Habitable Worlds Observatory

[Spaceception]

I thought this might be an interesting discussion. Last year, almost exactly a year ago today (Jan 15th, today's the 17th) there was a release for possible targets of the HWO, an upcoming flagship telescope based on previous proposals for LUVOIR/HabEx looking to survey and categorize Earth-like planets in the habitable zone.

According to NASA's page for it (https://science.nasa.gov/astrophysics/programs/habitable-worlds-observatory/) they're looking to survey at least 25 different exoplanets, and to search for biosigniatures on them. 

After a bit of searching, I found their prospective list of targets to study, and you can read the paper here https://exoplanets.nasa.gov/internal_resources/2645_NASA_ExEP_Target_List_HWO_Documentation_2023.pdf, the list of stars (Table A) begins on page 25.

Their list included stars within 25 pc (~81 light years), and are largely sunlike (K, G, and F) with only 3 M type stars. They did consider A type stars, but the separation of the planet and star were found to be too large, so the planet-star brightness ratios and planet magnitudes would be too low.

Notably, none of the stars on the list include systems currently on PHL's list for known potentially habitable worlds https://phl.upr.edu/hwc, with the former exception of Tau Ceti (which was removed years ago from the list as none of its planets are confirmed). This is likely because nearly all of those planets known within 25 pc orbit small M type stars, and while 3 are candidates in this list, they're also among the largest and brightest known.

Some nearbly systems they're considering within 20 light years include;

Alpha Centauri A/B (Rigil Kentaurus/Toliman)

Tau Ceti

Epsilon Indi

40 Eridani (Keid)

Lalande 21185

61 Cygni A/B, and others.

Future telescopes that may look for exoplanets around these systems could help narrow down the list for the HWO to survey, as there are quite a few coming online before HWO's NET launch date of the late 2030s/early 2040s, like ELT, and PLATO/ARIEL (the former is aiming to image Earth-like planets, and the latter 2 are specifically for studying Earth-like worlds and atmospheres). Or otherwise could simply broaden our knowledge of potentially habitable worlds as HWO could study systems to discover what other telescopes can't.

Edited January 18 by Spaceception
Formatting, spelling, fixed the links

[JoeSchmuckatelli]

On 1/17/2024 at 5:27 PM, Spaceception said:

Some nearbly systems they're considering

I'm glad to see 18 Sco still on the list.  Years ago, Margaret Turnbull put it on a shortlist of sunlike stars  to look at.  In the time I've been watching for information on it - it has moved down quite a bit on the priority list... (Still Tier 'A')

Interestingly, it does have a candidate 'super earth' (albeit one that must be BLAZINGLY hot, if true.

in 2023 evidence of a different candidate planet was found, which would be of super-Earth mass with a period of 19.9 days

(Wikipedia)

Edited January 22 by JoeSchmuckatelli