NML Cygni

Last updated
NML Cygni
NML Cygni SDSS DR9.jpg
NML Cygni, seen as the deep red star at the center, from the Sloan Digital Sky Survey DR9. Note the green circumstellar nebula surrounding the star.
Observation data
Epoch J2000.0        Equinox J2000.0
Constellation Cygnus
Right ascension 20h 46m 25.54s [1]
Declination +40° 06′ 59.5″ [1]
Apparent magnitude  (V)16.60 (variable) [2]
Characteristics
Evolutionary stage OH/IR [3] red hypergiant [4]
Spectral type M4.5–M7.9 Ia–III [5]
Apparent magnitude  (K)0.791±0.204 [1]
Apparent magnitude  (G)11.148 [1]
Apparent magnitude  (J)4.877±0.037 [1]
Apparent magnitude  (H)2.389±0.2 [1]
B−V color index +2.04 [2]
Variable type Semiregular variable star [6]
Astrometry
Proper motion (μ)RA: −1.55 [4]   mas/yr
Dec.: −4.59 [4]   mas/yr
Parallax (π)0.620 ± 0.047  mas [4]
Distance 5,250+420
−360  ly
(1,610+130
−110 [4]   pc)
Details
Mass 25 [4] (initial)  M☉
Radius <1,350+195
−229 [7] [lower-alpha 1]   R☉
Luminosity 229,000+40,000
−41,000 [9]   L☉
Age 8 [4]   Myr
Other designations
NML Cyg, V1489  Cyg, RAFGL  2650, IRC  +40448, 2MASS  J20462554+4006594, AAVSO  2042+39
Database references
SIMBAD data

NML Cygni or V1489 Cygni (abbreviated to NML Cyg or V1489 Cyg) is a red hypergiant [4] or red supergiant (RSG) in the constellation Cygnus. It is possibly one of the largest known stars currently known, and is also possibly one of the most luminous and massive cool hypergiants, as well as one of the most luminous stars in the Milky Way.

Contents

The distance of NML Cygni from Earth is estimated to be around 1.6 kpc, about 5,300  light-years . [10] It is a part of the Cygnus OB2 association, one of the closest massive associations to the Sun, spanning nearly 2° on the sky or ~30 pc in radius at the distance of 1.74±0.2 kpc. [11] Based on the estimated distance and a measurement of its angular diameter of 7.8±0.64  milliarcseconds , [8] NML Cygni's physical radius is of 1,350  R☉. If placed at the center of the Solar System, its surface would potentially extend past the orbit of Jupiter.

Observational history

A near infrared (3.5 micron) light curve for V1489 Cygni, plotted from data published by Strecker (1975) V1489CygLightCurve.png
A near infrared (3.5 micron) light curve for V1489 Cygni, plotted from data published by Strecker (1975)

NML Cygni was discovered in 1965 by American astronomers Neugebauer, Martz, and Leighton who described two extremely red luminous stars, their colour being consistent with a black body temperature of 1,000 K. [13] The name NML comes from the names of these three discoverers. [14] The second star was briefly referred to as NML Tauri [15] but is now known as IK Tauri, [16] an M9 Mira variable. NML Cygni has since also been given the designation V1489 Cygni on account of the small semi-regular brightness variations, [17] but is still most commonly referred to as NML Cygni. Its composition began to be revealed with the discovery of OH masers (1612 MHz) in 1968. [18] H
2O , SiO , CO , HCN , CS , SO , SO
2 , and H
2S molecules have also been detected. [19]

Physical characteristics

H-alpha light image of Cygnus OB2, the stellar association in which NML Cygni is located CygOB2 med.jpg
H-alpha light image of Cygnus OB2, the stellar association in which NML Cygni is located

NML Cygni is an extremely large and luminous cool supergiant with parameters similar to that of another notable but more extreme cool hypergiant star, VY Canis Majoris, and is also known as a heavily mass-losing OH/IR supergiant. It is also a semiregular variable star with a period of either 1,280 or 940 days. [11] [5] It occupies the upper-right hand corner of the Hertzsprung–Russell diagram although most of the properties of the star depend directly on its distance.

