observational parameters by santosh takale at mu-basic (04-11-12)

7/31/2019 Observational Parameters by Santosh Takale at MU-Basic (04-11-12)

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Observat ional Param eters

Sant osh TakaleB. Tech (M ech. Engg.), Scient if ic Off icer,

Bhabha Atom ic Research Cent re , M um bai ,

09967584554 / santoshatbarc@gmai l .com

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Ast ro no m y St ud ies

Theoret ical

Observat ional

Field Observatio n Aspects

Requ ired t heo ret ical Aspects

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Field Obser vat ion Aspect s W hat w e are Loo k ing fo r ?

Constel lat ions Nakshtras

Sunsigns

Planets

No tab le Stars

M eteor Show er

Galaxies, Dwar f Galaxies

M essier Object s, Neb ulae, Star Cluster s etc.



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W hat are t he re ferences ?

Horizon

Direct ions

Po le St ar

Som e know n o bjects (con ste l ln) Planet ary Posit ion

Aid s / Accesso ries

Star M aps

Sof t w are : St el lar iu m , Celest ia

Bino cular & Telescop es



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M easur ing Sky w i th Deg, M in & Secon ds ?

Pole Star a t 19 degree f rom hor izon (M um )

Fu l l M oon / Sun 0 .5 degree (30 m in ) Link

M 44 ( Beeh ive cluster ) 90 m in

Sm allest constel ln

(Crux) 68.45 sq d eg Biggest Co nst elln (Hydra) 1304 sq d eg

Thu m b Rules for Degree m easurem ent :

Fist 10 d eg, Raised Thu m b 5 deg

Raised Thu m b w i th l i t t le f inger & Fist 19 deg

M um bai : 19 deg Lat t . & 72 deg Long.

India betn

: 57 to 97 & 8 to 37 (Long / Lat t )



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Gu ide l in es fo r Sky o bservat ion s :

W ait & W atch (7 to 10 m inutes for eyes to accl im at ize)

In i t ial ize sky ob servat ion f rom Hom e t errace

A, B, C, S o f Sky o bser vat io ns?

A : Aviat ion Head l ight s

B : M igrato ry Birds

C : Clo u ds

S : Sp ace aw aren ess



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Requ ired Theo ret ical Aspect s

Dist ances & U nit s ?

Techn iqu es of m easurem ent s & Lim i t s ?

Velo cit ies o f celest ial Object s ? M agn it u de, Scales & Calcu lat io n s ?

HR, Planck & W ien s ?

Co lou r Ind ex ? St and ard Cand les ?

Scales ZOOM IN ?



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Distances & Uni t s

m m , cm , inch, feet , yard, m eter, fur lon g, km , m i les .

AU , LY, Parsec.

Pico, nan o, m icro, m il i , Ki lo, m ega, giga, t era.

Avg. Hu m an Heigh t : 1 .5 t o 2 m et er.

Plane f ly at : 10 km s. (M t Everest 9 km s)

In d ia : 3000 EW x 2700 NS (km s x km s)

Diam eter o f ear t h : 12700 km s.

Dia of Geost a. satel l i te o rb i t : 1 0 0 000 km s.

Dist t o m o on f ro m e ar t h : 3 84 000 km s.

Dia o f Sun : 13 92 000 km s

Distance to sun f rom ear th : 15 00 00 000 km s ( ie . 1 AU)

Distance to sun f rom Jup i ter : 1 00 00 00 000 km s ( ie . 7 AU)



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Distances & Uni t s

Distance to sun f rom plut o : 40 AU.

