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The following is an archived discussion of a featured article nomination. Please do not modify it. Subsequent comments should be made on the article's talk page or in Wikipedia talk:Featured article candidates. No further edits should be made to this page.

The article was promoted by Laser brain via FACBot (talk) 25 May 2019 [1].

Herbig–Haro object

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Nominator(s): AhmadLX-)¯\_(ツ)_/¯) 20:36, 21 April 2019 (UTC)[reply]

This article is about a class of astrophysical objects that are by-product of star formation. This is a former featured article that was demoted, mainly because of citation concerns, in 2010. I started working on it more than a year ago, addressed citation issues, added missing info, and it passed GAN by Casliber last year. Since then I have been thinking of nominating it for FA, but didn't do because I wanted to add some more info. I have now come to conclusion that that info belongs to closely related Astrophysical jet and Bipolar outflow, so this article is comprehensive in my opinion. Thanks. AhmadLX-)¯\_(ツ)_/¯) 20:36, 21 April 2019 (UTC)[reply]

Comments from Tim riley

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My ignorance of this subject could not be surpassed, but I offer a few minor passing thoughts on the drafting:

  • "HH objects are indeed shock induced phenomenon": as they are plural shouldn't this be "phenomena"?
Changed. AhmadLX-)¯\_(ツ)_/¯) 00:05, 22 April 2019 (UTC)[reply]
  • The article seems to be in BrE (colour, kilometres, recognised) but "sulfur" pops up à l'américaine, as do "disks".
Done as US: color, kilometers etc. AhmadLX-)¯\_(ツ)_/¯) 00:05, 22 April 2019 (UTC)[reply]
  • On the same point, and I expect to be shot down in flames but just mention it anyway, the OED hyphenates "infra-red".
Books and journals almost always write it as "infrared". AhmadLX-)¯\_(ツ)_/¯) 00:05, 22 April 2019 (UTC)[reply]
  • "last around a few tens of thousand years" – seems to me that this should be "last around a few tens of thousands of years", but I'm perfectly willing to be told I'm wrong.
Done. AhmadLX-)¯\_(ツ)_/¯) 00:05, 22 April 2019 (UTC)[reply]
  • In the sources, if you really think it necessary to tell your readers that Cambridge is in the United Kingdom it might be as well to pile Pelion on Ossa and clarify where Hampshire is chez Raja, and which country Arizona is in for Frank and friends.
This has been done to avoid ambiguity. There is another famous Cambridge (MA), but only one famous Arizona ;) AhmadLX-)¯\_(ツ)_/¯) 00:05, 22 April 2019 (UTC)[reply]

I may say that although I didn't come within several parsecs of understanding the article it nonetheless impressed me. The narrative is clear, jargon seems to be kept to the essential minimum, the sourcing seems to my inexpert eye highly impressive, and everything is properly cited. On the prose I'd be happy to support, but I must emphasise that I am not equipped to comment on what the article is actually saying. I hope these few not very coherent comments are of some use. – Tim riley talk 21:35, 21 April 2019 (UTC)[reply]

Thank you. AhmadLX-)¯\_(ツ)_/¯) 00:05, 22 April 2019 (UTC)[reply]

Support Comments from Jim

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A few nitpicks Jimfbleak - talk to me? 15:28, 22 April 2019 (UTC)[reply]

  • It resides about 1400 light-years away— I'm not convinced that something non-living can " reside"
Yes ;) changed. AhmadLX-)¯\_(ツ)_/¯) 16:04, 22 April 2019 (UTC)[reply]
  • are a visible wavelength phenomena, many remain invisible at these wavelengths due to dust and gas envelope and are only visible at —bit repetitive with three visible/invisibles
Modified. AhmadLX-)¯\_(ツ)_/¯) 16:04, 22 April 2019 (UTC)[reply]
  • Shouldn't "shock-induced" be hyphenated?
Done. AhmadLX-)¯\_(ツ)_/¯) 16:04, 22 April 2019 (UTC)[reply]
  • Conversely, we don't hyphenate where there is a -ly descriptor, like "partially ionized"
Done. AhmadLX-)¯\_(ツ)_/¯) 16:04, 22 April 2019 (UTC)[reply]
  • Please check your use of "however". In at least one case I can't even see what the contrast is, and I'm not sure any are essential
Three removed, one kept. AhmadLX-)¯\_(ツ)_/¯) 16:04, 22 April 2019 (UTC)[reply]
  • Spectroscopic observations of their doppler shifts indicate velocities of — What does "their" refer to? Subjects of the preceding sentences are singular
Fixed. AhmadLX-)¯\_(ツ)_/¯) 16:04, 22 April 2019 (UTC)[reply]
  • at speeds of several hundred km/s — I'd spell out the units here
Done. AhmadLX-)¯\_(ツ)_/¯) 16:04, 22 April 2019 (UTC)[reply]
  • Shocking at the end of the jet can re-ionize some material, however, giving rise to bright "caps" at the ends of the jets. —too many "ends of jets", and another redundant "however"
Removed. AhmadLX-)¯\_(ツ)_/¯) 16:04, 22 April 2019 (UTC)[reply]
  • How many potential readers of this article do you think need a link to water?
Right ;) removed. AhmadLX-)¯\_(ツ)_/¯) 16:04, 22 April 2019 (UTC)[reply]
  • There are a few duplicated links, please check
Removed. AhmadLX-)¯\_(ツ)_/¯) 16:04, 22 April 2019 (UTC)[reply]
Thank you Jim. AhmadLX-)¯\_(ツ)_/¯) 14:04, 25 April 2019 (UTC)[reply]


