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In 1968 Shirley Chisholm became the first Black woman elected to the United States Congress. In 1972 she launched a campaign for the Democratic presidential nomination, breaking another political barrier.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
  | |
| Observation data Epoch J2000.0 Equinox ICRS | |
|---|---|
| Constellation | Indus |
| Right ascension | 22h 03m 21.65363s[1] |
| Declination | −56° 47′ 09.5228″[1] |
| Apparent magnitude (V) | 4.674±0.006[2] |
| Characteristics | |
| Evolutionary stage | main sequence[1] |
| Spectral type | K5V + T1 + T6[3] |
| U−B color index | 1.00[4] |
| B−V color index | 1.056±0.016[5] |
| Astrometry | |
| ε Ind A | |
| Radial velocity (Rv) | −40.4+0.9 −0.8[6] km/s |
| Proper motion (μ) | RA: +3,966.661 mas/yr[1] Dec.: −2,536.192 mas/yr[1] |
| Parallax (π) | 274.8431±0.0956 mas[1] |
| Distance | 11.867 ± 0.004 ly (3.638 ± 0.001 pc) |
| Absolute magnitude (MV) | 6.89[7] |
| ε Ind Ba/Bb | |
| Proper motion (μ) | RA: +3,981.977 mas/yr[8] Dec.: −2,466.832 mas/yr[8] |
| Parallax (π) | 270.6580±0.6896 mas[8] |
| Distance | 12.05 ± 0.03 ly (3.695 ± 0.009 pc) |
| Orbit[9] | |
| Primary | ε Ind Ba |
| Secondary | ε Ind Bb |
| Period (P) | 11.0197 ± 0.0076 yr |
| Semi-major axis (a) | 661.58 ± 0.37 mas (2.4058 ± 0.0040 au) |
| Eccentricity (e) | 0.54042 ± 0.00063 |
| Inclination (i) | 77.082 ± 0.032° |
| Longitude of the node (Ω) | 147.959 ± 0.023° |
| Argument of periastron (ω) (secondary) | 328.27 ± 0.12° |
| Details | |
| ε Ind A | |
| Mass | 0.782±0.023[10] M☉ |
| Radius | 0.713±0.006[10] R☉ |
| Luminosity | 0.21±0.02 [11] L☉ |
| Surface gravity (log g) | 4.50±0.07[10] cgs |
| Temperature | 4,649±65[10] K |
| Metallicity [Fe/H] | −0.17±0.04[10] dex |
| Rotation | 35.732+0.006 −0.003 days[12] |
| Rotational velocity (v sin i) | 2.00[11] km/s |
| Age | 3.5+0.8 −1.0[9] Gyr |
| ε Ind Ba | |
| Mass | 66.92±0.36[9] MJup |
| Radius | 0.080–0.081[13] R☉ |
| Luminosity | 2.04×10−5[13] L☉ |
| Surface gravity (log g) | 5.365±0.006[9] cgs |
| Temperature | 1,312±13[9] K |
| ε Ind Bb | |
| Mass | 53.25±0.29[9] MJup |
| Radius | 0.082–0.083[13] R☉ |
| Luminosity | 5.97×10−6[13] L☉ |
| Surface gravity (log g) | 5.288±0.003[9] cgs |
| Temperature | 972±13[9] K |
| Other designations | |
| ε Ind, CD−57°8464, CPD−57°10015, FK5 825, GJ 845, HD 209100, HIP 108870, HR 8387, SAO 247287, LHS 67, PLX 5314.00, UGP 544[14] | |
| B: CI Ind[15] | |
| Database references | |
| SIMBAD | The system |
| A | |
| Bab | |
| Bab (as X-ray source) | |
| Exoplanet Archive | data |
| ARICNS | data |
Epsilon Indi, Latinized from ε Indi, is a star system located at a distance of approximately 12 light-years from Earth in the southern constellation of Indus. The star has an orange hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.674.[2] It consists of a K-type main-sequence star, ε Indi A, and two brown dwarfs, ε Indi Ba and ε Indi Bb, in a wide orbit around it.[16] The brown dwarfs were discovered in 2003. ε Indi Ba is an early T dwarf (T1) and ε Indi Bb a late T dwarf (T6) separated by 0.6 arcseconds, with a projected distance of 1460 AU from their primary star.
