Talk:List of brightest stars

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Contents 1 from article 2 this list 3 Most luminous stars 4 Negative Brightness? 5 Stub? 6 Distance 7 S. Doradus 8 Alpha Centauri 9 Theta1 C Orionis 10 Distances derived from OB studies 11 L:st size 12 Historical brightest stars 13 Delta Orionis

[edit] from article

(moved from article:) Magnitudes should be added at some point, plus maybe some basis stellar data, tabulate...

I created a new list, this one of 100 brightest stars, started with the Observer's Handbook list of 314 bightest stars, and sorted by brightness, and reformatted here. I included apparent magnitude and constellation designation names, as well as proper names. There may be value in giving distance, luminosity, spectral types, or other information, but I didn't have these easily available now.

It looks like most of the proper names are good links to articles about the stars, although I didn't check them all.

Feel free to edit further.

--Tomruen 05:30, 13 May 2004 (UTC)

[edit] this list

This list is inaccurate. I have gone through and added proper names to the stars that have them, or links to Bayer designations where the star does not have one so that an entry can be created for them. I have not dealt with the inaccuracies yet (for example, τ CrB is listed as the 50th brightest star when it's visual magnitude is far dimmer than a 4) but may do so in the future. Arkyan 20:15, 25 May 2005 (UTC)

I agree it is inaccurate and also difficult to verify. It claims the Hipparcos as the source of distances but gives no good link for me to check (I tried and failed via http://astro.estec.esa.nl/Hipparcos/hipparcos.html). Also what is the source of the magnitudes? It does not appear to be the Bright Star Catalogue, 5th Revised Ed. (I checked a few). Finally I've moved the text about the list being ill defined to the top to warn the reader, and marked Polaris and Betelgeuse as variable. -Wikibob | Talk 18:13, 2005 Apr 3 (UTC)

[edit] Most luminous stars

Different sources give drastically different information for lists of the most luminous stars (by absolute magnitude). See for instance: http://www.rssd.esa.int/SA-general/Projects/Hipparcos/table364.html , from Hipparcos data.

I wonder about the usefulness of this information, when different sources give such radically different lists (and I do mean radically different). -- Curps 21:36, 4 August 2005 (UTC)

Why did you delete over 50% of the article (by absolute magnitude) without discussing this first? There are ofcourse different measures in the luminosity of a star, and there will always be. but that is already explained in the introduction of that section. You are assuming that the Hipparcos catalogue is like the 'holy bible'. However, that catalogue is not updated since: Mon Sep 15 17:08:57 MEST 2003, almost two years ago! New measurements have been taken since, if you search deeper on the web, other observatories have given more recent measurements. But besides this, google is not the holy bible either. I have compiled this list with consulting a lot of resources, and took me over 3 times 8 hours to verify & complete. In cases of doubt, I decided to follow the latest-to-date measurement, or else the maximum given for that specific star. All are from credible sources, catalogues and observatories around the globe. This list will ofcourse always be incomplete, and new measurements in the future might give a diffent reading on a star. But this should not mean that this section should not be present on wikipedia. Absence of knowledge is ignorance!

Patrick1982 10:31, 5 August 2005 (UTC)

I gave the reasons for the removal in the edit summary, and I did leave a comment here on the talk page, just above your own comment. When data is entirely unreliable, it is better not to present it at all.

By the way, your table included two entries each for Beta Crucis and Lambda Scorpii, with different information. When I noticed this, I tried to look up which of the two entries was correct, and that was when I discovered the problem with different online sources drastically disagreeing with one another.

Also, the last eleven entries (Spica through Sirius) should really be omitted; Sirius, in particular is not at all one of the intrinsically most luminous stars.

Can you provide references for the data table you present? References to scientific literature, for instance, via NASA ADS. This should be some widely available reference, not your own original research. Wikipedia usually recommends but does not require supplying references, but given the very great contradictions of various online sources, and given that you are claiming that your data is more accurate than Hipparcos data, it is really necessary to document where this data comes from.

It is not surprising that Hipparcos data hasn't been updated, because the satellite took its measurements and more accurate measurements aren't expected until the proposed European probe launches in 2012 or so. Are you saying that new ground-based parallax measurements have been made in recent years that are more accurate than Hipparcos? Can you provide references?

-- Curps 22:20, 8 August 2005 (UTC)

I propose moving By absolute magnitude and Other objects to List of most luminous stars. Most luminous is not the same as brightest and I think they deserve separate pages. --Fournax 14:07, 2 July 2006 (UTC)

Agreed. I wonder if List of largest stars ought to be merged with a List of most luminous stars in some way since they'll be closely related. Tom Ruen 22:58, 2 July 2006 (UTC)

I did the move and linked from List of most luminous stars to List of largest stars (and vice-versa). --Fournax 13:29, 4 July 2006 (UTC)

[edit] Negative Brightness?

