Saturday, October 21, 2023

Sun CaK What to see

 


What to see when we image the Sun in Ca K line?

- Plages or Chromospheric Faculae : Most of us are familiar with photospheric faculae which can normally only be observed towards the edge of the solar disc in white light when it is possible to view a higher region in the photosphere. These bright mottles can be up to 50,000km long and are caused by underlying magnetic fields. They are often a good predictor of future active region development and can also remain long after an active region has dissipated. The average lifetime of faculae is about 90 days and they are around several hundred degrees Kelvin hotter than the surroundings (therefore appear bright).Chromospheric faculae can be observed anywhere on the solar disc and they are an extension of the photospheric faculae into the chromosphere, details of this link are still not fully understood. Areas of very dense magnetically bright faculae or plage occur in active regions and are a good predictor of the occurrence of future sunspot formation (Evre, S. 1999). Polar faculae are short lived and only observed just before and around the solar minimum.

- Supergranulation Cells- Chromospheric Network Structure: in the quiet sun most of the chromosphere seen in Ca II K appears like a bright network pattern of irregularly shaped circles. The size of these cells is around 30,000-35,000 km in size and their average lifespan is around 20 hours. (Bhatnager, A. 2005). This is a pattern of weaker magnetic fields (the quiet network) where the magnetic elements are mixed in polarity. These are also called the intranetwork fields and the brighter edges can also be called faculae. The supergranulation cells are large scale convective horizontal flow, where material flows outwards from the centre and downward flow has been observed at the boundaries. The flow carries both polarities to the boundaries (Zirin H. 1988 p126).

- Bright rings around sunspots

- Sunspots

- K-Grains or bright points: K grains are 'intranetwork bright points' found in the quiet sun. Intranetwork bright points, cell flashes or cell grains, originate exclusively within cell interiors in quiet areas of the solar surface. These are observed almost exclusively in the Calcium H (396.85nm) and K lines (Rutten et al. 1991). They are intermittent localised brightenings which last less than a minute and often re-appear a few times at 2-4 min intervals at about the same place, and frequently occur in pairs. In Figure 2, the labelled brightenings are an example only. These bright points are tiny and good resolution is needed to observe these features. To identify them definitively, a time lapse study would need to be embarked upon and the brightenings studied to assess whether they follow the pattern of re-emergence and disappearance, again another good area for amateur study. It has been observed that these K grains do seem to correspond with G-band brightpoints observed in the intergranular lanes in the photosphere (Lite et al. 1998).

- Filaments

- Prominences

Source: https://solarnutcase.livejournal.com/1047.html

Sunday, October 15, 2023

Succesvol VVS Weekend 7/8 oktober 2023 Blankenberge

Opnieuw een succesvol VVS weekend dat doorging op 7 & 8 oktober te Blankenberge. Helios was aanwezig met 7 leden, een record. 
Enkele hoogtepunten :
* Professor dr. Harold Linnartz sprak over ijs in de ruimte en in het laboratorium met het doel op zoek te gaan naar de bouwstenen van het leven. De vorming van moleculen gebeurt in de interactielaag tussen stof en ijs. Dit Solid State Astrochemistry proces beschrijft hoe moleculen worden gevormd. Er is een broos evenwicht tussen de vorming van het ijs en het afbreken van het ijs. Denk maar aan het permanent bombarderen en afbreken van het ijs door electronen, UV-, IR-licht of kosmische straling  en anderzijds de extreem koude omstandigheden die het ijs laten aangroeien


* Professor dr. Nick Van Remortel sprak over de Einstein-telescoop. Hij gaf meer technisch inzicht over het project dat ons moet toelaten zwaartekrachtsgolven te detecteren met een gevoeligheid die 10x hoger ligt dan de huidige LIGO of Virgo.


*Professor dr. Nienke van der Marel gaf toelichting bij het bouwen van planeten. Zij besprak resultaten van de ALMA telescoop over de afbeeldingen van schijven en de eerste tekenen van planeetvorming. Zij ontving recent de New Horizons in Physics Prize 2024 voor de voorspelling, ontdekking en modellering van ‘stofvallen’ in jonge circumstellaire schijven, waarmee een al lang bestaand probleem in planeetvorming is opgelost.


Ik wil ook nog de interessante lezingen vermelden van Thierry Van Driessche (komeet C/2023 A3), Wout Goesaert (op zoek naar actief supermassief zwarte gaten),  Merline Bruyndonckx (Fast Burst en hun astronomisch nut), Koen Geukens (Artemis en Space X) en Claude Doom over 50 jaar hemelkalender.

Helios delegatie in volle glorie ...




Saturday, October 14, 2023

Scan time for Sol'Ex

The scanning of the solar disk using a Sol'Ex can be calculated using following formula

T = 8.79 * P / (f * v * Cos (delta))
  • T = exposure time in s
  • P = pixelsize in micron; include binning
  • f = focal point of telescope in mm
  • v = scanning time of telescoop, typical 4, 8, 16
  • delta = declination of the sun
It looks like that the outcome of the exposure time compared with the scanning time is rather exponential.











Sun in Ca H, Ca K and H-Alpha

This morning a clear sky for solar observation. After focussing my Sol'Ex pictures were made of the Sun in Ca H, Ca K and H-Alpha.

Setting:

TSAPO60/360 with ASI290MM
Sol'Ex with Hoya 1.6 SSD 
Ca H , Ca K and H-alpha 
Speed : 8x, Capture Area, 1936x276, MONO16, binning 1x1, capturing with SSD
CaH and CaK Exposure : 10.23ms ,tilt -10
H-Alpha Exposure : 3.75ms, tilt -3.9
Software : SharpCap4, Inti, IMPPG and CS4









Wednesday, October 4, 2023

Sun in CaK


Sun in CaK using my Sol'Ex instrument. Details of supergranulation and CaK prominences are clearly visible.

TSAPO60/360 with ASI290MM
Sol'Ex with Hoya 1,6
Area: 1936x114 (CaK) 
Ca K: 70fps, gain 49, 14,2ms, Mono 16, binning 1x1, Camera temperature 34°C
Software: SharpCap 4, Inti, IMPPG, CS4
Use of false colours

Sunday, October 1, 2023

Sol'Ex second session

My second Sol'Ex session after adjustment of the slit and slit edge. The edge of the slit was sharpened by pulling out the collimator bloc. Important is to keep the lens fixed and only pull the collimator with the slit out. It's only a mm. After sharpening the lines you will see that both lines and edge are sharp.
My first time I captured prominences in Ca K wavelengt.

Some other learnings: 
  1. allignment of the Sol'Ex; the plane of the Sol'Ex is parrallel with the equatorial plane
  2. at start the tilt was about 4°; when slightly adjusted this was reduced to -0,4°
  3. calculating the exposure time based on a speed of "8". this is about 8ms
Setting:
  • TSAPO60/360 with ASI290MM
  • Sol'Ex with Hoya 1,6
  • Area: 1936x114 (CaK) and 1936x276 (H-Alpha)
  • H-Alpha : 115fps, gain 0, 8,6ms, Mono 16, binning 1x1, Camera temperature 32°C
  • Ca K: 70fps, gain 49, 14,2ms, Mono 16, binning 1x1, Camera temperature 34°C
  • Software: SharpCap 4, Inti, CS4
  • Use of false colours




Saturday, September 23, 2023