Distance to sun f rom kupier bel t : 700 AU (100 b i l l ion km s) Oort s cloud is up to : 20000 AU

On e Ligh t year (1 Ly) : 63271 AU

On e parsec (Pc) : 3 .26 Ly = 206265 AU

The nearest st ar t o us : 4.3 Ly = AU = km s 10 Parsec : 32.6 Ly = 3 x 10 17 m t s

Cent er o f galaxy f ro m us : 8 .5 kpc = Ly

(beyond reach of paral lax met hod )

Dia o f M ilky w ay : 1 Lac Ly = 30 kpc = 1021

m t s Dia o f An d ro m ed a : 1 .8 Lac Ly

Dist bet n An d ro m ed a & M W : 22 Lac Ly

Dia o f Lo cal Clu st er o f galaxy : 1 M p c

Span o f Un iverse :15 bi l l ion Ly = 10 10 Ly = 1023 km s



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Convenient Un i ts in Ast ron o m y

Ast ro no m ical Un i t (A.U.)

The average distance bet w een t he sun and t he Eart h

150 m i ll ion km 1.5 x 10 8 km

Useful fo r p lanetary d istances

Ligh t Year

The d ist ance cover ed by l ight in 1 year

Approx im ate ly 1013

km = 1016

m

Parsec

The d ist ance at w hich 1A.U. sub t end s paral lax of 1 arc second



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Dist ance to nearest st ars

N ameDistance

(LY)Spectral

TypeR.A. Dec.

Luminosi ty(Solar U nit s)

Proxim a Cent au r i 4.2 M 5V 14 30 -62 41 6 x 10 -6

Alpha Cent aur i A 4.3 G2V 14 33 -60 50 1.5

Alpha Cent au r i B 4.3 K0V 14 33 -60 50 0.5

Barnard 's St ar 6.0 M 4V 17 57 +04 33 4 x 10 -4

W olf 359 (Gliese 406) 7.8 M 6V 10 56 +07 03 2 x 10 -5

Lalande 21185 (HD 95735) 8.2 M 2V 11 04 +36 02 5 x 10 -3

Luyt en 726-8 A 8.6 M 5V 01 38 -17 58 6 x 10 -5

Luyt en 726-8 B (UV Cet i) 8.6 M 6V 01 38 -17 58 4 x 10 -5

Sir ius A 8.6 A1V 06 45 -16 43 24Sir ius B 8.6 W D 06 45 -16 43 3 x 10 -3

Ross 154 (Gliese 729) 9.6 M 4V 18 50 -23 49 5 x 10 -4

Ross 248 (Gliese 905) 10.3 M 6V 23 42 +44 12 1 x 10 -4

Epsilon Er idan i 10.7 K2V 03 33 -09 27 0.3



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W hat is paral lax?arcsec

pDpc

1=

Techniques of measurements



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Basics o f Parall ax : Arc (S ) = radii (r) x angle (p) { angle is physically m easured, Arc is dist

bet S & E, radii is dist bet Earth & star }

r = S/ p x 360/ 2 x pi (degrees) ... { 1 deg = 3600 sec}

r = 206265 x S/ p { p is in arcsec}

r = 206265 AU / p (arcsec)

r = 1 parsec = 206265 x 15,00,00,000 km s = r / 9.46 x 1012 Ly = 3 .26 Ly

Dist ance in p arsec Dpc = 1/ p (arc sec)

1p c = 3.26ly = 206 265 A.U.

Techniques of measurements

For stars having co-latitude :

Measured change = True change / cos

Para l lax m e thod i s re l i ab le up to abou t 1 kpc



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Poin t o n Eart h Sur face : Velocity (kms/ hr) = Dist / Tim e = 12700 x 3.142 / 24

Velocity (kms/ sec) = 12700 x 3.142 / (24 x 3600)

Po int o n Sun Sur face : Velocity (kms/ hr) = Dist / Time = 13 92 000 x 3.142 / (25 x 24)

Velocity (kms/ sec) = 13 92 000 x 3.142 / (25 x 24 x 3600)

Poin t o n Altair Sur face : Velocity (kms/ hr) = Dist / Time = 1.5 x 13 92 000 x 3.142 / (6.5)

Velocity (km s/ sec) = 1.5 x 13 92 000 x 3.142 / (6.5 x 3600)

Eart h aro un d Sun : Velocity (kms/ hr) = Dist / Time = 2 x 15 x 107 x 3.142 / (365 x 24)

Velocity (km s/ sec) = 2 x 15 x 107 x 3.142 / (365 x 24 x 3600)

Sun in M i lky w ay :

Orbit dia = 30000 Ly, Perio d is 240 m ill ion Yr.

