Characteristics of quiet Sun cell and network brightenings

نویسنده

  • L. K. Harra
چکیده

Extreme ultraviolet observations of the quiet Sun are made with the Coronal Diagnostic Spectrometer (cds) on board the Solar and Heliospheric Observatory (soho). It has been previously noted that frequent transition region brightenings occur in both the bright network and dark cell regions. Analysing 1125 events, we determined the characteristics of the brightenings in the cell and network regions which include the duration, energy, and intensity increase above the background. Network brightenings are found to be larger than cell events occurring with a mean duration of 150 s and releasing an average of 1026.9 ergs per event. Cell brightenings, on the other hand, last for an average of 96 s and release 1025.8 ergs per event. It has also been found that the distribution of energy is a power-law which is different in the cell (γ=2.5) and network (γ=1.5) regions. When the entire quiet Sun region is analysed the value of γ is 1.7. The number of events per cds pixel is approximately the same, and a histogram of the ratio ([peak value – background]/background) shows similar values for both the cell and network. It is important to analyse the cell and network regions separately in the context of coronal heating by such small flare-like events.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Quiet Sun Brightenings -cell and Network Behaviour

Observations of the quiet Sun are made with the Coronal Diagnostic Spectrometer on board the SOHO spacecraft. We have investigated the diierences in characteristics of the cell and network regions. It has been found that the powerlaw distribution of energy (f(E) = f o E ?) is diierent in the cell and network regions, with the cell region having higher values of. This result is found irrespectiv...

متن کامل

A study of the unification of quiet-Sun transient-event phenomena

A number of small-scale, globally distributed solar transient event-types have been reported in the literature. Their potential role in fundamental processes in the solar atmosphere, such as coronal heating and wind acceleration, is under active investigation. However, the event-types, such as those known as blinkers, explosive events, EUV (extreme-UV) network and cell brightenings, network fla...

متن کامل

Quiet Sun EUV transient brightenings and turbulence A panoramic view by EIT on board SOHO

Since January 1996, the Extreme-Ultraviolet Imaging Telescope (EIT, onboard SOHO) has produced unique image sequences covering a wide field of view with a high temporal resolution, in the He ii transition region line and in several Fe coronal emission lines. Using two sequences acquired with cadences of the order of one minute and with durations ranging from one hour to several hours, we analys...

متن کامل

Comparison of Transient Network Brightenings and Explosive Events in the Solar Transition Region.

The relation between transient network brightenings, known as blinkers, and explosive events is examined based on coordinated quiet Sun observations in the transition region line O v lambda630 recorded by the Coronal Diagnostic Spectrometer (CDS), in the transition region line Si iv lambda1402 recorded by the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) instrument, and in photosp...

متن کامل

A nanoflare model of quiet Sun EUV emission

Nanoflares have been proposed as the main source of heating of the solar corona. However, detecting them directly has so far proved elusive, and extrapolating to them from the properties of larger brightenings gives unreliable estimates of the power-law exponent α characterising their distribution. Here we take the approach of statistically modelling light curves representative of the quiet Sun...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2000