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LPV Humps

LPV Humps

I can often be found, most evenings in the AAVSO chat room. If you want to chat about this project or any other facets of variable stars please stop by any evening and talk with the people on chat! https://www.aavso.org/chat

  • SFRA Frank Schorr - fschorr at comcast dot net
  • Special thanks to MDW Walter MacDonald
  • Special thanks to Neil Butterworth

Introduction:

I started this project for the learning experience and to delve deeper into the aspects of the  "humps" on light curves of various LPVs I noticed while observing.  At this point this is not a "scientific" project but a project to create a list or "catalog" and gather more information on LPVs that show this particular type of behavior to see if there is a reason to start a scientific "project" to discover more about this type of behavior.  I hope to collect data that might be helpful to a researcher. These "humps" or "bumps" seem to mostly appear on the rising portion of LPV's light curve as seen in the light curve of the 900 day light curve of RU HER above.  A "hump" is a spot on the light curve where the slope of the curve is altered to make it look like the brightening (or dimming) of the LPV "stalls" for a period of time sometimes also called "stalling" or a "shoulder".

On some of these stars the brightness (or dimness) reverses direction giving the impression of an early maxima or even a double maxima for that cycle.  This may or may not be related to the "double" or "dual" maxima behavior of some "LPV" stars.

At this time I am focusing my energies on my favorite target S ORI and any of the "hump" LPVs that can give me data for it's full cycle such as T Cas, W Cas, S Cas, T Cam, R Aur, V Cam, R Lyn, T Umi, WZ Dra, ST Cyg, T Cep, S Cep and CT Laq. I would argue that perhaps the most interesting parts of the light curve for these stars are at the maxima at the beginning of the LC (light curve) cycle, the part of the LC leading into the start of the "hump" event, the time of the "hump" event itself, and the LC as the "hump" event ends. At this time I would think one observation a day is the proper cadence of observations to be able to gather the most useful information.

3/16/2016 Just finishing up a very detailed @250 day look at the latest "hump/stall" event for S Ori which included images from 7 AAVSONET telescopes and data from my own observatory.  I did a number of "time series" studies at various points in the ascending light curve at the times the "hump" started and ended.  Hopefully I can get an article started soon talking about my experiences.

One of the most exciting things I've read recently is a massive project done by Tomas Karlsson (KTHA) that provides detailed O-C diagrams for hundreds of Mira LPVs.  This remarkable effort can be viewed at http://var.astronet.se/mirainfooc.php.  He also provides major information for the "period length over time" for this same set of Mira stars. This data is available at http://var.astronet.se/mirainfoper.php Along with this other data he provides the mean light curves for this same set of Mira LPVs. These mean light curves are particularly exciting for me as they seem to show "the humps" on the mean light curves for many of the Mira LPVs shown.  This may mean that Tomas's data might be able to be used to show which Mira LPVs currently show this hump behavior.  This exciting data can be viewed online at http://var.astronet.se/mirainfomax.php.

Classification attempt

In N. D. Melikian's paper, "Classification of the Light Curves of Mira Variables" (Astrophysics, Vol. 42, No. 4, 1999), Melikian puts forth arguments to classify the light curves of Mira variables based on the "shape" of their light curves.  Mira stars that have a purely sinusoidal shapes would be "simple" light curves and Mira stars that have very complicated light curves, often with "hump" on the ascending (or decending) light curve including potential dual maxima.

  • The period-spectrum correlation for the "complicated Mira" stars is weak or non-existant.
  • The period distribution of stars with the 'complex' light curves the maximum in the period distribution was
         350-400 days while just 250-300 days for the Miras with 'simple' light curves.
  • Absolute bolometric magnitudes tended to be higher in the Miras with 'complex' light curves
  • According to Melikian, polarimetric observations of a group of Mira variables that contained both 'simple' and
         'complex' light curves,  50% of the 'complex' light curve stars found polarization which was over twice as much
         of the Miras with 'simple' light curves.

He felt there was a real difference in the light curves based on the shape of their light curves.

Some astronomers have said that all MIRAs have "humps" at one time or the other.  Perhaps this happens at different times as they grow older?

Measurement attempt

A paper published in Astrophysics, Vol. 50, No. 1, 2007, titled  "VARIABILITY OF LONG-PERIOD PULSATING STARS. III. CHANGES IN THE PARAMETERS OF HUMPS AT THE ASCENDING BRANCH" by V. I. Marsakova and I. L. Andronovmay have answered a lot of the questions I have concerning the "humps".  The paper can be found at http://www.springerlink.com/content/q82910824434n110/.  Thanks to James Bedient for this information.

