Author Topic: SUPERNOVA OF THE DAY  (Read 19077 times)

robert gagliano

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SUPERNOVA OF THE DAY
« on: December 10, 2010, 03:48:39 pm »
NAME           RA                   DEC               DATE         MAG     TYPE         Z
PTF10xla      00:45:16.27   -14:13:42.5   Oct 4.341    19.2     SN Ib/c     0.053

ATel #2961   http://www.astronomerstelegram.org/?read=2961

Coral Towers Observatory   http://www.flickr.com/photos/43846774@N02/5119988431/sizes/l/in/photostream/

Type Ib Non-ionized helium (He I) line at 587.6 nm and no strong silicon absorption feature near 615 nm.
Type Ic Weak or no helium lines and no strong silicon absorption feature near 615 nm.

 
These events, like supernovae of Type II, are probably massive stars running out of fuel at their centers; however, the progenitors of Types Ib and Ic have lost most of their outer (hydrogen) envelopes due to strong stellar winds or else from interaction with a companion. Type Ib supernovae are thought to be the result of the collapse of a massive Wolf-Rayet star. There is some evidence that a few percent of the Type Ic supernovae may be the progenitors of gamma ray bursts (GRB), though it is also believed that any hydrogen-stripped, Type Ib or Ic supernova could be a GRB, dependent upon the geometry of the explosion.

Discoverers: HelmutU, kuyanik, robert gagliano, graham d, Blackprojects, nilium, voyager1682002, krobanxee, mark moffatt, thisguyiknow, OrleoMarinaro, chrostek, Star gazer 1924, RobH2, broylesd, anaclaudia, hpaakkanen, b.umberto, OLH, kdavydova13

« Last Edit: April 22, 2011, 08:07:21 pm by robert gagliano »

robert gagliano

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Re: SUPERNOVA OF THE DAY - PTF 10yzt
« Reply #1 on: December 11, 2010, 10:37:24 pm »
NAME           RA                   DEC                 DATE          MAG     TYPE         Z
PTF10yzt     00:11:50.02     +26:41:13.7    Oct 29.61    18.6      SN IIn       0.076

ATel #3027   http://www.astronomerstelegram.org/?read=3027

NM Skies       http://www.flickr.com/photos/43846774@N02/5173192998/sizes/l/in/photostream/

As part of the attempt to understand supernovae, astronomers have classified them according to the absorption lines of different chemical elements that appear in their spectra. The first element for a division is the presence or absence of a line caused by hydrogen. If a supernova's spectrum contains a line of hydrogen (known as the Balmer series in the visual portion of the spectrum) it is classified Type II.
The "n" denotes narrow, which indicates the presence of intermediate or very narrow width H emission lines in the spectra. In the intermediate width case, the ejecta from the explosion may be interacting strongly with gas around the star – the circumstellar medium. There are indications that they originate as stars similar to Luminous Blue Variables with large mass losses before exploding.

Discoverers: habrahamson, foboz, waldo3, carycsp1, Ann Stevens, mecurtin, tjreedy, mark moffatt, jinvl, fireballjim, smkolins, zzy, drronmccoy, brenton.whitenoise, kuyanik, graham d, bentemming, tborzan, John P Langridge, voyager1682002


 
« Last Edit: April 22, 2011, 08:08:57 pm by robert gagliano »

robert gagliano

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Re: SUPERNOVA OF THE DAY - PTF 10vyl
« Reply #2 on: December 12, 2010, 02:45:57 pm »
Name           RA                   Dec                 Disc Date (UT)   Disc Mag (r)   Type       z        Phase(d)
PTF10vyl      23:51:07.76    -03:35:33.1       Sep 20.73          18.5                 SN Ia     0.1          7

ATel #3027   http://www.astronomerstelegram.org/?read=3027

Type Ia Lacks hydrogen and presents a singly ionized silicon (Si II) line at 615.0 nm (nanometers), near peak light.

There are several means by which a supernova of this type can form, but they share a common underlying mechanism. If a carbon-oxygen white dwarf accreted enough matter to reach the Chandrasekhar limit of about 1.38 solar masses (for a non-rotating star), it would no longer be able to support the bulk of its plasma through electron degeneracy pressure and would begin to collapse. However, the current view is that this limit is not normally attained; increasing temperature and density inside the core ignite carbon fusion as the star approaches the limit (to within about 1%), before collapse is initiated. Within a few seconds, a substantial fraction of the matter in the white dwarf undergoes nuclear fusion, releasing enough energy (1–2 × 1044 joules) to unbind the star in a supernova explosion. An outwardly expanding shock wave is generated, with matter reaching velocities on the order of 5,000–20,000 km/s, or roughly 3% of the speed of light. There is also a significant increase in luminosity, reaching an absolute magnitude of -19.3 (or 5 billion times brighter than the Sun), with little variation.

