And another book review - Spectroscopy the key to stars

[AstroTiger]

Another in SPM series.

Again i ordered this one a few weeks ago (my wife will love me for that!)

Again has anyone got/read this one?

There is another like it for the practicle astronomer, inviting us i think to make one.

A purchase for another time perhaps

[Merlin66]

I have this book and you'll find it very good for giving you a better understanding of what makes a spectrum a spectrum, i.e. the physics behind the emission and absorption features and how astronomers can use this knowledge to better understand the stars, galaxies and nebula using spectral data.

Tonkin's "Practical Astronomical Spectroscopy" is out of print, but still available and addresses needs of the amateur astronomer and his/her spectroscope.

Kitchin's books "Optical Astronomical Spectroscopy" and his "Astrophysical Techniques" are well worth adding to your library if you're interested in spectroscopy.

Young's book "The Sun" ( available through Alibris etc) although published in 1888 is excellent and gives an insight into early spectroscopes and their work.

Henshaw's "150 years of starlight" covers the history and development of the spectroscope.

Then there's the bible, Kalers " Star's and their spectra"

These books will give you a full overview of the subject.

I believe there's already a couple of books for amateurs in preparation to expand on previous texts and bring the subject matter up to date.

[AstroTiger]

cheers for that Merlin

As an ex chemist who used to study spectra of molecules, this is rather interesting lol

Sad i know, i should get out more lol

[AstroTiger]

tell you what, that Kalers book looks interesting, think i might invest in a copy of that!

[Merlin66]

Spectroscopy is one of the last challenges left for the amateur astronomer, and easier than imagined. All you need is a small transmission grating and you can see all the absorption lines in the brighter stars and even determine the red shift of galaxies. Really is an great way to do scientific observations!!

[narrowbandpaul]

spectroscopy is a fantastic subject. I really enjoy it.

do you know where I think there could be a real contribution from amateurs...nebulae.

professional astronomers are too busy obtaining hi res spectra of redshift 6 quasars.

apart from the famous Ha S2 and O3 emission lines, what else is there? I know of N2 and He2. I cant find this information in astronomical catalogues.

so I think this could be interesting, identification of emission lines in the visible and NIR using a standard CCD, and a low res grating. Even a ballpark guess accurate to 1nm wouldnt be too bad a start. You could identify from there.

[Merlin66]

The Webb Society Deep-Sky Observers Handbook, Volume 2 - Planetary and Gaseous Nebulae, p45-49, has a comprehensive listing, with indicated intensities of most of the visible emission lines.

Predominanty OII, OIII, NeIII, NII, SII, OI, HeI in Planetary nebulae and then some HII, and H in gaseous nebulae plus in the reflection nebulae, lines from the embedded engergising stars.

Unfortunately to get good spectral resolution, you really need to apply a slit spectroscope to nebulae, which is a step above the basic star spectroscope; you can, however get some basic results even with a 100lm grating....

[Ben Ritchie]

Then there's the bible, Kalers " Star's and their spectra"

Ken, if you like that i'd suggest picking up a copy of Gray & Corbally's Stellar Spectral Classification

Stellar Spectral Classification Princeton Series in Astrophysics: Amazon.co.uk: Richard O. Gray, Christopher J. Corbally: Books

which is very good. It's a bit more advanced than Kahler - I like his work very much, as he writes well, but "stars and their spectra" is at a fairly basic level and there's a fair bit missing.

professional astronomers are too busy obtaining hi res spectra of redshift 6 quasars.

Only some of them, I do nebular stuff all the time - currently working through a fascinating sgB[e] emission-line nebula.

apart from the famous Ha S2 and O3 emission lines, what else is there? I know of N2 and He2. I cant find this information in astronomical catalogues.

There are a huge number of well-known nebular emission lines. You need a copy of "a multiplet table of astrophysical interest" by Moore (Google will turn up a .pdf) and the NIST spectral line database. The standard reference book for this is Osterbrock & Ferland's book (AGN)2, aka "The astrophysics of gaseous nebulae and active galactic nuclei", it's a wealth of information but can be quite advanced.

