Talk:Sirius

Under the section 'Apparent Third Star', a reference is made to "0.09 arcseconds". If someone just hovers over 'mas' and reads what the popup says, they might think mas means 'minute of arc'. In other words, it would be nice if when you hover cursor over mas, the first word you see is 'milliarcseconds'. 162.207.203.26 (talk) 04:47, 11 October 2019 (UTC)

But it is already set up in this way? Ruslik_Zero 21:07, 11 October 2019 (UTC)

Not sure set up is the right way to describe it. The {{val}} template wikilinks the unit mas to milliarcsecond, which is a redirect to Minute and second of arc#Symbols and abbreviations. The tooltip for non-logged-in users shows the main image for the linked article and a short piece of the lead. It doesn't respect sections, so in this case it doesn't really say anything about milliarcseconds specifically. I don't see any simple workaround, short of the wiki tooltips getting smarter. {{val}} can be configured to link to something else, but I don't see anything obvious that would help. An article for this relatively obscure unit, just to solve this issue, seems out of step with the relevant policies. Lithopsian (talk) 19:07, 12 October 2019 (UTC)

It has been suggested that the furture fate of Sirius B is to become a type Ia supernova, and although uncited that this is obvious. This is not obvious. Only a small proportion of white dwarfs will ever become a supernova. We still don't fully understand (or understand at all) exactly what type of situation produces a type Ia supernova but it is relatively (relatively, as in extremely) rare compared to the number of white dwarf binaries. Regardless, it would certainly not be obvious to the average non-astronomer that this would be the case, so a reliable source is required before including it in the article. Lithopsian (talk) 16:56, 3 November 2019 (UTC)

Sirius A has 2 Solar masses. Don't stars from 1.4 Solar masses on go supernova, becoming neutron stars or black holes? Why shall Sirius A share a similar fate like the Sun? 212.186.15.63 (talk) 06:37, 8 February 2020 (UTC)

Only stars more massive than 8-10 solar masses go supernova. Ruslik_Zero 12:40, 8 February 2020 (UTC)

They usually say 1.4 solar masses, don't they? Since the Sun is said to lose almost half its mass during its red giant phase, maybe the same happens to Sirius A. Then it matches: it would become a white dwarf. 212.186.15.63 (talk) 16:45, 8 February 2020 (UTC)

You're getting confused with the Chandrasekhar limit, which relates to the mass of the star after it becomes a white dwarf Cas Liber (talk · contribs) 18:26, 8 February 2020 (UTC)

Thank you. So since Sirius A loses enough mass when becoming a red giant, and again by a planetary nebula, its remaining mass will be low enough that it will be a white dwarf? 212.186.15.63 (talk) 18:56, 8 February 2020 (UTC)

Yes Cas Liber (talk · contribs) 22:39, 8 February 2020 (UTC)

Actually, this mass can go to Sirius B, and maybe cause Sirius B to explode. Just my speculation- I have seen scenarios like this in the past. 122.60.58.55 (talk) 04:31, 23 March 2021 (UTC)

There is a dramatic layout mess and MOS:SANDWICHing throughout ... could someone address this ? SandyGeorgia (Talk) 19:41, 30 November 2020 (UTC)

(belatedly) have made a first sweep of redundant images...sigh Cas Liber (talk · contribs) 01:56, 7 February 2021 (UTC)

This article has been proposed to run as today's featured article in March. (Click here for more details.) However, I have some concerns that this article might not meet featured article criteria. Some of my concerns include:

• Missing citations, which I have marked with "citation needed" tags. Some of these missing citations are for whole paragraphs.
• MOS:SANDWICHING as noted by Sandy in November

Done. Attic Salt (talk) 02:31, 7 February 2021 (UTC)

• Citations that do not give specific page numbers (mostly journal articles)

I did what I could. Ap J seems to only give first page (maybe due to transition to online articles). Attic Salt (talk) 02:31, 7 February 2021 (UTC)

• Some paragraphs that are very long (paragraph 4 in "Observational history") and some that are only one sentence (and very short)

am trying to rectify this - regarding that long para....@Z1720: where would you split it? Cas Liber (talk · contribs) 03:32, 7 February 2021 (UTC)

