EVALUATION OF SOLAR MASS LOSS RATE DUE TO THE SOLAR WIND

ABSTRACT Similar to the Sun, other stars shed mass and magnetic flux via ubiquitous quasi-steady wind and episodic stellar coronal mass ejections (CMEs). We investigate the mass loss rate via solar wind and CMEs as a function of solar magnetic variability represented in terms of sunspot number and solar X-ray background luminosity. We estimate the contribution of CMEs to the total solar wind mass flux in the ecliptic and beyond, and its variation over different phases of the solar activity cycles. The study exploits the number of sunspots observed, coronagraphic observations of CMEs near the Sun by SOHO/LASCO, in situ observations of the solar wind at 1 AU by WIND, and GOES X-ray flux during solar cycles 23 and 24. We note that the X-ray background luminosity, occurrence rate of CMEs and ICMEs, solar wind mass flux, and associated mass loss rates from the Sun do not decrease as strongly as the sunspot number from the maximum of solar cycle 23 to the next maximum. Our study confirms a true physical increase in CME activity relative to the sunspot number in cycle 24. We show that the CME occurrence rate and associated mass loss rate can be better predicted by X-ray background luminosity than the sunspot number. The solar wind mass loss rate which is an order of magnitude more than the CME mass loss rate shows no obvious dependency on cyclic variation in sunspot number and solar X-ray background luminosity. These results have implications for the study of solar-type stars.

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Origin of the Solar Wind and Open Coronal Magnetic Structures

Symposium - International Astronomical Union ◽

10.1017/s0074180900182622 ◽

2004 ◽

Vol 219 ◽

pp. 587-598

Author(s):

Shadia Rifai Habbal ◽

Richard Woo

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Mass Loss ◽

Loss Rate ◽

Interplanetary Space ◽

Mass Loss Rate ◽

Coronal Holes ◽

Significant Fraction ◽

Unexpected Result ◽

Magnetic Structures

Identifying the regions of open magnetic structures in the corona, namely regions where field lines expand outwards into interplanetary space, is equivalent to establishing the origin of the solar wind at the Sun. A review of recent studies, based on the comparison of the distribution, as a function of latitude, of density and velocity in the inner corona and in interplanetary space, is presented. It is shown how, at solar minimum, this comparison leads to the unexpected result that the fast solar wind expands indiscriminately from a significant fraction of the solar surface, not limited to polar coronal holes, as has been believed for the past three decades. It is also shown how polarization measurements of coronal forbidden lines, which yield the direction of the coronal magnetic field, lend further support to this result. The implications of these findings are that a significant fraction of the solar magnetic field is primarily open, expanding almost radially into interplanetary space, carrying with it the imprint of the distribution of density in the corona, while the ‘closed’ structures contribute a small fraction to the overall filling factor of coronal density structures. Furthermore, the solar wind particle flux is found to be correlated with density, implying a higher mass loss rate from the higher density quiet Sun regions, and the likelihood of a solar cycle dependence in the mass loss rate, as the are of polar coronal holes decreases with increased solar activity.

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Mass flow and evolution of UW Canis Majoris

Symposium - International Astronomical Union ◽

10.1017/s0074180900013619 ◽

1979 ◽

Vol 83 ◽

pp. 281-286

Author(s):

Yoji Kondo ◽

George E. McCluskey ◽

Jürgen Rahe

Keyword(s):

Mass Loss ◽

Mass Flow ◽

Radiation Pressure ◽

Stellar Wind ◽

Loss Rate ◽

Mass Loss Rate ◽

Primary Component ◽

Uv Spectrum ◽

Solar Mass ◽

Eclipsing Binary

The far-UV spectrum of the eclipsing binary UW CMa (O7f + O-B) had earlier been utilized to derive a mass-loss rate of about 10−6 to 10−5 solar mass per year. The mass flow seems to be basically in the form of a stellar wind emanating from the O7f primary component, with radiation pressure as the controlling factor. The main characteristics that make UW CMa a possible progenitor of a Wolf-Rayet system are discussed.

