Astronomy:EX Lupi
 Artist's illustration of the disk around EX Lupi, showing the formation of silicate crystals | |
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Lupus |
| Right ascension | 16h 03m 05.491s[1] |
| Declination | −40° 18′ 25.43″[1] |
| Characteristics | |
| Evolutionary stage | Pre-main-sequence[2] |
| Spectral type | M0[3] |
| Variable type | YY Ori[4] |
| Astrometry | |
| Radial velocity (Rv) | −0.9±0.1[2] km/s |
| Proper motion (μ) | RA: −10.157[1] mas/yr Dec.: −22.531[1] mas/yr |
| Parallax (π) | 6.4634 ± 0.0150[1] mas |
| Distance | 505 ± 1 ly (154.7 ± 0.4 pc) |
| Details | |
| Mass | 0.6[2] M☉ |
| Radius | 1.6[2] R☉ |
| Luminosity | 1.23±0.53[3] L☉ |
| Temperature | 3,850±177[3] K |
| Rotational velocity (v sin i) | 4.4±2.0[5] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
EX Lupi is a young, single[2] T-Tauri star in the southern constellation of Lupus. An irregular variable,[8] it is the prototype of young, low-mass eruptive stars named EXors,[2] with EX Lupi being this object's variable star designation. At its minimal activity level, EX Lupi resembles a classical T-Tauri star of the M0 dwarf type.[9] The low latitude of this star, at a declination of −40°, makes it difficult for northern observers to view.[9] Based on parallax measurements, it is located at a distance of about 505 light years from the Sun.[1] The star lies next to a gap in the Lupus cloud complex, a star forming region.[10]
During 1944, Edith M. Janssen at Harvard Observatory noticed a stellar spectrum that displayed bright lines on a photographic plate taken April 11, 1929, but these lines were missing on a spectrum from July 13, 1928. This star was found to be only two magnitudes fainter than at maximum, so a nova was ruled out. D. B. McLaughlin then undertook a study of this object going as far back as 1893, finding further outbursts in 1901, 1914, 1925, 1929, 1934. Each time the brightness increased by about two magnitudes, followed by smaller, irregular fluctuations lasting 1–2 years before returning to a near constant minimum at magnitude 13.2.[7] Now designated EX Lupi, George Herbig studied the spectrum of this irregular variable in 1950, finding that it is similar to other emission-line stars associated with nebulosity.[11]
The next observed outburst was during the period 1955–1957 and was tracked by A. F. Jones. It reached a peak magnitude of 8.4, followed by a secondary brightening about 300 days later.[9] After a period of quiescence during the 1980s, another eruptive burst was observed in March 1994.[8] It reached a peak magnitude of 11.5 on both April 30 and May 14.[9] The cause was now understood to be the result of a mass accretion event with the infalling matter releasing its kinetic energy on the T-Tauri star. This creates a hot emission region that dominates the light output from the star. Many of the emission lines show an inverse P Cygni profile, thereby demonstrating that it is coming from infalling material. Absorption lines in the spectrum show a redshift indicating a velocity of 300 km/s.[8]
A major outburst of EX Lupi began in January 2008,[13] and it reached a peak visual magnitude of 8 during February.[14] It remained optically brighter by five magnitudes for a period of seven months.[15] Infrared observations of the star's circumstellar disk during the outburst shows spectral features of crystalline silicates, including strong indications of forsterite. The features resembled those seen in comets and some protoplanetary disks. The temperature of the disk is mostly below 700 K, indicating a circumstellar dust-free inner hole with a radius of 0.2 astronomical unit|AU.[14] The disk may extend outward to at least 150 AU. At stellar quiescence, the infrared silicate feature at a wavelength of 10 μm can be explained as amorphous silicates of olivine and pyroxene.[2]
Matter from the circumstellar disk is being accreted onto the star by means of accretion columns.[5] This column may be the cause of the 7.417 day radial velocity variations observed with this star. EX Lupi is accreting mass at a typical estimated rate of 3.6×10−8 M☉·yr−1, which can climb as high as 10−7 M☉·yr−1 during peak bursts.[3] Between outbursts, the star undergoes moderate variability of 1–2 magnitudes due to variations in the rate of accretion.[5]
See also
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G. Gaia EDR3 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Sipos, N. et al. (November 2009), "EX Lupi in quiescence", Astronomy and Astrophysics 507 (2): 881–889, doi:10.1051/0004-6361/200911641, Bibcode: 2009A&A...507..881S.