I would split it after "Queen of the Heaven" Z1720 (talk) 03:41, 7 February 2021 (UTC)

This paragraph is on one topic, Polynesian observations. The other paragraphs are on other, also self-contained communities. So I think we should leave the paragraph as is. Just my opinion. Attic Salt (talk) 03:52, 7 February 2021 (UTC)

I think the thing to do is reduce all of those many, many, names that the Polynesians used. They are just a long list that adds little understanding. Doing this would make the paragraph shorter. Attic Salt (talk) 04:36, 7 February 2021 (UTC)

I'm hesitant to remove names. How do we pick which Polynesian cultures get their name of the star listed? I prefer a separate paragraph describing what different Polynesian cultures called the star. Z1720 (talk) 16:13, 7 February 2021 (UTC)

I am not generally in favour of lists of foreign language names, especially somewhat esoteric names, unless they contribute to the broader content of the article. Attic Salt (talk) 16:50, 7 February 2021 (UTC)

Would sandwiching in a small thumbnail make the slabs of text a little less daunting? I'm thinking specifically of the heiroglyph which should be less wide than the first word of the section title so hardly likely to be a layout problem. Lithopsian (talk) 16:05, 7 February 2021 (UTC)

• The "Other modern references" section is in list form. Would it be better served as prose?

I would prefer it in prose too. See the promoted version in 2008. Cas Liber (talk · contribs) 03:28, 7 February 2021 (UTC)

• The description of Sirius in fiction is too short and could bring information from Sirius in fiction

I added a short paragraph giving a few of the more prominent (IMO) uses in science-fiction. There is already a good list of cultural uses and some random references not strictly referring to the star as a location in a story. Lithopsian (talk) 16:08, 7 February 2021 (UTC)

Would anyone be interested in working on this article to get it ready for TFA? I'm pinging Casliber although any help would be appreciated. Z1720 (talk) 01:16, 7 February 2021 (UTC)

I am on it - @Lithopsian: has a better understanding of the hard science than me so would be good to help out too :) Cas Liber (talk · contribs) 02:10, 7 February 2021 (UTC)

How's it looking so far? I know there are still a couple of citation needed tags. One is related to ancient understanding of the Sothic cycle which I'm probably not going to be much help with, although the whole claim looks slightly dubious. The other is about the position of Sirius in 14,000 years. I have checked the calculation and it appears correct, with proper motion included, but can't find any source to explicitly make the same claim. Lithopsian (talk) 20:32, 12 February 2021 (UTC)

I've scheduled it TFA for March 21. I hope the remaining can be addressed by then? Suggest removing what can't be sourced by then, or modifying to fit what sources you can find. Thanks for your help in the matter.--Wehwalt (talk) 19:17, 16 February 2021 (UTC)

I think its all done, fingers crossed. Lithopsian (talk) 20:18, 16 February 2021 (UTC)

Strangely enough, a lot of time is spent explaining in which constellations stars live, but the galaxy to which they belong seems to be never mentioned. Sounds like prehistoric thinking to me... — Preceding unsigned comment added by 77.192.35.12 (talk) 19:11, 27 February 2021 (UTC)

You can see it, therefore it is in this galaxy. Not so much prehistoric as assuming a certain minimal level of knowledge - unfortunate perhaps, but necessary. Lithopsian (talk) 16:51, 28 February 2021 (UTC)

Sirius is 8 light years away from Sun.

Milky Way galaxy has a diameter of 100,000 light years.

So it's obvious that Sirius is inside the Milky Way Galaxy.

Note that the neighbour galaxy of Andromeda is 2,500,000 light years away.