ε Indi A has one known planet, ε Indi Ab, with a mass of 6.31 Jupiter masses in an elliptical orbit with a period of about 171.3 years. ε Indi Ab is the second-closest Jovian exoplanet, after ε Eridani b. The ε Indi system provides a benchmark case for the study of the formation of gas giants and brown dwarfs.[12]
The constellation Indus (the Indian) first appeared in Johann Bayer's celestial atlas Uranometria in 1603. The 1801 star atlas Uranographia, by German astronomer Johann Elert Bode, places ε Indi as one of the arrows being held in the left hand of the Indian.[17]
In 1847, Heinrich Louis d'Arrest compared the position of this star in several catalogues dating back to 1750, and discovered that it possessed a measureable proper motion. That is, he found that the star had changed position across the celestial sphere over time.[18] In 1882–3, the parallax of ε Indi was measured by astronomers David Gill and William L. Elkin at the Cape of Good Hope. They derived a parallax estimate of 0.22 ± 0.03 arcseconds.[19] In 1923, Harlow Shapley of the Harvard Observatory derived a parallax of 0.45 arcseconds.[20]
In 1972, the Copernicus satellite was used to examine this star for the emission of ultraviolet laser signals. Again, the result was negative.[21] ε Indi leads a list, compiled by Margaret Turnbull and Jill Tarter of the Carnegie Institution in Washington, of 17,129 nearby stars most likely to have planets that could support complex life.[22]
The star is among five nearby paradigms as K-type stars of a type in a 'sweet spot' between Sun-analog stars and M stars for the likelihood of evolved life, per analysis of Giada Arney from NASA's Goddard Space Flight Center.[23]
ε Indi A is a main-sequence star of spectral type K5V. The star has only about three-fourths the mass of the Sun[24] and 71% of the Sun's radius.[11] Its surface gravity is slightly higher than the Sun's.[4] The metallicity of a star is the proportion of elements with higher atomic numbers than helium, being typically represented by the ratio of iron to hydrogen compared to the same ratio for the Sun; ε Indi A is found to have about 87% of the Sun's proportion of iron in its photosphere.[3]
The corona of ε Indi A is similar to the Sun, with an X-ray luminosity of 2×1027 ergs s−1 (2×1020 W) and an estimated coronal temperature of 2×106 K. The stellar wind of this star expands outward, producing a bow shock at a distance of 63 AU. Downstream of the bow, the termination shock reaches as far as 140 AU from the star.[25]
This star has the third highest proper motion of any star visible to the unaided eye, after Groombridge 1830 and 61 Cygni,[26] and the ninth highest overall.[27] This motion will move the star into the constellation Tucana around 2640 AD.[28] ε Indi A has a space velocity relative to the Sun of 86 km/s,[4][note 1] which is unusually high for what is considered a young star.[29] It is thought to be a member of the ε Indi moving group of at least sixteen population I stars.[30] This is an association of stars that have similar space velocity vectors, and therefore most likely formed at the same time and location.[31] ε Indi will make its closest approach to the Sun in about 17,500 years when it makes perihelion passage at a distance of around 10.58 light-years (3.245 pc).[32]
As seen from ε Indi, the Sun is a 2.6-magnitude star in Ursa Major, near the bowl of the Big Dipper.[note 2]
In January 2003, astronomers announced the discovery of a brown dwarf with a mass of 40 to 60 Jupiter masses in orbit around ε Indi A with a projected separation on the sky of about 1,500 AU.[34][35] In August 2003, astronomers discovered that this brown dwarf was actually a binary brown dwarf, with an apparent separation of 2.1 AU and an orbital period of about 15 years.[13][36] Both brown dwarfs are of spectral class T; the more massive component, ε Indi Ba, is of spectral type T1–T1.5 and the less massive component, ε Indi Bb, of spectral type T6.[13] More recent parallax measurements with the Gaia spacecraft place the ε Indi B binary about 11,600 AU (0.183 lightyears) away from ε Indi A, along line of sight from Earth.[8]
Evolutionary models[37] have been used to estimate the physical properties of these brown dwarfs from spectroscopic and photometric measurements. These yield masses of 47 ± 10 and 28 ± 7 times the mass of Jupiter, and radii of 0.091 ± 0.005 and 0.096 ± 0.005 solar radii, for ε Indi Ba and ε Indi Bb, respectively.[38] The effective temperatures are 1300–1340 K and 880–940 K, while the log g (cm s−1) surface gravities are 5.50 and 5.25, and their luminosities are 1.9 × 10−5 and 4.5 × 10−6 the luminosity of the Sun. They have an estimated metallicity of [M/H] = –0.2.[13]
The brown dwarf pair is variable, and has received the variable star designation CI Indi.[15]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (years) |
Eccentricity | Inclination (°) |
Radius |
|---|---|---|---|---|---|---|
| b | 6.50+0.72 −0.59[6]: 34 MJ 7.6±0.7[39]: 12 MJ |
15.76+1.73 −1.39[6]: 34 20.9+5.8 −3.3[39]: 12 |
70+12 −9[6]: 34 108+49 −25[39]: 12 |
0.25±0.09[6]: 34 | 102.2±1.7[6]: 34 | 1.038+0.012 −0.009[6]: 28 RJ |
The existence of a planetary companion to Epsilon Indi A was suspected since 2002 based on radial velocity observations.[40] The planet Epsilon Indi Ab was confirmed in 2018[41] and formally published in 2019 along with its detection via astrometry.[12]
A direct imaging attempt of this planet using the James Webb Space Telescope was performed in 2023,[42] and the image was released in 2024. The detected planet's mass and orbit are different from what was predicted based on radial velocity and astrometry observations.[43] It was found to have a mass of 6.31 Jupiter masses and an elliptical orbit with a period of about 171.3 years.[44] Later observations found the orbit to be shorter and closer to circular, with a period of 70+12
−9[6]: 34 to 108+49
−25 years.[39]: 12 This difference is attributed to a more careful treatment of the data.[6][39]
No excess infrared radiation that would indicate a debris disk has been detected around ε Indi.[45] Such a debris disk could be formed from the collisions of planetesimals that survive from the early period of the star's protoplanetary disk.
