What type of supernova is PS15by and what kind of star exploded?
Astrophysics & Progenitor
PS15by has not been spectroscopically classified. It was reported as an astronomical transient, which means an object was detected changing in brightness, but its nature is not yet established. Classification requires a spectrum: the presence or absence of hydrogen lines separates Type II from Type I, and Type Ia is identified by silicon absorption near 6150 Å combined with the absence of hydrogen. Until such a spectrum is published, claims about the progenitor star or explosion mechanism would be speculation. Check the sources below for follow-up spectroscopy.
What was the progenitor star doing in the millions of years leading up to PS15by?
Astrophysics & Progenitor
The progenitor of PS15by cannot be identified without a classification. Stellar evolutionary history depends entirely on the explosion type: a Type Ia event would require a carbon-oxygen white dwarf in a binary system, whereas a core-collapse event would require a massive star exhausting its fuel within tens of millions of years. These are mutually exclusive histories that produce different spectra and light curves. No progenitor or precursor has been reported for this transient in the available literature.
How far away is PS15by from Earth and how old is the light reaching us?
Cosmic Distance & Time
The distance to PS15by has not been measured. No spectroscopic redshift or luminosity distance is published for this transient, so neither its distance from Earth nor its lookback time can be stated. A redshift requires a spectrum, and a photometric redshift requires multi-band imaging that has not been reported. Without a distance, its intrinsic luminosity and total energy release are also undetermined. Check the sources below for follow-up spectroscopy or host-galaxy identification.
What does the cosmological redshift of PS15by tell us about the expansion of space?
Cosmic Distance & Time
No spectroscopic redshift has been measured for PS15by. Without a published z, its place in the Hubble flow, recession velocity, and lookback time cannot be stated. A redshift requires a spectrum (or a well-calibrated photometric redshift from multi-band imaging). Check the sources below for follow-up spectroscopy.
How bright did PS15by become at its peak, and how many Suns does that equal?
Explosion Energetics
At peak brightness, PS15by achieved an apparent magnitude of 19.51 around 2015/02/17.
How much total energy was released by PS15by, and where did that energy go?
Explosion Energetics
The total energy released by PS15by is unknown. Energy budgets differ by orders of magnitude depending on mechanism: a thermonuclear Type Ia liberates ~10⁵¹ ergs mostly as kinetic energy, while a core-collapse event liberates ~10⁵³ ergs of which ~99% escapes as neutrinos. Without a spectroscopic classification, neither figure applies to this transient.
How fast are the supernova ejecta and shockwave of PS15by expanding through space?
Explosion Energetics
No ejecta velocity is measured for PS15by. Blast-wave speed is obtained from Doppler shifts of spectral absorption features (e.g. Si II λ6355 for Type Ia), not from cosmological redshift. Any recession velocity derived from z describes Hubble flow, not the explosion debris.
What powers the prolonged glow of PS15by weeks and months after detonation?
Radioactive Engine
The power source sustaining PS15by cannot be identified without a classification. Classified supernovae are typically powered after peak by the radioactive decay of ⁵⁶Ni → ⁵⁶Co → ⁵⁶Fe, but nickel yields and whether a shock-breakout flash occurred depend on the explosion mechanism. No spectrum is published for this transient, so no ⁵⁶Ni mass or decay-powered light-curve narrative applies.
What chemical elements did PS15by create and disperse into the universe?
Nucleosynthesis & Elements
The nucleosynthetic products of PS15by are unknown because its type is unresolved. Element yields depend directly on the explosion mechanism: a thermonuclear Type Ia produces mostly iron-peak elements such as 56Ni and 56Fe, whereas a core-collapse event produces large quantities of oxygen, neon, magnesium and silicon from successive burning shells. No spectrum has been published for this transient, so which of these occurred is not established.
Did PS15by leave behind a black hole, a neutron star, or nothing at all?
Cosmic Remnant
Whether PS15by left a remnant is unknown. A thermonuclear Type Ia leaves no compact remnant (the white dwarf is fully disrupted), whereas a core-collapse event leaves a neutron star or black hole depending on progenitor mass. Without a spectroscopic classification, none of these outcomes can be asserted for this transient.
What will PS15by's explosion site look like in 1,000 to 10,000 years?
Cosmic Remnant
Supernova remnants in general evolve through free-expansion, Sedov–Taylor, and radiative phases over centuries to millennia, sometimes becoming bright X-ray shells and occasionally compressing nearby molecular clouds. These are standard remnant-evolution models, not forecasts measured for PS15by. Whether this site will trigger star formation, reach particular X-ray temperatures, or match Cassiopeia A depends on local density and magnetic field—none of which are constrained by the data shown here.
In which galaxy did PS15by explode, and where is it located relative to the galactic center?
