Author Topic: NASA - Transiting Exoplanet Survey Satellite ( TESS ) updates  (Read 72895 times)

Offline jebbo

  • Full Member
  • ****
  • Posts: 899
  • Cambridge, UK
  • Liked: 555
  • Likes Given: 304
And another one:

TESS Discovery of an ultra-short-period planet around the nearby M dwarf LHS 3844
Quote
Data from the newly-commissioned \textit{Transiting Exoplanet Survey Satellite} (TESS) has revealed a "hot Earth" around LHS 3844, an M dwarf located 15 pc away. The planet has a radius of 1.32±0.02 R⊕ and orbits the star every 11 hours. Although the existence of an atmosphere around such a strongly irradiated planet is questionable, the star is bright enough (I=11.9, K=9.1) for this possibility to be investigated with transit and occultation spectroscopy. The star's brightness and the planet's short period will also facilitate the measurement of the planet's mass through Doppler spectroscopy.

https://arxiv.org/abs/1809.07242

Edit: incidentally, there is an AO followup campaign in progress at Keck.

--- Tony
« Last Edit: 09/20/2018 06:34 am by jebbo »

Offline Star One

  • Senior Member
  • *****
  • Posts: 13344
  • UK
  • Liked: 3668
  • Likes Given: 220
Hot Earth, how many of them did we know about before?

Offline jebbo

  • Full Member
  • ****
  • Posts: 899
  • Cambridge, UK
  • Liked: 555
  • Likes Given: 304
Hot Earth, how many of them did we know about before?

Loads ... 614 in the "hot zone" in the 0.8Re - 1.5Re range.

Edit: good visualisation at the PHL
« Last Edit: 09/20/2018 08:35 am by jebbo »

Offline Star One

  • Senior Member
  • *****
  • Posts: 13344
  • UK
  • Liked: 3668
  • Likes Given: 220
Hot Earth, how many of them did we know about before?

Loads ... 614 in the "hot zone" in the 0.8Re - 1.5Re range.

Edit: good visualisation at the PHL

Thank you for that especially the link

Offline jebbo

  • Full Member
  • ****
  • Posts: 899
  • Cambridge, UK
  • Liked: 555
  • Likes Given: 304
From @NASA_TESS on Twitter:

Quote
A second @NASA_TESS candidate planet has been discovered! Slightly bigger than Earth, this planet orbits LHS 3844, a M dwarf star 49 light-years away, every 11 hours. This find is being reviewed by other scientists, and we're looking forward to studying this cool "hot Earth."

Original tweet

--- Tony

Offline ChrisGebhardt

  • Assistant Managing Editor
  • Global Moderator
  • Senior Member
  • *****
  • Posts: 7841
  • ad astra scientia
  • ~1 AU
  • Liked: 7869
  • Likes Given: 853
It's #EPSC2018 but yes, I was a bit surprised this came out with no associated media stuff :-)

This is a draft of a not-yet final paper and was not published with permission.  It's an embargo break, and not a good one either.

UPDATE on this.  The person who told me the paper was not published with permission was incorrect.

These are being published by the TESS team themselves so that ground telescopes can be used to quickly confirm the exoplanet candidates.

There was some initial confusion on that point as NASA is not used to operating on such quick turn-around of candidate planet info -- hence why the draft papers are hitting and becoming public hours before NASA tweets confirmation (as opposed to the usual method where NASA announces first or in conjunction with official paper publication).

Offline jebbo

  • Full Member
  • ****
  • Posts: 899
  • Cambridge, UK
  • Liked: 555
  • Likes Given: 304
These are being published by the TESS team themselves so that ground telescopes can be used to quickly confirm the exoplanet candidates.

Both papers use data from the beta test of their Alert system, which is all about speed. This also explains why there are publications from non-public data (all beta testers can see the data) even though there will be no proprietary period.

--- Tony
« Last Edit: 09/20/2018 03:59 pm by jebbo »

Offline deruch

  • Senior Member
  • *****
  • Posts: 2422
  • California
  • Liked: 2006
  • Likes Given: 5634
It's #EPSC2018 but yes, I was a bit surprised this came out with no associated media stuff :-)

This is a draft of a not-yet final paper and was not published with permission.  It's an embargo break, and not a good one either.

UPDATE on this.  The person who told me the paper was not published with permission was incorrect.

These are being published by the TESS team themselves so that ground telescopes can be used to quickly confirm the exoplanet candidates.

There was some initial confusion on that point as NASA is not used to operating on such quick turn-around of candidate planet info -- hence why the draft papers are hitting and becoming public hours before NASA tweets confirmation (as opposed to the usual method where NASA announces first or in conjunction with official paper publication).


