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V1400 Centauri

Coordinates: Sky map 14h 07m 47.930s, −39° 45′ 42.77″
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V1400 Centauri

V1400 Centauri imaged by the Dark Energy Survey
Observation data
Epoch J2000      Equinox J2000
Constellation Centaurus
Right ascension 14h 07m 47.92976s[1]
Declination −39° 45′ 42.7671″[1]
Apparent magnitude (V) 12.2–15.6[2]
Characteristics
Evolutionary stage Pre-main sequence[3]
Spectral type K5 IVe Li[3][4]
Variable type rotational T Tau and eclipsing[2]
Astrometry
Radial velocity (Rv)5.904±0.151[4] km/s
Proper motion (μ) RA: −23.108±0.015 mas/yr[1]
Dec.: −21.048±0.017 mas/yr[1]
Parallax (π)7.2351 ± 0.0140 mas[1]
Distance450.8 ± 0.9 ly
(138.2 ± 0.3 pc)
Details
MassGaia DR3 with magnetism:[5]
0.977+0.023
−0.045 M☉
Gaia DR3 without magnetism:[5]
0.891+0.062
−0.144 M☉
Gaia DR2:[6]: 2 
0.95±0.10 M☉
Radius1.0661+0.0062
−0.0139[7] R☉
Luminosity0.3431+0.0067
−0.0064[7] L☉
Surface gravity (log g)4.302+0.0243
−0.0243[7] cgs
Temperature4343+24
−29[7] K
Metallicity [Fe/H]−0.1903+0.0448
−0.0422[7] dex
Rotation3.21±0.01 d[8]
Rotational velocity (v sin i)14.6±0.4[8] km/s
Age~16[3] or 21.38+4.30
−7.60[6]: 2  Myr
Other designations
V1400 Cen, GSC 07807-00004, 2MASS J14074792-3945427, 1SWASP J140747.93-394542.6[4]
Database references
SIMBADdata

V1400 Centauri (known under its SuperWASP catalog entry 1SWASP J140747.93−394542.6 or J1407) is a young, pre-main-sequence star that was eclipsed by a likely unbound substellar object with a circumstellar disk or rings (known as J1407b or Mamajek's Object) in April–May 2007. With an age around 20 million years, the star is about as massive as the Sun and is located in the constellation Centaurus at a distance of 451 light-years away from Earth. V1400 Centauri is a member of the Scorpius–Centaurus association, a stellar association of young stars moving at similar velocities.

The discovery of J1407b's 2007 eclipse of V1400 Centauri was announced in 2012 by a team of astronomers led by Eric E. Mamajek, who directed an analysis of photometric data from the Super Wide Angle Search for Planets (SuperWASP) sky survey. Mamajek's team hypothesized that J1407b is a substellar object that could either be orbiting the star as a planet or binary companion, or is a gravitationally unbound object that coincidentally passed in front of the star.[3] Later studies have since found evidence disfavoring the bound companion hypothesis, which leaves the unbound hypothesis as the most likely explanation for J1407b's nature: no additional eclipses in V1400 Centauri have been observed after 2007 nor during 1890–1990,[6][9] which leaves out very few possible orbits where the massive rings of J1407b can theoretically repeat eclipses of V1400 Centauri while being stable against the star's gravitational influence.[6]: 7 

High-resolution imaging by the Atacama Large Millimeter Array (ALMA) in 2017 revealed a single faint object near V1400 Centauri, which could either be a young substellar object surrounded by a circumstellar disk, or a background galaxy. This faint object is far enough away from V1400 Centauri that it cannot be gravitationally bound to the star, which makes it a very likely candidate for J1407b. However, the faint object has only been observed once, so it is not yet confirmed whether it is a moving foreground object or a stationary background galaxy. If this faint object is a substellar object, then it would have a mass below 6 Jupiter masses, which would also make it a sub-brown dwarf or a rogue planet.[10]

Star properties[edit]

Location and age[edit]

V1400 Centauri is located in the constellation Centaurus.
V1400 Centauri is located in the constellation Centaurus.
V1400 Centauri
class=notpageimage|
Location of V1400 Centauri in the constellation Centaurus

