KT Eridani

KT Eridani (Nova Eridani 2009) was a bright nova in the constellation Eridanus that produced an outburst in 2009. It was the first classical nova ever detected in that constellation.^[6] The nova was discovered at 12:52 UT on 25 November 2009 by K. Itagaki at Yamagata, Japan with a 21 cm patrol telescope. At the time of its discovery, it was a magnitude 8.1 object.^[7] The discovery occurred after the nova's peak brightness, but the All Sky Automated Survey system had detected the nova on three earlier occasions, allowing a more complete light curve to be produced. The peak magnitude, 5.4, was seen at 15:10 UT on 14 November 2009,^[5] at which time it would have been visible to the naked eye.

KT Eridani

KT Eridani on 2009 November 30 during a full moon
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Eridanus
Right ascension	04h 47m 54.2015s[1]
Declination	−10° 10′ 42.9633″[1]
Apparent magnitude (V)	5.4 Max. 15.0 Min.[2]
Characteristics
Variable type	Classical Nova[2]
Astrometry
Proper motion (μ)	RA: 6.469±0.053[1] mas/yr Dec.: −11.009±0.052[1] mas/yr
Parallax (π)	0.2044 ± 0.0384 mas[1]
Distance	3744+591 −328[2] pc
Details
White dwarf
Mass	1.15-1.25[3] M☉
Other designations
Nova Eridani 2009, Gaia DR2 3184664584368981760[4][2]
Database references
SIMBAD	data

The light curve of KT Eridani from AAVSO data and Raj et al.^[5] The red line indicated the date of discovery.

A very high temporal resolution light curve, beginning on 13 November 2009, was obtained from images taken by the Solar Mass Ejection Imager on the Coriolis satellite. These observations show that the peak brightness, magnitude 5.42±0.02, occurred at November 14.67±0.04 UT. The satellite was able to detect the nova until November 27.23±0.04, by which time it had dropped to magnitude 8.3±0.1. It is classified as a very fast nova, meaning it dimmed rapidly after peak brightness.^[8]

On 28 December 2009 (44 days after peak brightness) it was detected as a 0.21 milliJansky source at 5 GHz by the Very Large Array. In the following weeks its radio brightness increased and it was detected in additional radio bands.^[9] On the other end of the electromagnetic spectrum, the Swift satellite was used to look for X-ray emission from KT Eridani starting on 27 November 2009, and the satellite detected it on 24 December 2009.^[10]

The location of KT Eridani (circled in red)

In the most common nova systems, the white dwarf accretes matter from a main sequence star. The white dwarf in the KT Eridani system has a mass of between 1.15 and 1.25 M_☉.^[3] KT Eridani is probably a recurrent nova, although no previous eruption has been observed. It has an orbital period of 𝑃=2.615950±0.00060 days. The companion is probably a subgiant, with a temperature around 6200 K.^[11]

See also

• List of novae in the Milky Way galaxy

References

1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
2. Schaefer, Bradley E. (2018). "The distances to Novae as seen by Gaia". Monthly Notices of the Royal Astronomical Society. 481 (3): 3033–3051. arXiv:1809.00180. Bibcode:2018MNRAS.481.3033S. doi:10.1093/mnras/sty2388. S2CID 118925493.
3. Pei, Songpeng; Orio, Marina; Ness, Jan-Uwe; Ospina, Nataly (2021). "Chandra observations of nova KT Eridani in outburst". Monthly Notices of the Royal Astronomical Society. 507 (2): 2073–2086. arXiv:2108.03577. doi:10.1093/mnras/stab2298.
4. "KT Eridani". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-08-26.
5. Raj, Ashish; Banerjee, D.P.K.; Ashok, N.M. (August 2013). "Nova KT Eri 2009: Infrared studies of a very fast andsmall amplitude He/N nova". Monthly Notices of the Royal Astronomical Society. 433 (2657–2666): 2657–2666. arXiv:1305.7460. doi:10.1093/mnras/stt946. Retrieved 8 December 2020.
6. Imamura, Kazuyoshi; Tanabe, Kenji (January 2012). "High galactic latitude classical nova KT Eridani: spectroscopic and photometric observational report ". Mem. S.A.It. 83: 820–824. Bibcode:2012MmSAI..83..820I. Retrieved 9 December 2020.
7. "Possible Nova in Eridanis". Central Bureau Electronic Telegram. 2050: 1. 26 November 2009. Retrieved 8 December 2020.
8. Hounsell, R.; Bode, M.F.; Hick, P.P.; Buffington, A.; Jackson, B.V.; Clover, J.M.; Shafter, A.W.; Darnley, M.J.; Mawson, N.R.; Steele, I.A.; Evans, A.; Eyres, S.P.S.; O'Brien, T.J. (November 2010). "Exquisite Nova Light Curves from the Solar Mass Ejection Imager (SMEI". The Astrophysical Journal. 724 (1): 480–486. arXiv:1009.1737. Bibcode:2010ApJ...724..480H. doi:10.1088/0004-637X/724/1/480.
9. O'Brien, T.J.; Muxlow, T.W.B.; Stevens, J.; Datta, A.; Roy, N.; Eyres, S.P.S.; Bode, M.F. (11 February 2010). "Radio detections of KT Eri". The Astronomer's Telegram. 2434: 1. Bibcode:2010ATel.2434....1O. Retrieved 9 December 2020.
10. Bode, M.F.; Osborne, J.P.; Page, K.L.; Beardmore, A.P.; Walter, F.M.; Ness, J.U.; Schwarz, G.; Starrfield, S.; Kuulkers, E.; O'Brien, T.J.; Balman, S.; Darnley, M.J.; Evans, A.; Evans, P.; Eyres, S.P.S.; Krautter, J. (January 2010). "Emergence of a Bright and Highly Variable Super-soft Source Phase in Nova KT Eri (2009)". The Astronomer's Telegram. 2392: 1. Bibcode:2010ATel.2392....1B. Retrieved 9 December 2020.
11. Schaefer, Bradley E.; Walter, Frederick M.; Hounsell, Rebekah; Hillman, Yael (2022-10-28). "The Nova KT Eri Is a Recurrent Nova With a Recurrence Time-Scale of 40-50 Years". Monthly Notices of the Royal Astronomical Society. 517 (3): 3864–3880. arXiv:2210.10448. doi:10.1093/mnras/stac2923. ISSN 0035-8711.