That's good to know.  Thanks for the update.  Not terribly surprising that there was some confusion as the TESS pipeline is going to be so different from the Kepler one.

You should probably include an edit/correction in the initial post as well.
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Offline Chris Bergin

Support NSF via L2 -- Help improve NSF -- Site Rules/Feedback/Updates
**Not a L2 member? Whitelist this forum in your adblocker to support the site and ensure full functionality.**

Offline theinternetftw

  • Full Member
  • ****
  • Posts: 768
    • www.theinternetftw.com
  • Liked: 1928
  • Likes Given: 936
Chris Gebhardt's article (in the right thread):

https://www.nasaspaceflight.com/2018/09/tess-excellent-health-1st-two-exoplanet-first-orbit/

Quote from: the article
While it is not entirely clear what happened after launch, what is known is that the commissioning phase lasted 27 days longer than expected, stretching to the end of July.  TESS’ first science and observational campaign began not in June but on 25 July 2018.


From the end of Jeff Volosin's Mars Society talk:

Quote
Volosin: "Performance so far has been excellent. We had a little bit of a problem with our pointing stability. We've since resolved that, and so we're now able to stay pointed appropriately for our mission."

[...]

"We changed the way we dump momentum out of the wheels. We were only supposed to dump momentum once per orbit, but to keep the jitter down we're now doing it three times per orbit.

So that change in ops concepts, every time we dump momentum, we have to use thrusters. And that is the one consumable that we will run out of. We currently have 40kg of fuel onboard because we were so nicely put in our orbit, we didn't need to use a lot of fuel on our own. And so that 40kg of fuel, we use 10g of fuel to dump momentum. So if you calculate that out, we've got a good bit of a hundred years worth of fuel left. So yeah, we're good."

[...]

"So the goal was to get away from the reaction wheels that were used on Kepler, but our reaction wheels had their own problems that induced jitter that we didn't expect. So there is no perfect solution for pointing stability using reaction wheels."


Edit: added one last relevant quote from the talk that I'd missed.
« Last Edit: 09/21/2018 04:42 am by theinternetftw »

Offline mlindner

  • Software Engineer
  • Senior Member
  • *****
  • Posts: 2717
  • Space Capitalist
  • Silicon Valley, CA
  • Liked: 1866
  • Likes Given: 675
Orbital period is 13.7 days so 13.7 days/30 grams * 40,000 grams = ~18,300 days = 50 years

Offline theinternetftw

  • Full Member
  • ****
  • Posts: 768
    • www.theinternetftw.com
  • Liked: 1928
  • Likes Given: 936
Orbital period is 13.7 days so 13.7 days/30 grams * 40,000 grams = ~18,300 days = 50 years

Might be a combination of info that's mistakenly both pre and post jitter mitigation.  Whether the gram usage is an old value, or the years of fuel left is an old value, or it's something else entirely, I dunno.
« Last Edit: 09/21/2018 03:39 am by theinternetftw »

Offline theinternetftw

  • Full Member
  • ****
  • Posts: 768
    • www.theinternetftw.com
  • Liked: 1928
  • Likes Given: 936
Also an unrelated quote from that Volosin talk that I had to add.  This from a question about the consequences that flipping the survey space every year has on their long-dwell overlap area.

Quote
Remember for Kepler, they kind of relied on three transits to really prove that it was a planet. So even at the poles, we might only see one, maybe two of a period that's similar to our Earth.  And so what we're hoping is that in an extended mission we would end up spending more time on fields of view that had shown promise.

I knew that some of the extended mission plans were long-dwell, but I hadn't really caught that the mission team was hoping for those extended mission types in particular (there were others), or the fact that they would use the survey to find the best candidates for those dwell regions.

Offline jebbo

  • Full Member
  • ****
  • Posts: 899
  • Cambridge, UK
  • Liked: 555
  • Likes Given: 304
Confirmation of pi Mensae c:

TESS's first planet: a super-Earth transiting the naked-eye star π Mensae
Quote
We report on the confirmation and mass determination of Pi Men c, the first transiting planet discovered by NASA's TESS space mission. Pi Men is a naked-eye (V=5.65 mag), quiet G0 V star that was previously known to host a sub-stellar companion (Pi Men b) on a long-period (Porb=2091 days), eccentric (e=0.64) orbit. Using TESS time-series photometry, combined with GAIA data, published [email protected] Doppler measurements, and archival [email protected] radial velocities, we find that Pi Men c is an inner planet with an orbital period of Porb=6.25 days, a mass of Mp = 4.51 +/- 0.81 MEarth, and a radius of Rp = 1.828+/-0.053 REarth. Based on the planet's orbital period and size, Pi Men c is a super-Earth located at, or close to, the radius gap, while its mass and bulk density suggest it may have held on to a significant atmosphere. Because of the brightness of the host star, this system is highly suitable for a wide range of further studies to characterize the planetary atmosphere and dynamical properties. We also performed a seismic analysis of the TESS light curve and found a hint of an excess power at ~2600 micron-Hz with individual peaks spaced by ~120 micron-Hz. Though the signal-to-noise ratio is very low, this is consistent with the predicted frequency of oscillations for a star of this type, hinting at the asteroseismic potential of the TESS mission.

arxiv

Edit: oddly, no analysis of active pixel offsets; nor any difference imaging.