Size, luminosity, and temperature

The bolometric luminosity (Lbol) for NML Cygni was originally calculated to be 500,000 L☉ at an assumed distance of 2  kpc and the radius was calculated to be 3,700 R☉ based on an 8.6  mas angular diameter and distance. [20] [21] [22] A 2006 study, similar to those conducted on VY Canis Majoris, suggests that NML Cygni is a normal red supergiant with consequently much lower luminosity and radius values. [23] More modern and accurate measurements give a distance around 1.6 kpc, which gives a luminosity around 200,000 L☉. A radio angular diameter of 44 mas was given based on the distance, suggesting the optical angular diameter may be around 22 mas. [4] This distance and a luminosity of 270,000 L☉ were combined with assumptions of the effective temperature of the star, giving a radius of 1,640 R☉ for a temperature of 3,250 K or possibly 2,770 R☉ for a temperature of 2,500 K. [lower-alpha 2] [4] However, another paper gives a much lower radius of 1,183 R☉ based on an assumed effective temperature of 3,834 K and a lower distance of 1.22 kpc. [6] There is a Gaia Data Release 2 parallax for NML Cygni of 1.5259±0.5677  mas , but the underlying measurements show a considerable level of noise and the parallax is considered unreliable. [24]

NML Cygni's uniform disk angular diameter was measured by the CHARM2 survey, leading to an apparent size of 7.8±0.64  milliarcseconds . [8] Assuming the distance measured by Zhang et al. (2012) (1610+130
−110  parsecs ), [4] it leads to a physical radius of 1,350 R☉. [7] If placed in the center of the Solar System, its photosphere would past the orbit of Jupiter. NML Cygni is covered by a complex dust shell, so the measured angular diameter likely contain some parts of this disk, and therefore its physical radius may be smaller. [25]

Mass and mass loss

NML Cygni lies close to the expected position that a 25 M☉ star would evolve to after eight million years. [4]

NML Cygni is evolved and a number of heavy elements and molecules have been detected in its atmosphere, particularly oxygen, hydroxyl, and water. It is surrounded by dusty material [4] [11] and it exhibits a bean-shaped asymmetric nebula that is coincident with the distribution of its H2O vapor masers. [26]

NML Cygni has an estimated mass loss rate of 4.2 to 4.8×10−4 M☉ per year, [3] one of the highest known for any star. The annual parallax of NML Cygni is measured to be around 0.62 milliarcseconds. [4] From the observations, it is estimated that NML Cygni has two discrete optically thick envelopes of dust and molecules. The optical depth of the inner shell is found to be 1.9, whereas that of the outer one is 0.33. [27] These dust envelopes are formed due to the strong post-main-sequence wind, which has a velocity 23 km/s. [11]

Because of the star's position on the outskirts of the massive Cygnus OB2 association, the detectable effects of NML Cygni's radiation on the surrounding dust and gas are limited to the region away from the central hot stars of the association. [11]

See also

Notes

  1. ↑ Surrounding dusty region is very complex making the radius hard to determine. [8]
  2. ↑ Applying the Stefan-Boltzmann Law with a nominal solar effective temperature of 5,772  K:

Related Research Articles

<span class="mw-page-title-main">Red supergiant</span> Stars with a supergiant luminosity class with a spectral type of K or M

Red supergiants (RSGs) are stars with a supergiant luminosity class and a stellar classification K or M. They are the largest stars in the universe in terms of volume, although they are not the most massive or luminous. Betelgeuse and Antares A are the brightest and best known red supergiants (RSGs), indeed the only first magnitude red supergiant stars.

<span class="mw-page-title-main">Mu Cephei</span> Red supergiant star in the constellation Cepheus

Mu Cephei, also known as Herschel's Garnet Star, Erakis, or HD 206936, is a red supergiant or hypergiant star in the constellation Cepheus. It appears garnet red and is located at the edge of the IC 1396 nebula. Since 1943, the spectrum of this star has served as a spectral standard by which other stars are classified.

<span class="mw-page-title-main">KY Cygni</span> Star in the constellation Cygnus

KY Cygni is a red supergiant of spectral class M3.5Ia located in the constellation Cygnus. It is approximately 4,700 light-years away.

<span class="mw-page-title-main">MY Cephei</span> Red supergiant star in the constellation Cepheus

MY Cephei is a red supergiant located in open cluster NGC 7419 in the constellation of Cepheus. It is a semiregular variable star with a maximum brightness of magnitude 14.4 and a minimum of magnitude 15.5.