Conclusion: When you want to know which galaxy a star belongs to, just know the distance of the star. Because constellations are an area in the sky from our perspective; hence two or more galaxies can be in one constellation. Note that when you look at the sky and see stars they might be several light years away from each other both horizontally and vertically. Just like when you look at a distant tree and a distant car from a distance, and you see both beside each other. But in fact they are far from each other. Aminabzz (talk) 21:23, 20 May 2023 (UTC)

Do we have any NAMED stars in Andromeda or the Magellanic Clouds, anyway? 2603:6080:21F0:6140:54CA:9001:27B8:D63 (talk) 21:33, 22 January 2024 (UTC)

@Lithopsian: - https://en.wikipedia.org/w/index.php?title=Sirius&diff=prev&oldid=1027586003, I don't disagree, but if you know the date the sentence was written @ the article, i.e. which is a copy is determinable by comparison of the dates of publication ... as you know Autonomous agent 5 (talk) 20:12, 8 June 2021 (UTC)

The text was already in Wikipedia on the date the paper claims to have been written, and several years before that. If it was the other way round, it would be a copyright violation and should be removed. Doesn't reflect well on the journal paper though. Lithopsian (talk) 19:28, 9 June 2021 (UTC)

I guess imitation is the best form of flattery...Cas Liber (talk · contribs) 23:44, 8 November 2021 (UTC)

The proper motion value in the infobox sets its reference as van Leeuwen, F. (November 2007), doi:10.1051/0004-6361:20078357, but that paper does not mention Sirius at all. Urhixidur (talk) 19:38, 8 November 2021 (UTC)

The paper is a description of the derivation of a large database of astrometric data for essentially all the Hipparcos stars. You can query it online at, for example, VizeR. Or the highlights are reproduced on the Simbad page for the star. Lithopsian (talk) 20:04, 8 November 2021 (UTC)

Is it really relevant that Sirius is "the fifth closest stellar system"? I would suppose that the reader would be more interested in learning, that Sirius is the seventh closest system, after Alpha Centauri, Barnard's Star, Luhman 16 (no star!), WISE J085510.74-071442.5 (no star!), Wolf 359, and HD 95735. I suggest that the passage is rephrased to "and it is the seventh closest system to the Sun" and a link is added to the article List_of_nearest_stars_and_brown_dwarfs. CalRis (talk) 12:35, 23 July 2022 (UTC)

Yes, it is "relevant" (strange choice of words) - interesting fact that should stay. 50.111.25.27 (talk) 08:37, 10 August 2022 (UTC)

The absolute magnitude stated on Sirius A is said to be 1.42 I downloaded the cited source and in there it's stated (twice) that it's actually -1.42

"This was determined through a comparison with stars in the North Polar Sequence5, or bright stars in the vicinity of Sirius, and yielded mV (Sirius)=–1.42±0.03,..." (Page 97, also table at page 189)

This is also in range of the absolute magnitude stated by other sources. E.g. VizieR states that it's -1.58 ( http://vizier.u-strasbg.fr/viz-bin/VizieR-S?HD%2048915 ) 2A02:8388:A84:DE80:49CE:24BF:CEC0:7D04 (talk) 17:41, 29 July 2022 (UTC)

See absolute magnitude and apparent magnitude, two different things. Lithopsian (talk) 18:14, 29 July 2022 (UTC)

That's correct, but still the source cited doesn't even mention the absolute magnitude.

The German version of Wikipedia does a better job at it linking to this statement:

Berechnet sich aus scheinbarer Helligkeit und Parallaxe: M = m + 5 + 5·log(Parallaxe) = −1,46 + 5 + 5·log(0,379″) = +1,43 mag (siehe Entfernungsmodul).

(Calculates from the apparent magnitude and parallax: M = m + 5 +5·log(parallax) = −1,46 + 5 + 5·log(0,379″) = +1,43 mag (see distance modulus)

So the value is correct, but the stated source isn't even talking about it. 2A02:8388:A84:DE80:49CE:24BF:CEC0:7D04 (talk) 18:42, 29 July 2022 (UTC)

Also even if the values used in that source were used (as quoted apparent magnitude = -1.42, parallax 380.023) the calculated absolute magnitude would be

-1.42 + 5 + 5*log(0.380023) = 1.479

So stating that this source leads to an absolute magnitude of 1.42 is wrong. 2A02:8388:A84:DE80:49CE:24BF:CEC0:7D04 (talk) 19:05, 29 July 2022 (UTC)

Better? Lithopsian (talk) 20:00, 29 July 2022 (UTC)

