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Jeremy Shears

Publications and source records attributed to Jeremy Shears.

At least 37 records · Page 2Linked to original sources
arXiv2014

David Elijah Packer: cluster variables, meteors and the solar corona

David Elijah Packer (1862-1936), a librarian by profession, was an enthusiastic amateur astronomer who observed from London and Birmingham. He first came to the attention of the astronomical community in 1890 when he discovered a variable star in the globular cluster M5, only the second periodic variable to be discovered in a globular cluster. He also observed meteors and nebulae, on one occasion reporting a brightening in the nucleus of the galaxy M77. However, his remarkable claims in 1896 that he had photographed the solar corona in daylight were soon shown to be flawed.

physics.hist-ph↗
arXiv2014

In the footsteps of Ebenezer Porter Mason and his nebulae

In 1839 Ebenezer Porter Mason (1819-1840) produced detailed drawings of the Omega Nebula (M17), the Trifid Nebula (M20) and the eastern part of the Veil Nebula (NGC 6992 and 6995). He used a 12-inch (30 cm) reflector that he and his friends had built at Yale College, which at the time was the largest telescope in the USA. The drawings were remarkable for their accuracy and for his adoption of a new technique for delineating gradients in nebulosity using isophotes, or lines of equal brightness. This paper reviews his life and his observations, comparing his results with those of the modern amateur astronomer.

physics.hist-ph↗
arXiv2013

William Sadler Franks and the Brockhurst Observatory

William Sadler Franks (1851-1935) was astronomer-in-charge at F.J. Hanbury's private observatory at Brockhurst, near East Grinstead, Sussex, from 1909 until his death in 1935. This paper reviews the observational projects Franks undertook at Brockhurst, including his work on double stars, red stars, diffuse nebulae and dark nebulae, as well as his involvement with the commissioning of a 24-inch reflector built by Thomas William Bush (1839-1928).

physics.hist-ph↗
arXiv2013

Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae. V: The Fifth Year (2012-2013)

Continuing the project described by Kato et al. (2009a, arXiv:0905.1757), we collected times of superhump maxima for SU UMa-type dwarf novae mainly observed during the 2012-2013 season. We found three objects (V444 Peg, CSS J203937 and MASTER J212624) having strongly positive period derivatives despite the long orbital period (Porb). By using the period of growing stage (stage A) superhumps, we obtained mass ratios for six objects. We characterized nine new WZ Sge-type dwarf novae. We made a pilot survey of the decline rate of slowly fading part of SU UMa-type and WZ Sge-type outbursts. The decline time scale was found to generally follow the expected Porb^(1/4) dependence and WZ Sge-type outbursts also generally follow this trend. There are some objects which show slower decline rates, and we consider these objects good candidates for period bouncers. We also studied unusual behavior in some objects, including BK Lyn which made a transition from an ER UMa-type state to the novalike (standstill) state in 2013 and unusually frequent occurrence of superoutbursts in NY Ser and CR Boo. We applied least absolute shrinkage and selection operator (Lasso) power spectral analysis, which has been proven to be very effective in analyzing the Kepler data, to ground-based photometry of BK Lyn and detected the dramatic disappearance of the signal of negative superhumps in 2013. We suggested that the mass-transfer rates did not vary strongly between the ER UMa-type state and novalike state in BK Lyn, and this transition was less likely caused by a systematic variation of the mass-transfer rate.

astro-ph.SR↗
arXiv2013

The Reverend Walter Bidlake of Crewe

The Reverend Walter Bidlake, MA, FRAS, JP (1865-1938) was vicar of Crewe, England, for some 21 years. A member of the BAA, he was a keen amateur astronomer with an interest in celestial photography. At the request of another well-known BAA member, T.H.E.C. Espin, Bidlake took photographs of the night sky in support of Espin's search for dark nebulae in the Milky Way. This paper describes Bidlake's astronomical activities and life, including a high profile libel case he brought.

