Many new HARPS discoveries?

Hi!

Sirius_Alpha wrote:

YES!!!!!

The HARPS search for southern extra-solar planets. XVII. Super-Earth and Neptune-mass planets in multiple planet systems HD47186 and HD181433
http://arxiv.org/abs/0812.1608

Abstract wrote:

This paper reports on the detection of two new multiple planet systems around solar-like stars HD47186 and HD181433. The first system includes a hot NeptunHie of 22.78 M_Earth at 4.08-days period and a Saturn of 0.35 M_Jup at 3.7-years period. The second system includes a Super-Earth of 7.5 M_Earth at 9.4-days period, a 0.64 M$_Jup at 2.6-years period as well as a third companion of 0.54 M_Jup with a period of about 6 years. These detections increase to 20 the number of close-in low-mass exoplanets (below 0.1 M_Jup) and strengthen the fact that 80% of these planets are in a multiple planetary systems.

That's right, a third planet at HD 181433!!!
Also, HD 181433 b seems to be quite eccentric, with e = 0.396.

That' correct: http://exoplanet.eu/planet.php?p1=HD+181433&p2=d

And another new exoplanet: http://exoplanet.eu/planet.php?p1=HD+183263&p2=c

Bye!

HD 181433c a=1.76 AU, e=0.28 --> apastron = 2.25 AU
HD 181433d a=3 AU, e=0.48 --> periastron = 1.56 AU

I'd guess from those figures that the configuration presented is unstable... we must wait for the dynamical analysis paper mentioned to resolve this.

Lazarus wrote:

HD 181433c a=1.76 AU, e=0.28 --> apastron = 2.25 AU
HD 181433d a=3 AU, e=0.48 --> periastron = 1.56 AU

I'd guess from those figures that the configuration presented is unstable... we must wait for the dynamical analysis paper mentioned to resolve this.

Indeed, I look forward to that paper.
Perhaps HD 181433 is similar to Mu Arae. When plugging in the planets into Celestia, it looks very much like the three-planet Mu Arae model (though none of the orbits cross this time), even the masses of the planets are similar though scaled down.

We might learn about more of these low-mass candidates by July or so.

From an upcomming mid-2009 meeting,

Quote :

The Dynamics of Early Earth-Like Planets and Super-Earths


Convenors: Nader Haghighipour, Lisa Kaltenegger
Keynote: Diana Valencia (Harvard)
This session explores the dynamics of habitable planets through the questions: Is plate tectonic-like behavior a characterisitic of Super-Earths? Is it an inevitable dynamic regime on terrestrial planets in and outside our Solar System, both big and small? Is it a prerequisite for life? When did plate tectonics begin on Earth (current estimates range from ca. 4.4 to 0.8 Ga), and why does it stop? In 2007, astronomers detected the first Super Earths close to the Habitable Zone around a nearby cool star. Of the 35 known Super-Earth candidates, what are the prospects of their being habitable?

Quite an impressive statement to drop into an abstract primarily about a different subject (plate tectonics versus planetary discoveries)...

post delete

Link is broken.

post delete

If you have got the file, I dunno if you could host it somewhere.

If this doesn't make embargo breach, of course.

Hosting elsewhere is just a means of getting round the embargo. Not kosher.

However, from what I've read, there's no unpublished discovery.
Just remembers how much planets they have discovered in 2006.

The HARPS search for Earth-like planets in the habitable zone: I -- Very low-mass planets around HD20794, HD85512 and HD192310
http://arxiv.org/abs/1108.3447

Quote :