Surface gravity is expressed as an acceleration, conventionally, m/s2. Expressing it as cgs is gibberish. cgs is centimetre gram scale, a general description of a scale system, not a unit of acceleration. Sadly, this error has made its irritating wsy into almost every wiki on stars. Also log g is meaningless. There are many different logs, ln, log10 etc. It is therefore necessary to specify which log is being quoted. 209.93.146.80 (talk) 10:17, 19 February 2023 (UTC)

Thanks for your concern, but claiming that essentially every professional astronomer in existence is talking gibberish might be a little above your pay grade. cgs, as linked in all those articles you think are meaningless is a *system* of units in which, quoting from the Wikipedia article, "All CGS mechanical units are unambiguously derived from these three base units". Hence the cgs units of acceleration are unambiguously cm/s². The logarithm (base 10) of such an acceleration does not technically have units, but are understood from being designated in the cgs system. This usage is almost universal in astrophysics, probably for historical reasons, but perhaps just because the results fall in a nice range of small (almost always) positive numbers. You can read more, and follow the references, at Surface gravity. Lithopsian (talk) 16:03, 19 February 2023 (UTC)

As Lithopsian correctly stated, the unit of acceleration is cm s^-2 in the cgs (centimetre-gramme-second) system of units. The convention across the sciences is for log to mean log₁₀. The very old convention of expressing surface gravities of stars as log₁₀( g / cms^-2) has persisted, where g is the acceleration due to gravity at the surface, even though cgs units are virtually never encountered elsewhere. A more modern practice would be to express surface gravities as log₁₀( g / ms^-2), but this is still not done widely done. TowardsTheLight (talk) 20:17, 19 February 2023 (UTC)

Why does Sirius B has a surface temperature of 25,000 Kelvins, while it has a radius 0.0084 times that of the Sun and also a luminosity 0.056 times that of the Sun? Aminabzz (talk) 21:25, 20 May 2023 (UTC)

Sirius B is a white dwarf. SevenSpheres (talk) 21:58, 20 May 2023 (UTC)

This type of question should be referred to the Wiki Help Desk, unless you are requesting some change to the article. 2603:6080:21F0:6140:54CA:9001:27B8:D63 (talk) 21:36, 22 January 2024 (UTC)

The talk page banner says the page is written in American English yet I see non-American spelling (particularly colour) everywhere. Am I missing something?

Stanley Joseph Wilkins (talk) 05:35, 2 August 2024 (UTC)

A planet was found orbiting Sirius B, it is 1.5 Jupiter masses and has a semi-major axis of 0.9 au according to this source https://exoplanet.eu/catalog/sirius_bb--10752/ this is only a candidate. Orangefanta120 (talk) 00:28, 7 October 2024 (UTC)

The underlying source is arXiv:2409.16992 § 8.4, which discusses limits on the presence of a companion and could be added to the sections of the article about that. It's not really correct to claim a detection based on it. The parameters in EPE seem to come from taking the averages of ranges in the paper, which says that a <1–2 MJ companion at 0.5–1.3 au cannot be ruled out. SevenSpheres (talk) 02:29, 7 October 2024 (UTC)

The image of Sirius in the size & color comparison with other stars is inaccurate. Sirius is blue.

Jtadesse (talk) 02:24, 4 April 2025 (UTC)

I've removed "and colour" from the caption. The image is still potentially relevant as a size comparison. SevenSpheres (talk) 02:58, 4 April 2025 (UTC)

I noticed that the distances to the components of the Sirius system don't make sense. The article starts with claiming A&B are contact binaries orbiting at 10s of AU, yet the distances given for A are 8.6 and B 8.709 lyr. That would put the stars about 7000AU apart. The problem seems to stem mixing Hipparcos and GAIA measurements. While the GAIA measurements come with high uncertainty they don't cover the range of the Hipparcos distance. The matter is already discussed in the distance subsection. I would still suggest using both distances for A and B throughout the article. MMichkov (talk) 03:01, 5 August 2025 (UTC)

