Nearby Star Has 7 Earth-Sized Worlds

NASA to Host News Conference on Discovery Beyond Our Solar System

"NASA will hold a news conference at 1 p.m. EST Wednesday, Feb. 22, to present new findings on planets that orbit stars other than our sun, known as exoplanets. The event will air live on NASA Television and the agency's website. Details of these findings are embargoed by the journal Nature until 1 p.m."

Keith's update: I have now learned that tomorrow's NASA news announcement is not about Alpha Centauri as I had been guessing (darn) but it is is something even more cool - or "warm" to be precise. Instead, the NASA announcement on Wednesday will be about a nearby star that has at least 7 Earth-sized planets.

The individuals attending this press event at NASA have been looking for planets circling other stars. Last year one of the participants, Michael Gillon, was lead author on a paper "Temperate Earth-sized planets transiting a nearby ultracool dwarf star" in Nature detailing how his team had confirmed 3 small terrestrial (Earth-sized) planets circulating a cool dwarf star 2MASS J23062928-0502285 (now known as TRAPPIST-1), a M8V class star which is only 39.5 light years away.

It will be announced tomorrow by NASA that Gillon et al have confirmed 4 more Earth-sized planets circling TRAPPIST-1. It is possible that most of the planets confirmed thus circling far TRAPPIST-1 could be in the star's habitable zone. The inner 6 planets are probably rocky in composition and may be just the right temperature for liquid water to exist (between 0 - 100 degrees C) - if they have any water, that is. The outermost 7th planet still needs some more observations to nail down its orbit and composition.

Astronomers are clearly excited about these planets (see below). The article will appear in Nature magazine, as noted by NASA in its media advisory.

But - and this is important for all you UK tabloid writers - NO ONE HAS DISCOVERED LIFE ON ANOTHER PLANET. Got that?

Important note: No one sent us anything in advance about the details of this specific announcement or paper under embargo - or any other pre-announcement arrangement. No scientific paper - nothing. We honor embargoes - when we are under them. I saw what NASA had posted yesterday to tease people (including participant names and a topic) and went to work - hence my earlier Alpha Centauri sleuthing which strongly overlapped with TRAPPIST-1 discoveries. I eventually figured it out and sourced it - all by myself - using openly available preprints, observation proposals and results, email, and phone calls folks. I am leaving my earlier Alpha Centauri speculation up for all to see (below).

UV exploration of two Earth-sized planets with temperate atmospheres, Hubble Space Telescope Observing Program 14493

"Here we will observe the star with STIS at Ly-alpha to 1) try and measure the stellar line, and 2) search for signatures of hydrogen escape from the planets, which would hint at evaporating water oceans. Because several orbits remain possible for the third discovered planet, we will ensure the best scientific by focusing on the two inner ones."

14873 - Exploratory observations of the TRAPPIST-1 system: essential prelude to an immediate JWST follow-up

"Owing to over 1500 hours of monitoring including a recent 20-d long follow-up with the Spitzer Space Telescope, we have now constrained the architecture of TRAPPIST-1's system up to its ice line. There is no doubt left regarding the system uniqueness for Earth-sized comparative planetology and for the search for extrasolar habitats."

14900 - Confirming the Presence of an Hydrogen Exosphere around the Earth-sized Temperate Planet TRAPPIST-1c

"We request here 5 consecutive HST/STIS orbits to build upon our UV exploratory program and confirm the presence of an extended exosphere exosphere around TRAPPIST-1~c. These observations will inform us on its volatile reservoir while complementing the insights gained with HST/WFC3 (GOs 14500 and 14873). Our request for immediate HST/STIS followup will fulfill the urgent need to inform the community about TRAPPIST-1 planets in order to guide their follow-up, notably in the context of the upcoming JWST Cycle 1 proposal."

EARLIER SPECULATION

Keith's note: Once again NASA is teasing us with some sort of important news about something. Of course the tabloids will immediately parse words, see words that NASA never used, and imagine that life has been found on other planets. Apparently Spitzer has something to do with this and there are some planets involved in this too. So I did a quick search for articles by the participants in this event as they relate to Spitzer. They are interested in finding extrasolar planets like Earth.

- The Spitzer search for the transits of HARPS low-mass planets - II. Null results for 19 planets (Sara Seager, Michael Gillon)
- Illusion and Reality in the Atmospheres of Exoplanets (Sara Seager)
- Toward a Galactic Distribution of Planets. I. Methodology & Planet Sensitivities of the 2015 High-Cadence Spitzer Microlens Sample (Sean Carey)
- A combined transmission spectrum of the Earth-sized exoplanets TRAPPIST-1 b and c (Michael Gillon, Nikole Lewis)
- Temperate Earth-sized planets transiting a nearby ultracool dwarf star (Michael Gillon)

But then there is this interesting paper with press conference participants Sara Seager and Michael Gillon among the authors from 2015 "Hubble Space Telescope search for the transit of the Earth-mass exoplanet Alpha Centauri Bb" that says "We observed Alpha Centauri B twice in 2013 and 2014 for a total of 40 hours. We achieve a precision of 115 ppm per 6-s exposure time in a highly-saturated regime, which is found to be consistent across HST orbits. We rule out the transiting nature of Alpha Centauri Bb with the orbital parameters published in the literature at 96.6% confidence. We find in our data a single transit-like event that could be associated to another Earth-size planet in the system, on a longer period orbit. Our program demonstrates the ability of HST to obtain consistent, high-precision photometry of saturated stars over 26 hours of continuous observations."

This 2015 observation was followed up with Confirming the transit of the Earth-mass planet orbiting Alpha Centauri B HST Proposal 13927 (Co-I Sara Seager) which says "Now that we know where and when to look for, we propose to confirm the repeatability of this signal and to firmly establish Alpha Cen Bb's existence and tighten its physical and orbital properties. We base our observing strategy on the successful approach employed just one year ago with the same instrument." This observation has now been completed: "Confirming the transit of the Earth-mass planet orbiting Alpha Centauri B "Cycle: 21; Allocation: 9 orbits; Program Status: Program has been Completed"

There is also this proposed observation with Spitzer "Searching for the transit of Alpha Centauri Bb, Spitzer Proposal ID #10146" with press conference participant Sean Carey listed as an author that says "We propose a novel set of observations to measure the possible transit of the recently detected exoplanet, Alpha Cen Bb. This closest exoplanet is arguably one of the most exciting detections of the previous year due to the enormous potential for followup observations as well as far-reaching public interest outside the astronomical community."

Hmm ... the authors have been looking for planets circling Alpha Centauri ...

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This page contains a single entry by Keith Cowing published on February 21, 2017 9:43 AM.

TrumpSpace Update was the previous entry in this blog.

Temperate Earth-Sized Planets Found in Extraordinarily Rich Planetary System TRAPPIST-1 is the next entry in this blog.

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