Best Red Star???

[circumpolar]

When I attended IIS Jan 2007, I was shown a beautiful red star that was considered by the owner of the 20-inch obsession(I think correct size, it was the smaller of the two) to be his favourite. I think it may have been near Columba or Orion (not Betelgeuse or Aldebaran)?. It was not very bright but it was a beautiful deep blood red.

Does anyone know what star I might have been shown?

Does any have a favourite red star they would like to mention?

[sheeny]

When it comes to red stars, the big three for me are probably Betelgeuse, Aldebaran and Antares, but when it comes to "the little red star that could" I'd go for the one in the centre of NGC4755, the Jewel Casket.:thumbsup:;)

Sorry, no idea which star you were looking at near Orion.

Al.

[Liz]

Hi Matt ... not sure off hand as to which star that was, (would love to know though) ... but are quite a few threads around re carbon stars - this is one

http://www.iceinspace.com.au/forum/showthread.php?t=39221&highlight=carbon+stars


... am sure someone will come up with the answer.

One of my favourites is EsB 365 - that amazing little red star near Beta Crucis

[Liz]

".. my favorite Carbon Star is also EsB 365, however another stunning example is Hind's Crimson Star R Leporis.
This is a Mira Variable with a period of 432 days. I have read a few observing reports that don't rate Hind's Crimson Star, but it is a variable and if you catch it near max brightness it is magnificent." - per Trevor (Quark)


This was probably the one :)

[Blue Skies]

I was just about to suggest R Leporis, too. Thats a well known red star near Orion.

[Lismore Bloke]

I agree with sheeny (Al). The red star in the Jewel Box on a dark clear night is hard to beat for beauty and colour contrast.

[Enchilada]

X TrA / EsB 422 is the only one for me!

It is positioned in Triangulum Australe at 15h 14.3m -70 15.

B-V =3.62 is a real killer for this deep red carbon star.

A pretty southern baby and a must see!

Et tu. Brute!
I Scored 100 posts !!

[glenc]

There is a list here, but some variables can be faint. http://www.peripatus.gen.nz/Astronomy/CarSta.html

[pgc hunter]

That red star near Beta Crucis is the most richly coloured star I've seen, although I haven't hunted down any other carbon stars so can't compare it to those.

[erick]

Agreed :thumbsup: and so easy to find beside Mimosa. With practice, it can be seen using binoculars. I have located R Leporis as well - bit of a struggle star-hopping!

Now I have to go looking for "X TrA / EsB 422, positioned in Triangulum Australe at 15h 14.3m -70 15, B-V =3.62 - a real killer for this deep red carbon star." Sounds exciting, thanks Enchilada!

[pgc hunter]

I'm going to hunt this down, it better be as impressive as you say, otherwise you owe me 10 cases of beer :P

[Liz]

Oooh, I cant wait to hunt them down either, if that damn monsoon trough would only head waaay up north :shrug:

Congrats Enchilada on 100 posts ;)

[ausastronomer]

Hi Matt,

It was me that showed you that "red" star that night at IISAC 2007. The scope is in fact an 18"/F4.5 Obsession and Liz and Jacquie are spot on. It was R Leporis, also known as "Hinds Crimson Star". It is only about 5 degrees from Rigel in Orion. Despite some other comments, in my opinion it is most impressive as it dims, not at its brightest. This is a Mira type variable and these stars go redder as they dim and turn more pinkish/orange, as they brighten. Unfortunately, although they are redder as they dim, they are harder to see and hence they often don't show as impressive targets in smaller telescopes, when they are dim.

Cheers,
John B

PS: I will post a list of about 20 or so of my favourite "red" stars for anyone that is interested, tomorrow when I have a bit more time.

[Liz]

Thank you John ... mystery solved ... look forward to your favourite 'reds' list :)

[GrampianStars]

G'day y'all
here's a list I've thown together & been using :thumbsup:
hope it's of some :help:

[pgc hunter]

^^ great list, thanks!

