Barnard's Star and Bernard's Star b

Barnard's Star

Barnard Star

• Red dwarf star

• Spectral Type M4

• Fainted and needed a telescope to see

• Apparent Magnitude 9.5

• Current apparent magnitude visibility in the naked eye is 2.5

• Older than Sun (4.5 billion years old)

• The oldest star in the Milky Way galaxy

• Lost a great deal of rotational energy

• Constellation is Ophiuchus

• Largest proper motion (10.39 arc second)

• The fourth nearest star to the Sun (after the triple system of Proxima Centauri and Alpha Centauri’s A and B)

• 5.96 light-years away from Earth (1.8 parsecs from solar system)

• Rotates 130 days

• Brighter in infrared light than it is invisible light

• Astronomers observed an intense stellar flare (1998)

• It may be the oldest star in the Milky Way galaxy

• Barnard's star is a flare star

• Variable star designation V2500 Ophiuchi

• Other names are Gliese 699 or GJ 699 or Barnard's Runaway Star

• Due to motion first detectable change in the radial velocity (2003)

• lateral speed of 90 km/s

• Travels annually amount to a quarter of a degree in a human lifetime (10.3 seconds of arc)

• Radial velocity from Barnard's stars towards Sun measured from its blueshift ( −110 km/s)

• Space velocity (actual velocity relative to the Sun) −142.6 ± 0.2 km/s

• Barnard's Star will make its closest approach to the Sun (11800 AD i.e within 3.7 light-years)

• 0.14 solar masses (M☉)

• Radius 15% to 20%

• Roughly 150 times the mass of Jupiter and

• Radius 1.5 to 2.0 times larger because of higher density

• The effective temperature is 3,100 kelvin

• The visual luminosity of 0.0004 solar luminosities

• Solar metallicity (10–32%)

• It is a Stellar Population II stars (stays between a Halo and a disk star)

• Metal-poor halo stars

• Metallicity is higher than the halo star and keeping with the low end of the metal-rich disk star range

• M-Dwarf Star

• Intrinsic luminosity (1/12600 of Sun)

• Expecting between 40 percent of the Earth-sun distance (1 AU (93 million miles or 150 million kilometers))

• Visible from both the Northern and Southern hemispheres with a small telescope

• The fastest apparent motion compared to any star (traveling about the width of the full moon across our sky every 180 years)

• 1/6 massive as Earth's sun

• 3 percent as luminous

• Expecting 10 billion years old

• Dim Star

• Ancient Star

• Still experiencing Stellar events (one event observed in 1998)

• Named after E.E Barnard (He is not first observed)

• Fastest proper motion star

• Apparent angular motion of a star across the sky (10.3 arc seconds per year relative to the sun)

• M3.5 dwarf star

• Smaller than our Sun

When Barnard's Star makes its closes approach to our Sun before that Proxima Centauri will make it and at that time we can see Barnard's stars in the naked eye but its too much dim. Expect an apparent magnitude of 8.7. Suppose this star now stays between Earth and Sun it becomes 100 times brighter than our full moon when brightness compared to the Sun 80 astronomical units. Perturbation was interpreted as being caused by the gravitational pull of two planetary companions having orbital periods of 13.5 and 19 years. The mass is 2/3 of Jupiter. This was not accepted by other findings because of its variation in their research results.

Most studied red dwarfs because of their proximity and favorable location for observation near the celestial equator

Artist’s impression of the surface of a super-Earth orbiting Barnard’s Star

Barnard's Star b

• Discovered by International team of astronomers (14th November 2018 ) including the European Southern Observatory and Carnegie Institution for Science

• Consider it as a Super-Earth orbiting around Barnard's Star.

• Two decades of astronomers' observations (20 years).

