Discussion paper: Comments on physical properties of strongest perturbations on the Sun in the heliosphere and the magnetosphere

AbstractHelioseismology has provided us with the unique knowledge of the interior structure and dynamics of the Sun, and the variations with the solar cycle. However, the basic mechanisms of solar magnetic activity, formation of sunspots and active regions are still unknown. Determining the physical properties of the solar dynamo, detecting emerging active regions and observing the subsurface dynamics of sunspots are among the most important and challenging problems. The current status and perspectives of helioseismology are briefly discussed.

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Influence of Planets on the Magnetic Activity of Sun-Like Stars

Proceedings of the International Astronomical Union ◽

10.1017/s1743921318002041 ◽

2018 ◽

Vol 13 (S340) ◽

pp. 242-243

Author(s):

Shashanka R. Gurumath ◽

K. M. Hiremath ◽

V. Ramasubramanian

Keyword(s):

Physical Properties ◽

Power Law ◽

Magnetic Activity ◽

The Sun ◽

Stellar Activity ◽

Index Data ◽

Planetary Mass ◽

Power Law Decay ◽

Host Stars

AbstractBy considering the physical properties of Sun-like G stars and their exoplanets, present study examines whether presence of planets near the host stars enhances their stellar activity. In order to attain this goal, chromospheric RHK index data-a proxy for the magnetic activity-for the stars with and without planets is considered. With the reasonable constraints on the exoplanetary data, we obtained a power law decay relationship between the magnetic activity of host stars and their ages, for stars with and without planets. Both these results strongly suggest that there is no difference in magnetic activity of the sun-like stars with and without presence of planets. In order to confirm this result, further we also examine an association between the host stars RHK index that have exoplanets and their respective exoplanetary masses. We find that magnitude of RHK (hence magnetic activity) of the host stars is independent of presence of planetary mass in its vicinity.

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Size, physical properties, and orbital evolution of the comet Hale-Bopp (C/1995 O1) nucleus

International Astronomical Union Colloquium ◽

10.1017/s0252921100031687 ◽

1999 ◽

Vol 173 ◽

pp. 371-374

Author(s):

K.I. Churyumov ◽

V.G. Kruchynenko ◽

R.V. Makarchuk

Keyword(s):

Energy Balance ◽

Physical Properties ◽

Heat Conductivity ◽

Orbital Evolution ◽

The Sun ◽

Orbital Elements ◽

Heat Conductivity Coefficient ◽

Sublimation Rate ◽

The Moment ◽

Comet Halley

AbstractThe equation of the energy balance for the comet Hale-Bopp nucleus is analyzed for the moment when the comet passed perihelion and the sublimation rate (for water) was 1031molecules s−1≈ 3 × 105kgs−1. The minimal value of the nucleus radiusRequ(for γ = 1.0, i.e. the total surface sublimation) equals 14.6 km; for γ = 0.2 (the comet Halley nucleus had approximately this γ value)Requ= 33 km; the thickness of the mineral crust equals ≈ 10−2m for the heat conductivity coefficient ƛ ≈ 0.2 Jm−1s−1K−1. The results of calculations of the orbital elements evolution of the comet Hale-Bopp during one rotation around the Sun show that the comet will not collide with Jupiter (both passages near Jupiter will take place at distances more than 4 AU).

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Method for Spot-Detection on Solar-like Stars

Symposium - International Astronomical Union ◽

10.1017/s007418090018235x ◽

2004 ◽

Vol 219 ◽

pp. 379-384

Author(s):

Adriana V. R. Silva

Keyword(s):

Active Region ◽

Light Curve ◽

Physical Properties ◽

Quadratic Function ◽

The Sun ◽

Temperature Range ◽

Spot Detection ◽

Limb Darkening ◽

Parent Star ◽

Planetary Transits

As a planet eclipses its parent star, a dark starspot may be occulted, causing a detectable variation in the light curve. This work describes how features on the surface of a solar-like star can be studied by using planetary transits. Images of the Sun were used in order to simulate such transits, with the planet being modeled as a dark disk at various positions along its orbit. From modeling of these transits it might be possible to infer the physical properties of the spots, such as size, intensity, position, and temperature. Recent transits observations for HD 209458 were used as tests to the model. The results yield that the limb darkening of HD 209458 is not like that of the Sun, but rather follows a quadratic function. The dark features studied have radii varying between 3 — 6 104 km, and probably represent a group of spots, namely an active region. As for the temperature, these spots are hotter than sunspots with a temperature range of 4900-5500 K.