- ↑ 3.0 3.1 3.2 3.3 Alcalá, J. M. et al. (April 2017), "X-shooter spectroscopy of young stellar objects in Lupus. Accretion properties of class II and transitional objects", Astronomy & Astrophysics 600: 42, doi:10.1051/0004-6361/201629929, A20, Bibcode: 2017A&A...600A..20A.
- ↑ Samus, N. N. et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1 61 (1): 80–88, doi:10.1134/S1063772917010085, Bibcode: 2017ARep...61...80S.
- ↑ 5.0 5.1 5.2 Sicilia-Aguilar, Aurora et al. (August 2015), "Accretion dynamics of EX Lupi in quiescence. The star, the spot, and the accretion column", Astronomy & Astrophysics 580: 33, doi:10.1051/0004-6361/201525970, A82, Bibcode: 2015A&A...580A..82S.
- ↑ "HD 325367". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+325367.
- ↑ 7.0 7.1 McLaughlin, Dean B. (November 1946), "The nova-like variable star HV 11976", Astronomical Journal 52: 109, doi:10.1086/105935, Bibcode: 1946AJ.....52..109M.
- ↑ 8.0 8.1 8.2 Lehmann, T. et al. (August 1995), "The outburst of the T Tauri star EX LUPI in 1994", Astronomy and Astrophysics 300: L9, Bibcode: 1995A&A...300L...9L.
- ↑ 9.0 9.1 9.2 9.3 Herbig, G. H. et al. (December 2001), "The 1993-1994 Activity of EX Lupi", The Publications of the Astronomical Society of the Pacific 113 (790): 1547–1553, doi:10.1086/324420, Bibcode: 2001PASP..113.1547H.
- ↑ Herbig, G. H. (June 2007), "EX Lupi: History and Spectroscopy", The Astronomical Journal 133 (6): 2679–2683, doi:10.1086/517494, Bibcode: 2007AJ....133.2679H.
- ↑ Herbig, George H. (October 1950), "The Spectra of Five Irregular Variable Stars", Publications of the Astronomical Society of the Pacific 62 (367): 211, doi:10.1086/126276, Bibcode: 1950PASP...62..211H.
- ↑ "Download Data". AAVSO. https://www.aavso.org/data-download.
- ↑ Jones, A. F. A. L. (January 2008), Green, D. W. E., ed., "EX Lupi", Central Bureau Electronic Telegrams 1217 (1): 1, Bibcode: 2008CBET.1217....1J.
- ↑ 14.0 14.1 Ábrahám, P. et al. (May 2009), "Episodic formation of cometary material in the outburst of a young Sun-like star", Nature 459 (7244): 224–226, doi:10.1038/nature08004, PMID 19444209, Bibcode: 2009Natur.459..224A.
- ↑ Aspin, Colin et al. (August 2010), "The 2008 Extreme Outburst of the Young Eruptive Variable Star EX Lupi", The Astrophysical Journal Letters 719 (1): L50–L55, doi:10.1088/2041-8205/719/1/L50, Bibcode: 2010ApJ...719L..50A.
Further reading
- White, J. et al. (January 2021), "Radio Observations of EX Lupi's disk post-outburst", Bulletin of the American Astronomical Society 53 (1), 2021n1i229p06, Bibcode: 2021AAS...23722906W.
- White, Jacob Aaron et al. (November 2020), "ALMA and VLA Observations of EX Lupi in Its Quiescent State", The Astrophysical Journal 904 (1): 12, doi:10.3847/1538-4357/abbb94, 37, Bibcode: 2020ApJ...904...37W.