• Super-Earth named Barnard's Star b (another name GJ 699 b)

• Founded near snow line (frost line or ice line)

• Orbits at 0.4 AU every 233 days

• Proposed mass of 3.2 M⊕

• Frigid temperature

• The estimated surface temperature of about −170 °C (−274 °F; 103 K)

• Lies out habitable zone

• Water may be frozen

• Low luminosity

• Mass 3.2 times that of Earth

• Distance is 60 million kilometers (37 million miles)

• 6 light-years away from Earth

• Used common planet-hunting technique this proposed through the radial velocity method

• Currently believing it's a rocky planet

Barnard's Star b Characteristics

• 99% of astronomers believe its a planet (currently)

• A wobble observed in Barnard's Star's motion was confirmed to have a period of about 233 days and corresponding to a semi-major axis of 0.4 AU for a proposed companion

Researchers ensure that no improbable variations in brightness and motion in the star which helps for the discovery of Barnard's Star b. With the help of a ground-based telescope or WFIRST telescope, direct imaging opportunities of the planet is planing for an outside chance that a transit of the star might also allow for imaging. There is a chance for the second planet based on the unconfirmed wobbles in the current system.

Using radial velocity Barnard-b was among the smallest planet ever found using the technique. According to the Ignasi Rablis of Spain’s Institute of Space Studies of Catalonia, the discovery was the result of 771 observations. 100 years of search for an exoplanet in Barnard's Star. Bernard Star b is visible with an amateur 8-inch telescope.

Peter van de Kamp Barnard's Star planetary suggestions

Peter van de Kamp says that he used astrometry and Barnard's star has one or more planets comparable to mass to Jupiter. He says that he finds Barnard's star perturbation in the proper motion. For researching his observation colleagues at the Sproul Observatory at Swarthmore College participated. That colleague helps him to find minuscule variations of one micrometer in its position on photographic plates consistent with orbital perturbations that would indicate a planetary companion. There are 10 people included to correct the error looking into the photographic plates. He suggested that the planet has about 1.6 Mass Jupiter at a distance of 4.4 Astronomical Units in a slightly eccentric orbit. Based on the other astronomer's suggestion Peter van de Kamp never acknowledged his error.

Other Scientist Barnard's Star planetary Observations

• George Gatewood and Heinrich Eichhor (1973) used new photographic plates and they were failed. That observation was done in the different observatories.

• John L. Hershey published a paper four months earlier. He used the Swarthmore observatory. He found that changes in the astrometric field of various stars correlated to the timing of adjustments and modifications that had been carried out on the refractor telescope objective lens.

• His claim was also discussed in scientific review because he said that planet was attributed to an artifact of maintenance and upgrade work

There are some planetary claims that existed regarding Bernard's star

• 1888- 1890:- Barnard Star appeared on Harvard University plates

• 1916: A American astronomer Edward Emerson Barnard discovered Bernard's Star

• 1938:- Peter van de Kamp started observing Barnard's Star and its proper motion was observed.

• 1963 -1973:- A substantial number of astronomers accepted a claim by Peter van de Kamp

• 1969:- Peter van de Kamp measurements refined

• 1969:- Van de Kamp suggested that there were two planets of 1.1 and 0.8 Mass Jupiter in later

• 1973:- Two paper claims of planet and planets from other astronomers repeated experiments.

• 1976 onwards:- Wulff Heintz, Van de Kamp's successor at Swarthmore observatory and an expert on double stars, questioned his findings and began publishing criticisms

• The 1970s:- British Interplanetary Society's Project Daedalus proposed using fusion rockets to propel an uncrewed spacecraft to the Barnard's Star system for further study

• 1982:- Peter van de Kamp claimed the existence of two planets.

• 1981:- Shows periodic deviations of 0.02 second of arc (Barnard's Star)

• The 1980s-1990s:- Null results for planetary companions (included interferometric work with the Hubble Space Telescope in 1999)

• 1995:- George Gatewood was able to show planets with 10 Mass Jupiter were impossible around Barnard's Star

• 2003: - Kuerster determined the habitable zone around Barnard's Star, planets are not possible with an M sin i value greater than 7.5 times the mass of the Earth (M⊕) or with a mass greater than 3.1 times the mass of Neptune (much lower than van de Kamp's smallest suggested value).

• 2013:- A research paper was published that further refined planet mass boundaries for the star.