One model for the formation of this category of supernova is a close binary star system. The larger of the two stars is the first to evolve off the main sequence, and it expands to form a red giant. The two stars now share a common envelope, causing their mutual orbit to shrink. The giant star then sheds most of its envelope, losing mass until it can no longer continue nuclear fusion. At this point it becomes a white dwarf star, composed primarily of carbon and oxygen. Eventually the secondary star also evolves off the main sequence to form a red giant. Matter from the giant is accreted by the white dwarf, causing the latter to increase in mass.

Another model for the formation of a Type Ia explosion involves the merger of two white dwarf stars, with the combined mass momentarily exceeding the Chandrasekhar limit. A white dwarf could also accrete matter from other types of companions, including a main sequence star (if the orbit is sufficiently close).


Type Ia supernovae follow a characteristic light curve—the graph of luminosity as a function of time—after the explosion.

 This luminosity is generated by the radioactive decay of nickel-56 through cobalt-56 to iron-56. The peak luminosity of the light curve was believed to be consistent across Type Ia supernovae (the vast majority of which are initiated with a uniform mass via the accretion mechanism), having a maximum absolute magnitude of about -19.3. This would allow them to be used as a secondary standard candle to measure the distance to their host galaxies. However, recent discoveries reveal that there is some evolution in the average lightcurve width, and thus in the intrinsic luminosity of supernovae, although significant evolution is found only over a large redshift baseline.

Discoverers: RonDavidson, robert gagliano, shearman, chrostek, nilium, zszywak, zeee, OLH, bentemming, graham d, rob, paulusmagnus, ElisabethB, david girard, chairstar, jseach, careymccachern, fabihort, waldo3, elowitzr, edsonjr



 
« Last Edit: April 22, 2011, 08:09:53 pm by robert gagliano »

robert gagliano

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Re: SUPERNOVA OF THE DAY - PTF 10zhi
« Reply #3 on: December 13, 2010, 01:22:49 pm »
Name    RA                    Dec                  Disc Date (UT)      Disc Mag (r)    Type       z         Phase(d)
PTF10zhi  01:32:24.29    +21:27:21.0     Nov 1.69              20.3                  SN Ia      0.13    -4

ATel # 3027   http://www.astronomerstelegram.org/?read=3027

NM Skies        http://www.flickr.com/photos/43846774@N02/5171579206/sizes/l/in/photostream/

Discoverers: robert gagliano, abutera1, ElisabethB, elyan, Blackprojects, hgp88, abumaia, jegr, Jose Campos, ringofslag, graham d, mark moffatt

« Last Edit: April 22, 2011, 08:10:51 pm by robert gagliano »

robert gagliano

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Re: SUPERNOVA OF THE DAY - PTF 10zcd
« Reply #4 on: December 17, 2010, 05:31:40 pm »
Name           RA                     Dec                 Disc Date (UT)    Disc Mag (r)   Type        z     Phase(d)

PTF10zcd     01:08:32.97     +16:30:10.6     Oct 30.74             20.1                 SN Ia        0.132     8

ATel # 3027    http://www.astronomerstelegram.org/?read=3027

SDSS DR7        http://cas.sdss.org/astro/en/tools/explore/obj.asp?id=758877155741270241&spec=0

NM Skies         http://www.flickr.com/photos/43846774@N02/5174932220/sizes/l/in/photostream/

Discoverers: ruth mary perdomo, sepos, habrahamson, Jose Campos, altair2, glupciu, graham d, hgp88, PawelTluscik, thissideofgaudy, mark moffatt

« Last Edit: April 22, 2011, 08:14:13 pm by robert gagliano »

robert gagliano

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Re: SUPERNOVA OF THE DAY - PTF 10xjm
« Reply #5 on: December 18, 2010, 02:23:51 pm »
Name           RA                     Dec                 Disc Date (UT)    Disc Mag (r)   Type        z     Phase(d)


PTF10xjm     02:04:16.96      +03:58:43.3    Oct 4.466               19.1                 SN Ia      0.158    +1