Speaking of red stars, one night last year I was out on an impromtu hunt, and by chance I came across 4 striking orange stars in one FOV. I didn't have any atlas with me, but it was near the Scorpion's tail.

[Enchilada]

As my reputation is now at stake, here's some furthermore information, before you hang me from the yardarm...

X TrA is 5.6v magnitude. Spectral class is listed as C5 II, C6.4 - though later sources say C5,5 with the temperature of merely 2500K. B-V is an extraordinary +3.59 magnitude.
It is placed 15h 14.3m -70 deg 05' and lies 1.4 degrees SW of Gamma TrA (southern most star of the main southern triangle.)
One of the best references to this star (with several others) is found in Webb’s ‘Celestial Objects for Common Telescopes’ Vol. 2. under ‘Stars with Remarkable Spectra’.
This is probably the best Carbon star in the south - and is much brighter than EsB 365 near Beta Crucis.

[glenc]

In the northern sky T Lyrae has a B-V of 5.46, spectral type C8 and variable mag 7.8 to 9.6. It is 2 deg west of Vega.
T Cancri has B-V = 5.3 and spectral type R6v.
In the southern sky W Pictoris has B-V = 4.75 and spectral type N0v.

[circumpolar]

Thanks John. :thumbsup:
You know how everyone has moments at the eyepiece that they will remember for the rest of their lives (like seeing Saturn for the first time), well I had two such moments that night and seeing that star was one of them. The other was comet Mcnaught.

Thankyou everyone for the other suggestions. I will hunt them down asap.

[Enchilada]

Darn your so quick. I was looking at this star in Megastar 5.0 just before I'd read this post. (Scout's honour!) I'll agree with this star being ultra-red.

Here is a useful my description for observers;

W Pic / EsB 154 / HIP 26958 (05432-4627), whose position is 05h 43.2 -46 deg 27' (2000), being best found some 34 arcmin WNW (PA 285 deg) from double star HJ 3801 (05465-4636) with its 5.3 magnitude K0 primary star. HJ 3801 companion is 12.5 magnitude and is separated by 37 arcsec in PA 37 degrees.
This LB type variable type for W Pic, however, is given 7.98V - and is slightly misleading, as the star doesn't seem that bright on the occasions I've observed it. Magnitude in the GVSC4 varies between 11.8p and <15 magnitude is an unknown period. Mostly, the star in past observations hovers between 9.0v and 9.4v, but is notoriously difficult to judge visual with such an extraordinarily wide B-V variation. Few observations have been made in the last decade till 2009. Sadly it is mostly not a very bright star, and estimate it requires at least 7.5cm to 10.5 cm is see any outstanding colouration.

Two coloured images appear as attachments. Not the spiral shape of the scatter light from the telescope. How bizarre!!

** Note Those interest will find a great catalogue (rather technical, though) being the "Hipparcos red stars in the HpV_{T2} and VI_C systems" by Platais, I., et.al. (2002)
[Available at arvix resourcce;, http://arxiv.org/pdf/astro-ph/0211048v1 ]

The selection of interest are;

Star Var Mag B-V
HIP 62401 RU Vir 9.97v 4.63
HIP 38787 V406 Pup 7.62v 3.20:
HIP 23203 R Lep 11.63 4.60
HIP 93666 V Aql 6.78 3.98
HIP 43905 T Cnc 8.23 4.31

Comment : More example to follow, which those in the recent IIS Spectroscopy thread here might be interested in as well... :thumbsup:

[ausastronomer]

Hi all,

Attached is a list of "red" stars with more southerly declinations and easily visible from all Southern Latitudes. There are countless "other" lists floating around that list stars visible from more northern or "both" hemispheres.

I have also included 2 other scientifically interesting stars at the bottom of the list. Barnard's Star (GL699) in Ophiuchus and Kapteyn's Star (VZ Pictoris) in Pictor. Barnard's Star has the highest known proper motion (fastest moving) of any star. Prior to the discovery of Barnard's Star, this title was held by Kapteyn's Star.