V1400 Centauri is located in the constellation Centaurus, about 40 degrees south of the celestial equator. The most recent parallax measurements by the Gaia spacecraft indicate V1400 Centauri is located 450.8 ± 0.9 light-years (138.2 ± 0.3 parsecs) from Earth.[1] Observations of V1400 Centauri's position over time have shown that it has a southwestward[a] proper motion consistent with that of the Scorpius–Centaurus association, an OB association of young stars with ages between 11–17 million years and distances between 380–470 ly (118–145 pc) from Earth.[3]: 4  The Scorpius–Centaurus association is the nearest OB association to Earth, and is believed to have formed out of a molecular cloud that has since dispersed. V1400 Centauri is closest to the Upper Centaurus–Lupus subgroup of the Scorpius–Centaurus association, which has an age range of 14–18 million years and distance range of 380–460 ly (115–141 pc).[3]: 5-6  Given V1400 Centauri's similar distance and proper motion, it very likely belongs to the Scorpius–Centaurus association, which would mean it must be a young star within the age range of the Upper Centaurus–Lupus subgroup.[3]: 5-6  A 2012 estimate of V1400 Centauri's age assumes it is equal to 16 million years,[3]: 6  the mean age of the Upper Centaurus–Lupus subgroup, while a 2018 estimate from Gaia measurements puts the star's age at 21.38+4.30
−7.60 million years.[6]: 2 

Spectral type and physical characteristics[edit]

V1400 Centauri is a pre-main sequence star of spectral class K5 IVe Li.[4][3]: 5  "K" means V1400 Centauri is an orange K-type star, and the adjoining number "5" ranks V1400 Centauri's relative temperature on a scale of 9 (coolest) to 0 (hottest) for K-type stars. V1400 Centauri is given the subgiant luminosity class "IV", because it has a brighter luminosity than K-type main-sequence stars (luminosity class V).[3]: 5 [b] The letter "e" indicates V1400 Centauri exhibits weak hydrogen-alpha emission lines in its visible light spectrum.[3]: 5  Lastly, "Li" indicates V1400 Centauri is abundant in lithium.[3]: 5 

Measurements from the Gaia spacecraft's third and most recent data release (Gaia DR3) indicate V1400 Centauri is about 7% larger than the Sun in radius (1.07 R☉; 740,000 km; 460,000 mi),[7] but is slightly less massive than the Sun.[5][6]: 2  Depending on whether magnetic effects are taken into account in V1400 Centauri's stellar evolution or not, the star's mass could be either 0.98 M☉ or 0.89 M☉, respectively.[5]: 4  Young stars tend to be magnetically active,[11] and neglecting their magnetic effects results in an underestimation of their mass.[5]: 4, 9  An older estimate of V1400 Centauri's mass from Gaia's second data release (Gaia DR2) in 2018 gives 0.95 M☉, but does not take magnetic effects into account.[6]: 2 

V1400 Centauri is cooler and less luminous than the Sun, with an effective temperature of about 4,300 K (4,030 °C; 7,280 °F) and a luminosity about 34% that of the Sun.[7] V1400 Centauri has an estimated surface gravity of about 200 m/s2 (over 20 times the gravity of Earth), based on Gaia measurements of the star's brightness, distance, and color.[1][c] Gaia measurements also indicate V1400 Centauri has a lower metallicity than the Sun.[1][d] Viewed from Earth, V1400 Centauri appears slightly redder than a typical K5-type star due to light extinction by interstellar dust between Earth and the star.[8]: 5  The star does not exhibit excess thermal emission in near- and mid-infrared wavelengths and lacks strong emission lines in its spectrum, which indicates it lacks a substantial accretion disk.[3]: 10 

Rotation and variability[edit]

V1400 Centauri rotates rapidly with a rotation period of 3.21±0.01 days.[8] Spectroscopic measurements of Doppler broadening in V1400 Centauri's absorption lines indicate a projected rotational velocity of 14.6±0.4 km/s. V1400 Centauri's true equatorial rotation velocity is 15.7±1.7 km/s,[8]: 8  which indicates that the star's rotation axis is inclined 68°±10° with respect to Earth's line of sight.[8]: 1 

V1400 Centauri is the variable star designation of this star, assigned in 2015.[12] It is known to be a young star, not yet on the main sequence, and is classified as a T Tauri variable which shows variability as it rotates due to starspots.[2] It also underwent a series of deep eclipse-like fadings in 2007 that have been ascribed to the coincidental transit of J1407b, a likely unbound substellar object with a circumstellar disk.[9]

The rotation of the V1400 Centauri every 3.2 days causes regular brightness changes with an amplitude of about 0.1 magnitudes. The star is also intrinsically variable, as is common for pre-main-sequence stars, with a slow decrease in brightness being shown over the periods 2001 to 2007 and 2012 to 2020. The 2007 eclipse was up to three magnitudes in depth.[9] By 2021, it was discovered the parent star is strongly variable, with a 5.4-year long magnetic activity cycle, and no evidence was detected of additional planets or a repeat of the deep eclipses attributed to a transiting ring system.[9]

