<p>Yes, apart from WASP-69b, there has been reports of other exoplanets emitting some form of planetary tails. Let's start from the <a href="https://en.wikipedia.org/wiki/Exoplanet" rel="nofollow noreferrer">Wikipedia</a>:</p>
<blockquote>
<p><strong>KIC 12557548 b</strong> is a small rocky planet, very close to its star, that is evaporating and leaving a trailing tail of cloud and dust like a comet. The dust could be ash erupting from volcanos and escaping due to the small planet's low surface-gravity, or it could be from metals that are vaporized by the high temperatures of being so close to the star with the metal vapor then condensing into dust.</p>
<p>In June 2015, scientists reported that the atmosphere of <strong>GJ 436 b</strong> was
evaporating, resulting in a giant cloud around the planet and, due to
radiation from the host star, a long trailing tail 14 million km (9
million mi) long.</p>
</blockquote>
<hr />
<p>More on the dust particles that is trailing from the exoplanets KIC 12557548 b as well as <strong>KOI-2700b</strong>:</p>
<blockquote>
<p>The observed tail lengths are consistent with dust grains composed of
corundum (Al<sub>2</sub>O<sub>3</sub>) or iron-rich silicate minerals (e.g., fayalite,
Fe<sub>2</sub>SiO<sub>4</sub>). Pure iron and carbonaceous compositions are not favored. In
addition, we estimate dust mass loss rates of 1.7 ± 0.5 M⊕ Gyr<sup>-1</sup> for
KIC 12557548b, and &gt; 0.007 M⊕ Gyr<sup>-1</sup> (1σ lower limit) for KOI-2700b.</p>
<p><sub><strong>Source</strong>: Dusty tails of evaporating exoplanets, I. Constraints on the dust composition, R. van Lieshout1, M. Min and C. Dominik, A&amp;A, Volume 572, December 2014, DOI: <a href="https://www.aanda.org/articles/aa/full_html/2014/12/aa24876-14/aa24876-14.html" rel="nofollow noreferrer">10.1051/0004-6361/201424876</a></sub></p>
</blockquote>
<hr />
<blockquote>
<p>Astronomers using NASA's Hubble Space Telescope have confirmed the
existence of a baked object that could be called a &quot;cometary planet.&quot;
The gas giant planet, named <strong>HD 209458b</strong>, is orbiting so close to
its star that its heated atmosphere is escaping into space.</p>
<p><sub><strong>Source</strong>: <a href="https://www.nasa.gov/mission_pages/hubble/science/planet-tail.html" rel="nofollow noreferrer">https://www.nasa.gov/mission_pages/hubble/science/planet-tail.html</a></sub></p>
</blockquote>
<hr />
<blockquote>
<p>Astronomers have confirmed that the planet <strong>Gliese 436b</strong> seems to be
trailing a gigantic, comet-like cloud of hydrogen.</p>
<p><a href="https://i.sstatic.net/YBUBH.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/YBUBH.jpg" alt="enter image description here" /></a></p>
<p><sub><strong>Source</strong>: <a href="https://skyandtelescope.org/astronomy-news/exoplanet-with-a-comet-tail-06302015234/" rel="nofollow noreferrer">https://skyandtelescope.org/astronomy-news/exoplanet-with-a-comet-tail-06302015234/</a></sub></p>
</blockquote>
<hr />
<blockquote>
<p>Disintegrating planets allow for the unique opportunity to study the
composition of the interiors of small, hot, rocky exoplanets because
the interior is evaporating and that material is condensing into dust,
which is being blown away and then transiting the star. Their transit
signal is dominated by dusty effluents forming a comet-like tail
trailing the host planet <strong>K2-22b</strong>, making these good candidates for
transmission spectroscopy.</p>
<p><sub><strong>Source</strong>: Eva H. L. Bodman et al 2018 AJ 156 173, DOI: <a href="https://iopscience.iop.org/article/10.3847/1538-3881/aadc60" rel="nofollow noreferrer">10.3847/1538-3881/aadc60</a></sub></p>
</blockquote>

CC BY-SA 4.0
2021-05-11T04:46:37.953Z
2021-05-11T04:46:37.953Z
Nilay Ghosh
<p>Just recently I learned that <a href="https://www.sciencealert.com/the-tail-of-mercury" rel="nofollow noreferrer">Mercury has a sodium tail</a> and it is actually <a href="https://www.nasa.gov/mission_pages/messenger/media/seven-things.html" rel="nofollow noreferrer">well studied since long</a>:</p>
<blockquote>
<p>As a result, the planet has the appearance of a comet, with a tail that's been observed streaming nearly 3.5 million kilometres away from the planet.</p>
</blockquote>
<p>This made me wonder about exoplanets with tails, like <a href="https://earthsky.org/space/jupiter-sized-exoplanet-wasp-69b-comet-like-tail" rel="nofollow noreferrer">WASP-69b</a>. How many (exo)planets are known to have a tail?</p>
<h3>References</h3>
<ul>
<li><a href="https://astronomy.stackexchange.com/questions/39774/why-would-a-planet-form-a-cometlike-tail-under-conditions-of-weaker-rather-than">Why would a planet form a cometlike tail under conditions of weaker rather than stronger solar wind?</a></li>
</ul>

CC BY-SA 4.0
2021-05-14T01:31:19.360Z
other tail questions: [How can Mercury's sodium tail be imaged?](https://astronomy.stackexchange.com/q/39094/7982) and [Why is sodium such a common ion for in ion tails?](https://astronomy.stackexchange.com/q/6266/7982) Do you think that just `tail` is the best and clearest name for a tag for planetary tails? I wonder if it should be "planetary-tail"since questions about cometary tails are more complex in nature, much more numerous and *already covered* by `comets`?
uhoh
<exoplanet><mercury>
Planetary tails: How many have we observed yet?
B--rian
# Planetary tails: How many have we observed yet?