<span class="mw-page-title-main">Cygnus OB2-12</span> Blue hypergiant star

Cygnus OB2 #12 is an extremely luminous blue hypergiant with an absolute bolometric magnitude of −10.9, among the most luminous stars known in the galaxy. This makes the star nearly two million times more luminous than the Sun, although estimates were even higher when the star was first discovered. It is now known to be a binary, with the companion approximately a tenth as bright. A very approximate initial estimate of the orbit gives the total system mass as 120 M☉ and the period as 30 years.

<span class="mw-page-title-main">S Persei</span> Red supergiant or hypergiant variable star in the constellation Perseus

S Persei is a red supergiant or hypergiant located near the Double Cluster in Perseus, north of the cluster NGC 869. It is a member of the Perseus OB1 association and one of the largest known stars. If placed in the Solar System, its photosphere would engulf the orbit of Jupiter. It is also a semiregular variable, a star whose variations are less regular than those of Mira variables.

<span class="mw-page-title-main">RW Cephei</span> Hypergiant star in the constellation Cepheus

RW Cephei is a K-type hypergiant and a semirregular variable star in the constellation Cepheus, at the edge of the Sharpless 132 H II region and close to the small open cluster Berkeley 94. It is among the largest stars known with a radius of 1,100 times that of the Sun (R☉), nearly as large as the orbit of Jupiter.

<span class="mw-page-title-main">WOH G64</span> Red supergiant in the constellation Dorado

WOH G64 is an unusual red supergiant (RSG) star in the Large Magellanic Cloud (LMC) satellite galaxy in the southern constellation of Dorado. It is the largest known star whose radius has been verified. It is also one of the most luminous and massive red supergiants, with a radius calculated to be around 1,540 times that of the Sun (R☉) and a luminosity around 282,000 times the solar luminosity (L☉).

<span class="mw-page-title-main">VY Canis Majoris</span> Star in the constellation Canis Major

VY Canis Majoris is an extreme oxygen-rich red hypergiant or red supergiant and pulsating variable star 1.2 kiloparsecs from the Solar System in the slightly southern constellation of Canis Major. It is one of the largest known stars, one of the most luminous and massive red supergiants, and one of the most luminous stars in the Milky Way.

<span class="mw-page-title-main">Hypergiant</span> Rare star with tremendous luminosity and high rates of mass loss by stellar winds

A hypergiant (luminosity class 0 or Ia+) is a very rare type of star that has an extremely high luminosity, mass, size and mass loss because of its extreme stellar winds. The term hypergiant is defined as luminosity class 0 (zero) in the MKK system. However, this is rarely seen in literature or in published spectral classifications, except for specific well-defined groups such as the yellow hypergiants, RSG (red supergiants), or blue B(e) supergiants with emission spectra. More commonly, hypergiants are classed as Ia-0 or Ia+, but red supergiants are rarely assigned these spectral classifications. Astronomers are interested in these stars because they relate to understanding stellar evolution, especially star formation, stability, and their expected demise as supernovae. Notable examples of hypergiants include the Pistol Star, a blue hypergiant located close to the Galactic Center and one of the most luminous stars known; Rho Cassiopeiae, a yellow hypergiant that is one of the brightest to the naked eye; and Mu Cephei (Herschel's "Garnet Star"), one of the largest and brightest stars known.

<span class="mw-page-title-main">Cygnus OB2</span> Cluster of massive and luminous stars

Cygnus OB2 is an OB association that is home to some of the most massive and most luminous stars known, including suspected Luminous blue variable Cyg OB2 #12. It also includes one of the largest known stars, NML Cygni. The region is embedded within a wider one of star formation known as Cygnus X, which is one of the most luminous objects in the sky at radio wavelengths. The region is approximately 1,570 parsecs from Earth in the constellation of Cygnus.

<span class="mw-page-title-main">OH/IR star</span>

An OH/IR star is an asymptotic giant branch (AGB) or a red supergiant or hypergiant star that shows strong OH maser emission and is unusually bright at near-infrared wavelengths.

<span class="mw-page-title-main">UY Scuti</span> Star in the constellation Scutum

UY Scuti (BD-12°5055) is a red supergiant star, located 5,900 light-years away in the constellation Scutum. It is also a pulsating variable star, with a maximum brightness of magnitude 8.29 and a minimum of magnitude 10.56, which is too dim for naked-eye visibility. It is considered to be one of the largest known stars, with a radius estimated at 909 solar radii, thus a volume of 750 million times that of the Sun. This estimate implies if it were placed at the center of the Solar System, its photosphere would extend past the orbit of Mars or even the asteroid belt.