2007 eclipse[edit]

Visual-band light curve of V1400 Centauri, showing the 2007 eclipse. The main plot shows the SuperWASP data.[13] The inset plot, adapted from Mamajek et al.,[3] shows the data near mid-eclipse. The purple markers show the pairs of small brightness dips due to eclipses by rings.
Artist's impression of a circumstellar disk eclipsing a star, similar to J1407b's eclipse of V1400 Centauri in 2007
Diagram of the hypothesized V1400 Centauri planetary system, with J1407's supposed planetary rings shown to scale. The range of possible elliptical orbits for J1407b is shown in red.
Artist's impression of OTS 44, a young brown dwarf surrounded by a dusty circumstellar disk. J1407b most likely resembles this if it is an unbound young substellar object.

The discovery of the J1407 system and its unusual eclipses were first reported by a team led by University of Rochester astronomer Eric Mamajek in 2012.[3] The existence and parameters of the ring system around the substellar companion J1407b were deduced from the observation of a very long and complex eclipse of the parent star lasting 56 days during April and May 2007.[3][14] The low-mass companion J1407b has been referred to as a "Saturn on steroids"[15][16] or "Super Saturn"[17] due to its massive system of circumplanetary rings with a radius of approximately 90 million km (0.6 AU).[18] The orbital period of J1407b is estimated to be around a decade (3.5 to 13.8 years or 3825 days), and its most probable mass is approximately 13 to 26 Jupiter masses which would make the companion a brown dwarf but with considerable uncertainty.[18] The ringed body can be ruled out as being a star with mass of over 80 Jupiter masses at greater than 99% confidence.[18] The ring system has an estimated mass similar to that of the Earth.[19] A major gap in the rings at about 61 million km (0.4 AU) from its center is considered to be indirect evidence of the existence of a shepherd exomoon with mass up to 0.8 Earth masses,[18] but the exomoon hypothesis was challenged by a 2019 study.[20]

J1407b is the first exoplanet or brown dwarf discovered with a ring system by the transit method. A sequence of occultations (eclipses) of the star occurred over a 56-day period in 2007. The pattern was consistent with that expected for the transit of a large array of multiple rings, indicating the substellar companion dubbed "J1407b".[3] The J1407b ring system has an outer radius of approximately 90 million km (about 640 times the extent of Saturn's rings).[21] Cleared gaps in the rings indicate satellites ("exomoons") have accreted from denser rings. The young age of the stellar system (about 16 million years) and the high mass of the ring system (roughly an Earth mass) are more consistent with it being an early (proto-)exomoon or moons, rather than a long-term stable ring system in an evolved planetary system (such as Saturn's rings).

J1407b has not been observed since its transit in 2007, suggesting that it may be on a highly eccentric orbit around the star.[22] Such an orbit could disrupt the ring system of J1407b.[15] Dynamical simulations run by astronomers Steven Rieder and Matthew Kenworthy indicate that in order for J1407b's ring system to be stable, the rings must orbit J1407b in a retrograde motion, opposite to the direction J1407b orbits its host star.[22][15] This retrograde solution for the ring system of J1407b allows for longer ring lifetimes as well as further constraints to the age of the ring system.[22] The rings may be replenished over timescales as a result of processes that produce additional debris around J1407b, such as the tidal disruption of comets.[22]

Alternatively, J1407b may also not be bound to J1407. The previous explanation involving J1407b orbiting J1407 would have J1407b as a brown dwarf companion with a large, Hill sphere filling ring system. However, issues with the stability of any rings combined with the lack of detection of another eclipse, suggests that J1407b may not be bound to J1407.[6] No other deep eclipses has been found in the data spanning from 1890 to 1990, nor in recent time-series photometry from 2012-2018. A significant proportion of orbital periods for J1407b from 5 to 20 years can be disregarded, therefore if there is an actual orbital period it is likely outside of this range.[6]

A search for J1407b with ALMA did not detect any bound companion, but did detect a point source consistent with an unbound object of 4-6 MJ. This may be the object which transited J1407 in 2007, or it may be a background galaxy or an artifact, which is considered less likely.[10]

From Earth's point of view, the ring system of J1407b would have an angular diameter of about 3.7 milliarcseconds across. For comparison, if Saturn were as many light years away, its rings in full breadth would be 0.006 milliarcseconds across,[1] and the diameter of Pluto from Earth varies between 60 and 110 milliarcseconds across.[23]

