Kepler-1520b

Kepler-1520b

Exoplanet		List of exoplanets
Artist's concept of Kepler-1520b orbiting its host star. The planet is rapidly losing mass through the sublimation of its planetary surface and has a tail of dust.
Parent star
Star		Kepler-1520
Constellation		Cygnus
Right ascension	(α)	19^h 23^m 51.89^s[1]
Declination	(δ)	+51° 30′ 17″[1]
Apparent magnitude	(mV)	16.7[2]
Distance		2074[1] ly (636[1] pc)
Spectral type		K4V[3]
Mass	(m)	0.76 (± 0.03)[1] M☉
Radius	(r)	0.71 (± 0.026)[1] R☉
Temperature	(T)	4677+82 −71[1] K
Metallicity	[Fe/H]	0.04 (± 0.15)[1]
Age		4.47[1] Gyr
Physical characteristics
Mass	(m)	0.1[4] M⊕
Radius	(r)	5.77+0.22 −0.30[1] R⊕
Stellar flux	(F⊙)	850 ⊕
Temperature	(T)	2,255 K (1,982 °C; 3,599 °F)[4]
Orbital elements
Semi-major axis	(a)	0.013[1] AU
Orbital period	(P)	0.653[1] d
Inclination	(i)	~90°
Discovery information
Discovery date		2012 (proposed) May 12, 2016 (confirmed)
Discoverer(s)		Kepler spacecraft
Discovery method		Transit
Discovery status		Confirmed
Other designations
KIC 12557548 b
Database references
Extrasolar Planets Encyclopaedia		data
SIMBAD		data
Exoplanet Archive		data
Open Exoplanet Catalogue		data

Kepler-1520b (formally known as KIC 12557548 b), is a confirmed exoplanet orbiting the K-type main sequence star Kepler-1520. It is located about 2,074 light-years (636 parsecs, or nearly 1.9625×10¹⁶ km) away from Earth in the constellation of Cygnus. The exoplanet was found by using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured. The planet was previously proposed in 2012 when reports of its host star recorded drops in its luminosity varying from 0.2% to 1.3%, which indicated a possible planetary companion rapidly disintegrating. In 2016, the planetary nature of the cause of the dips was finally verified. It is expected to disintegrate in about 100–200 million years.

Characteristics

Mass, radius, and temperature

Kepler-1520b is probably a gas dwarf based on its small mass but large radius. It has a surface temperature of 2,255 K (1,982 °C; 3,599 °F), far hotter than the surface of Venus.^[4] It has a radius of 5.77 R_⊕ and a mass of 0.1 M_⊕.

Host star

The planet orbits a (K-type) star named Kepler-1520. The star has a mass of 0.76 M_☉ and a radius of 0.71 R_☉. It has a temperature of 4677 K and is 4.47 billion years old. In comparison, the Sun is 4.6 billion years old^[5] and has a surface temperature of 5778 K.^[6]

The star's apparent magnitude, or how bright it appears from Earth's perspective, is 16.7. Therefore, it is too dim to be seen with the naked eye.

Orbit

Kepler-1520b orbits its host star with about 14% of the Sun's luminosity with an orbital period of slightly over 12 hours and an orbital radius of about 0.01 times that of Earth's (compared to the distance of Mercury from the Sun, which is about 0.38 AU). This is one of the closest orbital periods detected yet.

Remaining lifetime

Kepler-1520b orbits so close to its host star that it is essentially evaporating into space via sublimation, losing about one Earth mass per billion years. Based on predictions made by scientists, Kepler-1520b will cease to exist in about 100–200 million years.^[2] Based on its host star's age (about the age of the Sun, alias 200 million years younger), the planet probably had a mass of about 4.5 M_⊕ when it first formed.

This discovery helps shed light on how the Earth will interact with the Sun when it becomes a red giant, roughly 5–7 billion years from now.

Discovery

2012 detections

The existence of the planet was first evidenced in data collected by the Kepler spacecraft in 2012. However, the light curve of the star, a graph of its stellar flux versus time, showed that while there were regular drops in stellar flux approximately every 15 hours, the amount of light being blocked covered a wide range, from 0.2% to 1.3% of the starlight being blocked.^[2] Rappaport et al. (2012) proposed various possible phenomena which may have caused the anomalies in the light curve, including two planets orbiting each other,^[7] and an eclipsing binary orbiting the star in a larger triple-star system.^[2] However, the authors found the hypothetical binary planet system to be unstable^[2] and the latter scenario to be poorly supported by the data collected by Kepler.^[2]

Therefore, the authors posited that the most likely cause of the observed light curve was a closely orbiting planet, about twice the mass of Mercury, which was rapidly emitting small particles into independent orbits around the star.^[2] Exactly the cause of this phenomenon could be the direct sublimation of the planetary surface and its emission into space, the intense volcanism caused by the tidal effects of orbiting extremely close to the host star, or both processes mutually reinforcing the strength of each other in a positive feedback loop.^[2]

2016 confirmation

In the new database released by Kepler in May 2016, the planetary nature of then-KIC 12554578 b was confirmed, and was then upgraded to the name Kepler-1520 b.

References

1. "Kepler-1520 b". NASA Exoplanet Science Institute. Retrieved 2016-08-02.
2. Rappaport, S.; Levine, A.; Chiang, E.; El Mellah, I.; Jenkins, J.; Kalomeni, B.; Kite, E. S.; Kotson, M.; Nelson, L.; Rousseau-Nepton, L.; Tran, K. (2012). "Possible Disintegrating Short-Period Super-Mercury Orbiting KIC 12557548". The Astrophysical Journal. 752: 1. arXiv:1201.2662v2. Bibcode:2012ApJ...752....1R. doi:10.1088/0004-637X/752/1/1.
3. "KIC 12557548 b". Retrieved 2 August 2016. Note: The EPE has not fully updated this data to be renamed Kepler-1520, but the spectral type is listed, hence this is the reference for it.
4. Ouellette, Jennifer (May 26, 2012). "Dust to Dust: The Death of an Exoplanet". Discovery News. Discovery Communications, LLC. Retrieved June 9, 2012.
5. Fraser Cain (16 September 2008). "How Old is the Sun?". Universe Today. Retrieved 19 February 2011.
6. Fraser Cain (15 September 2008). "Temperature of the Sun". Universe Today. Retrieved 19 February 2011.
7. Howard, Jacqueline (May 20, 2012). "Exoplanet Turning To Dust Under Parent Star's Intense Heat, Scientists Say". HuffPost Science. TheHuffingtonPost.com, Inc. Retrieved June 11, 2012.

Coordinates: 19^h 23^m 51.89^s, +51° 30′ 17″