun's atmosphere as well as the Earth's environment. Quantifying the maximum possible energy of solar flares of the present-day Sun, if any, is thus a key question in heliophysics. Aims. The largest solar flares observed over the past few decades have reached energies of a few times 10 32 erg, possibly up to 10 33 erg. Flares in active Sun-like stars reach up to about 10 36 erg. In the absence of direct observations of solar flares within this range, complementary methods of investigation are needed to assess the probability of solar flares beyond those in the observational record. Methods. Using historical reports for sunspot and solar active region properties in the photosphere, we scaled to observed solar values a realistic dimensionless 3D MHD simulation for eruptive flares, which originate from a highly sheared bipole. This enabled us to calculate the magnetic fluxes and flare energies in the model in a wide paramater space. Results. Firstly, commonly observed solar conditions lead to modeled magnetic fluxes and flare energies that are comparable to those estimated from observations. Secondly, we evaluate from observations that 30% of the area of sunspot groups are typically involved in flares. This is related to the strong fragmentation of these groups, which naturally results from sub-photospheric convection. When the model is scaled to 30% of the area of the largest sunspot group ever reported, with its peak magnetic field being set to the strongest value ever measured in a sunspot, it produces a flare with a maximum energy of ∼6 × 10 33 erg. Conclusions. The results of the model suggest that the Sun is able to produce flares up to about six times as energetic in total solar irradiance fluence as the strongest directly observed flare of Nov. 4, 2003. Sunspot groups larger than historically reported would yield superflares for spot pairs that would exceed tens of degrees in extent. We thus conjecture that superflare-productive Sun-like stars should have a much stronger dynamo than in the Sun.

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Section: Summary and Discussionmentioning

confidence: 99%

Section: Taking Into Account the Fragmentation Of Fluxmentioning

confidence: 91%

Section: Excluding Unobserved Regions In the Parameter Spacementioning

confidence: 99%

Section: Excluding Unobserved Regions In the Parameter Spacementioning

confidence: 99%

See 2 more Smart Citations

The standard flare model in three dimensions

Aulanier

Démoulin

Schrijver

et al. 2012

A&A

202

144

View full text Add to dashboard Cite

show abstract

“…However the measured ratios of the integrated line intensities of 13 CO and C 18 O may not represent the intrinsic ratio because of fractionation, optical depth and filling factor effects (Taylor & Dickman 1989;Langer & Penzias 1990). Since the clouds in the present sample are located at approximately equal distances from the Sun (10 kpc) we can compare our results with those towards local dark clouds and GMC's, which have an intrinsic ratio of 7-8 (WM 92), and with the solar system ratio of 5.5.…”

Section: Wb 89-501mentioning

confidence: 99%