It is worth noting that whilst I have listed the stars down the page in order of magnitude, their magnitudes can fluctuate dramatically at different stages of their cycle. For instance the star at the top of the list, Mira (Omicron Ceti) fluctuates between magnitude 2 and 10.1

Cheers,
John B

[Enchilada]

Thanks a good short list.
Just curious.
Q: Any personal objections to W Pic or X TrA here?
Do you think we should combine the other lists and targets into a more definitive list here? :o

[Rob_K]

HIP 53085 (V Hydrae) in Hydra! :thumbsup: Mag 7 (var).

Red as red,
Clearly best -
See this one,
Forget the rest...

;)

Cheers -

[GrampianStars]

A detailed Carbon Stars list ;)
for the enthusiast observer
all difficult for me with protanopic vision :rolleyes:

[jjjnettie]

Great thread!
Thanks for the lists.

[glenc]

HIP 53085 (V Hydrae) has B-V = 2.6.
You can search the Hipparcos and Tycho Catalogues at http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=I/239 to find red stars.
Try using B-V > 4.

[Enchilada]

With the kindest respect...
1) Is there any reason why the range of stars are only between +40 and -40 declination?
2) That HIP 63955 with a K0 spectral class is in this list. I.e. The B-V is only +1.18 - and is not very red.
3) What is the source of the magnitude range and the Spectral Class?

Did you get this list from SIMBAD, as HIP 63955 is also wrongly given as a Carbon Star (which it is not)? In this instance, the CN tacked on the end is the chemical Cyogen lines not is not Carbon lines.
Also HIP 85148 is spectral class A0 !!

Note: I have attached a pdf file of your list, with highlights (in Red) some of the questionable data. Underlined stars probably shouldn't be in the list.

[Enchilada]

Glenn and all
This catalogue you quote is rather out of date, and there has been much research into these stars since. I.e. Most of the variables., for example are not even labelled.

As to the "General Catalog of galactic Carbon stars, 3d Ed. (Alksnis+ 2001) is often quoted http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=I/239, this is a pretty good source, though the magnitudes and spectral classes have been superseded in many sources.
I should comment, that Carbon stars are not necessarily the reddest ones, as dust absorption can also be significant.

Once classic example is 8.47V magnitude R Fornacis, whose B-V is an extraordinary 5.44 !! It is classed as a Mira variable, whose variations are 7.5v to 13.0v every 388.73 days, whose spectral class is C4,3e(Ne).

The best and latest source is actually "Carbon-rich giants in the HR diagram" (Bergeat+, 2002) You can source this catalogue at;
http://vizier.u-strasbg.fr/viz-bin/VizieR-2?-source=J/A%2bA/390/967
and select under Maximum Entries per Table as 1000 (instead of 50) Once shown, you can sort the columns with the little arrows, or query each star under "SIMBAD" Column.

This catalogue list 14 Carbon photometric groups that are based not just on spectra. ("Group" in the table to search) Hot carbon stars in fact are not the reddest. You will find in the source mentioned here, that Carbon stars are list as CV (Carbon variables), bluer to redder from CV1 to CV7. CV7's are the reddest stars known.
W Pic is CV6, while X TrA is CV5. R For is CV 7 (above). Just twenty seven CV7's are known.
The main Catalogue description for this data is at;
http://cdsarc.u-strasbg.fr/viz-bin/Cat?J/A%2bA/390/967

You can read and download the original paper in pdf at;
http://adsabs.harvard.edu/abs/2002A%26A...390..967B

(This is an interesting paper in itself - explaining about the evolution of Carbon stars. It is fairly technical for the uninitiated, though!)

Hope this helps.

Good little project for a rainy day! :rain:

[GrampianStars]

Here ya go guys
I may of rushed the list a bit
will correct errors as I find them :thumbsup:
http://www-astro.ulb.ac.be/Publications/dp_redstars.pdf

[ausastronomer]

Hi,

I actually put together a select list of 600 DSO's visible from Southern latitudes, for the benefit of the regular groups of US observers that myself and a couple of friends entertain here on a regular basis. I put the list together about 4 years ago. To date it has only been circulated to the "Aussie" 3RF members and the respective visiting American observers. I "added" a handful of "red" stars almost as an afterthought to round out the diversity of targets in the list, when I was putting it together. The list of "red" stars I provided is merely an edit from my list of 600 DSO's. It is highly likely I have missed a couple of good ones.