AH Scorpii is a red supergiant variable star located in the constellation Scorpius. It is one of the largest stars known by radius and is also one of the most luminous red supergiant stars in the Milky Way.

<span class="mw-page-title-main">HR 5171</span> Star in the constellation Centaurus

HR 5171, also known as V766 Centauri, is a yellow hypergiant in the constellation Centaurus. It is said to be either an extreme red supergiant (RSG) or recent post-red supergiant (Post-RSG) yellow hypergiant (YHG), both of which suggest it is one of the largest known stars. The star's diameter is uncertain but likely to be between 1,100 and 1,600 times that of the Sun. It is 3.6 kpc from Earth.

<span class="mw-page-title-main">BC Cygni</span> Star in the constellation Cygnus

BC Cygni is a red supergiant and pulsating variable star of spectral type M3.5Ia in the constellation Cygnus.

<span class="mw-page-title-main">RW Cygni</span> Star in the constellation Cygnus

RW Cygni is a semiregular variable star in the constellation Cygnus, about a degree east of 2nd magnitude γ Cygni. Its apparent magnitude varies between 8.05 and 9.70 and its spectral type between M3 and M4.

<span class="mw-page-title-main">BI Cygni</span> Star in the constellation Cygnus

BI Cygni(BI Cyg, IRC +40408, BD+36 4025) is a red supergiant in the constellation Cygnus. It is an irregular variable star with a maximum brightness of magnitude 8.4 and a minimum of magnitude 9.9. It is considered a member of the Cygnus OB1 stellar association, its distance is around 1,300 parsecs (4,200 ly) of the Solar System. It is less than a degree south of another variable red supergiant, BC Cygni.

Stephenson 2 DFK 49 or St2-11 is a putative post red supergiant star in the constellation Scutum, in the massive open cluster Stephenson 2. It is possibly one of the largest known stars with a radius estimated to be between 1,074 solar radii to 1,300 solar radii, corresponding to volumes of 1.2 and 2.2 times that of the Sun respectively. If it was placed at the center of the Solar System, its photosphere would potentially approach or engulf Jupiter's orbit. It loses mass at a very high rate, resulting in large amounts of infrared excess.

<span class="mw-page-title-main">AZ Cygni</span> Red supergiant star in the constellation Cygnus

AZ Cygni is a large red supergiant in the constellation of Cygnus. Located 2,090 parsecs from Earth, it has been studied by the CHARA array in order to understand the surface variations of red supergiants.