Velocity : 486000 miles / hr

: 220 Kms / Sec

Velocity Calculations



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M agni tu de sca le Or igina lly by H ipparchu s :

Af t er t he sunset t he f ir st set o f st ars t o be seen w ere 1 st magn i tudest ars, t hen 2nd , 3 rd, m agn it u d e st ar s ar e visib le .

Hen ce t h e b r igh t est st ar s ar e 1 st m a gn it u d e w h i le t h e fain t est st ar s ar e

6t h

m agn i tude sta rs.

W hen q u an t it at ive st u d ies w as d o n e w it h t h e visu alap p earan ce and t h e am o u n t o f l igh t received f ro m t hest ars it w as o bser ved t h at t h e m agn it u d es are

lo gar it hm ically re lat ed t o t he f lu x o f l igh t em i t t ed by t hestars.

Magnitude, Scales & Calculations



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The f lux l i s def ined as th e am ou nt o f energy rece ived perun i t a rea per un i t t im e. e.g. w e receive so lar f lux o f 1400 W / m 2.

The f lux received is inversely prop or t ional t o t he squ are oft he d istan ce.

If th e tw o stars em i t f lux l1 an d l2 , th en th e ir m agn i tudesm1 and m2 respect ively are re lated b y th e form ula:

m2 m1 = - 2 .5 log(l2/ l1)

The 6 t h m agni tu de star i s 100 t im es fain ter t han t he 1 st

m agni t ud e star.




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W hat s Ref : A su rvey o f hund red 6 t h m agn it ude (v isual ly t he faintest ) star s

aro un d t he po le st ar w as d on e. Th e average f lu x o f t hese 100n o r t h po lar sequen ce st ars w as t aken as t he f lux fo r t he 6 t h

m agn i tude sta r.

Fro m t h at , fo r m = 0, t he f lux is 2 .48 x 108 W / m 2

On ce t h e f ixed p oin t o f m agn it u de scale w as d ef in ed t h is w ay,t he b r ight est st ar h ave m agn it ud e even n egat ive. E.g. t heSir iu s h as m agn it ude o f 1.47, Venus can have m agn it udeo f 4.4




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M agn i tu de scale :




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Apparent / Visual and Absolut e m agni t ud es

In o rd er t o co m p are t h e real b r igh t ness o f st ars, o ne u ses

ab so lu t e m a gn it u de (M) - It is t he apparent m agn it ude o f ano bject w h en it is p laced at a d ist an ce o f 10 pc.

Th e su n s app aren t m agn it u d e is 26.8 , w h ile i t s

ab so lu t e m agn it u d e is 4 .5

A star m ight look br ighter t han anot her star

Eit her, i t is actu al ly br ight er

Or, it is c loser to u s t han t he o t her star




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Relat ion b et w een m and M :

M = m 5 log Dpc + 5

Can o p us (t h e seco n d b r igh t est st ar in t h en igh t sky) has ap p aren t m agn it u de o f -0.6 ,w h ile t h e ab so lu t e m agn it u d e is -5.5

Est im ate i t s dist ance.

Sir ius has m = - 1.47 and M = 1.42 Est im ate t he dist ance of Sir ius.




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Dist ance Est im at ion u sing HR d iagram

Kno w in g t h e sp ect ral class o fst ars o ne can det erm ine it sabso lu te m agn i tude

Kno w ing t he apparen t

m agn it ud e w e can det erm inei ts d istance

All O class st ars have sam eb righ tn ess. Hen ce b y f in din g

O t yp e st ar in d ist an t clu st er o ne can det erm ine clust erdistance



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Sun A per fect ly b lack bo dy!



