IPB

Welcome Guest ( Log In | Register )

2 Pages V  < 1 2  
Reply to this topicStart new topic
Transiting Exoplanet Survey Satellite
JRehling
post Jan 4 2019, 06:22 AM
Post #16


Senior Member
****

Group: Members
Posts: 2165
Joined: 20-April 05
Member No.: 321



There's a lot to pore over here! Just perusing casually, I see case 259962054 looks like a really interesting terrestrial planet candidate. As I see the numbers, it has an equilibrium temperate a bit cooler than Mars and a radius of 1.2 Earths – certainly within the realm of possibility of earthlike conditions.


Many months of reading Kepler data tables makes this a lot more explicit to me than it otherwise would be. They are presenting the data in Kepler-like formats, which is great, because that framework was very well thought out.

It's going to be great to get more of this data, a somewhat more condensed summary of the information, and more evaluation of the candidates.
Go to the top of the page
 
+Quote Post
JRehling
post Jan 5 2019, 04:27 PM
Post #17


Senior Member
****

Group: Members
Posts: 2165
Joined: 20-April 05
Member No.: 321



Having taken a bit more time to review the data release, with a mind towards locating the more earthlike candidates, I'll emphasize the following:

There are about 40 stars that have a planet candidate with a period of 8 or more days. I focused on these since shorter periods are very likely to be very hot, even for small M dwarfs.

TESS, for those who don't know, will look at most of the entire sky, but will look, in the primary mission, at most of the sky for only about one month, and can therefore only find, in those parts of the sky, planets with quite short periods. However, the observed segments overlap, and in the overlap, planets with longer periods can be found. This data release covers three observational periods, so the longest possible period offering three transits is about two months.

In this data, I found five planet candidates worthy of being called somewhat earthlike, including two in the same system. Of those, none really hits the Goldilocks area of parameter space "just right." We have some too big, some too hot, and some too cold, but given our lack of understanding of how planets evolve, I think these five are worth of mention. I'll list simply the star's TESS ID, magnitude, orbital period (days), planet radius (in Earths), and equilibrium temperature (K).

12421862 9.85 20.4 1.6 325
37749396 8.43 13.5 1.6 466
12421862 11.24 3.8 1.1 379
12421862 11.24 10.6 1.4 268
259962054 12.17 52.0 1.2 171

Important reference: The equilibrium temperatures of Venus, Earth, and Mars are 301, 255, and 207, respectfully. Only the fourth of those planets falls in that range. However, remember that these parameters have considerable uncertainty, and we have no good knowledge of what a climate might be for any of them.

The variable I'd most like to add, and can perhaps derive, is distance in light years, because these are all obviously quite close compared to any of the Kepler discoveries. Note that "magnitude" isn't a simple constant for each star, but depends upon the wavelengths to which a telescope responds.

To put this further in context, the TESS main mission will have 26 such observational periods, of which this data includes only 3, so we may naively expect a 9x increase in the results, but that both understates and overstates the matter in various ways. For the stars that TESS observational periods overlap, we will also explore outward, seeing longer periods, and that may turn up additional earthlike planets at greater distances from hotter stars. However, some candidates may prove not to be real.

Still, this gives us confidence that tens of generally earthlike planets will be found by TESS, and these are particularly exciting in terms of the potential for follow-up science. These, along with the handful of terrestrial planets already know to orbit nearby stars, will be the systems that JWST and the ELT will observe and maybe give us actual observed data for the planets' atmospheric composition and temperature. This is the start of a very interesting decade, and some of those planets on the list above may become very famous in the next few years.
Go to the top of the page
 
+Quote Post
antipode
post Jan 5 2019, 09:17 PM
Post #18


Member
***

Group: Members
Posts: 240
Joined: 1-October 06
Member No.: 1206



Very interesting taster of things tp come!

12421862 11.24 10.6 1.4 268 looks especially interesting.

Are we likely to see discovery papers soon on the arxiv, or will they wait til RV followup?

P
Go to the top of the page
 
+Quote Post
Hungry4info
post Jan 5 2019, 09:28 PM
Post #19


Senior Member
****

Group: Members
Posts: 1183
Joined: 26-July 08
Member No.: 4270



Depends on the system. All of these candidates can be found here. This site is regularly (assuming the U.S. government is not shut down) updated as TESS data rolls in. Others will work to confirm them with RV.