Could someone add a line explaining how luminosity is measured, and why the brightness of the brightest stars is negative? (Or link to same.) Mjs 11:46, 15 November 2005 (UTC)

• The brightness is quoted in arcane astronomer's units called "magnitudes". They are related to the real intensity F_x through the following relationship:

For more details see the pages on Apparent magnitude and Absolute magnitude.

Rnt20 12:14, 15 November 2005 (UTC)

• It's not really that arcane.

The Greeks categorized a star's brightness by placing it in one of six classes, from 1st magnitude (the brightest) down to 6th magnitude (the dimmest). Now it turns out that the human nervous system, including its sensitivity to light, reacts to stimuli on a logarithmic scale. It also turned out that, when we were able to measure starlight accurately, the approximate difference between a typical 1st mag star and a 6th mag star was 100:1. So, if the difference of five magnitudes is 100x the brightness, the difference of one magnitude is the fifth root of 100. That's what the formula above is all about.

Okay now, we've got a relative scale, but we still need some specific reference point to measure from. Polaris, the North Star was taken as the typical 2nd magnitude star and assigned the magnitude of 2.0 exactly. Any star between 1.5 and 2.5 was 2nd magnitude. By analogy 1st magnitude was between 0.5 and 1.5 on the same scale. It turned out that six stars were even brighter, falling between 0.0 and 0.5 with Arcturus and Vega at 0.0 exactly. (Things have been slightly refined since.) Still, no problem. Any star brighter than 0.5 is stll called "1st magnitude" as nobody felt like saying "zeroth magnitude."

However, three stars (Sirius, Canopus, and Alpha Centauri) are even brighter than Arcturus. So the scale was extended beyond 0.0 into negative numbers. That's all.

So a negative magnitude just means "even brighter than 1st." B00P 03:27, 20 February 2006 (UTC)

[edit] Stub?

Why is this still a stub? It seems long enough that the term should no longer apply. Whitepaw 20:04, 2005 May 4 (UTC)

[edit] Distance

The implied accuracy for some of these distance measurements seems a bit too high, at least to me. At best probably only three digits are reasonably accurate, so anything over 99 ly you could drop the decimal and be about as close. For example, the parallax of Canopus is 0.01043" ± 0.00053". That's equivalent to error range on the order of 297-329 ly. 313 ly should be good enough I would think, rather than 312.73. Thanks. :) — RJH 20:38, 29 November 2005 (UTC)

Agreed. The only star justified to 2 decimals is alpha Centauri. The Hipparcos catalog is within 10% only for distances less than 100 parsecs(~326 lys.), as per the Hipparcos site. Over 100 parsecs, the data are good for statistical analysis only. For a list such as this, there is no set protocol with manipulating the distance estimates. So, how about 1 decimal if less than 5 parsecs, to the nearest light year if 10 parsecs(~32.6 lys) or less; less than 100 lys- add a tilde (for roughly) and to the nearest ly or so. One hundred to a thousand-to the nearest 50 lys; one thousand to 2 thousand-nearest 100 lys. More than 2 thousand-nearest thousand lys. Mytg8 19:44, 2 February 2006 (UTC)

This is a very handsome and informative table but... The idea of changing the distances, e.g. Saiph from 722 to 720 is really not justified due to the inherent inaccuracies of the parallax method. In reality, this star could be 620 light years or 860; either is just as likely as 720 or 722, according to the quoted errors.Mytg8 15:29, 19 June 2006 (UTC)

Actually, 722 is very slightly more likely than 720 and both are significantly more likely than 617 light years (the one sigma lower limit) or 870 light years (the one sigma upper limit). But your point is well taken. The Hipparcos parallaxes are not of sufficient quality to justify three significant figures so I've changed the distances to two significant figures. Fournax 00:01, 20 June 2006 (UTC)

You're correct; I overstated my remarks. What I should have said, probably, was that there was a real possibility, however small, that the distance quoted could be 100 light years in error.Mytg8 15:27, 22 June 2006 (UTC)

[edit] S. Doradus

Why is S Doradus not on the list of stars with highest absolute brightness?

[edit] Alpha Centauri

For some unknown reason Alpha Centauri is treated differently than all other stars in Wikipedia.