There are two more papers in this series that talks about the methods used to produce the data in the above paper:

     Variability of long-period pulsating stars. I. Methods for analyzing observations
       http://www.springerlink.com/content/n611125846588r70/

     Variability of long-period pulsating stars. II. Additional parameters for classifying stars 
       http:www.springerlink.com/y03752753h358375

I may use a subset of the measurements mentioned in these three papers.

My project

Discovery/Identification:

  • I sampled the light curves for about 450 LPVs using data for the last 15 years from the AAVSO
    International database and the ASAS1, ASAS2 and ASAS3 databases and visually inspected their
  • light curves.
  • So far 77 LPVs that appears to have "hump" events - please see Table 1 below
  • 5 or so possible candidates - Please see Table 2

Table 1:

List of 77 LPVs that show distinct "humps" and/or double maximas since 2000 (or earlier). 

Please click on the star name to see a light curve for that star and possible other data if available.  

 
 RA (J2000.0)  DEC (J2000.0)  Star   Event type  Cycle Period  Spectrum  N d (4)  Type Source  Next Event (JD)  Next Event Calendar  Comments
 00 02 7  -14 40 33.1  W-CET  Hump on RLC  352  S6,3e-S9,2e      SFRA      
 00 15 22  -32 02 43  S-SCL  Hump on RLC  367  M3e-M9e(Tc)      SFRA      
 00 23 13  +55 47 33.2  T-CAS  Dual Maxima?      2.61    T. Lange     Study Star

 

 00 24 04  -09 36 20  S-CET  Hump on RLC  320.45  M3e-M6.5e      SFRA      
 00 54 54  +58 33 49.2  W-CAS  Hump on RLC  405.50  C7,1e  .47    SFRA     Study Star
 01 19 42  +72 36 40.7   S-CAS  Hump on RLC  612.4  S3,4e-S5,8e  .59    SFRA     Study Star
 01 29 42  +50 51 24 RZ-PER  Hump on RLC  355  S4,9e      SFRA      
 02 29 16  -26 05 55.7   R-FOR  Hump on RLC  388.7  C4,3e(Ne)  1.21    SFRA      
 04 33 33  -63 01 45.0  R-RET  Hump on RLC  278.6  M4e-M7.5e  .57    SFRA      
 04 40 09  +66 08 49  T-CAM  Hump and DM?  373.2  S4,7e-S8.5,8e  .61          Study Star
 04 40 30  -38 14 07  R-CAE  Hump on RLC  391  M6e  1.11    SFRA      
 05 04 51  -21 54 17  T-LEP  Hump on RLC  372  M6e-M9e      SFRA      
 05 17 18  +53 35 10  R-AUR  Hump on RLC  458  M6.5e-M9.5e  1.71         Study Star
 05 18 20  -16 21 7  X-LEP  Hump on RLC  279  M7e      SFRA      
 05 29 01  -04 41 33   S-ORI  Hump on RLC  @420  M6.5e-M9.5e  3.81m  D  SFRA     Study Star 
 05 40 08  +37 38 11  RU-AUR  Hump on RLC  466.47  M7e-M9e  1.21    MDW      
 05 41 57   +38 55 55.8  SZ-AUR  Hump on RLC  457.5  M6.5e-M9.5e  1.08  D        
 05 52 37  +15 58 14.4  RU-TAU  Hump on RLC  544.6  M3.5e-M6.5  3.52  D?  SFRA     Study Star 
 05 55 49  +20 10 30.7  U-ORI  Hump on RLC  368.3  M6e-M9e  .33    SFRA      
 06 02 32  +74 30 27.2  V-CAM  Hump on RLC    M7e  .28    SFRA     Study Star
 06 17 53  -00 20 33.5  S-SEX  Moving Hump?  264.9  M2e-M5e  2.85    SFRA      
 06 26 43   +47 14 24  GQ-AUR  Hump on RLC  304.8   M3  .87  S   MDW      
 07 01 18  +55 19 50  R-LYN  Hump on RLC  378.8  S2.5,5e-S6,8e  3.53    SFRA     Study Star
 07 05 36  -73 00 52  R-VOL  Hump on RLC  453.6   C(N)e  .54    SFRA      
 07 16 34  +25 59 43  WZ-GEM  Hump on RLC  333  M3e  2.83          
 07 29 46  -73 22 44  S-VOL  Hump on RLC  394.8  M4e  1.09    SFRA      
 07 32 38  -20 39 29  Z-PUP  Hump on RLC  516  M4e-M9e  1.22          
 07 41 20  +08 22 49  u-cmi  Hump on RLC  413.9  M4e      MDW      
 09 44 59  -24 01 16  RR-HYA  Hump on RLC  343.5  M3.0e-M8e  .65    SFRA      
 09 52 54   -54 10 48  Z-VEL  Hump on RLC  411.4  M9e  .17    SFRA      
 10 13 53  -59 01 12  AF-CAR  Hump on RLC  448  M8-M9e      SFRA      
 10 24 25  -60 11 29  CK-CAR  Dual Maxima  266  M3.5lab             
 10 51 19  -28 3 41  RS-HYA  Hump on RLC  338.6  M6e  2.86          
 10 52 06  -62 28 59.6  BX-CAR  Dual Maxima  427  M7e            
 12 16 17  -56 17 10  BH-CRU  Hump on RLC  530  SC4.5/8-e- SC7/8-e  6.09    BIW      "Dual-Maxima Mira project" star
 13 19 35  -60 46 46  TT-CEN  Hump on RLC  462  CSe            "Dual-Maxima Mira project" star
 13 29 43  -23 16 53  R-HYA  Hump on RLC   388.9  M6e-M9eS (Tc)  8.01    SFRA     "Dual-Maxima Mira project" star
 13 34 41  +73 25 53  T-UMI  Hump on RLC  301  M4e-M6e  23.90    G. Foster     Study Star
 13 37 36  -56 28 35  RV-CEN  Hump on RLC  457  Ce      SFRA      
14 16 34  -59 54 49  R-CEN  Moving Hump?  546.2  M4e-M8iie  8.63    SFRA      "Dual-Maxima Mira project" star
 15 17 15  +36 21 33  RT-BOO  Hump on RLC  275  M6.5e-M8e  1.16    JAAVSO V33 page 52      Possible DM
15 21 40   +14 18 53  S-SER  Hump on RLC  371.8  M5e-M6e  1.59    SFRA      
15 29 35   +78 38 00  S-UMI  Hump on RLC  331  M6e-M9e      GZN      
 15 36 13  -21 09 4  X-LIB  Hump on RLC  164.38  M4e      SFRA    