Hubble works further excluded planetary companions of 0.8 Mass Jupiter with an orbital period of fewer than 1000 days. With the help of radial velocity measurements taken over 25 years from the Lick and Keck Observatories and Monte Carlo analysis was applied for both circular and eccentric orbits. It helps to understand the upper masses of planets out to 1,000-day orbits were determined.

• Planets above two Earth masses in orbits of less than 10 days were excluded

• Planets of more than ten Earth masses out to a two-year orbit were also confidently ruled out

It helps to discover that the habitable zone of the star seemed to be devoid of roughly Earth-mass planets or larger and save for face-on orbits. This research greatly restricted the possible properties of planets around Barnard's Star. NASA's Space Interferometry Mission was reported to have chosen Barnard's Star as an early search target but its mission shut down in 2010 and ESA's Darwin interferometry mission had the same goal but was stripped of funding in 2007.

The analysis of radial velocities helps to discover the Super-Earth orbiting Barnard's Star. This discovery helps to look out more precisely for exoplanets in the habitable zone.

Maximum of 0.7 M⊕ up to the inner edge and 1.2 M⊕ on the outer edge of the optimistic needed for habitable zone and corresponding to orbital periods of up to 10 and 40 days. This helps to understand that Bernard's not able to Earth-mass planets or larger in hot and temperate orbits. Commonly M-dwarf stars have these types of planets in close-in orbits.

Proposals

1973- 1978:- Barnard's Star was studied as part of Project Daedalus for an interplanetary or interstellar sending spacecraft for unmanned travel. According to the proposal within 50 years of Earth time, we can reach there. The initial Project Daedalus model sparked further theoretical research.

1980:- Robert Freitas suggested a self-replicating spacecraft intended to search and make contact with extraterrestrial life. Built and launched in Jupiter's orbit and it would reach Barnard's Star in 47 years. When it reached the star, it would begin automated self-replication, constructing a factory, initially to manufacture exploratory probes and eventually to create a copy of the original spacecraft after 1,000 years.

Studies

This illustration shows radiation from flares from a red dwarf star like Barnard’s star eroding the atmosphere of an orbiting, rocky planet. Image credit: NASA / CXC / M. Weis.

Later, in 2020 an astronomical Journal study published by University of Colorado astronomers shows that About 25% of the time, Barnard’s star unleashes scorching flares, which may damage the atmospheres of planets closely orbiting it. They have takes Hubble observations taken in March 2019 revealed two ultraviolet high-energy flares and Chandra observations in June 2019 uncovered an X-ray one. Both observations were about seven hours long for understanding for study. The study shows that red dwarfs may present serious challenges for life on the planets near orbiting. The flare findings led the team to consider other possibilities for life on planets orbiting old red dwarfs like Barnard’s star.

Barnard's Star Environment

• Shares much the same neighborhood as the Sun

• A common type of neighbor are red dwarf size, the smallest and most common star type

• Closest Neighbour is red dwarf Ross 154 and it is 5.41 light-years from Barnard's Star.

• Another Neighbour is Alpha Centauri

• Another one is our Sun would appear on the diametrically opposite side of the sky at coordinates RA=5h 57m 48.5s, Dec=−04° 41′ 36″ in the eastern part of the constellation Monoceros.

An artist’s impression of Barnard’s star b. Image credit: Sci-News.com

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Stellar Flares

1998 Flare:-

• Detected based on changes in the spectral emissions on 17 July during an unrelated search for variations in the proper motion.

• After four years a study suggested that the flare's temperature was 8,000 K more than twice the normal temperature of the star.

• Flares are not completely understood but researchers believed that the cause of stellar flare is due to the strong magnetic fields, which suppress plasma convection and lead to sudden outbursts strong magnetic fields occur in rapidly rotating stars, while old stars tend to rotate slowly.

• Starlike Barnard's will happen such type of stellar event in rare cases only.

2019 Flare:-

• Two additional ultraviolet stellar flares were detected

• Each of them shows far-ultraviolet energy of 3*1022 joules together with one X-ray stellar flare with energy of 1.6*1022 joules

• The flare rate observed to date is enough to cause a loss of 87 Earth atmospheres per billion years through thermal processes and approximately 3 Earth atmospheres per billion years through ion loss processes on Barnard's Star b