Galactic Environment
PS15by is associated with cataloged host 2MASX J11522046+1210299 at an angular/physical offset of 4.03″ from the reported galactic center. That offset places the transient in the host's projected light distribution; it does not by itself prove which stellar population produced the progenitor.
Where is PS15by located in the night sky and which constellation is it in?
Sky Coordinates
In the celestial sphere, PS15by is located at Right Ascension 11:52:20.39 and Declination +12:10:33.8, situated in the constellation Coma Berenices (Berenice's Hair). Because its declination is +12:10:33.8, it is primarily placed in the Northern celestial hemisphere.
How much Milky Way interstellar dust obscures our view of PS15by?
Interstellar Dust
Along this line of sight, the catalog records a Milky Way foreground color excess of E(B−V) = 0.0273 mag (source: published extinction estimate), corresponding to roughly A_V ≈ 0.08 mag for R_V = 3.1. Band-specific corrections (e.g. A_r) differ from A_V and should be applied when available. Map-based values (IRSA / Schlafly & Finkbeiner 2011) must not be claimed unless that map was actually queried.
Across which photometric filter bands was PS15by monitored?
Astronomical Observations
No calibrated photometry is published for PS15by. Without multi-epoch flux measurements, neither a light curve nor a peak magnitude can be established. Follow-up imaging from survey alert streams would be required to map its brightness evolution.
What did astronomical spectroscopy reveal about PS15by's chemical makeup?
Astronomical Observations
No spectrum has been published for PS15by. Without spectroscopy, its chemical composition, expansion velocity, and physical classification cannot be established. Classification spectra from follow-up observatories would be required to identify diagnostic absorption and emission lines.
Who discovered PS15by and how was it first detected?
Discovery & History
PS15by was officially reported on 2015/02/16 by PS1. Discoveries are typically flagged by high-cadence robotic survey telescopes (such as ATLAS, ZTF, Pan-STARRS, ASAS-SN, or Gaia) and worldwide amateur astronomers scanning the night sky, followed by rapid spectroscopic classification by international observatories.
How many scientific publications and observatories have contributed data to PS15by?
Scientific Research
Data for PS15by are compiled from international astronomical notices, the IAU Transient Name Server (TNS), and peer-reviewed astrophysical journals.
How does PS15by contribute to measuring the Hubble Constant and the scale of the cosmos?
Cosmology & Distance Ladder
PS15by cannot currently be used for cosmological distance work because its classification is unresolved. The distance ladder relies on type-specific techniques: Type Ia supernovae use the Phillips relation between peak absolute magnitude and decline rate, while Type II events use the Expanding Photosphere Method or SCM-II. An unclassified transient fits neither, so no Hubble-constant constraint can be derived from it until a spectrum establishes its type.
Could gravitational waves or neutrinos from PS15by be detected on Earth?
Multi-Messenger Astronomy
No neutrino or gravitational-wave counterpart has been reported for PS15by, and none is expected to be identifiable without a classification. The multi-messenger signature differs sharply by type: core-collapse events emit a neutrino burst at shock breakout (detected once, for SN 1987A), while thermonuclear Type Ia events produce negligible neutrinos and gravitational waves. Searching for a counterpart before knowing which mechanism applies would be unfocused.
How does PS15by compare to famous historical supernovae like SN 1987A or the Crab Supernova?
Historical Comparison
Compared to historical landmarks like SN 1987A in the Large Magellanic Cloud (168,000 light-years away, naked-eye peak m = 2.9) or the Crab Supernova of 1054 (6,500 light-years away), the distance to PS15by is not established for a historical comparison (unclassified; no redshift or luminosity distance is published). While historical naked-eye supernovae occurred within our Milky Way or its immediate satellites, modern discoveries like PS15by allow astrophysicists to probe diverse galactic environments, metallicities, and stellar populations across the broader universe.
Can I see PS15by tonight with a backyard telescope or binoculars?
Backyard Observation
Unknown — no measured brightness. PS15by was discovered 4277 days ago (2015/02/16), but no calibrated photometry is published for it, so its current apparent magnitude cannot be stated. Without a magnitude there is no basis for a telescope-aperture recommendation. Use the coordinates and airmass chart above to plan a follow-up observation and report what you measure.
Does the radiation or shockwave from PS15by pose any threat to Earth?
Planetary Safety
Earth is in no danger from PS15by. The astrophysical 'lethal kill zone' for a supernova to damage our ozone layer is roughly 50 to 100 light-years. This transient is far outside the solar neighbourhood: it was discovered by a wide-field survey at a magnitude only reachable for an extragalactic object, and any transient in our own galaxy within that radius would have appeared far brighter than the ~18th magnitude reported here. Its exact distance is unmeasured, but the detection brightness alone rules out any nearby threat.
