[HN Gopher] A 1.55 R[?] habitable-zone planet hosted by TOI-715
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A 1.55 R[?] habitable-zone planet hosted by TOI-715
Author : taubek
Score : 163 points
Date : 2024-02-03 15:21 UTC (7 hours ago)
(HTM) web link (academic.oup.com)
(TXT) w3m dump (academic.oup.com)
| FrustratedMonky wrote:
| Please, Please, Please, be it.
| swarnie wrote:
| Be what?
| 1024core wrote:
| Be have, as my daughter thinks I'm saying...
| optimalsolver wrote:
| Magrathea
| somenameforme wrote:
| No idea when NASA put this up [1] but it's awesome. It's the
| basic data on the system as well as some pretty nicely done
| visualizations including the ability overlay our solar system for
| scale. Quite interesting actually seeing what a dramatic
| difference the star type makes on habitable distances. This
| planet is _way_ closer to its star than Mercury is the Sun, for
| instance. They could do with a lot more advertising for stuff
| like this, and not quite so much for dronecopters.
|
| [1] - https://exoplanets.nasa.gov/exoplanet-
| catalog/8921/toi-715-b...
| mmastrac wrote:
| This was quite a bit more helpful than the paper itself,
| thanks.
| msk-lywenn wrote:
| 0.083 AU means that its sun would be huge in its sky? But it's
| also smaller so maybe not...
| p1mrx wrote:
| In general, a lower temperature star (3075 K versus the sun
| at 5778 K) will appear larger in the sky on a habitable
| planet.
| zamadatix wrote:
| I'm getting about 3x the angular diameter of the Sun from
| Earth, so not particularly huge.
| MichaelZuo wrote:
| Thanks, there's so many resources tucked away in obscure places
| that there's probably a dozen more cool things like this that
| never get noticed.
| throwup238 wrote:
| It looks quite a bit bigger than Earth.
|
| I don't think anyone will be leaving that atmosphere with
| chemical propulsion any time soon...
| callamdelaney wrote:
| Just because it's bigger doesn't mean that the gravity is
| higher.
| dr_kiszonka wrote:
| "Its mass is 3.02 Earths."
| joombaga wrote:
| Right, but you also have to account for density when
| calculating surface gravity.
|
| TOI-715 b has a log g value of 5.0 +/- 0.2. Earth is
| 2.992.
| efitz wrote:
| Correct, but it's mass (weight) is 3x higher than earth's,
| and since gravity is proportional to mass, you'd likely be
| much heavier there. If the radius of the planet was the
| same as earth's, the gravity would be 3x higher, but if
| it's bigger than earth, it might not be as bad. The formula
| is g= m/r^2 , where m is the mass of the planet and r is
| the radius of the planet.
| wkat4242 wrote:
| Damn I'm gonna have to get serious about that diet before
| visiting :'(
| ls612 wrote:
| r^2 is around 2.3 for the alleged size so it won't be too
| big a difference.
| samstave wrote:
| Yeah, but look at its period:
|
| >>> _ts mass is 3.02 Earths, it takes 19.3 days to complete
| one orbit of its star, and is 0.083 AU from its star. Its
| discovery was announced in 2023_
|
| https://i.imgur.com/ghLnFrH.png
|
| --
|
| What would gravity be on that thing, it doesnt say what its
| circadian rhythm is.. so how long is a day, if a "year" is
| 19 earth days (or is the period in 'day' local-solar-
| system-days?)
| zamadatix wrote:
| Orbital period is in Earth days. The same as when we say
| the orbital period of Venus is 225 days even though a
| Venetian day is longer than that.
|
| It'd be pretty messy to instead define things in the
| database in object relative terms, particularly when you
| usually know things like the orbital period with
| significantly more accuracy than rotational velocity.
| samstave wrote:
| Well yeah, Venus is in our solar system.
|
| Thanks, though - I wasn't sure if we always use a local
| reference but then au is as local a unit as possible at
| these scales.
| hleszek wrote:
| The gravity on the surface should be 3,02/(1,55^(2)) times
| the gravity on earth. It is equal to ~1.257 so it's about
| 25% higher.