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Effects of the stellar wind on the Ly α transit of close-in planets

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3431 ◽

2020 ◽

Vol 500 (3) ◽

pp. 3382-3393

Author(s):

S Carolan ◽

A A Vidotto ◽

C Villarreal D’Angelo ◽

G Hazra

Keyword(s):

Mass Loss ◽

Stellar Wind ◽

Loss Rate ◽

Mass Loss Rate ◽

Escape Rate ◽

Stellar Winds ◽

Solar Mass ◽

Atmospheric Escape ◽

Exchange Processes ◽

Sonic Surface

ABSTRACT We use 3D hydrodynamics simulations followed by synthetic line profile calculations to examine the effect increasing the strength of the stellar wind has on observed Ly α transits of a hot Jupiter (HJ) and a warm Neptune (WN). We find that increasing the stellar wind mass-loss rate from 0 (no wind) to 100 times the solar mass-loss rate value causes reduced atmospheric escape in both planets (a reduction of 65 per cent and 40 per cent for the HJ and WN, respectively, compared to the ‘no wind’ case). For weaker stellar winds (lower ram pressure), the reduction in planetary escape rate is very small. However, as the stellar wind becomes stronger, the interaction happens deeper in the planetary atmosphere, and, once this interaction occurs below the sonic surface of the planetary outflow, further reduction in evaporation rates is seen. We classify these regimes in terms of the geometry of the planetary sonic surface. ‘Closed’ refers to scenarios where the sonic surface is undisturbed, while ‘open’ refers to those where the surface is disrupted. We find that the change in stellar wind strength affects the Ly α transit in a non-linear way (note that here we do not include charge-exchange processes). Although little change is seen in planetary escape rates (≃ 5.5 × 1011 g s−1) in the closed to partially open regimes, the Ly α absorption (sum of the blue [−300, −40 km s−1] and red [40, 300 km s−1] wings) changes from 21 to 6 per cent as the stellar wind mass-loss rate is increased in the HJ set of simulations. For the WN simulations, escape rates of ≃ 6.5 × 1010 g s−1 can cause transit absorptions that vary from 8.8 to 3.7 per cent, depending on the stellar wind strength. We conclude that the same atmospheric escape rate can produce a range of absorptions depending on the stellar wind and that neglecting this in the interpretation of Ly α transits can lead to underestimation of planetary escape rates.

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λ And: a post-main-sequence wind from a solar-mass star

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3468 ◽

2020 ◽

Vol 500 (3) ◽

pp. 3438-3453

Author(s):

D Ó Fionnagáin ◽

A A Vidotto ◽

P Petit ◽

C Neiner ◽

W Manchester IV ◽

...

Keyword(s):

Magnetic Field ◽

Mass Loss ◽

Stellar Wind ◽

Loss Rate ◽

Main Sequence ◽

Mass Loss Rate ◽

Mass Star ◽

Radio Observations ◽

Solar Mass ◽

5 Ghz

ABSTRACT We investigate the wind of λ And, a solar-mass star that has evolved off the main sequence becoming a subgiant. We present spectropolarimetric observations and use them to reconstruct the surface magnetic field of λ And. Although much older than our Sun, this star exhibits a stronger (reaching up to 83 G) large-scale magnetic field, which is dominated by the poloidal component. To investigate the wind of λ And, we use the derived magnetic map to simulate two stellar wind scenarios, namely a ‘polytropic wind’ (thermally driven) and an ‘Alfven-wave-driven wind’ with turbulent dissipation. From our 3D magnetohydrodynamics simulations, we calculate the wind thermal emission and compare it to previously published radio observations and more recent Very Large Array observations, which we present here. These observations show a basal sub-mJy quiescent flux level at ∼5 GHz and, at epochs, a much larger flux density (>37 mJy), likely due to radio flares. By comparing our model results with the radio observations of λ And, we can constrain its mass-loss rate $\dot{M}$. There are two possible conclusions. (1) Assuming the quiescent radio emission originates from the stellar wind, we conclude that λ And has $\dot{M} \simeq 3 \times 10^{-9}$ M⊙ yr −1, which agrees with the evolving mass-loss rate trend for evolved solar-mass stars. (2) Alternatively, if the quiescent emission does not originate from the wind, our models can only place an upper limit on mass-loss rates, indicating that $\dot{M} \lesssim 3 \times 10^{-9}$ M⊙ yr −1.

