Around a small, cool red star some thirty-four light years away, a second world has come into view, and it was found not by pointing new eyes at the sky but by listening again to measurements already gathered and set aside. In a quiet act of rereading, astronomers led by Alejandro Suárez Mascareño combined the archives of four instruments and heard in them a faint, rhythmic tug that had gone unrecognized. It is a reminder that the record of what we have seen often holds more than we first understood, and that the search for other worlds can advance as much through patience with the past as thr
Second Super-Earth Found Orbiting Nearby M Dwarf Gliese 536 in Archival Data Reanalysis
It took no new observations, only a fresh look at old data
Mark
So what's actually new here? The star was already known to have a planet.
Mimi
A second one, GJ 536 c. It has a minimum mass of about 5.89 Earth masses and a 32.76-day orbit. And it came from old data, not new observations.
Mark
Which instruments?
Mimi
HARPS, HARPS-N, CARMENES and HIRES, all combined into one radial velocity series.
Luke
Worth stressing that 5.89 is a minimum mass. Radial velocity alone doesn't give the true mass, and the source doesn't say what the planet is made of.
Mark
It's called a super-Earth, though.
Luke
On the basis of mass, yes. That label doesn't tell us whether it's rocky, and the reporting doesn't claim it is.
Mimi
The temperature is the interesting part. About 290.5 K equilibrium, and insolation slightly below what Venus receives.
Luke
Equilibrium temperature is a calculation, not a measurement of the surface. Nothing here says anything about habitability.
Mark
And the reflected light angle?
Mimi
The authors say it's one of the low-mass planets amenable to that kind of atmospheric study. That's a statement of potential, not a plan or a result.
Luke
Agreed. The confirmed part is the detection. The atmosphere work is still ahead.
El Pulso
- A new super-Earth, GJ 536 c, has surfaced around a dim M dwarf without a single fresh observation being made.
- The signal hid inside archival radial velocity data from HARPS, HARPS-N, CARMENES and HIRES, waiting for someone to look again.
- The planet circles its star every 32.76 days, receiving slightly less light than Venus gets from the Sun.
- Its equilibrium temperature of about 290.5 K and its reflected light make it a candidate for future atmospheric study.
- The discovery joins its sibling planet, the 8.7-day super-Earth found in 2017, to make this system a pair of super-Earths, and the open question now is whether the light from GJ 536 c will actually be measured.
Around a small, cool red star some thirty-four light years away, a second world has come into view, and it was found not by pointing new eyes at the sky but by listening again to measurements already gathered and set aside. In a quiet act of rereading, astronomers led by Alejandro Suárez Mascareño combined the archives of four instruments and heard in them a faint, rhythmic tug that had gone unrecognized. It is a reminder that the record of what we have seen often holds more than we first understood, and that the search for other worlds can advance as much through patience with the past as through the reach of new machines.
Astronomers have found a second planet around Gliese 536, a small red star about 34 light years away, and they did it without collecting a single new observation. The work, led by Alejandro Suárez Mascareño of the University of La Laguna in Spain, reanalyzed measurements that several instruments had already recorded. It is slated for an upcoming issue of Astronomy & Astrophysics and has already appeared on the arXiv preprint server.
The star is an M dwarf about half the size and half the mass of the sun, roughly 4.2 billion years old, with a rotation of one turn every 43.63 days. Its planets reveal themselves through radial velocity: each world's gravity gently pulls its star back and forth along our line of sight, and those tiny shifts have now exposed more than 600 worlds beyond our solar system.
GJ 536 already had a known companion, found in 2017, which circles every 8.7 days and is assumed to be a super-Earth. The new signal emerged from combining data from HARPS, HARPS-N, CARMENES and HIRES. The team calls the newcomer GJ 536 c. It has a minimum mass of about 5.89 Earth masses, completes an orbit every 32.76 days, and receives slightly less light than Venus gets from the sun, with an equilibrium temperature near 290.5 K.
Because of its properties, the planet may one day have its atmosphere studied through reflected light. The authors also note that revisiting archives like this one may uncover other worlds that earlier searches overlooked. Whether that reflected light will actually be measured remains the question that follows.
Astronomers have found a second planet circling Gliese 536, a small red star about 34 light years away, and they did it without taking a single new observation. The work, led by Alejandro Suárez Mascareño of the University of La Laguna in Spain, reanalyzed archived measurements already collected by several instruments. It is due to appear in an upcoming issue of Astronomy & Astrophysics and is already available on the arXiv preprint server.
The star, also catalogued as GJ 536, is an M dwarf roughly half the size and half the mass of the sun. Its effective temperature is 3,641 K, its metallicity sits at -0.08 dex, and its age is estimated at 4.2 billion years. The team also measured its rotation: one turn every 43.63 days.
The method is radial velocity. A planet's gravity tugs on its star as it orbits, and the direction of that pull keeps changing, which nudges the star's velocity back and forth along our line of sight. Detecting those variations has revealed more than 600 extrasolar worlds so far.
GJ 536 already had one known planet. Found in 2017, it circles the star every 8.7 days at about 0.067 AU. Its minimum mass is 6.37 Earth masses, which is why it is assumed to be a super-Earth, and its equilibrium temperature is roughly 451 K.
The new signal came from combining archival data from four spectrographs: HARPS, HARPS-N, CARMENES and HIRES. From the radial velocity time series built from those instruments, the researchers announced a second low-mass planet, which they call GJ 536 c.
GJ 536 c has a minimum mass of about 5.89 Earth masses and completes an orbit every 32.76 days, at a distance of about 0.16 AU from its star. Its equilibrium temperature is estimated at 290.5 K. The planet receives slightly less insolation than Venus does from the sun. That makes GJ 536 the host of two super-Earths.
The authors say the planet's properties place it among the low-mass exoplanets that could be studied through the light its atmosphere reflects. The star's own behavior also came out of the analysis: the rotation period, together with the observed radial velocity variations, suggests a surface dominated by starspots, with plages surrounding them.
In their closing remarks, the authors stress that revisiting archival data, as was done here, may uncover planets that earlier searches missed. Whether GJ 536 c's reflected light is actually measured is the open question that follows from this result.
Citas Notables
Based on an analysis of the radial velocity time series from HARPS, HARPS-N, CARMENES and HIRES, the team announced the discovery of a second low-mass planet orbiting the star.— Researchers led by Alejandro Suárez Mascareño, in the paper
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