It is being listed as the fourth brightest star in apparent magnitude when it is actually third. The discrepancy comes about because it is Alpha Centauri A that is being referred to. Then Alpha Centauri B gets a separate listing. Why? Capella, Acrux, and Mimosa, for example, are not treated component-by-component, but as the single point sources they appear to be to the naked eye. This is inconsistant. Worse, it is a positive source of confusion and misinformation. Consider, say, Acrux and Deneb. Based on this list alone, one would be led to think that all the 1st magnitude stars are singles except for α Cen, and that Acrux is brighter than Deneb. The reality is that Acrux is a binary and that Deneb is brighter than either α Cru A or B. Combined the stars of the Acrux system outshine Deneb, but unless one referred to the article on Acrux directly, one would never know.

Why is Alpha Centauri the only system whose components are individually listed? (Unsigned by B00P.)

It's a good point. We could have an additional table listing the brightest components that can't be resolved by the unaided eye, then merge your examples in there. — RJH 19:57, 2 March 2006 (UTC)

I've separated out Capella, Acrux, Castor, and Mizar. Capella B and Acrux B are bright enough to be on the list by themselves so now we have the 102 brightest stars. It might make more sense to make it a magnitude cutoff (2.50 would give us 95 stars). Other stars on the list are multiples but if the magnitude difference between them is greater than five then the total magnitude is changed by less than 0.01 so it probably doesn't make sense to break those out indivudually. Fournax 14:00, 2 July 2006 (UTC)

[edit] Theta1 C Orionis

Surely, there must be something wrong with the values for Theta 1 C Orionis. If it is 210000 times brighter than the sun, why does it only have an absoute magnitude of -4.3? Shouldn't it be in the neighbourhood of -9 to sort properly into the list? Drhex 20:27, 11 April 2006 (UTC)

[edit] Distances derived from OB studies

In an attempt to provide distances for the more remote stars on the list, I have the following URL for a survey of OB associations. This catalog is a compendium by the respected astronomer Roberta Humphreys.

http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1978ApJS...38..309H&db_key=AST&data_type=HTML&format=&high=4206e4e61f25463

There are a couple of problems with this, however. One, it's almost 30 years old of course. Two, I'm not sure, and it's not stated in the paper, the errors involved. I read somewhere--unfortunately where I can't find--that the errors are estimated at 20 per cent, plus or minus? Any one else know more? Would these distances therefore be more accurate than a trig. parallax? (they would only involve those stars in OB associations--namely Deneb, Rigel, and several others more than 1000 light years away) Mytg8 16:28, 19 July 2006 (UTC)

Yep, it is a rather old and apparently obscure paper.<gr> The author is a respected and veteran astrophysicist. It is a compendium of results; I'm not aware of a similiar more recent paper. She gives the distance modulus and extinction of each star so it's trivial to calculate the distance. Surely this wouldn't be original research? Anyway, when I get to it, I'll add the distances calculated from her results. It would result in modifying 5 stars belonging to OB associations.Mytg8 16:25, 27 July 2006 (UTC)

Hipparcos has now provided us with parallax data that Roberta Humphreys didn't have 30 years ago. Trigonometric parallax is the gold standard for stellar distances and I think it would probably be better to stick with Hipparcos distances when we have them. The closest of the five, Saiph, is definitely closer than the OB association distance (parallax distance of 720 light years with an uncertainty range of 620 to 870 light years, compared to the OB association distance of 1,500 light years). Given that the OB association distance is so far off in that case, I would recommend switching back to the parallax distances for all five. It's true that the OB association distances are within the parallax errors for the more distant four (for example, Deneb and Aludra have parallax distances of 3,200 light years, with uncertainty ranges of about 2,100 to 7,300 light years). But keeping all distances as Hipparcos parallax distances gives us a consistent set. Even if they are wrong, they are likely to be wrong in the same way. Also, the individual star pages gives the parallax distance, so we should probably stick to that for consistency. --Fournax 23:26, 27 July 2006 (UTC)

I have to agree your consistency argument makes sense and you've made some good points. The errors for such well known stars as Deneb and Saiph seem to be so huge, despite the remarkable successes of the Hipparcos satellite with many closer stars, that I thought there might be other sources as accurate or more so. I guess we'll have to await for the proposed new astrometric satellites to settle this complicated issue.Mytg8 17:49, 28 July 2006 (UTC)

On the other hand :), your example Saiph has been consistently listed as B0 or B0.5 spectral class; a Ia or Iab supergiant. Compendium estimates for the M_visual for that class is -6 or -7. http://www.astro.lsa.umich.edu/users/hdproj/mosaicinfo/absmag.html or http://www.isthe.com/chongo/tech/astro/HR-temp-mass-table-bymag.html Which would indicate Saiph is much further away than 700 light years and closer to Humphrey's OB estimate, if the extinction is small. I'm not trying to belabor the point, but we're talking about one of the brightest stars in probably the most famous constellation in the sky.Mytg8 16:41, 29 July 2006 (UTC)

