Saturday, December 14, 2019

Cl Melotte 22 1426 ,steaua pierduta si regasita din Pleiade

La 23 Noiembrie 2018 am raportat pe forumul '''' observarea unei posibile ''stele-carbon'' in Pleiade :

Deoarece nu am facut schita la momentul observatiei ,care sa ma ajute la identificarea obiectului ,a trebuit ulterior sa fac incercari si presupuneri.
Dar prezumtiva stea-carbon nu am mai vazut-o.Pana aseara,Vineri 13 Decembrie.

Cam de o saptamana ,am folosit patru  fereastre de cer ( cat de cat)  senin pentru testarea noului meu ocular zoom Baader Mark III 8-24mm.
Aceasta faceam si aseara Joi 13 Decembrie cand ,in Pleiade am regasit steluta despre care am raportat la 23 Noiembrie 2018.

Steaua rosie sau oranj din Pleiade ,pierduta in 2018 si regasita in 2019.Multumesc Baader Mark III !

De aceasta data am facut o schita mentala a pozitiei stelei si azi mi-a fost usor sa gasesc niste informatii -nu prea multe - despre ea.

Pagina din Simbad a stelei Cl Melotte 22 1426

In absenta unei clasificari spectrale,nu putem sa o numim ''stea-carbon'' ,sa o numim deci stea oranj sau stea rosie.
Codul de identificare al stelei este Cl Melotte 22 1426 si apare ca stea de culoare oranj atat in fotografiile DSS2 , Panstarrs/DR1 cat si Mellinger.

Cl Melotte 22 1426 in DSS2

Cl Melotte 22 1426 in DSS2,detaliu , vezi culoarea oranj

Cl Melotte 22 1426 in PanSTARRS/D1, vezi culoarea oranj

Cl Melotte 22 1426 in PanSTARRS/D1 ,detaliu , vezi culoarea oranj

Stellarium 0.15.1 ( pe care il am instalat pe PC-ul meu)  cunoaste obiectul dar nu afiseaza nimic la locatie ci doar coordonatele si codul in coltul stanga -sus a ecranului.

Pe baza unei similitudini  vizuale,deci subiective ,putem oare presupune ca Cl Melotte 11 1426 este o stea carbon prin compararea imaginii acesteia cu steaua variabila V*V1227 cu spectru M1 ?
Priviti imaginea lui Cl Melotte si a lui V1227 Tau  din ''Mellinger Color Optical Survey''.

Cl Melotte 22 1426 versus V* V1227 cu spectrul clasificat M1

Informatii despre V* V1227 in CDS ,vezispectrul de giganta rosie M1

Chiar daca steaua cea pierduta si regasita Cl Melotte 22 1426 nu este o giganta rosie / o stea carbon, este totusi interesanta observarea ei deoarece in Pleiade partidul dominant este cel al stelelor albe.

Sunday, December 1, 2019

Messier 1 - Crab Nebula

M1 is not hard to find if your observation site have a dark sky.
However,if there is the slightest light pollution around ,things start going not very well when you try to spot the Crab Nebula.
Just looking to the parameters it shouldn't be like that : M1 have a visual magnitude of 8.4 mv.
But this light of a 8.4mv star is spread over an oval area of 8' x 4' or about 25 square minutes so the surface brightness is dropping to 11.9 mv.
To see stars of 12mv ,one need a six inch telescope and even in that instrument,those stars will be in the faint league ,in the last half of accesible magnitudes.
This is why is hard to find M1 by scanning the area.
Let's go another route...

Here is a 100% proof method to find the supernova remnant Messier 1 , aka Crab Nebula.
At one degree West-North West of star Zeta Tauri there is STF 742 ,a double star of 7mv.
Double star STF 742 at one degree W-NW of Zeta Tau

The primary star and the companion of STF 742 are separated by 4.16''.

The page of STF 742 on StelleDoppie

On 25-th of November it was not hard to notice at 33x /Plossl 25mm ,the binary character of STF 742 in my 60x828mm ''zoth'' refractor.
The power of 92x/Plossl 9mm confirmed I was spot on STF 742.
I knew (from many previous  observations) that M1 IS IN THE SAME FIELD WITH STF 742.
Altough dim ,quite dim, M1 was there ,as expected in the visual field of 94arc minutes at 33x.
Pumping up the power to 92x did not bring additional details.

M1/ Crab Nebula in the same 90' field with STF 742
60mm F/14 refractor at 33' /Plossl 25mm

To summarize , my trick to find M1 : search for double star STF 742 and center it in an eyepiece providing  80 or 90 arc minutes.
Once you are sure your telescope is centered on STF 742, scan carefuly the field because M1 is hiding somewhere there.

My trick is working for observations made from the downtown of our 180.000+++ city.
Good luck !