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W iens d isp lacem ent Law

m axT= 0.29 cm -K

Larger t he sur face t em peratu re, t he star peaks at smal ler w avelength



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Co lou r Ind ex

M agn it ud e gives o n ly in fo rm at io n ab o u t t he f lu x, w h ile

t h e co lo u r in d ex gives in fo rm at io n ab o u t t h e co lo u r o ft he st ar, w h ich m igh t b e u sefu l t o kn o w t he st ru ct ure o f

t h e st ar / it s p osit io n in HR d iagram .

To f in d t he co lo ur in dex, t yp ically t hree d if feren t f i l t ers

are u sed . U, B, V

B: Blu e f il t er h as cen t ral w avelen gt h o f 4 40 nm

V: Visu al f il t e r h as ce nt r al w ave le ngt h o f 5 68 n m



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The app arent m agni t ud es using th ese f i l ters are foun d.

The n B-V colo ur ind ex is calculat ed.

For b luish st ar, m agnitu de using B f i l t er is sm aller th an t hatusing V f i l t er. Hence B-V num ber is negative.

Sim ilar ly B-V num ber po sit ive m eans t he st ars are redd ish incolour.

E.g. Betelguese h as colou r in dex BV = 1.50 w hi le Rigel hascolo ur ind ex = 0.03



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St andard Cand les :

If w e h ad st an d ard l igh t bu lbs aro u nd t h e

u n iverse, w e co u ld have fo u n d d ist an ce f ro m

t he so u rce by m e asu r in g t he in t ensit y o f l igh tf ro m t hat source a lone.

Su ch sou rces are cal led st and ard can d les.

Th ey are:

Cepheid Variab les

Supernovae



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Var iab le St ars

Som e stars are fou nd to have var iable m agni t ud es.

Their m agni t ud es increase and d ecrease over t he p er iod .

The f i rst such st ar w as ob ser ved in 159 6 by Fabr icius.

I t w as o-Cet i or M ira. I ts per io d is 11 m ont hs (332 d ays)

It s m agni tud e var ies betw een 3 .5 to 9

In 1784, Ceph ei , a yellow sup ergiant star w as fou nd tobe var iable : I ts per io d is 5d 8 h 37m



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Cep heid Variab les

St ars having sim ilar l igh tvar iat ion as Cep hei areca lled Cepheid var iab les.

Ceph eid var iab les are

su pergian t st ars and can beseen at d ist an ces o ut t o ab o ut1 0-2 0 M p c.

On e needs a d ist an ce

m easu rem ent f ro m so m eo t her m et ho d fo r at least oneCeph eid parallax fo r delt aCep h ei o r d ist an ce t o SM C.

o American astronomer

Henrietta Leavitt looked at

many Cepheid variables in

SMC.

o She found the period

luminosity relation (repor ted

in 1912).



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Per iod Lum ino sit y re lat ion



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Typ es o f spect ra

Hot sol id bo dies sho w con t inuo us spectra

Ato m ic gases sho w l ine spe ctra



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Do pp ler Effect

Approach ing veh icle sw h ist le b lo w s w i t h h igh erp i tch .

The reced ing veh icle sw h ist le h as lo w e r p it ch .

The f requency o f t he

w h ist le is t h e sam e .

W e hear d if ferent no t esb ecau se o f t h e m o t io n.



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Determ inin g St el lar d ist ance

f rom Dopp ler Sh i f t Co m p ar in g w avelen gt h s

o f t he abso rp t io n lin es o fst ars w it h t h o se in t h e

lab orat o ry f ram e , w e canf ind w het h er t h e st ar isap p ro ach in g u s o rr eced in g f ro m u s.

Ent ire p at t ern n eed s t ob e co m p ar ed fo r t h is.



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Hu bb les Law

Edw in Hubb le in 30s foun d t hat a l l the far o f f galaxies sho w red shi f tindicat in g that t hey al l are receding away f rom us.

Fart her t he galaxy, t hey r ecede faster.