--- Tony
« Last Edit: 09/21/2018 06:20 am by jebbo »

Offline jebbo

  • Full Member
  • ****
  • Posts: 899
  • Cambridge, UK
  • Liked: 555
  • Likes Given: 304
TESS in the Solar System
Quote
The Transiting Exoplanet Survey Satellite (TESS), launched successfully on 18th of April, 2018, will observe nearly the full sky and will provide time-series imaging data in ~27-day-long campaigns. TESS is equipped with 4 cameras; each has a field-of-view of 24x24 degrees. During the first two years of the primary mission, one of these cameras, Camera #1, is going to observe fields centered at an ecliptic latitude of 18 degrees. While the ecliptic plane itself is not covered during the primary mission, the characteristic scale height of the main asteroid belt and Kuiper belt implies that a significant amount of small solar system bodies will cross the field-of-view of this camera. Based on the comparison of the expected amount of information of TESS and Kepler/K2, we can compute the cumulative etendues of the two optical setups. This comparison results in roughly comparable optical etendues, however the net etendue is significantly larger in the case of TESS since all of the imaging data provided by the 30-minute cadence frames are downlinked rather than the pre-selected stamps of Kepler/K2. In addition, many principles of the data acquisition and optical setup are clearly different, including the level of confusing background sources, full-frame integration and cadence, the field-of-view centroid with respect to the apparent position of the Sun, as well as the differences in the duration of the campaigns. As one would expect, TESS will yield time-series photometry and hence rotational properties for only brighter objects, but in terms of spatial and phase space coverage, this sample will be more homogeneous and more complete. Here we review the main analogues and differences between the Kepler/K2 mission and the TESS mission, focusing on scientific implications and possible yields related to our Solar System.
arxiv

--- Tony

Offline RotoSequence

  • Senior Member
  • *****
  • Posts: 2208
  • Liked: 2068
  • Likes Given: 1536
Edit: oddly, no analysis of active pixel offsets; nor any difference imaging.

--- Tony

Something interesting in their observations that they want to check and re-check before talking about?

Offline jebbo

  • Full Member
  • ****
  • Posts: 899
  • Cambridge, UK
  • Liked: 555
  • Likes Given: 304
Something interesting in their observations that they want to check and re-check before talking about?

Unlikely. APOs and difference images are used to identify false positives, so are a key part of the vetting process. More likely, the analysis is done as part of the default pipeline output and was clean. But I'd still expect a mention.

Edit: two other things occur to me. First, these are very bright stars, so some pixels might be saturated, which makes analysis much more difficult, if not impossible (need to think about this). Second, I don't think the alert data  includes the pixel data
« Last Edit: 09/22/2018 01:31 pm by jebbo »

Offline ncb1397

  • Senior Member
  • *****
  • Posts: 3497
  • Liked: 2307
  • Likes Given: 29
Exoplanet candidate list grows to 73...

Quote
Astronomers are waiting for independent confirmation from other telescopes, but a surfeit of new planets could be rolling in thanks to a candidate list 73 deep and counting
https://www.smithsonianmag.com/science-nature/tess-space-telescope-will-find-thousands-planets-astronomers-seek-select-few-180970411/

Offline jebbo

  • Full Member
  • ****
  • Posts: 899
  • Cambridge, UK
  • Liked: 555
  • Likes Given: 304
Light curves, Target Pixel Files and validation reports are now available for 44 planet candidates from the Sector 1 observations!

Data is here

--- Tony

Offline jebbo

  • Full Member
  • ****
  • Posts: 899
  • Cambridge, UK
  • Liked: 555
  • Likes Given: 304
Similarly, v07.02 of the CTL is now available at MAST.  Links on this page.

The release notes for this are here

--- Tony
« Last Edit: 10/05/2018 07:53 am by jebbo »

Tags: 1x9yfw ekh 626 
 

Advertisement NovaTech
Advertisement SkyTale Software GmbH
Advertisement Northrop Grumman
Advertisement
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
0