ATel #2961   http://www.astronomerstelegram.org/?read=2961

NM Skies       http://www.flickr.com/photos/43846774@N02/5174932220/sizes/l/in/photostream/

Discoverers: aspringer, HelmutU, kuyanik, OLH, chairstar, WV_Pulsar, RonDavidson, thelady, robert gagliano, b.umberto, graham d, ElisabethB, nilium, Blackprojects, rommie, raindcon, waldo3


« Last Edit: April 22, 2011, 08:15:38 pm by robert gagliano »

robert gagliano

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Re: SUPERNOVA OF THE DAY - some definitions
« Reply #6 on: December 20, 2010, 06:15:31 pm »
Name        RA           DEC            Disc Date (UT)     Disc Mag (r)    Type         z           Phase (d)


NAME = the Palomar Transient Factory identification number
RA = right ascension (hours:minutes:seconds)....the north - south point on the celestial sphere, comparable to longitude on earth
DEC = declination (degrees: minutes: seconds...(+) means above and (-) means below the celestial equator)....the east - west point on the celestial sphere, comparable to latitude on earth
(taken together RA and DEC give an objects exact location in the sky)
Disc Date (UT) = date of discovery in universal time
Disc Mag (r) = magnitude (brightness) with a red filter at time of discovery
Type = type of SN, I or II, based on its spectrum and/or light curve
Z = redshift...a measure of distance and time, the greater the redshift the farther back in time and the more distant is the SN and host galaxy
Phase (d) = the time in days before (-) or after (+) maximum brightness for type I supernovae

« Last Edit: December 20, 2010, 06:46:22 pm by robert gagliano »

Jose Campos

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Re: SUPERNOVA OF THE DAY
« Reply #7 on: January 03, 2011, 04:39:22 pm »
Hi Robert Gagliano! Interesting info you give us on this thread on SN's. Tks for all your hard work!

robert gagliano

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Re: SUPERNOVA OF THE DAY - PTF 11bop
« Reply #8 on: April 01, 2011, 10:44:02 pm »
Name            RA                    DEC                Disc Date (UT)     Disc Mag (r)  Type    z     Phase(d)
PTF 11bop    15:03:02.69     +31:31:54.5    March 15, 2011       20 (g)            Ia        0.11   -9

ATel #3253    http://www.astronomerstelegram.org/?read=3253

SDSS DR7      http://cas.sdss.org/dr7/en/tools/quicklook/quickobj.asp?ra=15:03:02.69&dec=+31:31:54.5

NM Skies         http://www.flickr.com/photos/43846774@N02/5583446794/sizes/l/in/photostream/

Discoverers: robert gagliano, graham d, Jose Campos, nilium, chrostek, HelmutU, bentemming, sTruKo, x303, damonb, bentemming

« Last Edit: April 22, 2011, 08:20:54 pm by robert gagliano »

robert gagliano

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Re: SUPERNOVA OF THE DAY
« Reply #9 on: April 06, 2011, 12:46:52 pm »
Six entries (PTF 10xla, PTF 10yzt, PTF 10zhi, PTF 10zcd, PTF 10 xjm, PTF 11bop) have been updated with links to Joseph Brimacombe's astrophotography images and ATel links. Where possible I will also include links to SDSS DR7 data on the host galaxy (PTF 11bop). I anticipate that we will add a lot more of our discoveries to this post in the future now that PTF is publishing a weekly SN discovery report in ATel.
« Last Edit: April 08, 2011, 10:57:43 pm by robert gagliano »

robert gagliano

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Re: SUPERNOVA OF THE DAY - PTF 11bpx
« Reply #10 on: April 17, 2011, 02:00:44 pm »
Name            RA                    DEC                Disc Date (UT)     Disc Mag (r)    Type         z
PTF 11bpx    12:35:09.22     -00:13:17.2        4/4/2011              19.5 (g)            II              0.024

ATel 3288     http://www.astronomerstelegram.org/?read=3288

NGC 4541 (SDSS DR7)     http://cas.sdss.org/astro/en/tools/explore/obj.asp?id=587722982817660957&spec=0

NGC 4541 (Simbad)   http://simbad.u-strasbg.fr/simbad/sim-id?Ident=%401965865&Name=NGC%20%204541&submit=submit

NGC 4541 (Aladin)     http://aladin.u-strasbg.fr/java/alapre.pl?-c=12+35+10.664-00+13+15.78&ident=NGC++4541&submit=Aladin+previewer

NGC 4541 (NED)       http://nedwww.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=NGC+4541&img_stamp=YES&extend=no

NM Skies                   http://www.flickr.com/photos/43846774@N02/5634134360/sizes/l/in/photostream/   

Type II supernova
 
The onion-like layers of a massive, evolved star just prior to core collapse. (Not to scale.)Stars with at least nine solar masses of material evolve in a complex fashion. In the core of the star, hydrogen is fused into helium and the thermal energy released creates an outward pressure, which maintains the core in hydrostatic equilibrium and prevents collapse.