I would be more than happy for you to add to the list as you see fit and ultimately compile a more complete list of "red" Southern Skies stars to be archived on IIS database.

Cheers,
John B

[Rob_K]

I reckon you should have a look at V Hya Glen - it's my favourite and it regularly appears in observing lists around the web as the reddest star in the sky. Google "V Hya" and 'reddest, carbon, star' and you'll see it pop up all over the place. Here's some examples:
http://www.aho.ch/pilotplanets/files/carbonred1.htm
http://ar.geocities.com/varsao/Curva_V_Hya.htm
http://www.bpccs.com/lcas/Articles/coolstar.htm

Enchilada's post was extremely interesting, and the links were well worth following - V Hya is CV6, which puts it right up there on that particular scale. But I suspect for ordinary visual observers, your aperture, the magnification you're using, the sky conditions and your eyesight will be big contributors to what you see as the reddest, so there's room for lots of opinions on this! Great thread! :)

Cheers -

[glenc]

Rob, will have a look when it fines up. When is the next max?

[Enchilada]

Glen

The last visual observation on the 19th January finds it is 9.2v magnitude and falling. It reached its peak brightness in mid-November 2008.
Based on the 530.7 day period, I'd say you will find it about 10th magnitude. I wouldn't dally though, as by around May it will not be well placed. The latest AAVSO data, shows the observations as per the attachment. As you can see it is fading fast. (See the black line)

You can generate this curve yourself at; http://www.aavso.org/data/lcg/

Object as V Hya, "Plot last" at 1000 days.

The next maxima, sadly, will be about February 2010 - being well placed for southern observers as well near the zenith...

A suitable finder chart is at the same site, as;
http://www.aavso.org/cgi-bin/shrinkwrap.pl?path=/charts/HYA/V_HYA/VHYA-A.GIF or

With fainter stars at its fainter magnitude (like now), use;

http://www.aavso.org/cgi-bin/shrinkwrap.pl?path=/charts/HYA/V_HYA/VHYA-BR.GIF

Hava good one!

Hope this helps...

Encha..
(Nicknaming you avatar... now its getting a bit too serious!! :lol:)

[glenc]

Thanks.

[pgc hunter]

great! I might go on a red star hunt next clear night.

[Liz]

Thanks guys, for the info and lists of carbon stars ... all very interesting, and will get out to check when these clouds clear ... prob another 6 weeks!!! :shrug:

Ummm ... the B-V (am not familiar with this) is a reference related to the colour, and the lower the number, the stronger the red ... is this right??

Ok, after a bit of reading I see that the star is observed through special B and V filters, and subtracting the 2 values gives you the colour index. Blue stars have a negative index, whereas red stars have an index from 0-3.

Looking at a chart - R leporis 2.7/U Hya 2.7/CE tauri 2.08/Betelgeuse 1.85/Antares 1.83

[glenc]

The Hipparcos Main Catalogue (118,218 rows) with constraint B-V > 4

HIP 26958, Vmag = 7.98, B-V = 4.750, declination -46
HIP 43905, Vmag = 9.27, B-V = 5.300, declination 19
HIP 62401, Vmag = 11.98, B-V = 4.400, declination 04
HIP 77501, Vmag = 10.10, B-V = 4.410, declination 39
HIP 90883, Vmag = 7.57, B-V = 5.460, declination 36
HIP 108205, Vmag = 9.23, B-V = 4.100, declination 50

see http://en.wikipedia.org/wiki/B-V_colour for B-V

[glenc]