| mmoskal wrote:
| I learned something today :)
|
| Gravity on surface of this planet will be 3(times heavier
| than earth)/(1.55(radius)^2), so 1.25g, however escape
| velocity also depends on planet radius so we get sqrt(1.55 *
| 1.25) = 1.4 earths escape velocity (so 15.7km/s). Assuming
| Isp specific impulse of engine of around 300s, let's compute
| m0/mf (initial mass of rocket / payload) = exp(vEsc/(Isp*g0))
| (g0=9.8m/s^2 (on both planets)):
|
| For earth, it's 45.
|
| For this planet, it's 208.
|
| So, the rocket (using our current chemical engine technology)
| needs 4.6 times more fuel than on earth. Much more difficult,
| but maybe possible...
|
| edit: formatting
| sgt101 wrote:
| I like dronecopters!
| dr_kiszonka wrote:
| The retro graphics here are gorgeous:
| https://exoplanets.nasa.gov/alien-worlds/exoplanet-travel-bu...
|
| (Stellar, one could say.)
| dylan604 wrote:
| I think they are out of this world myself.
|
| The guided tours are interesting. I've mentioned this before,
| but I am very jealous of this kind of content available for
| school kids. We had the slide shows with a tape recording
| with the unforgettable tone to signal to switch to the next
| slide. We had crappy VHS copies instead of the 8mm film
| projector, but I'm not sure it was an improvement. All of
| this interactive material is just so much more immersive.
| jonhohle wrote:
| When Costco still did printing we printed serval of those out
| as posters and hung them up in the kid's bathroom. The
| designs are pretty timeless and are fun to daydream about.
| s1artibartfast wrote:
| I dont know the intricacies of stellar physics, but my
| understand that smaller cooler stars are less stable. Despite
| an average temperature that is habitable, the variability and
| EM environment is not suitable for an atmosphere.
|
| Edit: 1) proximity also leads these planets to be tidally
| locked, which some argue is not conducive to habitability,
| though I don't find that especially compelling.
|
| 2) The local EM environment and solar flares would not preclude
| sub-surface habitability, but that is true for planets outside
| of what we consider the habitable zone as well. e.g. life on
| Europa has been hypothesized, but it is FAR outside the suns
| habitable zone.
| api wrote:
| At 138 light years any intelligence in this system would start
| potentially receiving our radio signals in the next two
| decades. They'd need a massive radio telescope to hear them
| though since at that distance even the strongest signals would
| be extremely weak.
| dylan604 wrote:
| NASA has provided some very compelling visualizations of data
| over the years. One of my favorites is the meteor showers
| showing where the debris fields for each one are located within
| the solar system. You can see the original orbit of the comet
| that left the debris, where it currently is, when the Earth's
| orbit crosses the debris field, and just the overall size of
| the debris so that you can see why some meteor showers are
| "better" than others.
|
| There's plenty of others where you can zoom in/out of the solar
| system to see the modeled view of the Oort cloud and get a
| sense of scale interactively of Sol's influence. There's also
| the interactive image viewers of Hubble and JWST data so we can
| see the differences between visible/IR spectrum. There are
| plenty of others as well. Oh, and the fact you can access so
| much of the raw data to make your own visualizations as you
| like.
|
| Overall, I think my tax dollars are performing nicely for my
| interests.
| zamadatix wrote:
| The tool has been around in some form since 2007ish, though the
| latest update was probably within the last decade. The age
| probably being why it's not so heavily advertised anymore
| compared to new activities.
|
| I've always been more partial to exoplanet.eu though:
| https://exoplanet.eu/catalog/toi_715_b--8668/. It's not quite
| as prettied up but it's usually more practical in presentation.
| delta_p_delta_x wrote:
| I personally prefer the Caltech Exoplanet Archive, which has
| downloadable datasets, APIs, and also presents everything in
| one shot: https://exoplanetarchive.ipac.caltech.edu/
| hypertexthero wrote:
| See also the Jet Propulsion Lab's gorgeous Visions of the
| Future posters:
|
| https://www.jpl.nasa.gov/galleries/visions-of-the-future
| mmastrac wrote:
| The domain-specific notation in this paper is inscrutable to me.