When the core's supply of hydrogen is exhausted, this outward pressure is no longer created. The core begins to collapse, causing a rise in temperature and pressure which becomes great enough to ignite the helium and start a helium-to-carbon fusion cycle, creating sufficient outward pressure to halt the collapse. The core expands and cools slightly, with a hydrogen-fusion outer layer, and a hotter, higher pressure, helium-fusion center. (Other elements such as magnesium, sulfur and calcium are also created and in some cases burned in these further reactions.)

This process repeats several times; each time the core collapses, and the collapse is halted by the ignition of a further process involving more massive nuclei and higher temperatures and pressures. Each layer is prevented from collapse by the heat and outward pressure of the fusion process in the next layer inward; each layer also burns hotter and quicker than the previous one—the final burn of silicon to iron consumes its fuel in just a few days at most. The star becomes layered like an onion, with the burning of more easily fused elements occurring in larger shells.

In the later stages increasingly heavier elements with higher binding energy undergo nuclear fusion. Fusion produces progressively less energy, and also at higher core energies photodisintegration and electron capture occur which cause further energy loss in the core, requiring a general acceleration of the fusion processes to maintain hydrostatic equilibrium. This escalation culminates with the production of nickel-56, which is unable to produce energy through fusion (but does produce iron-56 through radioactive decay). As a result, a nickel-iron core builds up that cannot produce further outward pressure on the scale needed to support the rest of the structure. It can only support the overlaying mass of the star through the degeneracy pressure of electrons in the core. If the star is sufficiently large, then the iron-nickel core will eventually exceed the Chandrasekhar limit (1.38 solar masses), at which point this mechanism catastrophically fails. The forces holding atomic nuclei apart in the innermost layer of the core suddenly give way, the core implodes due to its own mass, and no further fusion process is available to ignite and prevent collapse this time.



Core collapse

The core collapses in on itself with velocities reaching 70,000 km/s (0.23c), resulting in a rapid increase in temperature and density. The energy loss processes operating in the core cease to be in equilibrium. Through photodisintegration, gamma rays decompose iron into helium nuclei and free neutrons, absorbing energy, while electrons and protons merge via electron capture, producing neutrons and electron neutrinos, which escape.

In a typical Type II supernova the newly formed neutron core has an initial temperature of about 100 billion kelvin (100 GK), 6000 times the temperature of the sun's core. A further release of neutrinos carries away much of the thermal energy, allowing a stable neutron star to form (the neutrons would "boil away" if this cooling did not occur). These 'thermal' neutrinos form as neutrino-antineutrino pairs of all flavors, and total several times the number of electron-capture neutrinos. About 1046 joules of gravitational energy—approximately 10% of the star's rest mass—is converted into a ten-second burst of neutrinos, which is the main output of the event. These carry away energy from the core and accelerate the collapse, while some neutrinos are absorbed by the star's outer layers and provide energy to the supernova explosion.

The inner core eventually reaches typically 30 km diameter, and a density comparable to that of an atomic nucleus, and further collapse is abruptly stopped by strong force interactions and by degeneracy pressure of neutrons. The infalling matter, suddenly halted, rebounds, producing a shock wave that propagates outward. Computer simulations indicate that this expanding shock does not directly cause the supernova explosion; rather, it stalls within milliseconds in the outer core as energy is lost through the dissociation of heavy elements, and a process that is not clearly understood is necessary to allow the outer layers of the core to reabsorb around 1044 joules (1 foe) of energy, producing the visible explosion. Current research focuses upon a combination of neutrino reheating, rotational and magnetic effects as the basis for this process.