 Possible DM

 15 35 57  -49 30 29  R-NOR  Double Maxima  507.5  M3e-M6ii  2.89    M. Templeton      "Dual-Maxima Mira project" star
 16 10 15  +25 04 14  RU-HER  Hump on RLC   484.3  M6e-M9  .89  D  SFRA     Study Star
 16 51 54  +14 56 31  S-HER  Hump on RLC  307.3  M4,Se-M7.5,Se  .75    R. Huziak      
 16 59 50  +52 19 04  WZ-DRA  Hump on RLC  401.7  M6e           Study Star
 17 10 35  +83 50 28  Y-UMI  DM?  293  ?      RGN     Possible Dual-Maxima
 17 42 25  -43 45 01  RU-SCO  Hump on RLC  370.8  M4/6e-M7ii-iiie  3.70    SFRA      
 17 54 11  -34 20 27  BN-SCO  Hump on RLC  616  ?            "Dual-Maxima Mira project" star
 18 28 49  +06 17 53  T-SER  Hump on RLC  338.1  M7e  .19    SFRA      
 18 44 52  +34 40 33  RY-LYR  Hump on RLC    325.8  .15    SFRA      
 19 19 01  +67 16 37  U-DRA  Hump on RLC    316.1  .15    GZN      
 19 13 20  +32 03 18  EL-LYR  Hump on RLC  234    2.81          
 19 13 55  -18 51 42  RX-SGR  Hump on RLC  335.2  M5e  .87    SFRA      
 19 19 52  -31 42 54  SW-SGR  Hump on RLC   289.9  M5e-M8  1.19    SFRA      
 19 50 34  +32 54 51  CHI-CYG  Hump on RLC  408  S6,2e-S10,4e(MSe)  .63    R. Huziak      
 20 49 01  +31 50 56  AM-CYG  Hump on RLC  370.6  M6e            
 20 05 30  +57 59 09  S-CYG    322.9  S2.5.1e (M3.5-M7e)  1.39    R. Huziak     No event for a number of cycles
 20 13 24  +38 43 45  RS-CYG  DM?  417  C8,2e(N0pe)      SFRA      
 20 14 45  -46 58 55  R-TEL  Hump on RLC  467  M5iie-M7e      SFRA      
 20 15 34  +31 04 20  SX CYG  Hump on RLC  411  M7e  .08    SFRA      
  20 32 33  +54 57 01  ST-CYG  Hump on RLC  337.3  M5.5e-M8.0e  .23     R. Huziak     Study Star
  20 38 52  +37 53 23  FF-CYG  Hump on RLC  323.8  S6,8e(M4e)       SSIM      
  21 09 32  +68 29 27  T-CEP  Hump on RLC  388.1  M5.5e-M8.8e 1.47 m         Study Star
 21 35 13  +78 37 28  S-CEP  Moving Hump?  486.8  C7,4e(N8e)  1.01    Marsakova     Study Star
 22 07 30  +37 44 07  W-LAC  Hump on RLC  328.5  M7e-M8e 3.28  S  SFRA      
 22 08 54  +12 32 25  T-PEG  Hump on RLC  379.4  M6e-M8e  1.73    SFRA      
 22 12 16  +14 33 12  RS-PEG  Hump on RLC  415.4  M6e-M9e  3.40    SFRA      
 22 23 13  -22 03 24  RT-AQR  Moving Hump?  252.2  M5e-M6e  .39    SFRA      
 22 25 41  -37 34 09  T-GRU  DM?  136.5  M1iae-M2ibe  .53    SFRA      
 22 57 06   -20 20 36  S-AQR  Hump on RLC  279.3  M4e-M6e  1.47    SFRA      
 23 06 39  +10 32 36  R-PEG  Hump on RLC  378.1  M6e-M9e  .91    SFRA      
 23 19 51  +26 16 44  W-PEG  Hump on RLC  345.5  M6e-M8e  .54    SFRA      
 23 20 33  +08 55 08  S-PEG  Hump on RLC  319.2  M5e-M8.5e  .70    SFRA      
 23 56 28  -49 47 13  R-PHE  Hump on RLC  269.3  M2(ii)e- M4(iii)e  .99    SFRA      
                       