Using the main part of Tycho Catalogue (1,058,332 rows) and B-V > 4

#_RAJ2000, (http://javascript%3Cb%3E%3C/b%3E:alert%28%27Right%20ascension%2 0%28FK5%29%20Equinox=J2000.0%20Epoc h=J2000.000,%20proper%20motions%20t aken%20into%20account%20%20%28compu ted%20by%20VizieR,%20not%20part%20o f%20the%20original%20data%29%27%29) ....._DEJ2000, (http://javascript%3Cb%3E%3C/b%3E:alert%28%27Declination%20%28FK 5%29%20Equinox=J2000.0%20Epoch=J200 0.000,%20proper%20motions%20taken%2 0into%20account%20%20%28computed%20 by%20VizieR,%20not%20part%20of%20th e%20original%20data%29%27%29) ....TYC, (http://javascript%3Cb%3E%3C/b%3E:vNote%28%27//%2a&-5N&%3C&quot;Label&quot;&catid=1239&tabid=15&colid=1%27%29) ..........Vmag, (http://javascript%3Cb%3E%3C/b%3E:vNote%28%27//%2a&-5N&%3C&quot;Label&quot;&catid=1239&tabid=15&colid=5%27%29) B-V (http://javascript%3Cb%3E%3C/b%3E:vNote%28%27//%2a&-5N&%3C&quot;Label&quot;&catid=1239&tabid=15&colid=36%27%29)
1 (http://vizier.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=I/239/tyc_main&recno=719643)01 26 58.091,-32 32 35.44, 7002 1357 1, 6.64, 4.148
2 (http://vizier.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=I/239/tyc_main&recno=442619) 03 41 48.162,+62 38 54.40, 4066 1219 1, 7.34, 4.139
3 (http://vizier.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=I/239/tyc_main&recno=631936) 10 51 37.249,-21 15 00.28, 6082 1140 1, 7.60, 4.143
4 (http://vizier.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=I/239/tyc_main&recno=642481) 17 29 43.658,-19 28 22.95, 6243 462 1, 7.75, 4.320
5 (http://vizier.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=I/239/tyc_main&recno=244049) 18 32 20.073,+36 59 55.57, 2636 1142 1, 8.02, 4.353
6 (http://vizier.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=I/239/tyc_main&recno=498669) 21 35 12.796,+78 37 28.18, 4603 770 1, 7.83, 4.090
7 (http://vizier.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=I/239/tyc_main&recno=320766)21 43 16.325,+38 01 03.01, 3184 2150 1, 7.98, 4.119

http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=I/239

[Enchilada]

Liz. Your summary is quite correct, but here is some further information to aid your thinking.

B-V magnitudes (or B-V Colour Index - or sometimes Total Colour Index) is very simply are a way of measuring colours in stars. It comprises of two separate magnitudes, which are measured through specialised filter, either using a photoelectric photometer (an instrument to measure the intensity of light) or photographically. The B stands for the Blue filter or band, while the V is the Visual filter or band. These filters were introduced by H. Johnston and W. Morgan in 1953. (Photographically, this effect was known in the 1890's, whose colours could be identified using a blue and visual photographic plate. It was not employed successfully for measuring colours until the 1920's, due to the blue sensitivity of the plates at the time.)

Other filters and colours can be obtained too, such as U (Ultra-violet), R (Red) and I (Infra-red) - collectively known as the UBVRI system or the Johnston-Morgan standards. Colours can also be expressed as U-B or V-I, for example. All well and good.

Now the magnitudes measured in the B and V can be subtracted from each other, and the difference in magnitude becomes the B-V value. So;


Blue stars have values of about -0.2 (some are negative up to about -0.38, from memory)
White stars are about 0.00, where +0.00 corresponds to A0. This is called the white point - meaning essentially no colour (even though the whte light may be broken into different colours of the spectrum
Yellow stars (F6 spectral class star are about +0.43)
Orange stars are about +0.80
Red stars are about +1.20
Deep-red stars (carbon stars) are usually below +2.00
The reddest stars known have B-V values of about +5.5

If some star has a B-V of +0.43, then the magnitude in the B filter appears +0.43 magnitude brighter than the V magnitude.

