<p>Current measurements give a distance &quot;somewhere between 567 light years and 835 light years&quot;, with a &quot;best guess&quot; of 724 light years.</p>
<p>So wikipedia is being honest and saying &quot;about 700&quot;. We really don't know any better.</p>
<p>Earthsky.org is giving the &quot;best guess&quot; value.</p>
<p>The app is probably using the distance measured by the Hippcaros space telescope.  This value is generally considered to be an underestimate.</p>
<p>Another answer explains why we find it so hard to measure this distance: <a href="https://astronomy.stackexchange.com/q/36365/24157">What will it finally take to accurately measure the distance to Betelgeuse?</a></p>

CC BY-SA 4.0
2020-07-02T12:17:02.737Z
Needs to give details and sources of information/quotes and how the distance was arrived at.
ProfRob
CC BY-SA 4.0
2020-07-02T16:34:51.923Z
@antispinwards it doesn't give the distance as 131 pc though does it? You can't just invert a poorly determined parallax.
ProfRob
CC BY-SA 4.0
2020-07-02T19:59:04.997Z
@antispinwards who determined it?
ProfRob
CC BY-SA 4.0
2020-07-02T10:21:54.040Z
2020-07-02T18:15:43.050Z
2020-07-02T18:15:43.050Z
James K
<p>Look at this article: <a href="https://arxiv.org/abs/1706.06020" rel="nofollow noreferrer">https://arxiv.org/abs/1706.06020</a>. Depends on studies distance varies and this is probably the reason of this discrepancy. For instance Hipparcos catalogue gives <span class="math-container">$131^{+35}_{−23}$</span>~pc, assuming pc=3.26ly it gives <span class="math-container">$\sim$</span>427~ly. More details in attached article ;).</p>
<p>We are waiting for results from Gaia mission, because at first it made parallax of fainter stars and very bright, as Betelguse will come next, but I don't know when, maybe it was measured already, but I can't find any credible information. They wrote in <a href="https://www.aanda.org/articles/aa/pdf/2016/11/aa29272-16.pdf" rel="nofollow noreferrer">https://www.aanda.org/articles/aa/pdf/2016/11/aa29272-16.pdf</a></p>
<p>&quot;The 230 brightest stars in the sky (G &lt; 3 mag, loosely referred
to as very bright stars) receive a special treatment to ensure
complete sky coverage at the bright end&quot;</p>