 
Within a massive, evolved star (a) the onion-layered shells of elements undergo fusion, forming an iron core (b) that reaches Chandrasekhar-mass and starts to collapse. The inner part of the core is compressed into neutrons (c), causing infalling material to bounce (d) and form an outward-propagating shock front (red). The shock starts to stall (e), but it is re-invigorated by a process that may include neutrino interaction. The surrounding material is blasted away (f), leaving only a degenerate remnant.When the progenitor star is below about 20 solar masses (depending on the strength of the explosion and the amount of material that falls back), the degenerate remnant of a core collapse is a neutron star. Above this mass the remnant collapses to form a black hole. (This type of collapse is one of many candidate explanations for gamma ray bursts, possibly producing a large burst of gamma rays through a hypernova explosion.) The theoretical limiting mass for this type of core collapse scenario was estimated around 40–50 solar masses.

Above 50 solar masses stars were believed to collapse directly into a black hole without forming a supernova explosion, although uncertainties in models of supernova collapse make accurate calculation of these limits difficult. Above about 140 solar masses stars may become pair-instability supernovae that do not leave behind a black hole remnant.

Discoverers: Blackprojects, ElisabethB, chrostek, bentemming, razvan66m, HelmutU, nilium, graham d, Jose Campos, shropshireman, carterlangley, robert gagliano, tbott5, rob, x303, whanlon, Jonathan, hkhm, rikster2222, voyager1682002, vkorszen, marek kaluzny





« Last Edit: May 13, 2011, 07:01:21 pm by robert gagliano »

robert gagliano

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Re: SUPERNOVA OF THE DAY - PTF 11cdo
« Reply #11 on: April 22, 2011, 06:01:05 pm »
Name            RA                    DEC                Disc Date (UT)     Disc Mag (r)    Type    z      Phase(d)
PTF 11cdo     16 25 35.42      +33 32 01.6   4/12/2011              19.5                   Ia       0.146   -7   

ATel            http://www.astronomerstelegram.org/?read=3288

SDSS DR7   http://cas.sdss.org/astro/en/tools/explore/obj.asp?id=587733431919576469&spec=0

Discoverers: Pavlyk E.M., dmach10, robert gagliano, rob, ixiharri54ixi, Blackprojects, farfaelia, nilium, benj82, marek kaluzny

« Last Edit: April 22, 2011, 08:25:42 pm by robert gagliano »

robert gagliano

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Re: SUPERNOVA OF THE DAY - PTF 11bui
« Reply #12 on: May 13, 2011, 06:37:49 pm »
Name            RA                    DEC                Disc Date (UT)     Disc Mag (r)    Type    z      Phase(d)
     
PTF 11bui      13 12 56.40     +47 27 12.5       Apr 11.50            18.6                  Ia        0.02846    -14

ATel   #3348  http://www.astronomerstelegram.org/?read=3348

SDSS DR7      http://cas.sdss.org/astro/en/tools/explore/obj.asp?id=588298664114520158&spec=411462841879494656

NED               http://nedwww.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=PGC045903&extend=no&hconst=73&omegam=0.27&omegav=0.73&corr_z=1&out_csys=Equatorial&out_equinox=J2000.0&obj_sort=RA+or+Longitude&of=pre_text&zv_breaker=30000.0&list_limit=5&img_stamp=YES

Simbad    http://simbad.u-strasbg.fr/simbad/sim-id?Ident=PGC045903&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id

Aladin      http://aladin.u-strasbg.fr/java/alapre.pl?-c=13+12+56.682%2B47+27+24.06&ident=MCG%2B08-24-089&submit=Aladin+previewer

Discoverers: robert gagliano, graham d, chrostek, nilium, andsul, Jose Campos, ttfnrob, HelmutU, x303, bentemming

         

     

     
« Last Edit: May 13, 2011, 08:32:26 pm by robert gagliano »

robert gagliano

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Re: SUPERNOVA OF THE DAY - PTF 10xgx
« Reply #13 on: May 31, 2011, 09:23:22 pm »
A rare and important discovery! A Super-Chandrasekhar Type Ia Supernova!

http://www.galaxyzooforum.org/index.php?topic=278391.0#msg547799


« Last Edit: July 01, 2011, 01:03:05 pm by robert gagliano »

robert gagliano

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Re: SUPERNOVA OF THE DAY - PTF 10weh
« Reply #14 on: June 02, 2011, 01:00:22 pm »
A type IIn supernova.

http://www.astronomerstelegram.org/?read=2961

http://en.wikipedia.org/wiki/Type_II_supernova#Type_IIn_supernovae

Discoverers: OLH, nilium, ashkantar, chrostek, marek kaluzny, Bohne2k7, aspringer, vea122

« Last Edit: July 01, 2011, 01:03:25 pm by robert gagliano »