[AstroTiger]

i bet it can be.

I was thinking about the subject of stella spectroscopy some time ago. Perhaps building a small spectrscope to have a play.

If my memory serves me you can decipher

a) Temperature

Surface Composition

c) Red Shift

But its no good for determining the distance of stella objects, thats correct is it not?

[Ben Ritchie]

But its no good for determining the distance of stella objects, thats correct is it not?

There are lots of ways to do this - for example the O I 7774 triplet is a good luminosity indicator in supergiants, which gives you a way of determining absolute magnitude and therefore distance.

To give you an idea of what can be figured out, the paper i'm about to submit (literally, once I get off SGL) uses spectroscopy to determine luminosity, radius, effective temperature, mass loss rate, wind velocity, structure and clumping, rotational velocity, surface gravity, and abundances for H, He, C, N, O, Ca, Mg, Si, Fe (as well as implied limits for Ti, Cr, Ni, V, S and Sc). Those then give the evolutionary state of the star, it's mass-loss history and the fact that it's a binary (with otherwise unseen companion). So a massive amount of information is accessible.

[narrowbandpaul]

thats why spectroscopy is so powerful

[Merlin66]

Ben,

Would Gray's book have any info on WR stars?

I have a couple of spectra which show significant differences between the CII peaks at 5600-5800 for WC7 ( WR140) and WC8 ( WR 11) It this significant??

[Ben Ritchie]

You're seeing C III λ5696 and C IV λλ5801, 5812 lines - these are used for WC classification, so the differences you see are significant and the reason one's a WC7 and the other a WC8.

See, for example -> [astro-ph/0610356] Physical Properties of Wolf-Rayet Stars

there are examples of a range of WCL and WNL spectra in fig.1 on p.70

There's a good chapter in Gray & Corbally about WRs and LBVs, including nice WN and WC spectral sequences covering the region you're interested in.

[Merlin66]

Ben,

Thanks for the reference! That solves the mystery, and goes to show that even with a 100lpm grating we can record the different WR curves.

[AstroTiger]

See this is what i am talking about, getting into the thick of astronomy!

Can't wait for that book to arrive now.

Perhaps a opportunity for a meet or something to discuss equipment etc needed for this and the results. I browsed the contents pages on amazon last night of Kalers stars and their spectra.

It goes into detail for each classification of star.

I wonder if this is an avenue i might be heading down in more detail.

It would be interesting to start first with the Sun i think, then perhaps a few of the brighter objects.

[AstroTiger]

There are lots of ways to do this - for example the O I 7774 triplet is a good luminosity indicator in supergiants, which gives you a way of determining absolute magnitude and therefore distance.

To give you an idea of what can be figured out, the paper i'm about to submit (literally, once I get off SGL) uses spectroscopy to determine luminosity, radius, effective temperature, mass loss rate, wind velocity, structure and clumping, rotational velocity, surface gravity, and abundances for H, He, C, N, O, Ca, Mg, Si, Fe (as well as implied limits for Ti, Cr, Ni, V, S and Sc). Those then give the evolutionary state of the star, it's mass-loss history and the fact that it's a binary (with otherwise unseen companion). So a massive amount of information is accessible.

Can i ask how does one get to read this paper?

It sounds like rocket science, but interesting.

Are you a professional astronomer?

[Merlin66]

AstroTiger,

To start with the Sun is OK, but the spectroscope you need must have a slit mechanism, whereas if you want some star spectra you can get away with a small transmission grating like the StarAnalyer.

Paton Hawksley Education Ltd, star analyser

Have a look at a couple of my project files on IIS; I've built a few amateur spectroscopes which are about 1/10 of the commercial cost and perform very well!

Classical Spectroscope - IceInSpace

Spectroscopes: Part 2 – New 200mm Littrow design - IceInSpace

Hope this helps!