Image review

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Fixed. AhmadLX-)¯\_(ツ)_/¯) 17:30, 24 April 2019 (UTC)[reply]
This is kinda vague on the copyright status; @Nikkimaria:? Jo-Jo Eumerus (talk, contributions) 18:47, 24 April 2019 (UTC)[reply]
The image use policy for that site seems contradictory: on the one hand it says any use is allowed without permission, but on the other it claims not to make any representations as regards who actually holds copyright. I would lean towards it being permitted, but it's not as straightforward as a simple NASA claim. Nikkimaria (talk) 22:28, 24 April 2019 (UTC)[reply]
Yeah, the uncertainty of who created it is the big problem here. Jo-Jo Eumerus (talk, contributions) 06:26, 25 April 2019 (UTC)[reply]
Sorry I'm a bit ignorant on copyright matters, but the page says that the image was produced by spitzer, so won't NASA/JPL be its creators? The Image Use page just says that the university has nothing to do with copyright of the images. AhmadLX-)¯\_(ツ)_/¯) 14:04, 25 April 2019 (UTC)[reply]
The photo is from a publication, but I don't know if it is released as PD by the author. Remove? AhmadLX-)¯\_(ツ)_/¯) 16:56, 24 April 2019 (UTC)[reply]
Yeah, it's a little unclear. Better remove IMO. Jo-Jo Eumerus (talk, contributions) 18:47, 24 April 2019 (UTC)[reply]
Done. AhmadLX-)¯\_(ツ)_/¯) 14:04, 25 April 2019 (UTC)[reply]
I see there is ALT text everywhere. Jo-Jo Eumerus (talk, contributions) 08:34, 23 April 2019 (UTC)[reply]
You mean it should be shortened, or?AhmadLX-)¯\_(ツ)_/¯) 16:56, 24 April 2019 (UTC)[reply]
No, they are OK. Jo-Jo Eumerus (talk, contributions) 18:47, 24 April 2019 (UTC)[reply]
Ah okay, I misunderstood ;) AhmadLX-)¯\_(ツ)_/¯) 14:04, 25 April 2019 (UTC)[reply]

Source review

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Edit to add: The comments pertain to this revision. Jo-Jo Eumerus (talk, contributions) 15:59, 25 April 2019 (UTC)[reply]

Judging by the publisher information, it seems all sources are reliable. From a random source check.