CC BY-SA 4.0
2020-07-02T16:38:20.173Z
The abstract of the paper you cite does not give a Hipparcos distance of 131 pc and the means by which your disance is obtained (I doubt it is in the Hpparcos catalogue) is highly dubious. You cannot just invert a noisy parallax to get the probable distance..I doubt that Gaia will make great strides forward on the distance to Betelgese because it is not the precision of the parallax that is the problem, it is its accuracy because of the inhomogeneous atmosphere of Betelgeuse..
ProfRob
CC BY-SA 4.0
2020-07-02T23:29:57.137Z
Yes in abstact is different, newer value, but inside the paper they mention:
 "The release of the original Hipparcos catalog (Perryman et al. 1997; ESA 1997) suggested that Betelgeuse had a distance of $131^{+35}_{−23}$~pc" and this one I cited. What do you mean by "inhomogeneous atmosphere"? That in different wavelength the thickness of atmosphere differs, or because of star pulsation ?
Mateusz
CC BY-SA 4.0
2020-07-02T23:34:41.690Z
I have found sth which probably is your point:  "Instead of the star's atmosphere expanding uniformly due to gas heated to high temperatures near its surface, it now appears that several giant convection cells propel gas from the star's surface into its atmosphere". Therefore, because of inhomogeneity and fluctuation of its, we cannot really properly estimate distance with e.g. parallax method. Ok,, I got it :)
Mateusz
CC BY-SA 4.0
2020-07-02T14:29:34.627Z
2020-07-02T14:29:34.627Z
Mateusz
<p>Distance measurements for Betelgeuse are a bit of a mess. Solutions based on parallax would be ideal, but Betelgeuse has a rather large angular diameter at most wavelengths thanks to its extended envelope; optical and infrared observations usually fall in the 40-60 mas range (see <a href="https://ui.adsabs.harvard.edu/abs/2016ApJ...819....7D/abstract" rel="nofollow noreferrer">Dolan et al. 2016</a> for a recent review), while radio observations show a disk of emission roughly twice that size (<a href="https://ui.adsabs.harvard.edu/abs/2017A%26A...602L..10O/abstract" rel="nofollow noreferrer">O'Gorman et al. 2017</a>). The parallax is expected to be much smaller that the angular diameter, on the order of ~5 mas, and so it depends strongly on the choice of the center of emission.</p>
<p>One of the first decent parallax results was obtained by the <em>Hipparcos</em> satellite in 1997, whose astrometric measurements allowed comparatively precise measurements of location, parallax and proper motion for over 100,000 stars. <em>Hipparcos</em> measured a parallax for Betelgeuse of <span class="math-container">$\pi=7.63\pm1.64$</span> mas, corresponding to a distance of <span class="math-container">$131\pm30$</span> pc<span class="math-container">$^{\dagger}$</span>. This is that 427 light-year number the app cited. The <em>Hipparcos</em>-only result was subsequently improved upon significantly by <a href="https://ui.adsabs.harvard.edu/abs/2007ASSL..350.....V/abstract" rel="nofollow noreferrer">van Leeuwen 2007</a>, who found <span class="math-container">$\pi=6.56\pm0.83$</span> mas, cutting the old uncertainty in half; this would correspond to a distance of 152 parsecs. If you're going to quote a <em>Hipparcos</em> result, this is the one to pick.</p>
<p>More recent results indicate that this value is likely too low. Combining <em>Hipparocs</em> data with multiple multifrequency radio measurements using the Very Large Array, ALMA and e-MERLIN (<a href="https://ui.adsabs.harvard.edu/abs/2008AJ....135.1430H/abstract" rel="nofollow noreferrer">Harper et al. 2008</a>, <a href="https://ui.adsabs.harvard.edu/abs/2017AJ....154...11H/abstract" rel="nofollow noreferrer">Harper et al. 2017</a>) gives derived values of <span class="math-container">$197\pm45$</span> pc and <span class="math-container">$222^{+48}_{-34}$</span> pc, with the former barely consistent with the purely optical results (the latter value converts to 724 light-years). These groups note that the <em>Hipparcos</em> stochastic astrometric solution required the addition of so-called &quot;cosmic error&quot; or &quot;cosmic noise&quot; terms to individual position measurements.</p>
<p>The papers above note that the photocenter at both and optical radio wavelengths does <em>not</em> coincide with the barycenter, and may change on timescales of months to years. Therefore, extended, long-term observations would be necessary to reduce any photospheric &quot;jitter&quot; or other variations which could lead to variations in emission and thus astrometric fitting. Harper et al. 2017 proposed joint ALMA and <a href="https://science.nrao.edu/science/meetings/presentation/JVLAcapabilities-web.pdf" rel="nofollow noreferrer">Expanded VLA/Jansky VLA</a> observations and mm and sub-mm bands over a period several years, but also suggested that this would require &quot;a Herculean effort&quot; to achieve, for logistical reasons (how many telescope committees would be inclined to commit that much time up front?). Perhaps interest in Betelgeuse's recent luminosity dip could motivate this sort of observation.</p>
<hr />
<p><span class="math-container">$^{\dagger}$</span>Rob Jeffries makes the point that given the pretty terrible signal to noise ratios of many of these parallaxes (<em>Hipparcos</em> was in particular was bad, but none of the observations are amazing), it's not clear that you can really get good, meaningful uncertainties on the distance measurement from them via <span class="math-container">$d=1/p$</span>. I agree; it's safe to say that the jury is still out on those, and any source that claims a distance and an error should give make that quite clear.</p>

CC BY-SA 4.0
2020-07-02T15:35:09.807Z
@antispinwards Looks like I have some reading to do - thanks. Interesting to see MESA involved.
HDE 226868
CC BY-SA 4.0
2020-07-02T16:32:59.103Z
FYI That parallax measurement should not give the distance as shown. The reciprocal of a parallax with a SNR of only ~5 is subject to a significant bias and the uncertainties cannot be calculated in a simple way.
ProfRob
CC BY-SA 4.0
2020-07-02T20:02:09.373Z
Further, the revised Hipparcos catalogue gives a revised and more precise parallax.
ProfRob
CC BY-SA 4.0
2020-07-03T01:49:16.113Z
Thanks everyone!  Appreciate the information and clarification.  This question has been puzzling me to no ends lately.  I've based my calculations on the app's answer; but apparently I'm underestimating value.
ewokx
CC BY-SA 4.0
2020-07-03T07:33:24.837Z
@ewong especially so since the 2007 revision of the Hipparcos parallax (which should always be used in preference to the older value) is $6.56\pm 0.83$ mas.
ProfRob
CC BY-SA 4.0
2020-07-02T15:24:52.483Z
2020-07-03T14:28:43.203Z
2020-07-03T14:28:43.203Z
HDE 226868
<p>Reading [1], [2] and this smartphone app[3], I'm getting different answers to the question.</p>
<p>The smartphone app is stating 427ly. [1] states approx. 700 ly,  and [2] states approx. 724ly.</p>
<p>Even if I take [1] as the correct value, why does [2] state 724ly and the app stating 427ly?</p>
<p>Thanks</p>
<p>[1] - <a href="https://en.wikipedia.org/wiki/Betelgeuse" rel="noreferrer">https://en.wikipedia.org/wiki/Betelgeuse</a></p>
<p>[2] - <a href="https://earthsky.org/astronomy-essentials/how-far-is-betelgeuse" rel="noreferrer">https://earthsky.org/astronomy-essentials/how-far-is-betelgeuse</a></p>
<p>[3] - <a href="https://www.escapistgames.com/sc.html" rel="noreferrer">https://www.escapistgames.com/sc.html</a></p>

