The Dog Stars: The hope-filled story of a world changed by global catastrophe

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With an apparent magnitude of −1.46, Sirius is the brightest star in the night sky, almost twice as bright as the second-brightest star, Canopus. [71] From Earth, Sirius always appears dimmer than Jupiter and Venus, and at certain times also dimmer than Mercury and Mars. [72] Sirius is visible from almost everywhere on Earth, except latitudes north of 73°N, and it does not rise very high when viewed from some northern cities (reaching only 13°above the horizon from Saint Petersburg). [73] Because of its declination of roughly −17°, Sirius is a circumpolar star from latitudes south of 73°S. From the Southern Hemisphere in early July, Sirius can be seen in both the evening where it sets after the Sun and in the morning where it rises before the Sun. [74] Along with Procyon and Betelgeuse, Sirius forms one of the three vertices of the Winter Triangle to observers in the Northern Hemisphere. [75] Alpha Canis Majoris appears as a single star to the unaided eye, but it is really a binary star system, composed of a white main sequence star belonging to the spectral class A1 V, known as Sirius A or Alpha Canis Majoris A, and a dim white dwarf with the stellar classification DA2, designated Sirius B or Alpha Canis Majoris B. Holberg, J.B. (2007). Sirius: Brightest Diamond in the Night Sky. Chichester, UK: Praxis Publishing. ISBN 978-0-387-48941-4. In 2005, data from the Hubble Space Telescope helped astronomers determine that Sirius B has almost the diameter of the Earth, around 12,000 kilometres or 7,500 miles, and a mass 98 percent that of the Sun. This was the first time that astronomers were able to accurately measure the mass of Sirius B. Facts Designations: Sirius, Dog Star, α Canis Majoris (α CMa), 9 Canis Majoris (9 CMa), Canicula, Al Shira, Sothis, Alhabor, Mrgavyadha, Lubdhaka, Tenrōsei, HD 48915, HR 2491, BD −16°1591, GCTP 1577.00 A/B, GJ 244 A/B, LHS 219, ADS 5423, LTT 2638, HIP 32349, B: EGGR 49, WD 0642-166

Sirius is a binary star system consisting of two white stars orbiting each other with a separation of about 20AU [e] a b c Hoffleit, D.; Warren, W. H. Jr. (1991). "Entry for HR 2491". Bright Star Catalogue (5th Revised Ed. (Preliminary Version)ed.). CDS. Bibcode: 1991bsc..book.....H. Daintith, John; Mitchell, Sarah; Tootill, Elizabeth; Gjertsen, D. (1994). Biographical Encyclopedia of Scientists. CRC Press. p.442. ISBN 0-7503-0287-9.For the Evulz: This appears to be the motive of the airport couple, Higs notes that they certainly weren't getting anything useful off their victims. Duarte, Paulo Araújo. "Astronomia na Bandeira Brasileira". Universidade Federal de Santa Catarina. Archived from the original on 2 May 2008 . Retrieved 9 July 2009. a b Gingerich, O. (1987). "Zoomorphic astrolabes and the introduction of Arabic star names into Europe". Annals of the New York Academy of Sciences. 500 (1): 89–104. Bibcode: 1987NYASA.500...89G. doi: 10.1111/j.1749-6632.1987.tb37197.x. S2CID 84102853.

Maskelyne, N. (1759). "LXXVIII. A proposal for discovering the annual parallax of Sirius". Philosophical Transactions of the Royal Society. 51: 889–895. Bibcode: 1759RSPT...51..889M. doi: 10.1098/rstl.1759.0080. Tomkin, Jocelyn (April 1998). "Once and future celestial kings". Sky and Telescope. 95 (4): 59–63. Bibcode: 1998S&T....95d..59T. Bragança, Pedro (15 July 2003). "The 10 Brightest Stars". SPACE.com. Archived from the original on 16 June 2009 . Retrieved 4 August 2006. In his 1698 book, Cosmotheoros, Christiaan Huygens estimated the distance to Sirius at 27,664times the distance from the Earth to the Sun (about 0.437light-year, translating to a parallax of roughly 7.5arcseconds). [42] There were several unsuccessful attempts to measure the parallax of Sirius: by Jacques Cassini (6seconds); by some astronomers (including Nevil Maskelyne) [43] using Lacaille's observations made at the Cape of Good Hope (4seconds); by Piazzi (the same amount); using Lacaille's observations made at Paris, more numerous and certain than those made at the Cape (no sensible parallax); by Bessel (no sensible parallax). [44] a b Holberg, J.B.; Oswalt, T.D.; Sion, E.M.; Barstow, M.A.; Burleigh, M.R. (2013). "Where are all the Sirius-like binary systems?". Monthly Notices of the Royal Astronomical Society. 435 (3): 2077–2091. arXiv: 1307.8047. Bibcode: 2013MNRAS.435.2077H. doi: 10.1093/mnras/stt1433. S2CID 54551449.

More recent (and accurate) astrometric observations by the Hubble Space Telescope ruled out the existence of such a SiriusC entirely. The 1995 study predicted an astrometric movement of roughly 90 mas (0.09arcsecond), but Hubble was unable to detect any location anomaly to an accuracy of 5mas (0.005arcsec). This ruled out any objects orbiting SiriusA with more than 0.033solar mass (35Jupiter masses) orbiting in 0.5years, and 0.014 (15 Jupiter masses) in 2years. The study was also able to rule out any companions to SiriusB with more than 0.024solar mass (25Jupiter masses) orbiting in 0.5year, and 0.0095 (10Jupiter masses) orbiting in 1.8years. Effectively, there are almost certainly no additional bodies in the Sirius system larger than a small brown dwarf or large exoplanet. [100] [12] Star cluster membership [ edit ] a b c Whittet, D. C. B. (1999). "A physical interpretation of the 'red Sirius' anomaly". Monthly Notices of the Royal Astronomical Society. 310 (2): 355–359. Bibcode: 1999MNRAS.310..355W. doi: 10.1046/j.1365-8711.1999.02975.x. Bonnet-Bidaud, J. M.; Pantin, E. (October 2008). "ADONIS high contrast infrared imaging of Sirius-B". Astronomy and Astrophysics. 489 (2): 651–655. arXiv: 0809.4871. Bibcode: 2008A&A...489..651B. doi: 10.1051/0004-6361:20078937. S2CID 14743554. The colour of Sirius has caused some debate over the centuries, as a number of ancient accounts indicated that the star was red. The Greek astronomer Ptolemy was one of the many who described its appearance as reddish. Around the year 150 AD, he mentioned the star’s reddish colour, including it with five other stars that are all known to be either red or orange: Antares in Scorpius constellation, Arcturus in Bo ötes, Betelgeuse in Orion, Aldebaran in Taurus, and Pollux in Gemini. Seneca, too, had noted that Sirius was of a deeper red colour than Mars. However, at the same time, there were many observers who described the star as blue or white. Vigan, A.; Gry, C.; Salter, G.; Mesa, D.; Homeier, D.; Moutou, C.; Allard, F. (2015). "High-contrast imaging of SiriusA with VLT/SPHERE: looking for giant planets down to one astronomical unit". Monthly Notices of the Royal Astronomical Society. 454 (1): 129–143. arXiv: 1509.00015. Bibcode: 2015MNRAS.454..129V. doi: 10.1093/mnras/stv1928. S2CID 119260068.