  • 22: Maybe it's a (absence of) pagenumber problem, but I can't find neither the 8000K value nor the density of the other stellar objects nor the ionization patterns.
Temp is there in the source (see conclusions section). There was, however, an inaccuracy in the article. Fixed that now. Source added for other nebula. I don't think ionization pattern is discussed here. You mean the part "other ionized nebulae"?AhmadLX-)¯\_(ツ)_/¯) 16:56, 24 April 2019 (UTC)[reply]
Seems like the source was now renumbered as 23. As it is it seems like the "ionization" thing is resolved. Jo-Jo Eumerus (talk, contributions) 15:59, 25 April 2019 (UTC)[reply]
  • 20: That seems OK.
  • 25: That seems OK, although the source being from 2002 makes me wonder if we know even more today.
Yes, updated. AhmadLX-)¯\_(ツ)_/¯) 14:04, 25 April 2019 (UTC)[reply]
  • 1: That seems OK.
  • 17: Sorta OK although I wonder if the article is being a bit too certain on the precession aspect, the source is a bit more qualified. Also, it seems like the source on p.489 gives a number 10x smaller for the mass output.
No, the values you say are for a particular object (HH 54). General value that the paper reports is 10^-8 to 10^-6 M-solar.AhmadLX-)¯\_(ツ)_/¯) 12:00, 23 April 2019 (UTC)[reply]
Sorry missed the precession issue. Yes you are right. Fixed. AhmadLX-)¯\_(ツ)_/¯) 14:04, 25 April 2019 (UTC)[reply]
  • 35: This one needs page numbers at a minimum, and I don't see "gravitational" anywhere.
Multiple systems disintegrate because orbitals become unstable. Not in this source, but it is just a regular thing, so I think it doesn't need a source. Anyway, added [34] which describes this. As for specific page numbers, as far as I know, they are required for books, as journal articles are normally only a few pages. I have always used, and seen used on other pages, the page numbers for whole articles. Also WP:CS says "volume number, issue number, and page numbers (article numbers in some electronic journals)". Moreover, if specific page numbers are to be included, what about the article's page range. One will need harv footnotes I think to accommodate the two. Or?AhmadLX-)¯\_(ツ)_/¯) 17:01, 23 April 2019 (UTC)[reply]
Page numbers are not obligatory here, but they make it harder to find information. Jo-Jo Eumerus (talk, contributions) 19:37, 23 April 2019 (UTC)[reply]
  • 29: I don't think "Herbig-Haro" is mentioned anywhere, nor the age information or the "class 0".
It basically focuses on outflows in young stars. As mentioned at multiple places in the article (i.e WP article), these those outflows give rise to HHOs. Class 0 absent (they came later in the scheme) and no age info; yes, fair enough. Will replace then. Replaced. AhmadLX-)¯\_(ツ)_/¯) 11:27, 24 April 2019 (UTC)[reply]
  • 7: Can I have a copy of the chapter?
Yes sure, just send me email, I will send the chapter. AhmadLX-)¯\_(ツ)_/¯) 12:00, 23 April 2019 (UTC)[reply]
Got it, I am not sure if "continuum spectrum" can be rephrased as "continuous". Where are "caps" mentioned? Jo-Jo Eumerus (talk, contributions) 19:37, 23 April 2019 (UTC)[reply]
1.It is same thing. 2."Caps" is rephrasing. See figure 1 and its description in the source.AhmadLX-)¯\_(ツ)_/¯) 14:14, 24 April 2019 (UTC)[reply]
  • 14: Seems OK.
  • 3: I don't think that "It was cataloged merely as an emission nebula" is supported by the source, and neither "With discovery of collimated jet in HH 46/47" which seems to be missing a "the" before the "collimated". Where is "a few years" reported?
Good point. Yes, cataloged is certainly not there. I have changed it to thought for now. For second part, about H 46/47, see para 2 on page 7, and [5]. Which "a few years"?
In As they move away from the parent star, HH objects evolve significantly, varying in brightness on timescales of a few years. Individual knots within an object may brighten and fade or disappear entirely, while new knots have been seen to appear. Also I notice that "so small" in the history section does not appear to be supported by the source. Jo-Jo Eumerus (talk, contributions) 15:59, 25 April 2019 (UTC)[reply]
1) Sources were, maybe, somehow mixed here. Replaced with two others. 2) The source talks about semi-stellar appearance, so "so small" was used, perhaps, to signify this. Removed. AhmadLX-)¯\_(ツ)_/¯) 20:20, 25 April 2019 (UTC)[reply]
  • 23: Seems OK assuming that "cannon ball" is metaphorical.
  • 24: The source says that it's only approximately in chronological order, and of identification not discovery.
Yes, thanks for pointing this out. Added approximately. IMO identification and discovery are same in this regard, but changed anyway.AhmadLX-)¯\_(ツ)_/¯) 16:05, 23 April 2019 (UTC)[reply]
  • 33: Can I have a copy of the chapter?
Yes, see above. AhmadLX-)¯\_(ツ)_/¯) 12:00, 23 April 2019 (UTC)[reply]
Got it, seems like it supports part of the text. Jo-Jo Eumerus (talk, contributions) 19:37, 23 April 2019 (UTC)[reply]
Moved to that part. AhmadLX-)¯\_(ツ)_/¯) 14:14, 24 April 2019 (UTC)[reply]
  • 18: Seems OK.
  • 15: It only discusses one HH object.
Yes, that's why there is another source (again discussing one object). One with general statement can be added if you like. I found two examples adequate to support the claim. AhmadLX-)¯\_(ツ)_/¯) 15:53, 23 April 2019 (UTC)[reply]
Ah, OK. Jo-Jo Eumerus (talk, contributions) 15:59, 25 April 2019 (UTC)[reply]
  • 27: Some chemicals are named; I take the others are mentioned in the other source?
Now [28]. Yes, but CO is common in all molecular outflows. I don't know why I had included it here;) Removed now. AhmadLX-)¯\_(ツ)_/¯) 16:56, 24 April 2019 (UTC)[reply]
  • 28: Some "the" are missing in the text. Where is "class I" in the source? I take "Two bright bow shocks, separated by about 0.44 parsec, are present on the opposite sides of the source, followed by series of fainter ones at larger distances, making the whole complex about 3 parsecs long. Jet is surrounded by 0.3 parsec long weak molecular outflow near the source." is supported by the other source?
This is what [28] supports: HH object, 460 pc away, in orion nebula, 3 pc long, has jet and counterjet, weak molecular outflow. The rest is supported by the other source. AhmadLX-)¯\_(ツ)_/¯) 15:48, 23 April 2019 (UTC)[reply]