                       
 

Table 2
Below is a table of LPV hump stars candidates and other "Dual-Maxima" project stars.

 COORDS    STAR  Type  N d (4)
 
 Curve  Source  Status
 0051+34    RR AND   Asc  .34    RR-AND  MDW  
 2105+29    TW CYG  Asc  2.37    TW-CYG  SFRA  *
 2122+21    SW PEG  Asc.      SW-PEG    
     U UMI  Asc  2.21        
    PQ CEP         Michael Poxon  possible
     S-SCO            
 Other Dual-Maxima Sturdy stars                
     CT LAC         Templeton et al  Dual Maxima Study Star
     R AQR  Dbl Max           "Dual-Maxima Mira project" star
 1003-46    V415 VEL            SRA - "Dual-Maxima Mira project" star
 1053-61    CL CAR  Unstable      CL-CAR    SRC - Unstable light curve -  "Dual-Maxima Mira project" star
     UZ CIR  Dbl Max           "Dual-Maxima Mira project" star
     FK PUP  Dbl Max           SR - "Dual-Maxima Mira project" star
 Lacking Data                
 1305-26    KN HYA  Asc & Desc      kn-hya   SR -  Ascending & descending

Classification/Description:

Some ideas:
  
- Accurately measure the time from the Maxima at the beginning of the cycle to the Maxima at the 
end of the cycle for each LPV that shows hump event.  Accurately measure each period for that LPVs 
for all cycles (get the period of the cycle).  If a particular cycle does not have a "hump" in it compare 
it's period to the period of a cycle with a "hump" event to see if this affects the cycle period.
R
- Measure the time from the Maxima at the beginning of the cycle to the beginning of "hump" event to 
understand how far into each cycle the "hump" event starts and the relationship of the start of the event 
from the beginning Maxima to the length of the overall cycle.  Compare this value between cycles for 
the same LPV

- Measure the time from the beginning of the hump to the end of the hump.  Compare how the length
     of the "hump" event changes between cycles.

- Calculate the length of the "hump" event compared to the length of the period of the cycle the hump
     occurs in to see if there is a relationship.

- Calculate the length of the "hump" events between cycles to see if there is a period to the "length".

- Calculate the length of time from the beginning or one "hump" event to the beginning of the next 
     "hump" event to see if there any hidden periods in the "hump" events.

- Any other suggestions?

References and articles

Good article on Humps and Bumps: Templeton poster

Mattei, Mayall and Waagen, "Maxima and Minima of Long Period Stars, 1949-1975", AAVSO 

 

M.R Templeton, J.A. Mattei and L.A. Willson, "Secular Evolution in MIRA Variable Pulsations",

The Astronomical Journal, 130:776-778, 2005 August

Footnotes

Note 1 - "Fast Variations of the Mean Brightness and Other Light Curve Parameters of the Carbon
Mira-Type Star S CEP", JAAVSO Volume 27, Number 2, 1999, Pages 141-145, Vladislova I.
Marsakova. He describes in detail the "hump" on the ascending curve that this star showed for
about a half of it's studied cycles. He also reports two cycles in a rows between JD 2428250 and
242950 where the light curve becomes unstable with an almost Double Maxima look on the second cycle.

Note 2 - JAAVSO Volume 25, Number 2, 1997, page 58

Note 3 - N.D. Melikian, Astrophysics, Vol. 42, No. 4, 1999, pages 408-418 - Melikian did a study of
223 Miras with light curve information from the HIPPARCOS space telescope. No list of the stars studied
is supplied.

 

 

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