Now colours from star travel through space, and as they travel the light becomes redder. It is cause by gas and dust that lies between us and the star or object. Therefore a correction must be accounted, often in term of magnitudes per kiloparsec, which is either estimated (or measurable with another photometric system used by astronomer). Values are typically about +0.04 magnitudes extinction from the absorption of light. When corrected, this is given as (B-V) or (B-V)0 (zero as subscript). Most cases seen to the naked-eye are usual just disregarded, but sometimes they are not.
Galaxies can have B-V colours (usually solar-like at about +0.4), and in this case (B-V)0 accounts for the redshift by the Hubble expansion of the Universe.

Probably one last thing, B-V is proportional to the spectral type and the surface temperature of stars, and can be used as a rough estimate.

An examples of its uses in astronomy are, By plotting B-V versus (x-axis /bottom) the V magnitude (y-axis vertical axis) produces the so called colour-magnitude diagram, which can be usefully employed to tell us something about the evolution of the stars.

You might like to look and read the following pages on Colour-Magnitude Diagrams an Open Star Clusters, at;
http://homepage.mac.com/andjames/Page03006.htm
http://homepage.mac.com/andjames/Page03007.htm
http://homepage.mac.com/andjames/Page03008.htm

To quote David Malin in the Encyclopaedia of Astronomy "The Colour of Stars";

"The colors of the stars are real but not apparent. They are not seen by the unaided eye because stars are both intrinsically faint and at the same time minute points of light, almost always observed by a more-or-less dark-adapted eye. However, the colors of the stars are an important and quantifiable observational property that is indicative of their surface temperature. This in turn is a function of a star’s mass and its evolutionary status. These ideas are brought together in the well-known color magnitude diagram, a cornerstone of stellar astrophysics."

Anyway, hope all this helps you...

NOTE: If you are interested in the perception of star colours, you can read a through article on Star Colours at;

http://homepage.mac.com/andjames/Page029b.htm and
http://homepage.mac.com/andjames/Page029b1.htm

[Enchilada]

Glen,
Thanks for the HIP and Tycho lists. However, in terms of its usefulness for Carbon Stars it is probably not the best available because of the photometry range that could be of the satellite. Furthermore, as most are variables, many were therefore missed altogether. Hence, why we see the number of independent catalogues through the literature.
Empirically Constrained Color-Temperature Relations (I or II)" in 2003.]
A definitive list can probably only be obtained from various sources, which will need to be constrained on magnitudes and B-V.

I generally suggest a maximum limit of 9.0 magnitude, and B-V above +2.5, and a minimum magnitude above, say, 13th.

Have you tried a Criteria Query in SIMBAD yet?
I.e. http://simbad.u-strasbg.fr/simbad/sim-fsam

Here you can do the constraints as you wish, including location, magnitudes, spectral class and B-V , etc.

(If you like, I can try this tomorrow (busy schedule today))

What should such a list be constrained in your opinion?

Cheers.

[Liz]

Many thanks Enchilada ...... :thumbsup:

[ngcles]

Hi All,

Interestingly, the VLT crowd seem to be monitoring all this chat on IIS about R Leporis and carbon stars etc and decided to take a look at R Leporis for themselves -- with a 100m synthesized aperture ...

See: http://www.spaceref.com:80/news/viewpr.html?pid=27586


Best,

Les D

[Quark]

Thanks for posting the link Les.

Most interesting article and image.

Regards:thumbsup:
Trevor

[theodog]

Hi All,
Finally managed to find R Lep and take a spectra.
8x5sec exp -darks Med combined.
Callibrated using same method as B Car in spectroscopy thread in the Astronomy Science thread.

Hopefully it's right.
Comments?:shrug:

Now onto X TrA.:D
:)

[Enchilada]

Can't wait!

[theodog]

Just finished X TrA.
Same process as last night with R Lep.
I have tried to match their spectra in the attached image.

:)

[pgc hunter]

I just had a look at this one, but it was more orange than red, the colour is reminiscent of the Eta Carina. I'd say DY Crucis is much "redder" actually.

Downloaded a couple of lists so I'm gonna make use of this full moon period by checking these red stars out.