- Rigliaco, E. et al. (September 2020), "The circumstellar environment of EX Lupi: SPHERE and SINFONI views", Astronomy & Astrophysics 641: 10, doi:10.1051/0004-6361/202038337, A33, Bibcode: 2020A&A...641A..33R.
- Banzatti, A. et al. (January 2015), "Depletion of Molecular Gas by an Accretion Outburst in a Protoplanetary Disk", The Astrophysical Journal Letters 798 (1): 6, doi:10.1088/2041-8205/798/1/L16, L16, Bibcode: 2015ApJ...798L..16B.
- Kóspál, Á. et al. (January 2014), "Radial velocity variations in the young eruptive star EX Lupi", Astronomy & Astrophysics 561: 12, doi:10.1051/0004-6361/201322428, A61, Bibcode: 2014A&A...561A..61K.
- Teets, William K. et al. (November 2012), "Detection of a Cool, Accretion-shock-generated X-Ray Plasma in EX Lupi during the 2008 Optical Eruption", The Astrophysical Journal 760 (1): 10, doi:10.1088/0004-637X/760/1/89, 89, Bibcode: 2012ApJ...760...89T.
- Sicilia-Aguilar, A. et al. (August 2012), "Optical spectroscopy of EX Lupi during quiescence and outburst. Infall, wind, and dynamics in the accretion flow", Astronomy & Astrophysics 544: 48, doi:10.1051/0004-6361/201118555, A93, Bibcode: 2012A&A...544A..93S.
- Banzatti, A. et al. (January 2012), "EX Lupi from Quiescence to Outburst: Exploring the LTE Approach in Modeling Blended H2O and OH Mid-infrared Emission", The Astrophysical Journal 745 (1): 16, doi:10.1088/0004-637X/745/1/90, 90, Bibcode: 2012ApJ...745...90B.
- Kóspál, Á. et al. (July 2011), "Near-infrared Spectroscopy of EX Lupi in Outburst", The Astrophysical Journal 736 (1): 11, doi:10.1088/0004-637X/736/1/72, 72, Bibcode: 2011ApJ...736...72K.
- Goto, M. et al. (February 2011), "Fundamental Vibrational Transition of CO During the Outburst of EX Lupi in 2008", The Astrophysical Journal 728 (1): 13, doi:10.1088/0004-637X/728/1/5, 5, Bibcode: 2011ApJ...728....5G.
- Grosso, N. et al. (November 2010), "A few days before the end of the 2008 extreme outburst of EX Lupi: accretion shocks and a smothered stellar corona unveiled by XMM-Newton", Astronomy and Astrophysics 522: 10, doi:10.1051/0004-6361/200913850, A56, Bibcode: 2010A&A...522A..56G.
- Sipos, N. et al. (October 2009), "Emission lines in EX Lup optical spectrum", VizieR On-line Data Catalog: J/A+A/507/881, doi:10.26093/cds/vizier.35070881, Bibcode: 2009yCat..35070881S.
- Patten, B. M. (July 1994), "Optical Spectroscopy and Photometry of EX Lupi", Information Bulletin on Variable Stars 4049 (1): 1, Bibcode: 1994IBVS.4049....1P.
- Jones, A. F. et al. (May 1993), Green, D. W. E., ed., "EX LUPI", IAU Circular 5791 (2): 2, Bibcode: 1993IAUC.5791....2J.
- Herbig, G. H. et al. (November 1992), "The Photometric Range of EX Lupi: a Correction to IBVS 3755", Information Bulletin on Variable Stars 3808 (1): 1, Bibcode: 1992IBVS.3808....1H.
- Bateson, F. M. et al. (1991), "Thirty-six years visual monitoring of the eruptive variable EX Lupi.", Publications of Variable Star Section (Royal Astronomical Society of New Zealand -) 16: 49–65, Bibcode: 1991PVSS...16...49B.
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