In 2009 we started, within the dedicated HARPS-Upgrade GTO program, an intense radial-velocity monitoring of a few nearby, slowly-rotating and quiet solar-type stars. The goal of this campaign is to gather, with high cadence and continuity, very-precise radial-velocity data in order to detect tiny signatures of very-low-mass stars potentially in the habitable zone of their parent stars. 10 stars have been selected among the most stable stars of the original HARPS high-precision program, uniformly spread in hour angle, such that three to four of them are observable at any time of the year. For each star we record 50 data points spread over the observing season. The data point consists of three nightly observations of a total integration time of 10 minutes each and separated by 2 hours. This is an observational strategy adopted to minimize stellar pulsation and granulation noise. In this paper we present the first results of this ambitious program. The radial-velocity data and the orbital parameters of five new and one confirmed low-mass planets around the stars HD20794, HD85512} and HD192310, respectively, are reported and discussed, among which a system of three super-Earths and one harboring a 3.6-Earth-mass planet at the inner edge of the habitable zone. This result already confirms previous indications that low-mass planets seem to be very frequent around solar-type stars and that this occurrence frequency may be higher than 30%.

I've made a thread here to discuss the (modelling of the) habitability of HD 85512 b, as no doubt more research on that topic will appear.

Very bearby and some even habitable. The best planets so far found. And it's getting closer some discovery concering stars as Alpha Centauri, Tau Ceti or Zeta Tucanae.

Edasich wrote:

And it's getting closer some discovery concering stars as Alpha Centauri, Tau Ceti or Zeta Tucanae.

Talking of the "big name" stars, HD 20794 might be more familiar as 82 Eridani...

Significant update for 82 Eri. One of the planets appears to be somewhere else, and there may be three more planets.

Evidence for at least three planet candidates orbiting HD20794
https://arxiv.org/abs/1705.05124

Quote :

We explore the feasibility of detecting Earth analogs around Sun-like stars using the radial velocity method by investigating one of the largest radial velocities datasets for the one of the most stable radial-velocity stars HD20794. We proceed by disentangling the Keplerian signals from correlated noise and activity-induced variability. We diagnose the noise using the differences between radial velocities measured at different wavelength ranges, so-called "differential radial velocities", as well as the combination of radial velocities measured for other stars to account for instrumental effects. We apply this method to the radial velocities measured by HARPS, and identify four signals at 18, 89, 147 and 330 d. The two signals at periods of 18 and 89 d are previously reported and are better quantified in this work. The signal at a period of about 147 d is reported for the first time, and corresponds to a super-Earth with a minimum mass of 4.59 Earth mass located 0.51 AU from HD20794. We also find a significant signal at a period of about 330 d corresponding to a super-Earth or Neptune in the habitable zone. Since this signal is close to the annual sampling period and significant periodogram power in some noise proxies are found close to this signal, further observations and analyses are required to confirm it. The analyses of the eccentricity and consistency of signals provide weak evidence for the existence of the previously reported 43 d signal and a new signal at a period of about 11.9 d with a semi amplitude of 0.4 m/s. We find that the detection of a number of signals with radial velocity variations around 0.5\,m/s likely caused by low mass planet candidates demonstrates the important role of noise modeling in searching for Earth analogs.

The HARPS search for southern extra-solar planets. XXXVI. Eight HARPS multi-planet systems hosting 20 super-Earth and Neptune-mass companions
https://arxiv.org/abs/1705.05153

Quote :

We present radial-velocity measurement of eight stars observed with the HARPS Echelle spectrograph mounted on the 3.6-m telescope in La Silla (ESO, Chile). Data span more than ten years and highlight the long-term stability of the instrument. We search for potential planets orbiting HD20003, HD20781, HD21693, HD31527, HD45184, HD51608, HD134060 and HD136352 to increase the number of known planetary systems and thus better constrain exoplanet statistics. After a preliminary phase looking for signals using generalized Lomb-Scargle periodograms, we perform a careful analysis of all signals to separate \emph{bona-fide} planets from spurious signals induced by stellar activity and instrumental systematics. We finally secure the detection of all planets using the efficient MCMC available on the Data and Analysis Center for Exoplanets (DACE web-platform), using model comparison whenever necessary. In total, we report the detection of twenty new super-Earth to Neptune-mass planets, with minimum masses ranging from 2 to 30 MEarth, and periods ranging from 3 to 1300 days. By including CORALIE and HARPS measurements of HD20782 to the already published data, we also improve the characterization of the extremely eccentric Jupiter orbiting this host.