GJ 143 + HD 23472, https://arxiv.org/abs/1812.04501
Pi Men, https://arxiv.org/abs/1809.05967
LHS 3844, https://arxiv.org/abs/1809.07242
HD 2685, https://arxiv.org/abs/1811.05518
HD 202772, https://arxiv.org/abs/1810.02341
HD 1397, https://arxiv.org/abs/1811.01882
HD 219666, https://arxiv.org/abs/1812.05881

Altogether nine planets have been confirmed so far (two at HD 23472).

QUOTE ("JRehling")
12421862 9.85 20.4 1.6 325
37749396 8.43 13.5 1.6 466
12421862 11.24 3.8 1.1 379
12421862 11.24 10.6 1.4 268
259962054 12.17 52.0 1.2 171


Which correspond to GJ 7, GJ 1008, LHS 1140 (TIC 92226327) and 2MASS J02520450-6741155. Both planets at LHS 1140 have been discovered (and confirmed) prior to TESS.
LHS 1140 b https://arxiv.org/abs/1704.05556
LHS 1140 c https://arxiv.org/abs/1808.00485


--------------------
-- Hungry4info (Sirius_Alpha)
Go to the top of the page
 
+Quote Post
JRehling
post Jan 6 2019, 06:46 PM
Post #20


Senior Member
****

Group: Members
Posts: 2165
Joined: 20-April 05
Member No.: 321



That's a fantastic update (backdate!). How did you unify the TESS results with the existing discoveries? RA and Dec are given for each star, so you could do it that way. The number of nearby red dwarfs is not limitless, but I'd like to have a method to merge the data automatically if possible, as TESS data pours in.

The LHS 1140 system is about 40 light years away, the same as TRAPPIST-1, which, with ten planets between the two systems, will make ~40 light years an interesting distance threshold in discussions of nearby exoplanets.
Go to the top of the page
 
+Quote Post
Hungry4info
post Jan 6 2019, 07:01 PM
Post #21


Senior Member
****

Group: Members
Posts: 1183
Joined: 26-July 08
Member No.: 4270



QUOTE ("JRehling")
How did you unify the TESS results with the existing discoveries?

Just going through SIMBAD and searching each RA+Dec. If you want I can e-mail you an Excel document containing each TOI and their respective ID where known.


--------------------
-- Hungry4info (Sirius_Alpha)
Go to the top of the page
 
+Quote Post
Hungry4info
post Jan 8 2019, 01:56 AM
Post #22


Senior Member
****

Group: Members
Posts: 1183
Joined: 26-July 08
Member No.: 4270



And now TOI-197.01 (HIP 116158 / HD 221416) is confirmed.
https://arxiv.org/abs/1901.01643


--------------------
-- Hungry4info (Sirius_Alpha)
Go to the top of the page
 
+Quote Post
Hungry4info
post Jan 29 2019, 02:01 AM
Post #23


Senior Member
****

Group: Members
Posts: 1183
Joined: 26-July 08
Member No.: 4270



Five low-mass planet candidates orbiting TYC 8856-192-1 (TOI-125), two of which have been confirmed.
https://arxiv.org/abs/1901.09092


--------------------
-- Hungry4info (Sirius_Alpha)
Go to the top of the page
 
+Quote Post
Hungry4info
post Jan 30 2019, 11:20 AM
Post #24


Senior Member
****

Group: Members
Posts: 1183
Joined: 26-July 08
Member No.: 4270



An Eccentric Massive Jupiter Orbiting a Sub-Giant on a 9.5 Day Period Discovered in the Transiting Exoplanet Survey Satellite Full Frame Images
https://arxiv.org/abs/1901.09950

TOI-172 = TYC 6932-301-1


--------------------
-- Hungry4info (Sirius_Alpha)
Go to the top of the page
 
+Quote Post

2 Pages V  < 1 2
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 24th August 2019 - 08:28 PM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is a project of the Planetary Society and is funded by donations from visitors and members. Help keep this forum up and running by contributing here.