The V1400 Centauri planetary system[24][20]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b (unconfirmed) 20.0±6.0 MJ 3.9±1.7 3725±900 >0.6 — —

No additional transits from Jupiter-sized or larger planets were discovered in a 21-year long observational series by 2023.[9]

See also[edit]

Notes[edit]

  1. ^ Proper motion is split into right ascension (RA) and declination (Dec) components. By convention, positive RA is eastward and positive Dec is northward in the equatorial coordinate system. The measured proper motion components of V1400 Centauri are −23.108±0.015 mas/yr and −21.048±0.017 mas/yr in RA and Dec, respectively.[1] Since both RA and Dec components of V1400 Centauri's proper motion are negative, its proper motion is pointed towards the west and south directions, hence southwest.
  2. ^ The term "subgiant" and its associated luminosity class "IV" can either refer to the life stage between the main-sequence and giant phases near the end of a star's life, or it can strictly refer to a star's luminosity only. In the case of V1400 Centauri, the latter definition is used since it is appropriate for the star's young age.
  3. ^ The Gaia DR3 table gives log g = 4.302 as the base 10 logarithm of surface gravity in cgs units.[1] Raising 10 to the power of log g gives the star's surface gravity g in cgs units of cm/s2; converting this to the SI acceleration units of m/s2 gives g ≈ 200.4 m/s2 for the V1400 Centauri's surface gravity.
  4. ^ The Gaia DR3 table gives the [Fe/H] metallicity (iron abundance relative to the Sun) as a base 10 logarithmic quantity. V1400 Centauri has a negative [Fe/H] metallicity of –0.1903, which indicates a lower iron abundance than the Sun.[1]

References[edit]