I have a question about the source usage here. Google Scholar has plenty more sources; what were the criteria for source usage in this article? Jo-Jo Eumerus (talk, contributions) 08:34, 23 April 2019 (UTC)[reply]

A few sources are review articles: 2ndary in nature and overview of the topic, so always preferred. Some others are books: preferred like review articles. Remaining are research articles. Yes there are many of them out there, but I think the purpose is to cite everything with a suitable set of reliable sources. Incorporating all published sources is rarely possible or desired. If there is something in those sources that should be, but is not, in the article, I will be glad to hear it. AhmadLX-)¯\_(ツ)_/¯) 12:00, 23 April 2019 (UTC)[reply]
Ah, OK then. Regarding #17 I think a pagenumber would help, as I can't find the mass estimates otherwise. Email sent. Jo-Jo Eumerus (talk, contributions) 13:44, 23 April 2019 (UTC)[reply]
Files sent. AhmadLX-)¯\_(ツ)_/¯) 17:01, 23 April 2019 (UTC)[reply]
@Jo-Jo Eumerus: Thanks for the image and source reviews. Especially for the latter. TBH this is a model review; rigorous and in-depth, it has enabled me to fix issues and inaccuracies that were overlooked. I am still waiting for your response on a couple points though: 22, 3, and 15. Thanks. AhmadLX-)¯\_(ツ)_/¯) 14:04, 25 April 2019 (UTC)[reply]
Commented on these. Note that I didn't re-check the claims after you altered them in some cases. Jo-Jo Eumerus (talk, contributions) 15:59, 25 April 2019 (UTC)[reply]

Comments Support from Cas Liber

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Having a look now....

  • Why the last two sentences of the lead in their own stubby paragraph? Surely that flows on from previous material and lead can be consolidated into two paras...?
Merged into the preceding para.AhmadLX-)¯\_(ツ)_/¯) 20:11, 29 April 2019 (UTC)[reply]
  • I must say I am not a fan of "turbulent-looking" in the first sentence. If it can be worked in in the 2nd or 3rd sentence I think that'd flow better.
Removed. AhmadLX-)¯\_(ツ)_/¯) 20:11, 29 April 2019 (UTC)[reply]
  • Explain or at least unabbreviate MHOs in lead
Done. AhmadLX-)¯\_(ツ)_/¯) 20:11, 29 April 2019 (UTC)[reply]
  • With discovery of collimated jet in HH 46/47... - "a" collimated jet?
Changed this part a bit: With the discovery of the first proto-stellar jet in HH 46/47. Is that fine? AhmadLX-)¯\_(ツ)_/¯) 20:11, 29 April 2019 (UTC)[reply]
  • Any reason why parsecs are used instead of light-years?
Because sources use parsecs, so it was just a lazy recipe to copy the numbers ;) Light-years added in brackets. AhmadLX-)¯\_(ツ)_/¯) 20:11, 29 April 2019 (UTC)[reply]

Otherwise looking good on comprehensiveness and prose Cas Liber (talk · contribs) 13:10, 29 April 2019 (UTC)[reply]

Thank you Cas. AhmadLX-)¯\_(ツ)_/¯) 10:06, 30 April 2019 (UTC)[reply]

Support: looks worthy of FA status. I've addressed my concerns by editing the article. Thanks. Praemonitus (talk) 14:29, 18 May 2019 (UTC)[reply]

Thank you Praemonitus for edits and support. AhmadLX-)¯\_(ツ)_/¯) 16:09, 18 May 2019 (UTC)[reply]
The above discussion is preserved as an archive. Please do not modify it. No further edits should be made to this page.
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