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Simulations of solar wind variations during an 11-year cycle and the influence of north–south asymmetry

Journal of Plasma Physics ◽

10.1017/s0022377818000880 ◽

2018 ◽

Vol 84 (5) ◽

Cited By ~ 5

Author(s):

B. Perri ◽

A. S. Brun ◽

V. Réville ◽

A. Strugarek

Keyword(s):

Solar Wind ◽

Mass Loss ◽

Loss Rate ◽

Transport Model ◽

Magnetic Energy ◽

Mass Loss Rate ◽

Phase Lag ◽

The Sun ◽

Flux Transport ◽

South Asymmetry

We want to study the connections between the magnetic field generated inside the Sun and the solar wind impacting Earth, especially the influence of north–south asymmetry on the magnetic and velocity fields. We study a solar-like 11-year cycle in a quasi-static way: an asymmetric dynamo field is generated through a 2.5-dimensional (2.5-D) flux-transport model with the Babcock–Leighton mechanism, and then is used as bottom boundary condition for compressible 2.5-D simulations of the solar wind. We recover solar values for the mass loss rate, the spin-down time scale and the Alfvén radius, and are able to reproduce the observed delay in latitudinal variations of the wind and the general wind structure observed for the Sun. We show that the phase lag between the energy of the dipole component and the total surface magnetic energy has a strong influence on the amplitude of the variations of global quantities. We show in particular that the magnetic torque variations can be linked to topological variations during a magnetic cycle, while variations in the mass loss rate appear to be driven by variations of the magnetic energy.

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Numerical simulations of ICME–ICME interactions

Journal of Space Weather and Space Climate ◽

10.1051/swsc/2018049 ◽

2019 ◽

Vol 9 ◽

pp. A4 ◽

Cited By ~ 2

Author(s):

Tatiana Niembro ◽

Alejandro Lara ◽

Ricardo Francisco González ◽

Jorge Cantó

Keyword(s):

Solar Wind ◽

Mass Loss ◽

Loss Rate ◽

Mass Loss Rate ◽

Single Structure ◽

Physical Insight ◽

Hydrodynamical Simulations ◽

The Magnetic Field ◽

Insight Into ◽

Ambient Solar Wind

We present hydrodynamical simulations of the interaction of Coronal Mass Ejections (CME) in the Interplanetary Medium (IPM). In these events, two consecutive CMEs are launched from the Sun in similar directions within an interval of time of a few hours. In our numerical model, we assume that the ambient solar wind is characterized by its velocity and mass-loss rate. Then, the CMEs are generated when the flow velocity and mass-loss rate suddenly change, with respect to the ambient solar wind conditions during two intervals of time, which correspond to the duration of each CME. After their interaction, a merged region is formed and evolve as a single structure into the IPM. In this work, we are interested in the general morphology of this merged region, which depends on the initial parameters of the ambient solar wind and the CMEs involved. In order to understand this morphology, we have performed a parametric study in which we characterize the effects of the initial parameters variations on the density and velocity profiles at 1 AU, using as reference the well-documented event of July 25th, 2004. Based on this parametrization we were able to reproduce the main features of the observed profiles ensuring the travel time and the speed and density magnitudes. Then, we apply the parametrization results to the interaction events of May 23, 2010; August 1, 2010; and November 9, 2012. With this approach and varying the values of the input parameters within the CME observational errors, our simulated profiles reproduce the main features observed at 1 AU. Even though we do not take into account the magnetic field, our models give a physical insight into the propagation and interaction of ICMEs.

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The solar wind in time

Proceedings of the International Astronomical Union ◽

10.1017/s174392131200498x ◽

2011 ◽

Vol 7 (S286) ◽

pp. 286-290

Author(s):

Jeffrey L. Linsky ◽

Brian E. Wood ◽

Seth Redfield

Keyword(s):

Solar Wind ◽

Mass Loss ◽

Loss Rate ◽

Mass Loss Rate ◽

Neutral Hydrogen ◽

Surface Flux ◽

Hydrogen Gas ◽

Main Sequence Stars ◽

X Ray ◽

Low X

AbstractWe describe our method for measuring mass loss rates of F–M main sequence stars with high-resolution Lyman-α line profiles. Our diagnostic is the extra absorption on the blue side the interstellar hydrogen absorption produced by neutral hydrogen gas in the hydrogen walls of stars. For stars with low X-ray fluxes, the correlation of observed mass loss rate with X-ray surface flux and age predicts the solar wind mass flux between 700 Myr and the present.

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