DistanceD

km/s/Mpc)(73ConstantHubbleH

velocitylrecessionav

Dv

=

=

=

= H



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Supernovae

Co n st an t ab so lu t e m a gn it u d e o f-19.6

Type I no hyd ro gen line in

spect r um , show s Si em ission

From w h it e d w ar fs o r st arsclo se t o t h e Ch an d rase kh ar lim i t

Very b r igh t in it ially, and slowd ecay in b r igh t ness due t ocobalt i ron conversion

Br ight ness est im at ed , hencestandard candle .



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Var ious M et ho ds t o m easure d ist ances



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References & Thanks t o :

Prof. M ahesh Shet t i s not es.

Shr i . M oh an Apt e sir s bo ok Astro no m ical Calculat ion .

M arat hi w ebsi te : w w w. Avakashvedh.com by Sachin Pi lankar

W ikipedia website : h t tp : / /en.w ik iped ia .org

http://en.wikipedia.org/http://www.pdffactory.com/http://www.pdffactory.com/http://www.pdffactory.com/http://en.wikipedia.org/


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Go o d Boo ks t o be read.

Ast ro no m y for Am ate ur s.. Prade ep Nayak.

Kgaaola pircaya pìdp naayak.

duiba-NaI AaiNa vaoQaXaaLa AanaMd GaOsaasa.

taraMgaNa pìdp naayak.

AakaXaaXaI jaDlao naato Da. jayaMt naarLIkr.

kRYNaivavar maaohna AapTo.

vaoQa ivaXvaacaa maanavaI XaaOyaa-caa pà. p. ra. AaDo-.

Ast on om ical Calculat ion ... M oh an Ap t e.

A Brief History of Time ... Stephen Hawking.

AMtraL AaiNa iva&ana Da. jayaMt naarLIkr.



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Details of Additional free Lectures delivered bySantosh Takale :

(Few lectures will be with Slide shows. Duration is 45 to 75 minutes)

Understanding the Universe ( ivaSvaacao AMtrMga).

Career Guidance ( kiryar maaga-dSa-na).

Snakes- Myths & Facts. ( saap: samaja- gaOrsamaja).

Sky Observation with naked eye & Telescope ( AakaSa inarIxaNa).

Human Society & Beliefs/Superstition (maanavaI samaaja AaiNa Eawa/AMQaEawa).

Communication skills & Personality Development (saMBaaYaNa klaa va vya@tIma%va ivakasa).

Management techniques & Time Management.

Being true Citizen of Country with vast diversity-India.



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Santosh Takale is senior Scientific Officer at Bhabha Atomic

Research Center, Mumbai. He has done B. Tech in Mechanical

Engineering & advance studies in Nuclear Engineering at BARC,

Mumbai. He has also obtained many certification in the field of

Welding, Non Destructive Testing & Radiation Safety, which includesIWE (International Welding Engineer), Radiation Safety Officer &

ISNT, ASNT Level III in Ultrasonic Testing & Level II in Radiographic

Testing, Eddy Current Testing, Dye Penetrant testing, Visual

Inspection & Magnetic Particle Testing.

He is Founder of TAKALE CHARITABLE TRUST & Institute for Computer &

Information Technology-Panvel. He is President of maharaYT/ AMQaEaQda inama U-lana saimatI Panvel & Sky Watchers Association of Raigad. He is also honorary member of many

reputed , regional and national oraganisations in technical & social field.

He has been honoured with many prestigious award which includes VISHESH

GAURAVARTHI PANVEL BHUSHAN, ANIS RAIGAD UTKRUSHTA KARYAKARTA-

2012 MAHARASHTRA GAURAV, YASHWANT GAURAV & RASHTRA GAURAV

for his outstanding contribution in the field of science & technology as well as social

field.

Contact Details : [email protected] and [email protected] 09967584554. Website : www.takalecharitabletrust.org

mailto:[email protected]:[email protected]://www.takalecharitabletrust.org/http://www.pdffactory.com/http://www.pdffactory.com/http://www.pdffactory.com/http://www.takalecharitabletrust.org/mailto:[email protected]:[email protected]


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Thank U al l

observational parameters by santosh takale at mu-basic (04-11-12)

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