(BTW I'm not a professional astronomer, but I think Ben might be!!)

[AstroTiger]

well reading both your threads, you could have fooled me that either of you were (then some might argue that is easily done lol)

Merlin, i have recieved your pm, look forward to working with you more buddy :-)

[Jamie]

I am sorry but can someone please correct me if i am wrong here.

The title of this thread is And another book review - Spectroscopy the key to stars

I don't know about anyone else but i was expecting to read an actual review on this particular book.

I don't have a problem with all the discussion that has gone on concernig the subject of Spectroscopy or even the posts about other books that would be interesting to read.

I just feel that they would be better served in the appropriate section.. No??

[AstroTiger]

Yes apologies Jamie, that is what its supposed to be.

A review on that book which has kind of turned into a chat thread on spectroscopy.

As with the Astrophysics book i do intend to write something on it here as well.

However unlike the astrophysics book, it still hasn't arrived as yet :-(

EDIT

__________________-

Perhaps in future, it might be prudent for people to open two threads on a book? One for the review, another for chat and comments on it?

I know (largely down to me) there are a fair few of these now popping up.

Not that i wish to create more work for the mods of course.

[AstroTiger]

Well the book has now arrived.

First glance, quiet comprehensive.

It kind of reminds me of my old chemistry days at uni, looking at energy levels etc.

So much about exclusion rules, which frankly sent me to sleep when i first read them 10 years ago.

Anyway with an older more developed (in theory) mind perhaps its not going to be as hard as it was.

I do feel though after looking at the contents, the book serves as an intro only.

There is a small part on emission nebula etc for which i will read in more detail.

To be honest though, first glance, i would not rush out to buy this one just yet.

However, we'll see.

Those who still have their old A-Level chemistry books, i think there is by and large as much info on this in that as their is in this. From an astronomical perspective of course.

But hey, we'll see :-)

I will concentrate for now on the astrophysics book then this one after. unlike a woman i am not a multitasker! lol

[Ben Ritchie]

I do feel though after looking at the contents, the book serves as an intro only.

It's a big topic!

For anyone really interested, i'd suggest moving on to Kahler's "Stars and their Spectra" and then Gray & Corbally's "Stellar Spectral Classification" as mentioned above

It kind of reminds me of my old chemistry days at uni, looking at energy levels etc.

So much about exclusion rules, which frankly sent me to sleep when i first read them 10 years ago

Energy levels etc. are important, but not really so much from a general interest point of view - worth covering what forbidden lines are, but the details only really start to matter when considering conditions in the line-forming region etc. which is a bit over the top for all but the most interested...

Are you a professional astronomer?

Depends on how you define professional but, yes, as well as the backyard sort of Astronomer too

[Merlin66]

Gray & Corbally's "Stellar Spectral Classification"

Thanks to Ben's reference, I've managed to find this book.

What can I say... it's like a grown up's version of Kaler's "Stars and their spectra", but at 600 pages quite a hefty tome.

Contains some excellent spectral graphs, just what the amateur needs!

Will take a couple of months to get through it, but looks like it will be well worth the effort!

[AstroTiger]

Apologies to all for not having posted for a while, less reviewing these books as promised.

What it is, is i landed a job rather suddenly which involves a lot of travel. So i have not been around.

having just finished a book i started reading way back, i will take a close look at these.

However please be advised with Salisbury next week again it might take me a tad while longer to get round to doing.

Apologies, rest assured though, it will be done :-)

[AstroTiger]

This book is a good general introduction to spectroscopy as a whole.

For anyone who has read a physical science at university might find much of the work familiar.

The book itself goes into stellar spectroscopy reasonable well, but again if one wants a greater treatment on the subject one of the other texts might be more appropriate.

you can probably tell i was a little disappointed a little by this purchase, after having read the text on astrophysics.

However, a good intro to the subject nevertheless.

Would i rush out and buy a copy again? No