However, it seems that derivations of the mass of cool brown dwarfs are uncertain even where estimates of the effective temperature, surface gravity, and luminosity exist.[permanent dead link]
'I find that certain nearby K stars like 61 Cyg A/B, Epsilon Indi, Groombridge 1618, and HD 156026 may be particularly good targets for future biosignature searches,' said Arney.
We will collect the first direct images of a radial velocity planet, by targeting Eps Indi Ab with JWST/MIRI. [...] Our simulations confirm that we will detect Eps Indi Ab's thermal emission at high confidence, regardless of its cloud properties or thermal evolution.
{{cite web}}: CS1 maint: deprecated archival service (link)
Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
Epsilon Indi, Latinized from ε Indi, is a star system located at a distance of approximately 12 light-years from Earth in the southern constellation of Indus. The star has an orange hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.674. It consists of a K-type main-sequence star, ε Indi A, and two brown dwarfs, ε Indi Ba and ε Indi Bb, in a wide orbit around it. The brown dwarfs were discovered in 2003. ε Indi Ba is an early T dwarf (T1) and ε Indi Bb a late T dwarf (T6) separated by 0.6 arcseconds, with a projected distance of 1460 AU from their primary star. ε Indi A has one known planet, ε Indi Ab, with a mass of 6.31 Jupiter masses in an elliptical orbit with a period of about 171.3 years. ε Indi Ab is the second-closest Jovian exoplanet, after ε Eridani b. The ε Indi system provides a benchmark case for the study of the formation of gas giants and brown dwarfs.
Epsilon Indi Ab is a gas giant exoplanet orbiting the star Epsilon Indi A, about 11.9 light-years away in the constellation of Indus. The planet was confirmed to exist in 2018. It orbits at around 30 AU (almost as far as Neptune from the Sun) with a period of around 180 years and a relatively high eccentricity of 0.4, and has a mass around seven times that of Jupiter. It was directly imaged using the James Webb Space Telescope in 2023 and the image was released on 24 July 2024. As of 2024, Epsilon Indi Ab is the nearest exoplanet to be directly imaged, and with a temperature of about 275 K (2 °C; 35 °F), is also the coolest exoplanet to be directly imaged. The Epsilon Indi system also contains a pair of brown dwarfs, Epsilon Indi Ba and Bb, at a wide separation from the primary star. As such, this system provides a benchmark case for the study of the formation of gas giants and brown dwarfs.
This is a list of extrasolar planets that have been directly observed, sorted by observed separations. This method works best for young planets that emit infrared light and are far from the glare of the star. Currently, this list includes both directly imaged planets and imaged planetary-mass companions (objects that orbit a star but formed through a binary-star-formation process, not a planet-formation process). This list does not, due to the inherent gray area between such objects and brown dwarfs, include free-floating planetary-mass objects in star-forming regions or young associations, which are also referred to as rogue planets. The data given for each planet is taken from the latest published paper on the planet to have that data. In many cases it is not possible to have an exact value, and an estimated range is instead provided. The coldest and oldest planet directly imaged are Epsilon Indi Ab and 14 Herculis c, which have six times Jupiter's mass, an effective temperature of 275 K, an age of about 3.5 Ga and eight times Jupiter's mass, an effective temperature of 275 K, an age of about 4.6 Ga, respectively. This list includes the four members of the multi-planet system that orbit HR 8799. It is unlikely or at least unclear if objects on a wide orbit (≥100 AU) formed in circumstellar disks and these objects are therefore more often referred as planetary-mass companions. Only in rare cases, such as for HD 106906 b, the formation of the object in the disk is seen plausible.
COCONUTS-2 b is a gas giant exoplanet that orbits the M-type star L 34-26. With a mass of 7.3 Jupiters, it takes over one million years to complete one orbit around the star orbiting 7,500 AU away from it. The planet was discovered in 2011 and was initially identified as a T9 free-floating brown dwarf WISEPA J075108.79−763449.6. During the COol Companions ON Ultrawide orbiTS (COCONUTS) survey, its association with L 34-26 was announced in 2021. At a distance of 35.5 light-years (10.9 parsecs), COCONUTS-2b was the closest directly imaged exoplanet to Earth until Epsilon Indi Ab was imaged in 2024.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Joe Louis.