References

  1. 1 2 3 4 5 6 "NML Cyg". SIMBAD . Centre de données astronomiques de Strasbourg.
  2. 1 2 Johnson, Harold L.; Eugenio E., Mendoza V.; Wisniewski, Weislaw Z. (October 1965). "Observations of "Infrared Stars."". The Astrophysical Journal. 142: 1249. Bibcode:1965ApJ...142.1249J. doi:10.1086/148393. ISSN   0004-637X.{{cite journal}}: CS1 maint: date and year (link)
  3. 1 2 Gordon, Michael S.; Humphreys, Roberta M.; Jones, Terry J.; Shenoy, Dinesh; Gehrz, Robert D.; Helton, L. Andrew; Marengo, Massimo; Hinz, Philip M.; Hoffmann, William F. (2018). "Searching for Cool Dust. II. Infrared Imaging of the OH/IR Supergiants, NML Cyg, VX SGR, S Per, and the Normal Red Supergiants RS per and T per". The Astronomical Journal. 155 (5): 212. arXiv: 1708.00018 . Bibcode:2018AJ....155..212G. doi: 10.3847/1538-3881/aab961 . S2CID   73650032.
  4. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Zhang, B.; Reid, M. J.; Menten, K. M.; Zheng, X. W.; Brunthaler, A. (August 2012). "The distance and size of the red hypergiant NML Cygni from VLBA and VLA astrometry". Astronomy & Astrophysics. 544: A42. arXiv: 1207.1850 . doi:10.1051/0004-6361/201219587. ISSN   0004-6361.
  5. 1 2 "GCVS Query=V1489 Cyg". Sternberg Astronomical Institute. General Catalogue of Variable Stars @ Sternberg Astronomical Institute, Moscow, Russia . Retrieved 2018-09-21.
  6. 1 2 De Beck, E.; Decin, L.; De Koter, A.; Justtanont, K.; Verhoelst, T.; Kemper, F.; Menten, K. M. (2010). "Probing the mass-loss history of AGB and red supergiant stars from CO rotational line profiles. II. CO line survey of evolved stars: Derivation of mass-loss rate formulae". Astronomy and Astrophysics. 523: A18. arXiv: 1008.1083 . Bibcode:2010A&A...523A..18D. doi:10.1051/0004-6361/200913771. S2CID   16131273.
  7. 1 2 Lang, Kenneth R. (2006). Astrophysical formulae. Astronomy and astrophysics library. Vol. 1 (3rd ed.). Berlin: Springer. ISBN   978-3-540-29692-8.{{cite book}}: CS1 maint: date and year (link). The radius (R*) is given by:
  8. 1 2 3 Richichi, A.; Percheron, I.; Khristoforova, M. (2005-02-01). "CHARM2: An updated Catalog of High Angular Resolution Measurements". Astronomy & Astrophysics. 431 (2): 773–777. Bibcode:2005A&A...431..773R. doi:10.1051/0004-6361:20042039. ISSN   0004-6361. Data about NML Cygni is found here at VizieR.
  9. ↑ Davies, Ben; Beasor, Emma R. (March 2020). "The 'red supergiant problem': the upper luminosity boundary of Type II supernova progenitors". MNRAS . 493 (1): 468–476. arXiv: 2001.06020 . Bibcode:2020MNRAS.493..468D. doi: 10.1093/mnras/staa174 . S2CID   210714093.
  10. ↑ Schuster, Michael Thomas (2007). Investigating the Circumstellar Environments of the Cool Hypergiants. University of Minnesota. ISBN   978-0-549-32782-0.
  11. 1 2 3 4 5 Schuster, M. T.; Marengo, M.; Hora, J. L.; Fazio, G. G.; Humphreys, R. M.; Gehrz, R. D.; Hinz, P. M.; Kenworthy, M. A.; Hoffmann, W. F. (2009). "Imaging the Cool Hypergiant NML Cygni's Dusty Circumstellar Envelope with Adaptive Optics". The Astrophysical Journal. 699 (2): 1423–1432. arXiv: 0904.4690 . Bibcode:2009ApJ...699.1423S. doi:10.1088/0004-637X/699/2/1423. S2CID   17699562.
  12. ↑ Strecker, D. W. (June 1975). "Variability of R CrB and NML Cyg at 3.5 μ". The Astronomical Journal. 80 (6): 451–453. Bibcode:1975AJ.....80..451S. doi: 10.1086/111763 .
  13. ↑ Neugebauer, G.; Martz, D. E.; Leighton, R. B. (July 1965). "Observations of Extremely Cool Stars" (PDF). Astrophysical Journal . 142: 399–401. Bibcode:1965ApJ...142..399N. doi:10.1086/148300.
  14. ↑ Hearnshaw, J. B. (2 May 1996). "New infrared sources and their interpretation". The Measurement of Starlight: Two Centuries of Astronomical Photometry. Cambridge University Press. p.  278. ISBN   978-0-521-40393-1 . Retrieved 23 August 2012.
  15. ↑ Pesch, P. (1967). "Objective-Prism Spectra of Some Very Red Stars". The Astrophysical Journal. 147: 381. Bibcode:1967ApJ...147..381P. doi:10.1086/149015.