  1. ^ a b c d e f g h i j Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. ^ a b c "V1400 Cen". International Variable Star Index. AAVSO. Archived from the original on 1 August 2023. Retrieved 1 August 2023.
  3. ^ a b c d e f g h i j k l m n o p q Mamajek, Eric E.; Quillen, Alice C.; Pecaut, Mark J.; Moolekamp, Fred; Scott, Erin L.; Kenworthy, Matthew A.; Collier Cameron, Andrew; Parley, Neil R. (March 2012). "Planetary Construction Zones in Occultation: Discovery of an Extrasolar Ring System Transiting a Young Sun-like Star and Future Prospects for Detecting Eclipses by Circumsecondary and Circumplanetary Disks". The Astronomical Journal. 143 (3): 72. arXiv:1108.4070. Bibcode:2012AJ....143...72M. doi:10.1088/0004-6256/143/3/72. S2CID 55818711.
  4. ^ a b c d "V* V1400 Cen". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 23 May 2024.
  5. ^ a b c d e Fernandes, Rachel B.; Hardegree-Ullman, Kevin K.; Pascucci, Ilaria; Bergsten, Galen J.; Mulders, Gijs D.; Cunha, Katia; et al. (October 2023). "Using Photometrically Derived Properties of Young Stars to Refine TESS's Transiting Young Planet Survey Completeness". The Astronomical Journal. 166 (4): 12. arXiv:2308.13039. Bibcode:2023AJ....166..175F. doi:10.3847/1538-3881/acf4f0. 404.04. Gaia DR3 data table and mass estimates for V1400 Centauri at VizieR.
  6. ^ a b c d e f g h i Mentel, R. T.; Kenworthy, M. A.; Cameron, D. A.; Scott, E. L.; Mellon, S. N.; Hudec, R.; Birkby, J. L.; Mamajek, E. E.; Schrimpf, A.; Reichart, D. E.; Haislip, J. B.; Kouprianov, V. V.; Hambsch, F.-J.; Tan, T.-G.; Hills, K. (November 2018). "Constraining the period of the ringed secondary companion to the young star J1407 with photographic plates". Astronomy & Astrophysics. 619: A157. arXiv:1810.05171. Bibcode:2018A&A...619A.157M. doi:10.1051/0004-6361/201834004. ISSN 0004-6361. S2CID 55015149.
  7. ^ a b c d e f g Gaia Collaboration (May 2022). "VizieR Online Data Catalog: Gaia DR3 Part 1. Main source". VizieR. Centre de données astronomiques de Strasbourg. Bibcode:2022yCat.1355....0G. doi:10.26093/cds/vizier.1355.
  8. ^ a b c d e f Kenworthy, M. A.; Lacour, S.; et al. (January 2015). "Mass and period limits on the ringed companion transiting the young star J1407". Monthly Notices of the Royal Astronomical Society. 446 (1): 411–427. arXiv:1410.6577. Bibcode:2015MNRAS.446..411K. doi:10.1093/mnras/stu2067.
  9. ^ a b c d e Barmentloo, S.; Dik, C.; Kenworthy, M. A.; Mamajek, E. E.; Hambsch, F.-J.; Reichart, D. E.; Rodriguez, J. E.; Van Dam, D. M. (2021), "A search for transiting companions in the J1407 (V1400 Cen) system", Astronomy & Astrophysics, 652: A117, arXiv:2106.15902, Bibcode:2021A&A...652A.117B, doi:10.1051/0004-6361/202140768, S2CID 235683556
  10. ^ a b Kenworthy, M. A.; Klaassen, P. D.; et al. (January 2020). "ALMA and NACO observations towards the young exoring transit system J1407 (V1400 Cen)". Astronomy & Astrophysics. 633: A115. arXiv:1912.03314. Bibcode:2020A&A...633A.115K. doi:10.1051/0004-6361/201936141.
  11. ^ Mathur, Savita; Claytor, Zachary R.; Santos, Ângela R. G.; García, Rafael A.; Amard, Louis; Bugnet, Lisa; et al. (June 2023). Evolution of rotation and magnetic activity of solar-like stars with age:magneto-(gyro-)chronology. PLATO Stellar Science Conference 2023. Milazzo, Italy. Bibcode:2023plat.confE..36M. doi:10.5281/zenodo.8140785. 404.04.
  12. ^ Kazarovets, E. V; Samus, N. N; Durlevich, O. V; Kireeva, N. N; Pastukhova, E. N (2015). "The 81st Name-List of Variable Stars. Part I - RA 00h to 17h30". Information Bulletin on Variable Stars. 6151: 1. Bibcode:2015IBVS.6151....1K.
  13. ^ "Search SuperWASP Time Series". NASA Exoplanet Archive. NASA. Archived from the original on 27 November 2022. Retrieved 27 November 2022.
  14. ^ "Eclipsing Ring System J1407". Cerro Tololo Inter-American Observatory. 22 June 2012. Archived from the original on 12 July 2017. Retrieved 27 January 2015.
  15. ^ a b c St. Fleur, Nicholas (13 October 2016). "Distant Ringed Object Could Be 'Saturn on Steroids'". New York Times. Archived from the original on 20 May 2018. Retrieved 14 October 2016.
  16. ^ O'Neill, Ian (12 January 2012). "'Saturn on Steroids' Exoplanet Discovered?". Discovery News. Archived from the original on 11 March 2016. Retrieved 27 January 2014.
  17. ^ Gigantic ring system around J1407b much larger, heavier than Saturn's Archived 2017-12-25 at the Wayback Machine, on University of Rochester website.
  18. ^ a b c d Kenworthy, Matthew A.; Mamajek, Eric E. (22 January 2015). "Modeling giant extrasolar ring systems in eclipse and the case of J1407b: sculpting by exomoons?". The Astrophysical Journal. 800 (2): 126. arXiv:1501.05652. Bibcode:2015ApJ...800..126K. doi:10.1088/0004-637X/800/2/126. S2CID 56118870.
  19. ^ "Gigantic ring system around J1407b much larger, heavier than Saturn's". University of Rochester. 26 January 2015. Archived from the original on 21 August 2017. Retrieved 27 January 2015.
  20. ^ a b Sutton, P. J. (2019). "Mean motion resonances with nearby moons: an unlikely origin for the gaps observed in the ring around the exoplanet J1407b". Monthly Notices of the Royal Astronomical Society. 486 (2): 1681–1689. arXiv:1902.09285. Bibcode:2019MNRAS.486.1681S. doi:10.1093/mnras/stz563. S2CID 119546405.
  21. ^ Brumfield, Ben (28 January 2015). "Discovery: 'Super Saturn' with rings 200 times as big". CNN.com. Archived from the original on 8 November 2020. Retrieved 1 June 2017.
  22. ^ a b c d Rieder, Steven; Kenworthy, Matthew A. (21 November 2016). "Constraints on the size and dynamics of the J1407b ring system". Astronomy & Astrophysics. 596 (A9): A9. arXiv:1609.08485. Bibcode:2016A&A...596A...9R. doi:10.1051/0004-6361/201629567. S2CID 118413749.
  23. ^ Pluto Fact Sheet Archived 2018-05-09 at the Wayback Machine, NASA
  24. ^ "The Extrasolar Planet Encyclopaedia — 1SWASP J1407 b". Extrasolar Planets Encyclopaedia. 29 October 2014. Archived from the original on 9 November 2023. Retrieved 1 June 2017.

External links[edit]

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