physics.hist-ph↗
arXiv2013

Harold Knox-Shaw and the Helwan Observatory

Harold Knox-Shaw (1885-1970) worked at the Helwan Observatory in Egypt from 1907 to 1924. The Observatory was equipped with a 30-inch (76 cm) reflector that was financed and constructed by the Birmingham industrialist, John Reynolds (1874-1949), to benefit from the clearer skies and more southerly latitude compared with Britain. Knox-Shaw obtained the first photograph of Halley's Comet on its 1910 perihelion passage. He also carried out morphological studies on nebulae and may have been the first to identify what later became to be known as elliptical galaxies as a distinct class of object. Photographic analysis of the variable nebula NGC 6729 in Corona Australis enabled him to conclude that the changes in brightness and shape were correlated with the light travel time from the illuminating star, R CrA.

physics.hist-ph↗
arXiv2013

Superoutbursts and grazing eclipses in the dwarf nova V1227 Herculis

We present photometry obtained during the 2012 May and September outbursts of the frequently outbursting dwarf nova, V1227 Her. Superhumps were present in both cases with a peak-to peak amplitude of up to 0.28 mag, showing these events to be superoutbursts. We show for the first time that the system undergoes small eclipses with a depth of up to 0.08 mag, lasting 11 to 14 min, which are likely to be grazing eclipses of the accretion disc. The September outburst was the better observed of the two and lasted at least 14 days with an outburst amplitude of approximately 4 magnitudes. The mean superhump period was Psh = 0.065103(20) d. Analysis of eclipse times of minimum gave an orbital period Porb = 0.064419(26) d, although there is some ambiguity due to the relatively short time over which the eclipses were observed. The fractional superhump period excess, epsilon, was 0.0106(7).

astro-ph.SR↗
arXiv2013

Dr. Harold Whichello: medicine and astronomy in Cheshire

Dr. Harold Whichello (1870-1945) was a Cheshire General Practitioner and an enthusiastic amateur astronomer. He joined the British Astronomical Association in 1898 and undertook observations for its Lunar, Solar and Variable Star Sections using a 6-inch Wray refractor. He also contributed lunar occultation predictions and comet ephemerides to its Computing Section.

physics.hist-ph↗
arXiv2013

Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae. IV: The Fourth Year (2011-2012)

Continuing the project described by Kato et al. (2009, arXiv:0905.1757), we studied 86 SU UMa-type dwarf novae. We confirmed the general trends such as the relation between period derivatives and orbital periods. There are some systems showing positive period derivatives despite the long orbital periods. We observed the 2011 outburst of the WZ Sge-type dwarf nova BW Scl, and recorded an O-C diagram similar to those of previously known WZ Sge-type dwarf novae. The WZ Sge-type dwarf nova OT J184228.1+483742 showed an unusual pattern of double outbursts composed of an outburst with early superhumps and one with ordinary superhumps. We propose an interpretation that a very small growth rate of the 3:1 resonance due to an extremely low mass-ratio led to a quenching of the superoutburst before the ordinary superhumps appeared. We studied ER UMa-type dwarf novae and found that V1159 Ori showed positive superhumps similar to ER UMa in the 1990s. The recently recognized ER UMa-type object BK Lyn dominantly showed negative superhumps, and its behavior was very similar to the present-day state of ER UMa. The pattern of period variations in AM CVn-type objects were very similar to short-period hydrogen-rich SU UMa-type dwarf novae, making them helium analogue of hydrogen-rich SU UMa-type dwarf novae. SBS 1108+574, a peculiar hydrogen-rich dwarf nova below the period minimum, showed a very similar pattern of period variations to those of short-period SU UMa-type dwarf novae. The mass-ratio derived from the detected orbital period suggests that this secondary is a somewhat evolved star whose hydrogen envelope was mostly stripped during the mass-exchange. CC Scl, MASTER OT J072948.66+593824.4 and OT J173516.9+154708 showed only low-amplitude superhumps with complex profiles. These superhumps are likely a combination of closely separated two periods.