| I assume that this means a possible "Minshara class" planet (as
| Gene would say) around a star much different than our own, in
| that the distance from its sun and insolation received don't rule
| it out?
|
| EDIT: R[?] appears to be something related to Earth. Perhaps a
| planetary radius?
| somenameforme wrote:
| It's a planet that has 1.55 Earth's radius orbiting a much
| cooler star. Planets in the habitable zone are those that are
| at a distance from their star, such that they have the
| reasonable potential for liquid water to exist on the planet.
| dwaltrip wrote:
| "Earth radius (denoted as R or R_E) ..."
|
| https://en.wikipedia.org/wiki/Earth_radius
| nullhole wrote:
| [?] is the symbol for earth. R[?] is earth-radius, as you
| guessed.
|
| It is domain-specific, so it should probably be changed in the
| title.
|
| I will say that it is a very nice symbol - easy to write out by
| hand, makes for quick note-taking. Same for the symbol used for
| the sun (which isn't rendering for me, but is a circle with a
| dot in the middle).
|
| https://en.wikipedia.org/wiki/Planet_symbols
| chrsw wrote:
| "The domain-specific notation in this paper is inscrutable to
| me."
|
| That's almost every paper to me.
| k__ wrote:
| I always thought it to be funny if we would get faster than light
| travel in the future and other civilizations are just seeing
| dinosaurs roaming the earth the moment we visit them.
| 1024core wrote:
| That would be if they were 70M LY away from us. In order to see
| dinosaurs from that distance, they would need a telescope wider
| than our solar system.
| malfist wrote:
| If you can make a dyson sphere, a solar system sized
| telescope doesn't seem out of the question.
| bemmu wrote:
| Yes, once we're commanding autonomous little bots in space,
| capable of also autonomously creating their own factories,
| we can build anything on a whim as long as we can design it
| and have the energy and materials.
|
| (I may have played too much Factorio)
| Baeocystin wrote:
| All I want is logibots IRL, is that too much to ask
| awb wrote:
| Harvesting that much material might be a challenge.
|
| I guess you'd also have to build it in interstellar space
| to avoid planets and asteroids.
| Projectiboga wrote:
| The Milkyway is 'only' 100 to 150,000 light years across, in
| total.
| redcobra762 wrote:
| According to our current understanding of telescopes, but if
| FTL is possible, then perhaps we missed something.
| poisonborz wrote:
| If FTL is possible, we didn't just missed something, but
| can throw all of our physics books on fire.
| calamari4065 wrote:
| I think at that point, you'd go find a really big black hole
| to use as a lens instead
| lgkk wrote:
| What would even be the point of existence anymore once FTL is
| figured out? Just curious.
|
| Seems like it would just remove any grandeur about the universe
| entirely.
| MattGaiser wrote:
| It wouldn't go away. It would just mean we could go see it.
| api wrote:
| Does the fact that you can drive to a national park make it
| stop being beautiful?
| FrustratedMonky wrote:
| "point of existence"
|
| To go see it.
|
| Why would the ability to visit other planets, and see them,
| suddenly negate the point of existence, since we can then go
| see it.
|
| Like there is only a point if things can only be imagined,
| and not actually seen.
|
| That would be like. "now that cars exists, and we can visit
| the Grand Canyon, suddenly there is no point of existence".
| AlexAndScripts wrote:
| Remove any grandeur? On the contrary, it would be the
| beginning of a new era of appreciating its grandeur.
| calamari4065 wrote:
| The universe is infinite. FTL just makes it slightly less
| infinite.
|
| FTL means we actually get to _see_ the grandeur of the
| universe instead of hypothesizing mathematical models of it.
| Without FTL, we 'll never leave this star system. The
| grandeur of the universe will be nothing but our imagination,
| instead of a real thing you can see with your own eyes.
| jonhohle wrote:
| I was explaining to my kids yesterday that it took 33 years
| for Voyager to leave the solar system, the next closes star
| is 2,000x further than it's already travelled. That would
| require infrastructure to support 100 generations of
| humans, 99 of which would be indentured by their ancestors
| to a life stuck inside a space-ark. And it would only
| require one of those generations to fail for the whole
| endeavor to fail. And there's nothing there, it would take
| another 50 generations to get to what is hypothesized to be
| a habitable planet.