CC BY-SA 4.0
2020-07-02T12:17:50.937Z
Tip: Relying on wikipedia and smartphone apps is not the way to get reliable information.
ProfRob
CC BY-SA 4.0
2020-07-03T01:45:23.037Z
coincidentally and possibly misleadingly, 427 and 724 are anagrams of each other.
Michael
<betelgeuse>
What's the correct distance to Betelgeuse?
ewokx
# What's the correct distance to Betelgeuse?

(Asked by: username_0 on 2020-07-02)

Reading [1], [2] and this smartphone app[3], I'm getting different answers to the question.

The smartphone app is stating 427ly. [1] states approx. 700 ly, and [2] states approx. 724ly.

Even if I take [1] as the correct value, why does [2] state 724ly and the app stating 427ly?

Thanks

[1] - <https://en.wikipedia.org/wiki/Betelgeuse>

[2] - <https://earthsky.org/astronomy-essentials/how-far-is-betelgeuse>

[3] - <https://www.escapistgames.com/sc.html>

**Tags:** betelgeuse
> **Comments:**
> **username_1**: Tip: Relying on wikipedia and smartphone apps is not the way to get reliable information.  
> **username_2**: coincidentally and possibly misleadingly, 427 and 724 are anagrams of each other.  

---

## 3 answers

### Answer by username_5 on 2020-07-02. Score: 17 | Accepted answer

Distance measurements for Betelgeuse are a bit of a mess. Solutions based on parallax would be ideal, but Betelgeuse has a rather large angular diameter at most wavelengths thanks to its extended envelope; optical and infrared observations usually fall in the 40-60 mas range (see [Dolan et al. 2016](https://ui.adsabs.harvard.edu/abs/2016ApJ...819....7D/abstract) for a recent review), while radio observations show a disk of emission roughly twice that size ([O'Gorman et al. 2017](https://ui.adsabs.harvard.edu/abs/2017A%26A...602L..10O/abstract)). The parallax is expected to be much smaller that the angular diameter, on the order of ~5 mas, and so it depends strongly on the choice of the center of emission.

One of the first decent parallax results was obtained by the *Hipparcos* satellite in 1997, whose astrometric measurements allowed comparatively precise measurements of location, parallax and proper motion for over 100,000 stars. *Hipparcos* measured a parallax for Betelgeuse of $\pi=7.63\pm1.64$ mas, corresponding to a distance of $131\pm30$ pc$^{\dagger}$. This is that 427 light-year number the app cited. The *Hipparcos*-only result was subsequently improved upon significantly by [van Leeuwen 2007](https://ui.adsabs.harvard.edu/abs/2007ASSL..350.....V/abstract), who found $\pi=6.56\pm0.83$ mas, cutting the old uncertainty in half; this would correspond to a distance of 152 parsecs. If you're going to quote a *Hipparcos* result, this is the one to pick.

More recent results indicate that this value is likely too low. Combining *Hipparocs* data with multiple multifrequency radio measurements using the Very Large Array, ALMA and e-MERLIN ([Harper et al. 2008](https://ui.adsabs.harvard.edu/abs/2008AJ....135.1430H/abstract), [Harper et al. 2017](https://ui.adsabs.harvard.edu/abs/2017AJ....154...11H/abstract)) gives derived values of $197\pm45$ pc and $222^{+48}\_{-34}$ pc, with the former barely consistent with the purely optical results (the latter value converts to 724 light-years). These groups note that the *Hipparcos* stochastic astrometric solution required the addition of so-called "cosmic error" or "cosmic noise" terms to individual position measurements.

