ASASSN-V J213939.3-702817.4

ASASSN-V J213939.3-702817.4 (also known as ASAS-SN-V J213939.3-702817.4 and J213939.3-702817.4) is a star, previously non-variable, found to be associated with an unusual, deep dimming event that was uncovered by the All Sky Automated Survey for SuperNovae (ASAS-SN) project, and first reported on 4 June 2019 in The Astronomer's Telegram.[2][3][4]

ASASSN-V J213939.3-702817.4

Context star field of
ASASSN-V J213939.3-702817.4
Observation data
Epoch       Equinox
Constellation Indus[1]
Right ascension  21h 39m 39.3s[2]
Declination −70° 28′ 17.4″[2]
Characteristics
Spectral type F0V[3]
Astrometry
Distance3630±110[3] ly
(1113±33[3] pc)
Absolute magnitude (MV)2.5[2]
Details
Temperature6800±110[3] K
Other designations
2MASS ASAS-SN-V J213939.3-702817.4, J213939.3-702817.4
Database references
SIMBADdata

The star, in the Indus constellation about 3,630 ± 110 ly (1,113 ± 33 pc)[3][5] away, was first observed on 13 May 2014 (UT) by ASAS-SN, and, as of 4 June 2019, has resulted in more than 1580 data points, including a quiescent mean magnitude of g~12.95.[2] On 4 June 2019, the star was reported to have dimmed gradually from g~12.96 at HJD 2458635.78, to g~14.22 at 2458637.95, and, as of 4 June 2019, seems to be returning to its quiescent state of g~13.29 at HJD 2458638.89.[2] According to astronomer Tharindu Jayasinghe, one of the discoverers of the deep dimming event, "[The star has] been quiescent for so long and then suddenly decreased in brightness by a huge amount ... Why that happened, we don’t know yet.”[4]

See also

References
  1. Staff (2 August 2008). "Finding the constellation which contains given sky coordinates". DJM.cc. Retrieved 8 June 2019.
  2. Jayasinghe, T.; et al. (4 June 2019). "ASAS-SN Discovery of an Unusual, Deep Dimming Episode of a Previously Non-Variable Star". The Astronomer's Telegram. Retrieved 8 June 2019.
  3. McCollum, B.; Laine, S. (8 June 2019). "Spectral Type of the Unusual Variable ASASSN-V J213939.3-702817.4". The Astronomer's Telegram. Retrieved 8 June 2019.
  4. Seidel, Jamie (6 June 2019). "A suddenly dimming star has caught the attention of alien hunters". The Advertiser. Retrieved 8 June 2019.
  5. Gilster, Paul (5 June 2019). "HD 163296: Emerging Insights into Circumstellar Disks - Comment (Harry R Ray on 5 June 2019, 9:56)". Centauri-Dreams.org. Retrieved 8 June 2019.

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