You make an excellent point. I found a recent paper ( Cowther et al., 2006, A&A, Vol. 446, pp. 279-293 ) that references Brown et al. 1994 for the distances to Alnilam (1200 light years) and Saiph (1300 light years), rather than their 1997 Hipparcos distances of 1300 and 720 light years, respectively. Here's what they say about Saiph: "Kudritzki et al. (1999) adopted the Hipparcos distance to HD 38771, whilst we adhere its the membership of Ori OB1c." So there's a difference of opinion among stellar astronomers. Given my consistency arguments above, I still think we should stick to Hipparcos distances for this page. But adding the OB association distances to the individual star pages sounds like a good idea. It would, however, probably be better to use a more recent paper than Humphreys. Cowther et al. give distance references in their Table 1. Most of these references are from the last fifteen years or so, although the distance reference for two of the dimmer stars is Humphreys (1978), so some of her distances are still being used. --Fournax 20:45, 29 July 2006 (UTC)

[edit] L:st size

Should this list be the 100 brightest stars? It would make a round number list size. 70.55.87.147

• I think it makes more sense to have a brightness cutoff (in this case a V magnitude of 2.50) rather that a particular number of stars. --Fournax 20:24, 25 September 2006 (UTC)

[edit] Historical brightest stars

Reference: Sky and Telescope, April 1998 (p60), based on computations from HIPPARCOS data. The calculations exclude stars where distance or proper motion figures are uncertain.

Star	Start Year	End Year	Maximum Year	Maximum magnitude	Distance at maximum (LY)
Epsilon Canis Majoris	...	-4,460,000	-4,700,000	-3.99	34
Beta Canis Majoris	-4,460,000	-3,700,000	-4,420,000	-3.65	37
Canopus (first time)	-3,700,000	-1,370,000	-3,110,000	-1.86	177
Zeta Sagittarii	-1,370,000	-1,080,000	-1,200,000	-2.74	8
Zeta Leporis	-1,080,000	-950,000	-1,050,000	-2.05	5.3
Canopus (second time)	-950,000	-420,000	-950,000[1]	-1.09[1]	252[1]
Aldebaran	-420,000	-210,000	-320,000	-1.54	21.5
Capella	-210,000	-160,000	-240,000[2]	-0.82[2]	27.9[2]
Canopus (third time)	-160,000	-90,000	-160,000 [1]	-0.70[1]	302[1]
Sirius	-90,000	+210,000	+60,000	-1.64	7.8
Vega	+210,000	+480,000	+290,000	-0.81	17.2
Canopus (fourth time)[3]	+480,000	+990,000	+480,000[1]	-0.40	346[1]
Beta Aurigae	+990,000	+1,150,000	+1,190,000[2]	-0.40[2]	28.5[2]
Delta Scuti	+1,150,000	+1,330,000	+1,250,000	-1.84	9.2
Gamma Draconis	+1,330,000	+2,030,000	+1,550,000	-1.39	27.7
Upsilon Librae	+2,030,000	+2,670,000	+2,290,000	-0.46	30
HR 2853	+2,670,000	+3,050,000	+2,870,000	-0.88	14
Omicron Herculis	+3,050,000	+3,870,000	+3,470,000	-0.63	44
Beta Cygni	+3,870,000	...	+4,610,000	-0.52	80

[1] Peak magnitude is not the brightest for this star

[2] This peak occurs when another star is brightest

[3] This assumes that the star does not become a supernova before this time

-- B.D.Mills  (T, C) 08:08, 27 January 2008 (UTC)

Historical? Can we have some context here? Start and end of what? —Tamfang (talk) 00:23, 15 February 2008 (UTC)

Ah, having read Epsilon Canis Majoris I get it: "Start and End" of the given star's reign as brightest, in years relative to the present. —Tamfang (talk) 00:33, 15 February 2008 (UTC)

A very interesting table - worthy to put in the article I think! Tom Ruen (talk) 01:21, 15 February 2008 (UTC)

Here's a graph to get a better visual understanding. I "faked" 3 magnitude points per star to include start/end brightnesses since they'll cross at least. Better to get original source data from the article if included OR recompute real graphs (not too hard) for each star interval. Tom Ruen (talk) 02:02, 15 February 2008 (UTC)

[edit] Delta Orionis

Why isn't Mintaka on the list? Is it because it's a binary star with magnitude 3.3 each? Ginu.at (talk) 17:21, 2 April 2008 (UTC)