|
| Human existence doesn't scale to inter-star system travel.
| seattle_spring wrote:
| I see someone's read Project Hail Mary
| nrb wrote:
| How big of a lunatic would our great-great-great
| grandparents have considered us for telling them that
| soon the several-month trip across the USA will pretty
| soon take an afternoon, and going to the moon will take 3
| days?
|
| Sure, traveling at Voyager's (impressive, but essentially
| wagon) speed won't get it done. But betting against
| technological advancement has made fools of a vast many.
| calamari4065 wrote:
| Generally it's taken for granted that the technological
| problems with generation ships can be solved with
| sufficient time and resources. We can probably build a
| metal box that lasts for a thousand years. We can
| probably design a sustainable closed ecosystem. We could
| probably build fusion reactors that run on interstellar
| hydrogen collected with ramscoops.
|
| But the real problem with generation ships is not
| technological. Technology can't solve the fundamental
| social and psychological problems of locking some humans
| in a box for a hundred generations. That's the most
| important problem, and the one that's usually waved away
| with "oh you just can't imagine future technology"
| rglullis wrote:
| 0.0 eccentricity means that it has no seasonal variation?
| mitthrowaway2 wrote:
| It means its orbit is a circle. Seasonal variation is due to
| the tilt of the planet's axis of rotation relative to its
| orbit, not orbital eccentricity.
| rglullis wrote:
| I know what causes seasonal variations, but for some reason I
| thought 0.0 eccentricity meant no tilt. Thanks
| wkat4242 wrote:
| Well on _our_ planet that 's the case. Another planet might
| well have seasons due to orbital eccentricity. Though it
| would have to be pretty serious eccentricity I think.
|
| If they would have no tilt then the seasons would be the same
| all over the planet unlike ours where they're opposite in
| each hemisphere.
| MadnessASAP wrote:
| It means the orbit is perfectly circular. Earth's seasons are
| driven almost exclusively by our axial tilt*, not our orbital
| eccentricity. Our eccentricity also being 0.0(167).
|
| * Astrometeorologists feel free to correct me on this.
| fbdab103 wrote:
| Wikipedia says this The relative increase in
| solar irradiation at closest approach to the Sun (perihelion)
| compared to the irradiation at the furthest distance
| (aphelion) is slightly larger than four times the
| eccentricity. For Earth's current orbital eccentricity,
| incoming solar radiation varies by about 6.8%, while the
| distance from the Sun currently varies by only 3.4% (5.1
| million km or 3.2 million mi or 0.034 au).[9]
| Perihelion presently occurs around 3 January, while aphelion
| is around 4 July. When the orbit is at its most eccentric,
| the amount of solar radiation at perihelion will be about 23%
| more than at aphelion. However, the Earth's eccentricity is
| so small (at least at present) that the variation in solar
| irradiation is a minor factor in seasonal climate variation,
| compared to axial tilt and even compared to the relative ease
| of heating the larger land masses of the northern
| hemisphere.[10]
|
| https://en.wikipedia.org/wiki/Milankovitch_cycles
| at_a_remove wrote:
| So, surface gravity about twenty-five percent higher than that of
| Earth. We're looking at Antares-level of redness for color.
| Occupies a large portion of the sky. Good candidate for tidal
| lock, at which point a lot of the habitability issues become
| debatable.
| Projectiboga wrote:
| I read somewhere, slightly higher than Earth gravity would
| actually be better for life. So on that metric this is
| interesting. Magnetic field is likely another need and our
| single large moon helps a lot here too.
| at_a_remove wrote:
| I kind of despise these press releases because they almost
| never attempt to show anything other than what other
| astronomers might care about.
|
| Surface gravity? I just computed that. Color temp? Had to
| check the ole memory banks.
|
| They should be doing stuff like computing how much of the sky
| this sun occupies, so you could get a sense of it, with the
| color. Is it tidally locked? Or at least does it fit the
| criteria?