(Asked by: username_0 on 2021-05-10)

Just recently I learned that [Mercury has a sodium tail](https://www.sciencealert.com/the-tail-of-mercury) and it is actually [well studied since long](https://www.nasa.gov/mission_pages/messenger/media/seven-things.html):

> As a result, the planet has the appearance of a comet, with a tail that's been observed streaming nearly 3.5 million kilometres away from the planet.

This made me wonder about exoplanets with tails, like [WASP-69b](https://earthsky.org/space/jupiter-sized-exoplanet-wasp-69b-comet-like-tail). How many (exo)planets are known to have a tail?

### References

* [Why would a planet form a cometlike tail under conditions of weaker rather than stronger solar wind?](https://astronomy.stackexchange.com/questions/39774/why-would-a-planet-form-a-cometlike-tail-under-conditions-of-weaker-rather-than)

**Tags:** exoplanet, mercury
> **Comments:**
> **username_1**: other tail questions: [How can Mercury's sodium tail be imaged?](https://astronomy.stackexchange.com/q/39094/7982) and [Why is sodium such a common ion for in ion tails?](https://astronomy.stackexchange.com/q/6266/7982) Do you think that just `tail` is the best and clearest name for a tag for planetary tails? I wonder if it should be "planetary-tail"since questions about cometary tails are more complex in nature, much more numerous and *already covered* by `comets`?  

---

## 1 answers

### Answer by username_2 on 2021-05-11. Score: 3 | Accepted answer

Yes, apart from WASP-69b, there has been reports of other exoplanets emitting some form of planetary tails. Let's start from the [Wikipedia](https://en.wikipedia.org/wiki/Exoplanet):

> **KIC 12557548 b** is a small rocky planet, very close to its star, that is evaporating and leaving a trailing tail of cloud and dust like a comet. The dust could be ash erupting from volcanos and escaping due to the small planet's low surface-gravity, or it could be from metals that are vaporized by the high temperatures of being so close to the star with the metal vapor then condensing into dust.
>
> In June 2015, scientists reported that the atmosphere of **GJ 436 b** was
> evaporating, resulting in a giant cloud around the planet and, due to
> radiation from the host star, a long trailing tail 14 million km (9
> million mi) long.

---

More on the dust particles that is trailing from the exoplanets KIC 12557548 b as well as **KOI-2700b**:

> The observed tail lengths are consistent with dust grains composed of
> corundum (Al2O3) or iron-rich silicate minerals (e.g., fayalite,
> Fe2SiO4). Pure iron and carbonaceous compositions are not favored. In
> addition, we estimate dust mass loss rates of 1.7 ± 0.5 M⊕ Gyr-1 for
> KIC 12557548b, and > 0.007 M⊕ Gyr-1 (1σ lower limit) for KOI-2700b.
>
> **Source**: Dusty tails of evaporating exoplanets, I. Constraints on the dust composition, R. van Lieshout1, M. Min and C. Dominik, A&A, Volume 572, December 2014, DOI: [10.1051/0004-6361/201424876](https://www.aanda.org/articles/aa/full_html/2014/12/aa24876-14/aa24876-14.html)

---

> Astronomers using NASA's Hubble Space Telescope have confirmed the
> existence of a baked object that could be called a "cometary planet."
> The gas giant planet, named **HD 209458b**, is orbiting so close to
> its star that its heated atmosphere is escaping into space.
>
> **Source**: <https://www.nasa.gov/mission_pages/hubble/science/planet-tail.html>

---

> Astronomers have confirmed that the planet **Gliese 436b** seems to be
> trailing a gigantic, comet-like cloud of hydrogen.
>
> [![enter image description here](https://i.sstatic.net/YBUBH.jpg)](https://i.sstatic.net/YBUBH.jpg)
>
> **Source**: <https://skyandtelescope.org/astronomy-news/exoplanet-with-a-comet-tail-06302015234/>

---

> Disintegrating planets allow for the unique opportunity to study the
> composition of the interiors of small, hot, rocky exoplanets because
> the interior is evaporating and that material is condensing into dust,
> which is being blown away and then transiting the star. Their transit
> signal is dominated by dusty effluents forming a comet-like tail
> trailing the host planet **K2-22b**, making these good candidates for
> transmission spectroscopy.
>
> **Source**: Eva H. L. Bodman et al 2018 AJ 156 173, DOI: [10.3847/1538-3881/aadc60](https://iopscience.iop.org/article/10.3847/1538-3881/aadc60)


---