astro-ph.SR↗
arXiv2013

The first confirmed superoutburst of the dwarf nova GALEX J215818.5+241924

In 2011 October an optical transient was reported in Pegasus as a possible nova. The object had an ultraviolet counterpart, GALEX J215818.5+241924. In this paper we present follow-up photometry of the object which revealed the presence of superhumps, with peak-to-peak amplitude of up to 0.22 magnitudes, diagnostic of it being a member of the SU UMa family of dwarf novae. The outburst amplitude was 4.6 magnitudes and it lasted at least 10 days, with a maximum brightness of magnitude 14.3. We determined the mean superhump period from our first 5 nights of observations as Psh = 0.06728(21) d. However analysis of the O-C residuals showed a dramatic evolution in Psh during the outburst. During the first part of the plateau phase the period increased with dPsh/dt = +2.67(15) x 10-4. There was then an abrupt change following which the period decreased with dPsh/dt = -2.08(9)x 10-4. We found a signal in the power spectrum of the photometry which we tentatively interpret as the orbital signal with Porb = 0.06606(35) d. Thus the superhump period excess was epsilon = 0.020(8), such value being consistent with other SU UMa systems of similar orbital period.

astro-ph.SR↗
arXiv2012

Arthur Neville Brown: schoolmaster and variable star observer

Arthur Neville Brown, MA, FRAS (1864-1934) was a prolific variable star observer and served for many years as Secretary of the BAA Variable Star Section. This paper discusses Brown's life and career, both as a variable star enthusiast and as a dedicated and highly respected schoolmaster.

physics.hist-ph↗
arXiv2012

The astronomizings of Dr. Anderson and the curious case of his disappearing nova

Dr. Thomas David Anderson (1853-1932) was a Scottish amateur astronomer famed for his discovery of two bright novae: Nova Aurigae 1891 and Nova Persei 1901. He also discovered more than 50 variable stars as well as making independent discoveries of Nova Aquilae 1918 and comet 17P/Holmes in 1892. At the age of seventy, in 1923, he reported his discovery of a further nova, this time in Cygnus. This was set to be the culmination of a lifetime devoted to scanning the night sky, but unfortunately no one was able to confirm it. This paper discusses Anderson's life leading up to the discovery and considers whether it was real or illusory.

physics.hist-ph↗
arXiv2012

The orbital and superhump periods of the deeply eclipsing dwarf nova PU UMa

We report unfiltered photometry during superoutbursts of PU UMa in 2009 and 2012. The amplitude was 4.5 magnitudes above mean quiescence and lasted at least 9 to 10 days. Superhumps were present with a peak-to-peak amplitude of up to ~0.3 mag, thereby confirming it to be a member of the SU UMa family of dwarf novae. The mean superhump period during the later part of the 2012 outburst was Psh = 0.08076(40) d. Analysis of the eclipse times of minimum, supplemented with data from other researchers, revealed an orbital period of Porb = 0.077880551(17) d. The superhump period excess was epsilon = 0.037(5). During the 2012 outburst, which was the better observed of the two, the FWHM eclipse duration gradually declined from 9.5 to 5 min. The eclipse depth was up to 1.7 magnitudes.

astro-ph.SR↗
arXiv2012

Thomas Hinsley Astbury: from an English market town schoolroom to the internal constitution of the stars

T. H. Astbury (1858-1922) was for many years the much-respected headmaster of a boys' junior school in the English market town of Wallingford. By night he was a dedicated amateur astronomer who enjoyed observing meteors, variable stars and many other objects. He began to search few new variable stars, his first discovery being the bright Cepheid variable, RT Aurigae. This, along with his discovery of 4 other variable stars, brought him to attention of some of the most famous professional astronomers of the age, including Herbert Hall Turner, Frank Dyson and Arthur Eddington.

physics.hist-ph↗
arXiv2012

Limb Projections on Saturn

We present two unusual observations of Saturn recorded during the early years of the twentieth century

physics.hist-ph↗