|
| The distance, eccentricity (which here leaves the distance a
| constant), and temperature of the associated star could be
| used to give some kind of insolation number, and from there a
| very casual steady-state blackbody temperature of the planet,
| which is a _start_ and is better than nothing. At that point
| you can start looking up what gases would stay and which
| would go as kind of a maximum before you started thinking
| about stellar winds and the like.
| qayxc wrote:
| They don't know the mass of the planet yet, so surface gravity
| is an unknown as of yet. The paper suggests two scenarios: a
| rocky world (~7 earth masses) or a water world (~2 earth
| masses).
|
| Surface gravity would be 38m/s2 for a rocky planet (~390%
| earth's surface gravity) and 8.2m/s2 for a water world (~84%
| earth's surface gravity). I'm not an astronomer so I don't know
| if anything in between those values is a realistic scenario,
| but I wonder how you got your 125% of earth's surface gravity.
| at_a_remove wrote:
| Another poster had something else from NASA, suggesting 1.55
| Earth radii and 3.02 Earth masses.
| anticensor wrote:
| In such a planet, THE LINE becomes a necessity rather than far-
| fetched idea.
| lukan wrote:
| "Good candidate for tidal lock, at which point a lot of the
| habitability issues become debatable."
|
| A tidal locked planet might still allow life in the twilight
| zones.
|
| But since this one is orbiting close to a flare star, life
| might have other problems there
| chrsw wrote:
| It doesn't seem like it would take much to make Earth inhabitable
| for us humans. Like if we wanted to we can do it pretty quickly
| using primitive methods. It's a very delicate system and we're
| completely reliant on it.
|
| So it is a stretch for me to think there are even a few planets
| in the galaxy that could host human life as we know it.
| Denvercoder9 wrote:
| > Like if we wanted to we can do it pretty quickly using
| primitive methods.
|
| It seems that even if we don't want it, we can't help but do it
| anyway.
| rurban wrote:
| 46 parsec is nearby to them? Well, it's relative obviously. That
| means many, many generations away.
| qayxc wrote:
| What's 1500 years (at 0.1c) between friends?
| dvh wrote:
| Over and over and over again planets are reported in habitable
| zones around flare stars just because they are easy to detect,
| not because they are actually habitable.
| qayxc wrote:
| True. It's tiresome that a technical definition is so often
| misinterpreted as actual habitability. The authors are also
| overly optimistic when they point out that the M4 class host
| star is relatively calm due to its age. That fact wouldn't
| matter much, though, if the first billion years of the star's
| existence have sterilized the planet and stripped off its
| atmosphere...
| samstave wrote:
| Maybe just come up with a better/different label for planets
| who share a similar ratio of planet-to-star characteristics
| with Earth, which is a sample size of
| known_to_support_life=1.
|
| "Orbital Cousins to Earth" OCEs. Find the # of OCEs, and
| maybe we have finer granulation, Second Cousins have an
| atmosphere, Step-sisters have water and an OnlyPlanets
| account... (which seems to be making the rounds at Nasa)
| weard_beard wrote:
| https://youtu.be/ErpU_tMoV0E
| davedx wrote:
| The entire notion of a 'habitable zone' is also very over-
| simplistic.
|
| Europa is quite probably 'habitable'.
| 7373737373 wrote:
| I wish habitability metrics would be more holistic, taking
| into account the star and orbit characteristics, how
| sun+earthlike they really are
| moralestapia wrote:
| >just because they are easy to detect
|
| Well, for some threshold of "easy" I guess.
| makeworld wrote:
| What is notable about this specific exoplanet?
| yellow_lead wrote:
| Maybe this
|
| > Should this second planet be confirmed, it would represent
| the smallest habitable zone planet discovered by TESS to date.
| aendruk wrote:
| Novelty
| credit_guy wrote:
| It is 42.46 parsecs away, or about 140 light years. If the
| Founding Fathers had beamed to those guys the Declaration of
| Independence, we'd get their congratulations in about 30 years
| from now. Hopefully. Maybe they decide to side with the King, and
| they'll send an invasion force to help general Cornwallis.
| xyst wrote:
| This is an interesting read but I can't help to wonder...
|
| We can hardly take care of this planet. Why are we bothering with
| finding another planet that is habitable if we are only going to
| destroy it as well?
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