I think we should at least have a note beside the two components' distances mentioning they're not directly comparable, and that the Gaia measurement may be somewhat compromised with a systematic error. If it was readily apparent which measurement is more accurate, we should obviously defer to that in the whole article, but we don't have that at this point unfortunately. exoplanetaryscience (talk) 08:36, 5 August 2025 (UTC)

The systematic error in Gaia parallaxes is trivial in the case of such large parallaxes. However, the Sirius B parallax, while looking statistically not too bad, has a large astrometric noise value. The Hipparcos parallax is just statistically a little poorer, but both values are likely accurate to a tenth of a parsec, and consistent with eachother within that margin. We probably shouldn't be quoting any values in the body to a greater precision than that unless it is in a discussion of the systematic and statistical accuracy of the distances. Lithopsian (talk) 11:28, 5 August 2025 (UTC)

I'm not talking about typical background Gaia systematics, but the specific systematics with this star caused by B's orbit around A which is not modeled by Gaia and explicitly reflected by the larger excess noise and RUWE of >2 which indicates that the solution is not reliable (i.e. the quoted values and uncertainties are precise but not accurate, statistically speaking). exoplanetaryscience (talk) 16:06, 5 August 2025 (UTC)

I think the main issue is that large differences in distances between A&B run contrary to the system being a spectroscopic binary. One would expect such a system to be compact, not spread out over 7000AU.

By all means let's keep or add a bit on the issue with both distance measurements, but having the large separation in the infobox makes little sense. MMichkov (talk) 03:31, 6 August 2025 (UTC)

It is worth pointing out that you are using two distances, independent of eachother, to infer the distance between the two components. Your logic is invalid. The article makes no such claim and neither should you. What we need to decide is how to prevent readers making what seems like a simple—but incorrect—calculation and leaping to radical conclusions. Removing some of the data from the starbox is an obvious way, although I don't favour it. Perhaps footnotes explaining the limitations? There is nothing inherently wrong with the data, only in excessive faith in its accuracy, perhaps in showing a small statistical margin of error without referencing much larger potential sources of error. Obviously a featured article should discuss the conflicting parallax values in the body of the article, whether or not they are both in the starbox. Lithopsian (talk) 15:19, 6 August 2025 (UTC)

I don't know if this infobox format supports it at all, but maybe we could list both distances back-to-back for each star (or just A)? Both A and B (or just A) having 8.60 and 8.71 LY listed to make it clear that each given measurement practically applies to both? exoplanetaryscience (talk) 18:37, 6 August 2025 (UTC)

Then I'd say an update of the uncertainty is in order, together with a discussion on the noisy date in the distance section. I have no idea how the RUWE parameter works so I got nothing to add to that. MMichkov (talk) 20:57, 6 August 2025 (UTC)

The Gaia parallax for component B is unreliable and thus should be removed, or at very least assumed to be the same as of Sirius A. See this for a glimpse. It is likely affected by the system's orbit. 21 Andromedae (talk) 11:33, 5 August 2025 (UTC)

The main problem as understand is that Sirius A is too bright for Gaia. So, its parallax cannot be measured. Sirus B is much dimmer, is not saturated and its parallax can be measured. However due to probably the light contamination from very bright Sirius A its parallax has some rather large systematic error that is difficult to track down. Ruslik_Zero 18:54, 8 August 2025 (UTC)

I've made an edit to the infobox that hopefully everyone can find agreeable. Some of the footnote content can probably be split up into a main-body discussion (or entirely divested into just 'see xyz section'), but it works for now I think. exoplanetaryscience (talk) 16:31, 9 August 2025 (UTC)

Don't think that is right, the Gaia parallax for Sirius B is known to be unreliable given the RUWE; the Hipparcos value has no flag for unreliability and is fairly consistent with other measurements, such as that of Gatewood & Gatewood 1978. We probably should remove the Gaia value and use the Hipparcos one. Bond et al. 2017 use a value of 378.9±1.4, an average of the Hipparcos and Gatewood estimates, should we use it instead? 21 Andromedae (talk) 17:33, 9 August 2025 (UTC)

Sorry for being delinquent to get around to addressing this. That seems like a safe source for now- I've added it and refined the note a bit. exoplanetaryscience (talk) 11:12, 9 September 2025 (UTC)

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