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Evolution of interplanetary coronal mass ejections and magnetic clouds in the heliosphere

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313011058 ◽

2013 ◽

Vol 8 (S300) ◽

pp. 245-254

Author(s):

Pascal Démoulin

Keyword(s):

Solar Wind ◽

Physical Properties ◽

Coronal Mass Ejections ◽

Magnetic Measurements ◽

Flux Rope ◽

Magnetic Clouds ◽

The Sun ◽

Interplanetary Coronal Mass Ejections

AbstractInterplanetary Coronal Mass Ejections (ICMEs), and more specifically Magnetic Clouds (MCs), are detected with in situ plasma and magnetic measurements. They are the continuation of the CMEs observed with imagers closer to the Sun. A review of their properties is presented with a focus on their magnetic configuration and its evolution. Many recent observations, both in situ and with imagers, point to a key role of flux ropes, a conclusion which is also supported by present coronal eruptive models. Then, is a flux rope generically present in an ICME? How to quantify its 3D physical properties when it is detected locally as a MC? Is it a simple flux rope? How does it evolve in the solar wind? This paper reviews our present answers and limited understanding to these questions.

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Coronal streamers on the Sun and their physical properties

Journal of Physical Studies ◽

10.30970/jps.13.2901 ◽

2009 ◽

Vol 13 (2) ◽

Cited By ~ 1

Author(s):

G. A. Porfir'eva ◽

G. V. Yakunina ◽

A. B. Delone ◽

A. V. Oreshina ◽

I. V. Oreshina

Keyword(s):

Physical Properties ◽

The Sun ◽

Coronal Streamers

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Sunburn: Effects and Management

Pediatrics in Review ◽

10.1542/pir.5.1.13 ◽

1983 ◽

Vol 5 (1) ◽

pp. 13-17

Author(s):

James Leach

Keyword(s):

Solar Radiation ◽

Physical Properties ◽

Well Being ◽

Ultraviolet B ◽

The Sun ◽

Human Beings ◽

Ultraviolet A ◽

The Past ◽

Cutting Out ◽

Ancient Times

The salutary benefits of basking in the sun have been sought by human beings since ancient times. Regarded in the past as a deity, the sun still confers its radiant benedictions on its modern devotees who have been persuaded by contemporary fashions that a dark brown tan is a sure sign of well-being, both physical and psychological. At some time, virtually all ardent sun-worshippers discover the unpleasant acute cutaneous reaction commonly called sunburn. PHYSICAL PROPERTIES OF SOLAR RADIATION Constituting a continuous spectrum, the electromagnetic radiation from the sun ranges from the highly energetic short wavelengths to the less energetic longer wavelengths. The wavelengths that impinge on the earth's surface are between 290 and 3,000 nm. On the basis of our visual physiology, they can be arbitrarily divided into visible, ultraviolet, and infrared waves. The portion of solar radiation that elicits the sunburn reaction lies between 290 and 320 nm in the ultraviolet band and is traditionally designated ultraviolet B (UVB). The earth's stratosphere effectively absorbs the potentially more harmful shorter wavelengths. This filtering is accomplished by the thin ozone layer that continually absorbs ultraviolet radiation (UVR) from 200 to 320 nm, completely cutting out all radiation less than 290 nm. The longer ultraviolet wavelengths from 320 to 400 nm, designated ultraviolet A (UVA), are approximately one thousandth as effective as UVB in evoking erythema.

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Three Dimensional MHD Simulationof Comet Hale-Bopp Tail

Baghdad Science Journal ◽

10.21123/bsj.5.4.581-592 ◽

2008 ◽

Vol 5 (4) ◽

pp. 581-592

Author(s):

Baghdad Science Journal

Keyword(s):

Solar Wind ◽

Physical Properties ◽

Source Term ◽

Three Dimensional ◽

Careful Analysis ◽

The Sun ◽

Comet Tail ◽

Order Accuracy ◽

Matlab Program ◽

Present Simulation

The interaction between comet Hale-Bopp tail with the solar wind is investigated in the present paper using magneto-hydrodynamic (MHD) numerical simulation, which accounts for the presence of the interplanetary magnetic field (IMF). The simulation is based on three-dimensional Lax-Wendroff explicit scheme, providing second-order accuracy in space and time. The ions produced from the nucleus of the comet will add considerable effects on the microstructure of the solar wind, thus severely altering its physical properties. The present simulation focuses on careful analysis of these properties by means of simulating the behavior of the comet Hale-Bopp’s tail at 1 AU from the sun. These properties include the changes of the plasma density, particle velocity, IMF changes, pressure, and internal energy. The results indicated that comet tail will highly disturb the physical properties of the solar wind for a considerable distance. These changes reflect the effect of including the source term in the present simulation. It is shown that the comet tail will retain its original shape faster as it approaches the sun. Practical comparisons are also presented in the present research with earlier work. The present simulation was made using MATLAB program.

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