  16. ↑ Kukarkin, B. V.; Efremov, Yu. N.; Frolov, M. S.; Medvedeva, G. I.; et al. (8 November 1968). "Identification List of the New Variable Stars Nominated in 1968". Information Bulletin on Variable Stars . 311 (1): 1. Bibcode:1968IBVS..311....1K.
  17. ↑ Kukarkin, B. V.; Kholopov, P. N.; Kukarkina, N. P. (27 November 1975). "61st Name-List of Variable Stars". Information Bulletin on Variable Stars . 1068 (1): 1. Bibcode:1975IBVS.1068....1K.
  18. ↑ Cohen, R. J.; Downs, G.; Emerson, R.; Grimm, M.; et al. (1 April 1987). "Narrow polarized components in the OH 1612-MHz maser emission from supergiant OH-IR sources". Monthly Notices of the Royal Astronomical Society . 225 (3): 491–498. Bibcode:1987MNRAS.225..491C. doi: 10.1093/mnras/225.3.491 . PMID   11540900.
  19. ↑ Marvel, Kevin (19 December 1996). "NML Cygni". The Circumstellar Environment of Evolved Stars As Revealed by Studies of Circumstellar Water Masers. Universal-Publishers. pp. 182–212. ISBN   978-1-58112-061-5 . Retrieved 23 August 2012.
  20. ↑ Zubko, Viktor; Li, Di; Lim, Tanya; Feuchtgruber, Helmut; Harwit, Martin (2004). "Observations of Water Vapor Outflow from NML Cygnus". The Astrophysical Journal. 610 (1): 427. arXiv: astro-ph/0405044 . Bibcode:2004ApJ...610..427Z. doi:10.1086/421700. S2CID   14352419.
  21. ↑ Monnier, J. D; Bester, M; Danchi, W. C; Johnson, M. A; Lipman, E. A; Townes, C. H; Tuthill, P. G; Geballe, T. R; Nishimoto, D; Kervin, P. W (1997). "Nonuniform Dust Outflow Observed around Infrared Object NML Cygni". The Astrophysical Journal. 481 (1): 420. arXiv: astro-ph/9702103 . Bibcode:1997ApJ...481..420M. doi:10.1086/304050. S2CID   9503967.
  22. ↑ Monnier, J. D.; Millan-Gabet, R.; Tuthill, P. G.; Traub, W. A.; Carleton, N. P.; Coude Du Foresto, V.; Danchi, W. C.; Lacasse, M. G.; Morel, S.; Perrin, G.; Porro, I. L.; Schloerb, F. P.; Townes, C. H. (2004). "High-Resolution Imaging of Dust Shells by Using Keck Aperture Masking and the IOTA Interferometer". The Astrophysical Journal. 605 (1): 436–461. arXiv: astro-ph/0401363 . Bibcode:2004ApJ...605..436M. doi:10.1086/382218. S2CID   7851916.
  23. ↑ Massey, Philip; Levesque, Emily M.; Plez, Bertrand (1 August 2006). "Bringing VY Canis Majoris down to size: an improved determination of its effective temperature". The Astrophysical Journal. 646 (2): 1203–1208. arXiv: astro-ph/0604253 . Bibcode:2006ApJ...646.1203M. doi:10.1086/505025. S2CID   14314968.
  24. ↑ Xu, Shuangjing; Zhang, Bo; Reid, Mark J.; Zheng, Xingwu; Wang, Guangli (2019). "Comparison of Gaia DR2 Parallaxes of Stars with VLBI Astrometry". The Astrophysical Journal. 875 (2): 114. arXiv: 1903.04105 . Bibcode:2019ApJ...875..114X. doi: 10.3847/1538-4357/ab0e83 . S2CID   119192180.
  25. ↑ Type of source (Bin, Cal, Com, Diam, UR)
  26. ↑ Schuster, Michael T.; Humphreys, Roberta M.; Marengo, Massimo (January 2006). "The Circumstellar Environments of NML Cygni and the Cool Hypergiants". The Astronomical Journal. 131 (1): 603–611. arXiv: astro-ph/0510010 . Bibcode:2006AJ....131..603S. doi:10.1086/498395. ISSN   0004-6256.
  27. ↑ DanchiI, W. C.; Green, W. H.; Hale, D. D. S.; McEleroy, K.; et al. (July 2001). "Proper Motions of Dust Shells Surrounding NML Cygni". The Astrophysical Journal . 555 (1): 405. Bibcode:2001ApJ...555..405D. doi: 10.1086/322237 .
  28. Cutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E.; Fowler, John W.; Gizis, John E.; Howard, Elizabeth V.; Huchra, John P.; Jarrett, Thomas H.; Kopan, Eugene L.; Kirkpatrick, J. Davy; Light, Robert M.; Marsh, Kenneth A.; McCallon, Howard L.; Schneider, Stephen E.; Stiening, Rae; Sykes, Matthew J.; Weinberg, Martin D.; Wheaton, William A.; Wheelock, Sherry L.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues. 2246: II/246. Bibcode:2003yCat.2246....0C.
  29. Singh, A. P.; Edwards, J. L.; Humphreys, R. M.; Ziurys, L. M. (2021). "Molecules and Outflows in NML Cygni: New Insights from a 1 mm Spectral Line Survey". The Astrophysical Journal. 920 (2): L38. Bibcode:2021ApJ...920L..38S. doi: 10.3847/2041-8213/ac2c7c . S2CID   239023582.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.