The papers above note that the photocenter at both and optical radio wavelengths does *not* coincide with the barycenter, and may change on timescales of months to years. Therefore, extended, long-term observations would be necessary to reduce any photospheric "jitter" or other variations which could lead to variations in emission and thus astrometric fitting. Harper et al. 2017 proposed joint ALMA and [Expanded VLA/Jansky VLA](https://science.nrao.edu/science/meetings/presentation/JVLAcapabilities-web.pdf) observations and mm and sub-mm bands over a period several years, but also suggested that this would require "a Herculean effort" to achieve, for logistical reasons (how many telescope committees would be inclined to commit that much time up front?). Perhaps interest in Betelgeuse's recent luminosity dip could motivate this sort of observation.

---

$^{\dagger}$Rob Jeffries makes the point that given the pretty terrible signal to noise ratios of many of these parallaxes (*Hipparcos* was in particular was bad, but none of the observations are amazing), it's not clear that you can really get good, meaningful uncertainties on the distance measurement from them via $d=1/p$. I agree; it's safe to say that the jury is still out on those, and any source that claims a distance and an error should give make that quite clear.

> **Comments:**
> **username_5**: @antispinwards Looks like I have some reading to do - thanks. Interesting to see MESA involved.  
> **username_1**: FYI That parallax measurement should not give the distance as shown. The reciprocal of a parallax with a SNR of only ~5 is subject to a significant bias and the uncertainties cannot be calculated in a simple way.  
> **username_1**: Further, the revised Hipparcos catalogue gives a revised and more precise parallax.  
> **username_0**: Thanks everyone!  Appreciate the information and clarification.  This question has been puzzling me to no ends lately.  I've based my calculations on the app's answer; but apparently I'm underestimating value.  
> **username_1**: @ewong especially so since the 2007 revision of the Hipparcos parallax (which should always be used in preference to the older value) is $6.56\pm 0.83$ mas.  

---

### Answer by username_3 on 2020-07-02. Score: 3

Current measurements give a distance "somewhere between 567 light years and 835 light years", with a "best guess" of 724 light years.

So wikipedia is being honest and saying "about 700". We really don't know any better.

Earthsky.org is giving the "best guess" value.

The app is probably using the distance measured by the Hippcaros space telescope. This value is generally considered to be an underestimate.

Another answer explains why we find it so hard to measure this distance: [What will it finally take to accurately measure the distance to Betelgeuse?](https://astronomy.stackexchange.com/q/36365/24157)

> **Comments:**
> **username_1**: Needs to give details and sources of information/quotes and how the distance was arrived at.  
> **username_1**: @antispinwards it doesn't give the distance as 131 pc though does it? You can't just invert a poorly determined parallax.  
> **username_1**: @antispinwards who determined it?  

---

### Answer by username_4 on 2020-07-02. Score: 2

Look at this article: <https://arxiv.org/abs/1706.06020>. Depends on studies distance varies and this is probably the reason of this discrepancy. For instance Hipparcos catalogue gives $131^{+35}\_{−23}$~pc, assuming pc=3.26ly it gives $\sim$427~ly. More details in attached article ;).

We are waiting for results from Gaia mission, because at first it made parallax of fainter stars and very bright, as Betelguse will come next, but I don't know when, maybe it was measured already, but I can't find any credible information. They wrote in <https://www.aanda.org/articles/aa/pdf/2016/11/aa29272-16.pdf>

"The 230 brightest stars in the sky (G < 3 mag, loosely referred
to as very bright stars) receive a special treatment to ensure
complete sky coverage at the bright end"

> **Comments:**
> **username_1**: The abstract of the paper you cite does not give a Hipparcos distance of 131 pc and the means by which your disance is obtained (I doubt it is in the Hpparcos catalogue) is highly dubious. You cannot just invert a noisy parallax to get the probable distance..I doubt that Gaia will make great strides forward on the distance to Betelgese because it is not the precision of the parallax that is the problem, it is its accuracy because of the inhomogeneous atmosphere of Betelgeuse..  
> **username_4**: Yes in abstact is different, newer value, but inside the paper they mention:  "The release of the original Hipparcos catalog (Perryman et al. 1997; ESA 1997) suggested that Betelgeuse had a distance of $131^{+35}_{−23}$~pc" and this one I cited. What do you mean by "inhomogeneous atmosphere"? That in different wavelength the thickness of atmosphere differs, or because of star pulsation ?  
> **username_4**: I have found sth which probably is your point:  "Instead of the star's atmosphere expanding uniformly due to gas heated to high temperatures near its surface, it now appears that several giant convection cells propel gas from the star's surface into its atmosphere". Therefore, because of inhomogeneity and fluctuation of its, we cannot really properly estimate distance with e.g. parallax method. Ok,, I got it :)  

---

